Rapid changes in plasma corticosterone and medial amygdala transcriptome profiles during social status change reveal molecular pathways associated with a major life history transition in mouse dominance hierarchies

Plasma glucocorticoid levels across vertebrates are higher in dominant animals during periods of particularly intense competitive interactions between dominant animals such as during high reproductive competition or food shortage.

“studies that have demonstrated that plasma glucocorticoid levels across vertebrates are higher in dominant animals during periods of particularly intense competitive interactions between dominant animals such as during high reproductive competition or food shortage [7,38–43].”

• cites [7] TM Milewski, 2022, Behavioural and physiological plasticity in social hierarchies. Philosophical Transactions of the Royal Society B, Biological Sciences sourceNot checked — no full text of the source
• cites [38] JC Beehner, 2017, The next step for stress research in primates: To identify relationships between glucocorticoid secretion and fitness, Hormones and Behavior sourceNot checked — no full text of the source
• cites [39] SA Cavigelli, 2015, Sex, social status and physiological stress in primates: the importance of social and glucocorticoid dynamics. Philosophical Transactions of the Royal Society B, Biological Sciences sourcePartly supported

  Section 2 reports that dominant male primates often produce as much or more glucocorticoids than subordinates, particularly during social instability, but it also describes an opposite pattern in females and substantial exceptions. The paper does not establish the claimed pattern across vertebrates or specifically for plasma levels during reproductive competition or food shortage; its discussion of acute elevations during competition is partly predictive. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [40] HE Fox, 1997, Stress and Dominance in a Social Fish, J Neurosci sourcePartly supported

  The Discussion (page not available) acknowledges that some species have higher basal glucocorticoid levels in dominant animals. It does not link that pattern to intense competition, reproductive competition, or food shortage. In the fish studied here, dominant and subordinate males had similar cortisol levels during early social instability, and dominant males had lower levels as the hierarchy stabilized. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [41] SM Maguire, 2021, Social network dynamics predict hormone levels and behavior in a highly social cichlid fish, Hormones and Behavior sourceDisputed

  In the Results (section 3.3; page unavailable), dominant male cichlids had significantly lower cortisol than subordinate males, and cortisol was not related to aggressive behavior. The paper does not establish the claim’s specific conditions of intense reproductive competition or food shortage, but its reported dominance–cortisol finding runs in the opposite direction. (LLM, conf=0.78)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured
• cites [42] RM Sapolsky, 1993 sourceNot checked — no full text of the source
• cites [43] JC Wingfield, 1990, The “Challenge Hypothesis”: Theoretical Implications for Patterns of Testosterone Secretion, Mating Systems, and Breeding Strategies., The American Naturalist sourceNot checked — no full text of the source

Transitions in social rank are associated with significant modifications to individual behavior and physiology.

“Such transitions in social rank are associated with significant modifications to individual behavior and physiology [4–8].”

• cites [4] MF Dwortz, 2022, Neural systems that facilitate the representation of social rank, Philos Trans R Soc Lond B Biol Sci sourcePartly supported

  The section on amygdala circuits and social subordination (page unavailable) reports rank-related differences in social vigilance and stress hormones, as well as increased CRF release after social defeat in mice. These examples support associations between rank, behavior, and physiology, but the paper does not establish that transitions in rank themselves produce significant changes in both. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [5] CN Friesen, 2022, Social status mediates behavioral, endocrine, and neural responses to an intruder challenge in a social cichlid, Astatotilapia burtoni., Hormones and Behavior sourceNot checked — no full text of the source
• cites [6] KP Maruska, 2022, Endocrine and neuroendocrine regulation of social status in cichlid fishes, Hormones and Behavior sourceNot checked — no full text of the source
• cites [7] TM Milewski, 2022, Behavioural and physiological plasticity in social hierarchies. Philosophical Transactions of the Royal Society B, Biological Sciences sourceNot checked — no full text of the source
• cites [8] N Snyder-Mackler, 2016, Social status alters immune regulation and response to infection in macaques, Science sourceSupported

Animals will readily reorganize themselves into stable social hierarchies when placed into novel social groups.

“Our findings are also broadly consistent with studies in Burton’s mouthbrooder cichlid, A. burtoni [5,16,33], monk parakeets, Myiopsitta monachus [34], and rhesus macaques, M. mulatta, [8], which all demonstrate that animals will readily reorganize themselves into stable social hierarchies when placed into novel social groups.”

• cites [5] CN Friesen, 2022, Social status mediates behavioral, endocrine, and neural responses to an intruder challenge in a social cichlid, Astatotilapia burtoni., Hormones and Behavior sourceNot checked — no full text of the source
• cites [16] KP Maruska, 2015, Social Transitions Cause Rapid Behavioral and Neuroendocrine Changes., Integrative and Comparative Biology sourcePartly supported

  The Introduction (page not provided) says A. burtoni males form dominance hierarchies and can change rank when a territory becomes available. The experimental-paradigm section describes giving subordinate males an opportunity to ascend by removing a resident dominant male. These passages support rapid changes in rank, but do not show that animals placed into novel social groups readily form stable hierarchies. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [33] ID Chase, 2002, Individual differences versus social dynamics in the formation of animal dominance hierarchies, Proc Natl Acad Sci U S A sourceNot checked — no full text of the source
• cites [34] EA Hobson, 2015, Social Feedback and the Emergence of Rank in Animal Society., PLOS Computational Biology sourceSupported
• cites [8] N Snyder-Mackler, 2016, Social status alters immune regulation and response to infection in macaques, Science sourceSupported

Transcriptional remodeling of the MeA occurs during social status transitions.

“Further, our findings also support a role for transcriptional remodeling of the MeA occurring during social status transitions as has been suggested by immediate early gene studies of social ascending and descending A. burtoni cichlids [11] as well as socially defeated rats, Rattus norvegicus [46] and Syrian hamsters, Mesocricetus auratus [47].”

• cites [11] KP Maruska, 2013, Social Regulation of Male Reproductive Plasticity in an African Cichlid Fish., Integr Comp Biol sourcePartly supported

  The brain and GnRH1-neuron section and Fig. 2 report increased immediate-early-gene mRNA in socially relevant brain regions after male A. burtoni ascend in status, supporting the suggestion of transcriptional change during ascent. The cited paper does not identify the MeA as an affected region or establish the same response during descent; those parts of the attributed claim are unsupported. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [46] ÉM Fekete, 2009, Social defeat stress activates medial amygdala cells that express type 2 corticotropin-releasing factor receptor mRNA, Neuroscience sourceNot checked — no full text of the source
• cites [47] KE Morrison, 2014, Maintenance of dominance status is necessary for resistance to social defeat stress in Syrian hamsters, Behavioural Brain Research sourcePartly supported

  The Results (§3.4) report that defeat-induced c-Fos immunoreactivity in the vMeA differed by social status after 14 days, supporting the citing sentence’s reference to an immediate-early-gene study in Syrian hamsters. The paper measured c-Fos-positive cells after defeat, however; it did not directly measure transcriptional remodeling during a transition from one social status to another. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

Over-expression of Crym is associated with increased transcriptional plasticity of the MeA.

“Importantly, over-expression of Crym is associated with increased transcriptional plasticity of the MeA.”

• cites [77] DM Walker, 2022, Crystallin Mu in Medial Amygdala Mediates the Effect of Social Experience on Cocaine Seeking in Males but Not in Females, Biological Psychiatry sourcePartly supported

  The Results section, “Crym overexpression in adult meA mimics transcriptional effects of adolescent SI” (page unavailable), reports that Crym overexpression changes gene expression in the medial amygdala, with more differentially expressed genes in males than females. This supports an effect on transcription, but not an unqualified increase in transcriptional plasticity across the medial amygdala in both sexes. (LLM, conf=0.78)

  Experimental — accuracy not yet measured

There were no significant differences between plasma corticosterone levels of animals assigned to the control (74.7 ng/ml [53.9, 100.0]) and reorganized (88.6 ng/ml [63.7, 124.0]) conditions.

“As expected, we found no significant differences between the plasma corticosterone levels of animals who were assigned to the control 74.7ng/ml [53.9, 100.0] and reorganized 88.6ng/ml [63.7, 124.0] conditions (S7A Fig).”

Increases in genes associated with synaptic plasticity, excitatory glutamatergic signaling, and learning and memory pathways were observed in transitioning animals.

“Further, increases in genes associated with synaptic plasticity, excitatory glutamatergic signaling and learning and memory pathways were observed in transitioning animals suggesting that these processes may support rapid social status changes.”

Beta males (rank 2) had David's Scores that were typically above 0 (median [IQR] = 0.88 [0.23, 1.49]).

“Beta males (rank 2) had David’s Scores that were typically above 0 (median[iqr] = 0.88[0.23,1.49]).”

Neither body mass nor David's Score in the pre-reorganization group significantly predicted David's Score in the new hierarchy within groups of all alphas, all betas, all gammas or all deltas.

“We found that neither body mass nor David’s Score in the pre-reorganization group significantly predicted David’s Score in the new hierarchy within groups of all alphas, all betas, all gammas or all deltas.”

Seventy minutes following social hierarchy formation, males that were socially dominant prior to being placed into new social hierarchies exhibit higher increases in plasma corticosterone compared to males who were socially subordinate prior to being placed into a new hierarchy.

“Seventy minutes following social hierarchy formation, males that were socially dominant prior to being placed into new social hierarchies exhibit higher increases in plasma corticosterone and vastly greater transcriptional changes in the medial amygdala (MeA), which is central to the regulation of social behavior, compared to males who were socially subordinate prior to being placed into a new”

Within 70 minutes of social reorganization, all 52 groups of equal-status male mice rapidly formed new linear social hierarchies.

“Within 70 minutes of social reorganization, all 52 groups of equal-status male mice rapidly formed new linear social hierarchies.”

Novel genes associated with social transition show common changes in expression when animals undergo either social descent or social ascent compared to maintaining their status.

“We also identify novel genes associated with social transition that show common changes in expression when animals undergo either social descent or social ascent compared to maintaining their status.”

All groups had higher plasma corticosterone levels 70 minutes post-reorganization compared to pre-reorganization (Ascenders t13 = 3.2, p = 0.007; Subordinates t13 = 4.5, p < 0.001; Descenders t13 = 5.7, p < 0.001; Dominants t6 = 4.6, p = 0.003).

“We found that all groups had higher plasma corticosterone levels 70 minutes post-reorganization compared to pre-reorganization (Ascenders t13 = 3.2, p = 0.007; Subordinates t13 = 4.5, p<0.001; Descenders t13 = 5.7, p<0.001; Dominants t6 = 4.6, p = 0.003) (Fig 2D).”

Body mass on day 7/8 during group housing was not significantly associated with David's Scores (β = 0.11 ± 0.07, p = 0.106).

“Accordingly, body mass on day 7/8 during group housing was not significantly associated with David’s Scores (β = 0.11±0.07, p = 0.106).”

Groups of previously alpha and beta males were significantly faster to start fighting than cages of previously gamma or delta males, as determined by the latency to the first fight.

“Groups of previously alpha males and groups of previously beta males were significantly faster to start fighting than cages of previously gamma (alpha vs gamma β = -1.36±0.35, p<0.001; beta vs gamma β = -1.06±0.33, p<0.005) or delta (alpha vs. delta β = -1.35±0.35, p<0.001; beta vs delta β = -1.05±0.35, p<0.005) males as determined by the latency to the first fight (Fig 2C).”

Rates of aggression received prior to reorganization were positively associated with later David's Scores in groups of beta (β = 0.69 ± 0.26, p = 0.014), gamma (β = 0.29 ± 0.20, p = 0.144) and delta (β = 0.40 ± 0.22, p = 0.080) males.

“However, we did find that rates of aggression received prior to reorganization were positively associated with later David’s Scores in groups of beta (β = 0.69±0.26, p = 0.014), gamma (β = 0.29±0.20 p = 0.144) and delta (β = 0.40±0.22, p = 0.080) males (S6A Fig).”

All 65 groups of four male mice formed stable linear hierarchies with highly significant directional consistency (all p < 0.001) prior to any social reorganization.

“All 65 groups of four male mice formed stable linear hierarchies with highly significant directional consistency (all p <0.001) prior to any social reorganization.”

For groups comprised of betas (β = 0.20 ± 0.10, p = 0.047), gammas (β = 0.17 ± 0.08, p = 0.053) and deltas (β = 0.13 ± 0.09, p = 0.151), higher rates of aggression per group prior to reorganization were associated with an increased likelihood of becoming dominant.

“For groups comprised of betas (β = 0.20±0.10, p = 0.047), gammas (β = 0.17±0.08, p = 0.053) and deltas (β = 0.13±0.09, p = 0.151), we found that higher rates of aggression per group prior to reorganization were associated with an increased likelihood of becoming dominant, although this effect was only significant in previously beta males (S6B Fig).”

At 70 minutes post-reorganization, within all group types, all ranks had significantly different David's Scores from each other (post hoc tests: all p < 0.020).

“At 70 minutes, within all group types, all ranks had significantly different David’s Scores from each other (Fig 2B, post hoc tests: all p<0.020), confirming that new hierarchies emerged quickly.”

The largest differences in MeA gene expression were found when comparing animals that changed social status to those animals that were also socially reorganized but maintained their social status.

“The largest differences in gene expression were found when comparing animals that changed social status to those animals that were also socially reorganized but maintained their social status.”

Individual social rank had no overall effect on plasma corticosterone levels in stable hierarchies (alphas 87.3 ng/ml [71.0, 117], gammas 71.6 ng/ml [55.3, 108], deltas 82.4 [53.4, 128]).

“Individual social rank also had no overall effect on plasma corticosterone levels (S7B Fig; alphas 87.3 ng/ml [71.0,117], gammas 71.6 ng/ml [55.3,108], and deltas 82.4 [53.4,128]).”

Controls, which were placed into a new cage but not socially reorganized, had higher corticosterone at 70 minutes (Control t17 = 4.1, p < 0.001).

“Notably, controls, which were placed into a new cage to be consistent with all other groups, had higher corticosterone even though they were not socially reorganized (Control t17 = 4.1, p<0.001).”

Gaining social status in a new hierarchy (social ascent) is related to relatively few unique rapid changes in the MeA.

“Conversely, gaining social status in a new hierarchy (social ascent) is related to relatively few unique rapid changes in the MeA.”

Groups of previously alpha and beta males were significantly faster to engage in the first 8 agonistic behaviors compared to groups of previously gammas and deltas.

“Groups of previously alpha and beta males were significantly faster to engage in the first 8 agonistic behaviors compared to groups of previously gammas and deltas.”

Seventy minutes following social hierarchy formation, males that were socially dominant prior to being placed into new social hierarchies exhibit vastly greater transcriptional changes in the medial amygdala compared to males who were socially subordinate prior to being placed into a new hierarchy.

“Seventy minutes following social hierarchy formation, males that were socially dominant prior to being placed into new social hierarchies exhibit higher increases in plasma corticosterone and vastly greater transcriptional changes in the medial amygdala (MeA), which is central to the regulation of social behavior, compared to males who were socially subordinate prior to being placed into a new”

All alpha males (rank 1) had positive David's Scores.

“All alpha males (rank 1) had positive David’s Scores.”

Two genes, Mybpc1 and Crym, associated with VIP and thyroid hormone pathways respectively, are highly upregulated in socially transitioning individuals.

“Two genes, Myosin binding protein C1 (Mybpc1) and μ-Crystallin (Crym), associated with vasoactive intestinal polypeptide (VIP) and thyroid hormone pathways respectively, are highly upregulated in socially transitioning individuals.”

At 25 hours after social reorganization, there were no differences in plasma corticosterone compared to pre-reorganization levels for any group.

“At 25 hours after social reorganization, we observed no differences in plasma corticosterone compared to pre-reorganization levels for any group.”

Maintaining high social status is associated with high expression of genes related to cholinergic signaling in the MeA.

“Maintaining high social status is associated with high expression of genes related to cholinergic signaling in the MeA.”

Regardless of social condition, all animals that attained rank 1 after 70 minutes continued to possess the highest David's Score on day 2.

“Regardless of social condition, all animals that attained rank 1 (alpha males) after 70 minutes continued to possess the highest David’s Score on day 2 indicating that the alpha position was highly robust.”

Loss of social status in a new hierarchy (social descent) is associated with reductions in MeA expression of myelination and oligodendrocyte differentiation genes.

“Specifically, the loss of social status in a new hierarchy (social descent) is associated with reductions in MeA expression of myelination and oligodendrocyte differentiation genes.”

The sum of differences in post-reorganization ranks among animals from the same pre-reorganization group was significantly lower than a theoretical distribution of differences from random samples (p < 0.001).

“We found that the sum of all these differences was significantly lower than a theoretical distribution of differences from random samples (S6C Fig, p<0.001).”

Animals that were previously alpha males showed larger increases in corticosterone during reorganization compared to controls, regardless of whether they maintained their status (dominants β = 177.13 ± 48.87, p < 0.001) or lost their status (descenders β = 138.10 ± 39.67, p < 0.001).

“We found that animals that were previously alpha males showed larger increases in corticosterone during reorganization compared to controls, regardless of whether they maintained their status (dominants– β = 177.13 ± 48.87, p<0.001) or lost their status (descenders - β = 138.10 ± 39.67, p<0.001).”

Mice of all social ranks rapidly establish new stable social hierarchies when placed in novel social groups with animals of equivalent social status.

“We show that mice of all social ranks rapidly establish new stable social hierarchies when placed in novel social groups with animals of equivalent social status.”

64 out of 65 gamma (rank 3) males had David's Scores below 0 (median [IQR] = -1.87 [-2.42, -1.33]).

“64 out of 65 gamma (rank 3) males had David’s Scores below 0 (median[iqr] = -1.87[-2.42,-1.33]).”

Beta males had significantly more total fights in the 70 minutes following social reorganization than previously alpha, gamma, or delta males.

“beta males (median[iqr] = 37[29, 43]) had significantly more (vs alphas β = 0.26±0.07, p<0.001; vs gammas β = 0.37±0.07, p<0.001; vs deltas β = 0.27±0.07, p<0.001).”

All reorganized groups showed highly significant directional consistency (p < 0.001).

“All groups showed highly significant directional consistency (p <0.001).”

Concordance in the direction of gene expression changes between ascending and descending males was highly significant (Chi-Squared test: χ2 = 222.03, p<0.001, Φ = 0.89).

“This concordance in the direction of gene expression changes between ascending and descending males was highly significant (Chi-Squared test: χ2 = 222.03, p<0.001, Φ = 0.89).”

Five WGCNA modules (yellow, red, lightyellow, lightgreen, grey60) had lower deMEG expression in transitioning animals compared to both dominants and subordinates.

“Five modules (yellow TRN vs DOM β = 1.63 ± 0.25 p<0.001, TRN vs SUB β = 1.07 ± 0.25 p<0.001; red TRN vs DOM β = 1.31 ± 0.27 p<0.001, TRN vs SUB β = 1.44 ± 0.27 p<0.001; lightyellow TRN vs DOM β = 0.68 ± 0.2 p<0.001, TRN vs SUB β = 0.45 ± 0.2 p = 0.020; lightgreen TRN vs DOM β = 1.15 ± 0.33 p<0.001, TRN vs SUB β = 1.04 ± 0.33 p = 0.003; and grey60 TRN vs DOM β = 0.81 ± 0.28 p = 0.003, TRN vs SUB β”

• Also stated in: § Social descent and social ascent share transcriptomic signatures in the MeA · plain

  “had lower deMEG expression in transitioning animals compared to both dominants and subordinates (Fig 6).”

Only one of the yellow module hub genes, radixin (Rdx), also showed differential expression in ascenders compared to subordinates (log2FCdes-dom = 0.50, p<0.001; log2FCasc-sub = 0.31, p = 0.014).

“However, only one of the hub genes, radixin (Rdx) also showed differential expression in ascenders compared to subordinates (log2FCdes-dom = 0.50, p<0.001; log2FCasc-sub = 0.31, p = 0.014).”

The black module had higher deMEG expression in transitioning animals compared to dominants and subordinates.

“The black module had higher deMEG expression in transitioning animals compared to dominants and subordinates (Fig 6).”

Three WGCNA modules (brown, black, cyan) had higher deMEG expression in transitioning animals compared to both dominants and subordinates.

“Three modules (brown TRN vs DOM β = -1.37 ± 0.28 p<0.001, TRN vs SUB β = -1.36 ± 0.28 p<0.001; black TRN vs DOM β = -1.29 ± 0.25 p<0.001, TRN vs SUB β = -0.95 ± 0.25 p<0.001; and cyan TRN vs DOM β = -0.89 ± 0.31 p = 0.007, TRN vs SUB β = -1.04±0.31 p = 0.002) had higher deMEG expression in transitioning animals compared to both dominants and subordinates.”

Genes belonging to the brown module are involved in regulation of neurogenesis, synaptic plasticity, and membrane potential.

“GO-enrichment indicated that genes belonging to this module are involved in the regulation of neurogenesis, synaptic plasticity, and membrane potential.”

GO-enrichment analysis revealed that yellow module genes were largely involved in central nervous system myelination, axon ensheathment, and oligodendrocyte development.

“GO-enrichment analysis revealed that these genes were largely involved in central nervous system myelination, axon ensheathment, and oligodendrocyte development (Table T in S1 File).”

Previously subordinate and socially ascended (ASC) animals had 1,357 genes (9.6%) differentially expressed compared to subordinates that remained subordinate (SUB) in reorganized groups.

“whereas animals that were previously socially subordinate and socially ascended (ASC) had 1,357 genes (9.6%) that were differentially expressed compared to subordinates that remained subordinate in reorganized groups (SUB).”

Several myelination genes (e.g., Mal, Mag, Mog, Mobp, Cnp, Bcas1, and Lpar1) were significantly more highly expressed in animals maintaining dominant status after reorganization than control dominants.

“Moreover, several of these myelination genes were significantly more highly expressed in animals maintaining dominant status after reorganization than control dominants (e.g. Mal, Mag, Mog, Mobp, Cnp, Bcas1, and Lpar1)”

Socially descending animals had an over-representation of DEGs related to myelination, axon ensheathment, gliogenesis, glial cell, and oligodendrocytes differentiation.

“Most strikingly, we observed that socially descending animals had an over-representation of DEGs related to myelination, axon ensheathment, gliogenesis, glial cell, and oligodendrocytes differentiation.”

No module showed consistent differences between ascenders and both subordinate conditions.

“Indeed, no module showed consistent differences between ascenders and both subordinate conditions.”

Trhr expression was significantly higher in descending males than dominant males (log2FC=0.90, p=0.025).

“Descending males had significantly higher expression of thyroid hormone receptors a (Thra, log2FC = 0.29, p<0.001) and b (Thrb, log2FC = 0.58, p = 0.004), thyrotropin-releasing hormone receptor (Trhr, log2FC = 0.90, p = 0.025) and thyroid releasing hormone (Trh, log2FC = 1.75, p = 0.030) than dominant males.”

Several cholinergic genes (Lhx8, Slc18a3, Slc10a4, Slc5a7, Chrm2) are also significantly more highly expressed in the DOM vs CDOM comparison.

“Several of these genes (Lhx8 log2FC = 2.37, p = 0.033; Slc18a3 log2FC = 2.09, p = 0.012; Slc10a4 log2FC = 1.44, p = 0.048; Slc5a7 log2FC = 1.17, p = 0.030; Chrm2 log2FC = 1.02, p = 0.020) are also significantly more highly expressed in the DOM vs CDOM comparison.”

No genes showed discordant expression patterns between ascenders and descenders.

“No genes showed discordant expression patterns between ascenders and descenders, indicating that social transitions are significantly associated with concordant patterns of gene expression independent of the direction of the social status change (Chi-Squared test: χ2 = 4.30, p = 0.038, Φ = 0.73, Fig 5D).”

Genes in the cyan module are related to processing of ncRNAs and rRNAs, as well as rRNA and tRNA metabolic and mRNA catabolic processes.

“GO-enrichment identified that genes in the cyan module are related to processing of ncRNAs and rRNAs, as well as rRNA and tRNA metabolic and mRNA catabolic processes.”

Five other modules (salmon, brown, green, black, yellow) had significantly deMEGs when comparing descending animals to one of the other dominant groups.

“Five other modules (salmon, brown, green, black, yellow) had significantly deMEGs when comparing descending animals to one of the other dominant groups.”

Based on GO-enrichment analysis, pink module genes appear related to nervous system development, neurogenesis, synapse organization and negative regulation of kinase activity.

“Based on GO-enrichment analysis, genes in this module appear related to nervous system development, neurogenesis, synapse organization and negative regulation of kinase activity.”

7 out of the top 25 most differentially expressed genes in the DES vs DOM comparison were cholinergic signaling genes.

“Indeed, 7 out of the top 25 most differentially expressed genes in the DES vs DOM comparison were such genes.”

Reorganized subordinate animals do not show any substantial changes in expression of cholinergic related genes.

“Reorganized subordinate animals do not show any substantial changes in expression of cholinergic related genes”

Previously subordinate animals that maintained their status (SUB) or socially ascended (ASC) had about half the number of DEGs when compared to control subordinates (cSUB) that were not reorganized.

“Alternatively, previously subordinate animals that maintained their status (SUB) or socially ascended (ASC) had about half the number of DEGs when compared to control subordinates (cSUB) that were not reorganized (Table 1).”

There were many fewer IEGs differentially expressed between socially ascending animals (5.2%) and those that stayed subordinate (8.6%).

“However, there were many fewer IEGs differentially expressed between socially ascending animals (5.2%) and those that stayed subordinate (8.6%).”

Genes with higher expression in transitioning animals were more likely to be associated with regulation of synaptic organization and plasticity, hormone transport, and ion membrane transport.

“GO-enrichment indicated that genes that showed higher expression in transitioning animals were more likely to be associated with the regulation of synaptic organization and plasticity, hormone transport and ion membrane transport (Table O in S1 File).”

Descending animals had significantly increased deMEG expression compared to both dominant groups in the darkturquoise module (DES vs DOM β = -1.55 ± 0.40 p<0.001; DES vs CDOM β = -1.22 ± 0.42 p<0.001).

“Descending animals had significantly increased deMEG expression compared to both dominant groups in the darkturquoise module which consists of only 64 genes (DES vs DOM β = -1.55 ± 0.40 p<0.001; DES vs CDOM β = -1.22 ± 0.42 p<0.001, Fig 4B).”

Dominant males that maintained their dominance status (DOM) in new hierarchies had 1,609 DEGs compared to control dominants (CDOM).

“Dominant males that maintained their dominance status (DOM) in new hierarchies had 1,609 DEGs compared to control dominants (CDOM).”

Myelination genes Cnp, Bcas1, Mal, Mog, Mbp, Mob, and Lapr show lower expression in descending males compared to dominants.

“These include myelination genes: Cnp, Bcas1, Mal, Mog, Mbp, Mob, and Lapr that show lower expression in descending males compared to dominants.”

These new hierarchies were stable for at least 25 hours.

“These new hierarchies were stable for at least 25 hours.”

Vipr1 was relatively more highly expressed in ascenders compared to subordinates (ASC vs SUB: log2FC=0.87, p=0.023).

“Conversely, VIP receptor 1 (Vipr1) was relatively more highly expressed in ascenders compared to subordinates (ASC vs SUB: log2FC = 0.87, p = 0.023).”

The genes Bdnf, Cort, Egr2, Egr3, Egr4, Nr4a2, Fosb, and Junb were some of the most highly differentially expressed in socially descending animals.

“The genes Bdnf, Cort, Egr2, Egr3, Egr4, Nr4a2, Fosb, and Junb were some of the most highly differentially expressed in socially descending animals.”

GO-enrichment analysis indicated that orange module genes are related to mononuclear cell and lymphocyte differentiation.

“GO-enrichment analysis indicated that genes in this module are related to mononuclear cell and lymphocyte differentiation.”

Genes with lower expression in transitioning animals were associated with axonogenesis and regulation of catabolic processes.

“Genes that had lower expression in transitioning animals were associated with axonogenesis and the regulation of catabolic processes.”

GO-enrichment suggested that the black module contained genes related to histone modification, methylation, and peptidyl-lysine modification.

“GO-enrichment suggested that the black module contained genes related to histone modification, methylation, and peptidyl-lysine modification.”

Genes related to myelination production by oligodendrocytes with MM > 0.8 included several DEGs: Tspan2, Cnp, Plp1, Mobp, Mbp, Mog, Mag, Mal, Bcas1, Lpar1, Cntn2.

“Genes related to myelination production by oligodendroyctes with MM > 0.8 included several of those identified by our DEG analysis above, including Tspan2, Cnp, Plp1, Mobp, Mbp, Mog, Mag, Mal, Bcas1, Lpar1, Cntn2 (Fig 3A).”

Five genes (Car12, Unc13a, Lpl, Tesc, Pitpnm2) had higher expression in both ascenders and descenders compared to other groups.

“This comparison revealed far fewer genes, with five genes (Car12, Unc13a, Lpl, Tesc, Pitpnm2) having higher expression in both ascenders and descenders compared to other groups, and three genes (Rai2, Kif21a, Nap1l5) showing lower expression in both ascenders and descenders compared to other groups (Fig 5C).”

Three modules (darkturquoise, darkgreen, pink) had significantly differentially expressed module eigengenes (deMEGs) when comparing descending animals to both dominant groups (DOM and CDOM).

“Three modules (darkturquoise, darkgreen, pink) had significantly differentially expressed module eigengenes (deMEGs) when comparing descending animals to both dominant groups (DOM and CDOM).”

Three genes (Rai2, Kif21a, Nap1l5) showed lower expression in both ascenders and descenders compared to other groups.

“This comparison revealed far fewer genes, with five genes (Car12, Unc13a, Lpl, Tesc, Pitpnm2) having higher expression in both ascenders and descenders compared to other groups, and three genes (Rai2, Kif21a, Nap1l5) showing lower expression in both ascenders and descenders compared to other groups (Fig 5C).”

Dio3 expression was significantly higher in descenders than control dominants (DES vs CDOM: log2FC=1.86, p=0.017).

“Descenders also had significantly higher levels than control dominants of iodothyronine deiodinase 3 (DES vs CDOM: Dio3, log2FC = 1.86, p = 0.017), which encodes an enzyme that inactivates the production of circulating thyroid hormone.”

When considering log2 fold-changes greater than 1.5, socially descending animals had 3.4 times more DEGs than socially ascending animals when compared to animals that were reorganized but did not change ranks (51 vs 15; Binomial Test: p < 0.001).

“When considering log2 fold-changes greater than 1.5, socially descending animals had 3.4 times more DEGs than socially ascending animals when compared to animals that were reorganized but did not change ranks (51 genes in descenders vs. 15 genes in ascenders; Binomial Test: p<0.001) (Table 1).”

There was a great deal of concordance in the overlap in the expression of DEGs between reorganized and control males within each status.

“Strikingly, there was a great deal of concordance in the overlap in the expression of DEGs between reorganized and control males within each status (S1 Table).”

Both descending and dominant animals who experienced the disruption of social reorganization had significantly increased deMEG in the salmon module.

“Interestingly, both descending and dominant animals who experienced the disruption of social reorganization had significantly increased deMEG in the salmon module (Fig 4B).”

GO-enrichment analysis indicated that salmon module genes are involved in sugar and carbohydrate metabolic processes.

“GO-enrichment analysis indicated that these genes are involved in sugar and carbohydrate metabolic processes.”

Descenders and ascenders shared 279 DEGs out of the 3423 unique genes that were differentially expressed in either comparison.

“We found that the descenders and ascenders shared 279 DEGs out of the 3423 unique genes that were differentially expressed in either comparison (Fig 5 and S2 Table).”

Only one gene, Mt3 (Metallothionein-3), was upregulated in both reorganized dominant and subordinate males compared to controls.

“Interestingly, only one gene, Mt3 (Metallothionein-3) was upregulated in both reorganized dominant and subordinate males compared to controls.”

When considering log2 fold-changes > 0.2, animals that were previously dominant and socially descended (DES) had 2,255 (15.9% of all genes) differentially expressed genes compared to other alpha males that maintained their dominance (DOM) in reorganized groups.

“Notably, when considering log2 fold-changes > 0.2 (i.e. where there exists at least a 15% difference in mean gene expression between groups), animals that were previously dominant and socially descended (DES) had 2,255 (15.9% of all genes in our analysis) differentially expressed genes compared to other alpha males that maintained their dominance (DOM) in reorganized groups”

WGCNA analysis revealed 25 gene co-expression modules.

“This analysis revealed 25 gene co-expression modules (Fig 4A).”

Individuals maintaining subordinate status showed relatively higher expression of Ache, Chrm2, and Chrnb2 compared to socially ascending animals.

“those individuals maintaining subordinate status did show relatively higher expression of Ache (log2FC = 0.52, p = 0.041), Chrm2 (log2FC = 1.03, p = 0.034), and Chrnb2 (log2FC = 0.22, p = 0.017) compared to socially ascending animals.”

The proportion of shared DEGs between descenders and ascenders was significantly higher than expected by chance (Permutation Test: p = 0.000).

“Using a permutation analysis, this was a significantly higher proportion of shared DEGs than expected by chance (Permutation Test: p = 0.000).”

Comparing reorganized animals to control animals, animals that were previously dominant had more DEGs than those animals that were previously subordinate.

“Comparing reorganized animals to control animals, we also observed that animals that were previously dominant had more DEGs than those animals that were previously subordinate.”

Significantly more IEGs showed relatively higher expression in socially descending animals (23.3%) compared to animals that stay dominant (6.9%).

“we observed that significantly more of these genes showed relatively higher expression in socially descending animals (23.3% of IEGs) compared to animals that stay dominant (6.9%) (Binomial Test: p = 0.002)”

Fewer modules were differentially expressed between ascending and subordinate groups.

“Fewer modules were differentially expressed between ascending and subordinate groups (Fig 4).”

Only 14 out of 279 shared genes showed opposite patterns of expression change in individuals changing social status.

“Only 14 out of 279 genes showed opposite patterns of expression change in individuals changing social status.”

Mybpc1 had the largest fold change in both DES vs DOM and ASC vs SUB comparisons (DES vs DOM: log2FC=2.95, p=0.012; ASC vs SUB: log2FC=2.32, p=0.039).

“The gene with the largest fold change in both comparisons was myosin binding protein C1 (Mybpc1; DES vs DOM: log2FC = 2.95, p = 0.012; ASC vs SUB log2FC = 2.32, p = 0.039, Fig 5A).”

Both ascending and descending animals showed reduced deMEG expression in the pink module compared to controls.

“Strikingly, both ascending and descending animals showed reduced deMEG expression in the pink module compared to controls (Fig 4B).”

Compared to socially descending animals, the MeA of males that maintained dominant status in reorganized hierarchies had an over-representation of differentially expressed genes associated with cholinergic signaling.

“Compared to socially descending animals, the MeA of males that maintained dominant status in reorganized hierarchies had an over-representation of differentially expressed genes associated with cholinergic signaling.”

Only 1 hub gene in the black module was differentially expressed in ASC vs SUB animals (Gda log2FCdes-dom = 0.71, p = 0.004; log2FCasc-sub = 0.70, p = 0.039; MM = 0.82).

“Only 1 hub gene in this module was differentially expressed in ASC vs SUB animals (Gda log2FCdes-dom = 0.71, p = 0.004; log2FCasc-sub = 0.70, p = 0.039; MM = 0.82)”

Thrb expression was significantly higher in descending males than dominant males (log2FC=0.58, p=0.004).

“Descending males had significantly higher expression of thyroid hormone receptors a (Thra, log2FC = 0.29, p<0.001) and b (Thrb, log2FC = 0.58, p = 0.004), thyrotropin-releasing hormone receptor (Trhr, log2FC = 0.90, p = 0.025) and thyroid releasing hormone (Trh, log2FC = 1.75, p = 0.030) than dominant males.”

Several other genes related to thyroid hormone signaling were also differentially expressed.

“Several other genes related to thyroid hormone signaling were also differentially expressed (S11 Fig).”

• AssumptionRests on an assumption: Crym is a thyroid hormone binding protein.
• AssumptionRests on an assumption: Dio2 encodes an enzyme that converts the prohormone thyroxine (T4) to the active thyroid hormone 3,3’,5-triiodothyronine (T3).
• AssumptionRests on an assumption: Dio3 encodes an enzyme that inactivates the production of circulating thyroid hormone.

Descending animals had greatly reduced deMEG expression compared to rearranged dominants that maintained status in the yellow module (DES vs DOM β = 1.72 ± 0.38 p<0.001).

“Descending animals had greatly reduced deMEG expression compared to rearranged dominants that maintained status in the yellow module (DES vs DOM β = 1.72 ± 0.38 p<0.001, Fig 4B).”

Chrm2 and Ache are relatively less expressed in both ascending and descending animals.

“Two hub genes with MM > 0.9 of particular interest are those involved in cholinergic signaling, Chrm2 (log2FCdes-dom = -1.59, p<0.001, log2FCasc-sub = -1.03, p = 0.034) and Ache (log2FCdes-dom = 0.51, p = 0.015; log2FCasc-sub = 0.52, p = 0.041), which are relatively less expressed in both ascending and descending animals.”

Animals that maintained their subordinate status after reorganization had consistently higher deMEG expression compared to both ascenders and control subordinates in the orange module (SUB vs ASC β = 1.18 ± 0.42 p = 0.013; SUB vs CSUB β = 1.46 ± 0.44 p = 0.004).

“However, we did find that animals that maintained their subordinate status after reorganization had consistently higher deMEG expression compared to both ascenders and control subordinates in the orange module (SUB vs ASC β = 1.18 ± 0.42 p = 0.013; SUB vs CSUB β = 1.46 ± 0.44 p = 0.004).”

GO-enrichment analysis indicated myelination and axon ensheathment as biological processes associated with genes in the yellow module.

“GO-enrichment analysis indicated myelination and axon ensheathment as biological processes associated with genes in the yellow module (Fig 6).”

Dio2 expression was significantly higher in descending reorganized dominants compared to control dominants (DES vs CDOM: log2FC=1.22, p=0.002).

“Further, reorganized dominants that descended or stayed in the same rank had significantly higher expression of iodothyronine deiodinase 2 (Dio2) compared to control dominants (DES vs CDOM: log2FC = 1.22, p = 0.002, DOM vs CDOM: log2FC = 0.96, p = 0.030)”

New hierarchies were established within minutes after animals were socially reorganized and placed into new groups with novel conspecifics of equivalent rank.

“Further, when animals were socially reorganized and placed into new groups with novel conspecifics of equivalent rank, new hierarchies were established within minutes.”

Trhr expression was significantly higher in ascending males compared to reorganized males that remained subordinate (log2FC=0.96, p=0.019).

“Ascending males also had significantly higher expression of Trhr (log2FC = 0.96, p = 0.019) compared to reorganized males that remained subordinate.”

Many of these genes showed large fold changes (>0.75) in descending animals when compared to both animals maintaining dominant status and control dominants.

“Many of these genes showed large fold changes (>0.75) in descending animals when compared to both animals maintaining dominant status and control dominants.”

This was around 47% more DEGs than the 1,093 DEGs observed in dominant males who socially descended (DES) when compared to CDOMs (1,609 vs 1,093; Binomial Test: p < 0.001).

“This was around 47% more DEGs than the 1,093 DEGs observed in dominant males who socially descended (DES) when compared to CDOMs. (1,609 vs. 1,093 DEGs; Binomial Test: p<0.001).”

Thra expression was significantly higher in descending males than dominant males (log2FC=0.29, p<0.001).

“Descending males had significantly higher expression of thyroid hormone receptors a (Thra, log2FC = 0.29, p<0.001) and b (Thrb, log2FC = 0.58, p = 0.004), thyrotropin-releasing hormone receptor (Trhr, log2FC = 0.90, p = 0.025) and thyroid releasing hormone (Trh, log2FC = 1.75, p = 0.030) than dominant males.”

GO-enrichment analysis suggested that darkturquoise module genes were related to regulation of synapse organization and postsynaptic activity.

“GO-enrichment analysis suggested that these genes were related to regulation of synapse organization and postsynaptic activity.”

Trh expression was significantly higher in descending males than dominant males (log2FC=1.75, p=0.030).

“Descending males had significantly higher expression of thyroid hormone receptors a (Thra, log2FC = 0.29, p<0.001) and b (Thrb, log2FC = 0.58, p = 0.004), thyrotropin-releasing hormone receptor (Trhr, log2FC = 0.90, p = 0.025) and thyroid releasing hormone (Trh, log2FC = 1.75, p = 0.030) than dominant males.”

Dio2 expression was significantly higher in reorganized dominants that stayed in the same rank compared to control dominants (DOM vs CDOM: log2FC=0.96, p=0.030).

“Further, reorganized dominants that descended or stayed in the same rank had significantly higher expression of iodothyronine deiodinase 2 (Dio2) compared to control dominants (DES vs CDOM: log2FC = 1.22, p = 0.002, DOM vs CDOM: log2FC = 0.96, p = 0.030)”

A significantly higher proportion of IEGs such as Bdnf, Egr2, Egr3, Fosb and Junb were relatively more highly expressed in descending animals.

“we found that a significantly higher proportion of IEGs such as Bdnf, Egr2, Egr3, Fosb and Junb were relatively more highly expressed in descending animals”

There were no differences in corticosterone levels between dominant and subordinate animals at baseline.

“Although we did not find any differences in corticosterone levels between dominant and subordinate animals at baseline”

Fewer genes and pathways were uniquely differentially regulated in socially ascending animals compared to reorganized subordinates who remained subordinates, in contrast to socially descending animals.

“In contrast to socially descending animals, fewer genes and pathways were found to be uniquely differentially regulated in socially ascending animals compared to reorganized subordinates who remained subordinates.”

A WGNCA module (darkturquoise) containing genes related to the regulation of synapse organization and postsynaptic activity were relatively more highly expressed in descending animals.

“We also identified a WGNCA module (darkturquoise) containing genes related to the regulation of synapse organization and postsynaptic activity that were relatively more highly expressed in descending animals.”

Multiple genes related to myelination and oligodendrocyte differentiation had greatly elevated expression in dominants that maintained their status compared to descending dominant animals.

“DEG and WGCNA analysis confirmed that multiple genes related to myelination and oligodendrocyte differentiation had greatly elevated expression in dominants that maintained their status compared to descending dominant animals.”

A small gene co-expression network (orange module) related to mononuclear cell and lymphocyte differentiation showed higher expression in animals that maintained subordinate status compared to ascenders and control subordinates.

“Using WGCNA, we identified a small gene co-expression network (orange module) related to mononuclear cell and lymphocyte differentiation that showed higher expression in animals that maintained subordinate status compared to ascenders and control subordinates.”

Social reorganization induced changes in the expression levels of approximately 70% more genes in dominant animals versus subordinate animals.

“Social reorganization induced changes in the expression levels of approximately 70% more genes in dominant animals versus subordinate animals.”

Plasma corticosterone levels of all animals returned to baseline 25 hours following the social reorganization.

“Notably, the plasma corticosterone levels of all animals returned to baseline 25 hours following the social reorganization”

7 out of the top 25 most differentially expressed genes between descenders and dominants were related to cholinergic signaling.

“7 out of the top 25 most differentially expressed genes between descenders and dominants were related to this signaling pathway.”

Socially descending animals had lower expression of genes related to cholinergic function compared to animals that maintained their dominance status.

“A profound difference between socially descending animals and those that maintained their dominance status was the lower expression of genes related to cholinergic function in descending animals.”

In the current study, we demonstrate for the first time that mice of all social ranks rapidly adjust their aggression and subordinate behavior following changes in their social environment.

“In the current study, we demonstrate for the first time that mice of all social ranks rapidly adjust their aggression and subordinate behavior following changes in their social environment.”

Animals that maintained dominance had higher expression of Chat, Slc18a3, Slc5a7, Slc10a4, Chrm2, and Ache compared to socially descending males.

“Compared to socially descending males, animals that maintain their dominance had higher expression of Chat which encodes the choline acetyltransferase enzyme, responsible for catalyzing the synthesis of acetylcholine in neurons; the vesicular acetylcholine transporters (Slc18a3, Slc5a7, Slc10a4), integral membrane proteins responsible for packaging and transporting acetylcholine into synaptic ves”

• Also stated in: § Dominant males exhibit the largest changes in corticosterone and transcriptome profiles following social reorganization · plain

  “the muscarinic receptor Chrm2; Ache which produces the enzyme acetylcholinesterase that rapidly degrades and inactivates acetylcholine in the synaptic cleft.”

No differences in myelination gene expression were observed between any group of subordinate animals.

“Notably, we did not observe differences in myelination gene expression between any group of subordinate animals”

Animals that remained dominant had significantly higher expression of the homeobox genes Gbx1 and Lhx8 compared to socially descending males.

“Further, animals that remained dominant had significantly higher expression of the homeobox genes, Gbx1 and Lhx8 that are regulators of cholinergic neuron development [52,53].”

Previously dominant (alpha) males, whether they maintained status or socially descended, had the highest increases in plasma corticosterone 70 minutes following social reorganization compared to previously subordinate (gamma or delta) males.

“When we assessed the impact of social reorganization on changes in plasma corticosterone levels, we found that previously dominant (alpha) males had the highest increases in plasma corticosterone 70 minutes following the social reorganization compared to previously subordinate (gamma or delta) males.”

• Also stated in: § Dominant males exhibit the largest changes in corticosterone and transcriptome profiles following social reorganization · plain

  “This was true for previously dominant animals that maintained their status, or those that socially descended.”

Previously beta males were those individuals who exhibited the highest levels of aggression during social reorganization.

“Similarly, previously beta males were those individuals who exhibited the highest levels of aggression during social reorganization”

When considering genes with large fold changes (>1.5), dominants vs descenders had 3.4 times as many differentially expressed genes as subordinates vs ascenders (51 vs 15 DEGs).

“When considering genes with large fold changes (>1.5), dominants vs descenders had 3.4 times as many differentially expressed genes as subordinates vs ascenders (51 vs 15 DEGs).”

Subordinates did not show higher levels of corticosterone compared to control animals who were not socially reorganized.

“Indeed, subordinates did not show higher levels of corticosterone compared to control animals who were not socially reorganized.”

The expression of many myelination-related genes was also relatively higher in reorganized dominants that maintained their status in new hierarchies compared to control dominants.

“Further, the expression of many of these genes was also relatively higher in reorganized dominants that maintained their status in new hierarchies compared to control dominants.”

A subset of genes are commonly differentially expressed in mice who socially transitioned in either direction (ascent or descent).

“Additionally, we identify a subset of genes involved in the regulation of synaptic plasticity and likely related to learning and memory processes that are commonly differentially expressed in mice who socially transitioned in either direction (ascent or descent).”

Animals from the same hierarchy prior to reorganization were more likely to show similar ranks in their new hierarchies post-reorganization.

“We also found that animals from the same hierarchy prior to reorganization were more likely to show similar ranks in their new hierarchies post-reorganization.”

Individuals who received relatively more aggression before the reorganization were more likely to socially ascend.

“However, we did find that individuals who received relatively more aggression before the reorganization were more likely to socially ascend.”

There were 279 DEGs shared between the DES/DOM and ASC/SUB comparisons.

“we found overlap between the two samples that was greater than or equal to our observed number (279) of DEGs shared between the DES/DOM and ASC/SUB comparisons.”

Previously dominant animals showed the largest response to social reorganization, exhibiting significantly higher levels of plasma corticosterone.

“Previously dominant animals showed the largest response to this social reorganization, exhibiting significantly higher levels of plasma corticosterone”

Mybpc1 and Crym are exceptionally highly expressed in animals that socially ascend or descend.

“Two of these genes, Mybpc1 and Crym are exceptionally highly expressed in animals that socially ascend or descend”

Descending males had much higher expression of thyroid releasing hormone as well as thyroid hormone receptors compared to dominant males that did not descend.

“Moreover, descending males had much higher expression of thyroid releasing hormone as well as thyroid hormone receptors compared to dominant males that did not descend.”

There were 2,255 DEGs from the DES/DOM comparison.

“These represent the gene ids of 2,255 DEGs from the DES/DOM comparison and 1,357 DEGs from the ASC/SUB comparison out of the 15,184 genes that we obtained expression data for after filtering.”

There were 1,357 DEGs from the ASC/SUB comparison.

“These represent the gene ids of 2,255 DEGs from the DES/DOM comparison and 1,357 DEGs from the ASC/SUB comparison out of the 15,184 genes that we obtained expression data for after filtering.”

Mybpc1 had the largest log fold change in both descenders and ascenders.

“Mybpc1 had the largest log fold change in both descenders and ascenders.”

Novel social transition genes show changes in expression in both socially descending and ascending animals.

“Additionally, we identified novel social transition genes that show changes in expression in both socially descending and ascending animals.”

Only 279 genes were differentially expressed in both descending animals compared to dominants and ascending animals compared to subordinates.

“We found that only 279 genes were differentially expressed in both descending animals compared to dominants and ascending animals compared to subordinates.”

Genes associated with synaptic plasticity and glutamatergic signaling are highly expressed in status transitioning animals.

“WGCNA also revealed that genes associated with synaptic plasticity and glutamatergic signaling are highly expressed in status transitioning animals”

Previously dominant animals showed a two-fold increase in DEGs in the MeA compared to other groups.

“and a two-fold increase in DEGs in the MeA, a central hub of the SDMN.”

Within the MeA, animals that maintained their high dominance status had relatively higher expression of genes related to cholinergic signaling and myelination compared to descending males.

“Within the MeA, animals that maintained their high dominance status had relatively higher expression of genes related to cholinergic signaling and myelination compared to descending males.”

Mybpc1 and Crym were identified by WGCNA as hub genes for the brown module of genes significantly elevated in transitioning animals.

“Both genes were also identified by our WGCNA as hub genes for the brown module of genes that are significantly elevated in transitioning animals.”

Both descenders and ascenders had higher expression of the receptor for thyrotropin-releasing hormone receptor (Trhr).

“Consistent with this, we found that both descenders and ascenders had higher expression of the receptor for thyrotropin-releasing hormone receptor (Trhr).”

Two genes, Mybpc1 and Crym, were extremely overexpressed in transitioning animals (both ascending and descending) compared to those that maintained status.

“Two genes were extremely overexpressed in transitioning animals (both ascending and descending animals) compared to those that maintained status. These were Myosin binding protein C1 (Mybpc1) and μ-Crystallin (Crym).”

Other genes that regulate the activity of NMDA and AMPA receptors, including Nsmf, Gria3, and Rin1, were overexpressed in transitioning animals.

“Other genes that regulate the activity of NMDA and AMPA receptors were also overexpressed in transitioning animals, including Nsmf (NMDA receptor synaptonuclear signaling and neuronal migration factor) which modulates NMDA receptor activity and downstream signaling pathways, Gria3 (glutamate ionotropic receptor AMPA type subunit 3) and Rin1 (Ras and Rab interactor)”

Following a social disruption, outbred CD-1 mice rapidly reorganize themselves into linear dominance hierarchies, even in animals with a history of being socially subordinate.

“We demonstrate that, following a social disruption, outbred CD-1 mice rapidly reorganize themselves into linear dominance hierarchies, even in animals with a history of being socially subordinate.”

Five genes (Car12, Unc13a, Lpl, Tesc, Pitpnm2) showed higher expression in both ascenders and descenders compared to both control animals and animals that maintained their ranks.

“Using a stricter comparison, we found five genes (Car12, Unc13a, Lpl, Tesc, Pitpnm2) showing higher expression in both ascenders and descenders compared to both control animals and animals that maintained their ranks.”

There were no significant differences between groups in the reorganized and control conditions in the average David's scores of each rank (One-Way ANOVA: all p > 0.440).

“As expected, there were no significant differences between groups that were in the reorganized and control conditions in the average David’s scores of each rank (One-Way ANOVA: all p>0.440, Fig 1C).”

In pre-reorganization hierarchies, more dominant animals directed aggression towards more subordinate animals.

“This indicates that all hierarchies were highly consistent with more dominant animals directing aggression towards more subordinate animals.”

Social dynamics prior to reorganization predisposed individuals living together to be more likely to attain similar ranks following their reorganization.

“This group-of-origin effect indicates that social dynamics prior to reorganization predisposed individuals living together to be more likely to attain similar ranks following their reorganization.”

Ranks were remarkably highly consistent across the first day of housing together.

“These data demonstrate the remarkably high consistency of ranks across the first day of housing together.”

Even animals that dramatically inhibited their aggression prior to social reorganization could engage rapidly in fighting when given the social opportunity.

“This demonstrates that even animals that dramatically inhibited their aggression prior to social reorganization could engage rapidly in fighting when given the social opportunity.”

Synaptic plasticity, excitatory glutamatergic signaling, and learning and memory processes may support rapid social status changes.

“Further, increases in genes associated with synaptic plasticity, excitatory glutamatergic signaling and learning and memory pathways were observed in transitioning animals suggesting that these processes may support rapid social status changes.”

Among lower ranked individuals, individuals who received relatively more aggression before the reorganization were more likely to socially ascend after hierarchy reorganization.

“Although this effect was only significant among previously beta males, this suggests that among lower ranked individuals, individuals who received relatively more aggression before the reorganization were more likely to socially ascend after hierarchy reorganization.”

The MeA is a strong candidate region for encoding dominance status and regulating social hierarchy formation and reorganization.

“The MeA is therefore a strong candidate region for encoding dominance status and regulating social hierarchy formation and reorganization, but which neuronal pathways are responsible for these processes in mice are currently unknown.”

Social transitions are significantly associated with concordant patterns of gene expression independent of the direction of the social status change (χ2=4.30, p=0.038, Φ=0.73).

“No genes showed discordant expression patterns between ascenders and descenders, indicating that social transitions are significantly associated with concordant patterns of gene expression independent of the direction of the social status change (Chi-Squared test: χ2 = 4.30, p = 0.038, Φ = 0.73, Fig 5D).”

The readiness of low-ranked individuals to socially ascend when given the opportunity indicates that social subordination is a product of the social environment and not a default phenotype of individuals.

“The readiness of low-ranked individuals to socially ascend when given the opportunity indicates that social subordination is a product of the social environment and not a default phenotype of individuals.”

Previous social status impacts how individual males respond to such a social stressor.

“and that previous social status impacts how individual males respond to such a social stressor (Table 1).”

Other modules appear to be more strongly related to social descent than social ascent.

“Other modules appear to be more strongly related to social descent than social ascent.”

Social reorganization leads to greater transcriptomic changes in dominant compared to subordinate males.

“These findings demonstrate that social reorganization leads to greater transcriptomic changes in dominant compared to subordinate males”

Higher expression of genes in the black module may be more selectively associated with social descent.

“suggesting that higher expression of genes in this module may be more selectively associated with social descent.”

Some aspect of the social dynamics of initial hierarchies has long-term effects on the social dominance behavior of individuals.

“This suggests that some aspect of the social dynamics of initial hierarchies has long-term effects on the social dominance behavior of individuals.”

Animals who engaged in high levels of competitive encounters are willing to continue to fight for dominance status for longer.

“indicating that animals who engaged in high levels of competitive encounters are willing to continue to fight for dominance status for longer.”

Cholinergic activity in the MeA may initiate molecular changes in neural pathways that promote social dominance in socially challenging environments.

“our findings suggest that cholinergic activity in the MeA may initiate molecular changes in neural pathways that promote social dominance in socially challenging environments.”

Initial changes in myelination associated pathways cooccur with mice rapidly learning to avoid socially dominant individuals.

“our findings suggest that initial changes in myelination associated pathways cooccur with mice rapidly learning to avoid socially dominant individuals.”

Those subordinate males that are more active and engage with relatively more dominant animals despite losing are those that socially ascend when a social opportunity presents itself.

“Our findings suggest that those subordinate males that are more active and engage with relatively more dominant animals despite losing are those that socially ascend when a social opportunity presents itself.”

Reductions in myelination processes may already begin to emerge within 70 minutes of a stressful social challenge.

“Our data extend these findings, suggesting that reductions in myelination processes may already begin to emerge within 70 minutes of a stressful social challenge.”

Social reorganization elicits a more pronounced physiological stress response in dominant than subordinate males.

“This suggests that social reorganization elicits a more pronounced physiological stress response in dominant than subordinate males.”

• AssumptionRests on an assumption: Plasma corticosterone levels reflect physiological stress responses in mice.

Reductions in myelination may be specific to losing social status.

“suggesting that reductions in myelination may be specific to losing social status.”

Modification of synaptic plasticity through changes in expression of these genes in the MeA may support the updating of social status representation in both dominant and subordinate animals.

“It is plausible that modification of synaptic plasticity through changes in the expression of these genes in the MeA may support the updating of social status representation in both dominant and subordinate animals.”

The MeA is remodeled as animals learn to navigate new social environments.

“suggesting that this critical node of the SDMN is remodeled as animals learn to navigate new social environments.”

Four of these genes play a significant role in regulating synaptic plasticity and learning.

“There is evidence that four of these genes play a significant role in regulating synaptic plasticity and learning.”

There exist common molecular changes associated with rapid social ascent and descent in the MeA.

“Overall, our results demonstrate the existence of some common molecular changes that are associated with rapid social ascent and descent in the MeA”

There is a coordinated suite of gene expression changes specifically associated with changing social rank.

“This suggests that there is a coordinated suite of gene expression changes that is specifically associated with changing social rank.”

Genes associated with synaptic plasticity and glutamatergic signaling may be relevant for learning of novel social relationships.

“which may be relevant for learning of novel social relationships.”

Altered thyroid hormone signaling may be a common theme in social transitions.

“suggesting that altered thyroid hormone signaling may be a common theme in social transitions.”

Our study is the first to characterize transcriptome changes in response to transitions in social status.

“Our study is the first to characterize transcriptome changes in response to transitions in social status.”

Modulation of the VIP neuron sub-population may regulate social status transitions in either direction.

“suggesting that modulation of this sub-population of VIP neurons may regulate social status transitions in either direction”