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Cited by 432Neuroinflammation and Neurodegeneration MechanismsNeurogenesis and neuroplasticity mechanismsNeuroscience and Neuropharmacology Research

Local cues establish and maintain region-specific phenotypes of basal ganglia microglia

Open access
De Biase, Lindsay M., Schuebel, Kornel E., Fusfeld, Zachary H., Jair, Kamwing, Hawes, Isobel A., Cimbro, Raffaello, Zhang, Hai-Ying, Liu, Qing-Rong +4 more·2017·Neuron
DOI 10.1016/j.neuron.2017.06.020PMC PMC5754189
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Abstract

SUMMARY Microglia play critical roles in tissue homeostasis and can also modulate neuronal function and synaptic connectivity. In contrast to astrocytes and oligodendrocytes, which arise from multiple progenitor pools, microglia arise from yolk sac progenitors and are widely considered to be equivalent throughout the CNS. However, little is known about basic properties of deep brain microglia, such as those within the basal ganglia (BG). Here, we show that microglial anatomical features, lysosome content, membrane properties, and transcriptomes differ significantly across BG nuclei. Region-specific phenotypes of BG microglia emerged during the second postnatal week and were re-established following genetic or pharmacological microglial ablation and repopulation in the adult, indicating that local cues play an ongoing role in shaping microglial diversity. These findings demonstrate that microglia in the healthy brain exhibit a spectrum of distinct functional states and provide a critical foundation for defining microglial contributions to BG circuit function.

AI snapshot

Written from the paper’s full text.

TL;DR

Microglia in basal ganglia nuclei differ in density, morphology, lysosome content, membrane properties, and transcriptome, with VTA/SNc and SNr/NAc representing distinct phenotypes. These region-specific phenotypes emerge during the second postnatal week and are re-established after adult microglial ablation/repopulation, indicating ongoing local cues.

Key findings

  • Microglial density varied across basal ganglia nuclei, from 262 ± 10 cells/mm² in VTA to 723 ± 12 cells/mm² in SNr; NAc density (380 ± 7 cells/mm²) was comparable to cortex and hippocampus. NAc and SNr microglia had more complex branching, while VTA and SNc microglia were sparsely branched with reduced tissue coverage.
  • Lysosome content differed significantly across basal ganglia nuclei except NAc vs. SNc and VTA vs. SNc; SNr microglia had higher lysosome content than VTA microglia and more somatic lysosomes despite similar soma volume.
  • SNr microglia showed more hyperpolarized resting potentials and larger membrane capacitance than VTA/SNc microglia. Voltage-activated Kv currents were seen in 17/28 (61%) SNr cells upon depolarization beyond −25 ± 1 mV and 24/37 (65%) upon steps beyond −19 ± 2 mV; these were TEA- and 4-AP-sensitive. In the discussion, Kv currents were reported in 65% of SNr microglia but only 3% of VTA and 0% of SNc microglia.
  • VTA microglial transcriptome differed most from other regions: Ctx–NAc overlap was 84.3%, while VTA overlap with other groups was 56.4–60.0%; differentially expressed genes were 0.4% for Ctx vs. NAc and 14.0–18.3% for VTA vs. others. Of genes analyzed, 2664 (48%) were conserved across all four regions and 2942 (52%) were differentially expressed; VTA microglia showed down-regulated glycolysis/mitochondrial genes and up-regulated Fcγ-receptor phagocytosis/phagosome maturation genes. Regional phenotypes were uniform at P6 (205–259 cells/mm²), emerged by P12, and were re-established after pharmacological or genetic ablation/repopulation, including SNr Kv currents in 8/13 (62%) repopulated cells.

Methods

  • Used CX3CR1EGFP/+ mice (P6–P90), ALDH1L1-EGFP mice, and CX3CR1CreER-IresEYFP/+;Rosafs-DTA/fs-DTA mice; both male and female mice were used.
  • Combined immunohistochemistry, confocal imaging, 3D reconstruction, whole-cell patch clamp in acute midbrain slices, and FACS-purified microglia from NAc, VTA, SN, and Ctx for RNAseq (N = 6 Ctx, 6 NAc, 7 VTA, 8 SN) and RT-PCR (N = 5 per group).
  • Microglial ablation/repopulation used PLX5622 (1200 mg/kg chow for 2 weeks, then 3-week repopulation) or 4-hydroxytamoxifen-inducible diphtheria toxin (6-week repopulation); statistics used one-way/two-way ANOVA with Bonferroni correction and EDGE for RNAseq differential expression.

Limitations

  • Stated: experimenters were not blind to source brain region during image analysis; VTA RNAseq samples showed greater sample-to-sample variability that can dampen detection of differentially expressed genes; RNAseq has limited sensitivity for low-abundance transcripts; elevated lysosome content cannot immediately be equated with increased degradative capacity; precise functional roles of microglial resting potential and voltage-activated conductances were not defined; local regulatory cues were not identified, and epigenetic programming was not excluded.
  • Stated: rare surviving microglia after ablation were acknowledged, though the authors argue they are unlikely to determine repopulated region-specific phenotypes.
  • Evident: the study does not causally manipulate candidate local cues or test downstream consequences for basal ganglia circuit function; the correlation between microglial and astrocyte density is suggestive but not causal.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/j.neuron.2017.06.020

Cites

66 of 66 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 30 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Oligodendrocyte precursor cell density is comparable across basal ganglia nuclei.

    “Density of oligodendrocyte precursor cells (OPCs, NG2+ cells) was comparable across BG nuclei”
    Quote in the paperSubstantial claim
  • Findingown data

    The ratio of microglia to astrocytes is consistent across basal ganglia nuclei.

    “the ratio of microglia to astrocytes was consistent”
    Quote in the paperSubstantial claim
  • Findingcitation

    NAc microglial density is comparable to that in cortex and hippocampus.

    “Only NAc displayed microglial density (380 ± 7 cells/mm2) comparable to that in cortex and hippocampus (Lawson et al., 1990).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Lawson et al., 1990 source

      Not checked in the free run.

    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.
  • Findingown data

    NAc and SNr microglia exhibit a similar degree of process complexity as measured by 3D Scholl analysis.

    “Although NAc and SNr microglia exhibited a similar degree of process complexity as measured by 3D Scholl analysis”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.
  • Findingown data

    Regional variation in basal ganglia astrocyte density closely resembles that of microglia.

    “regional variation in BG astrocyte density closely resembled that of microglia”
    Quote in the paperNot a substantial claim
  • May combine two claims. 38
  • The quote only partly states this claim. 1
  • Classified as probably not a substantial claim. 41

  • May combine two claims.

    Findingown data

    The ratio of microglia to OPCs and the ratio of microglia to neurons vary significantly across basal ganglia nuclei.

    “while the ratio of microglia to OPCs and microglia to neurons varied significantly across BG nuclei”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    NAc microglia possess greater total process length and more branch points than other basal ganglia microglia.

    “NAc microglia possess greater total process length and number of branch points than other BG microglia”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    NAc and SNr microglia exhibit complex process structure, whereas VTA and SNc microglia are sparsely branched and have significantly reduced tissue coverage.

    “NAc and SNr microglia exhibited complex process structure, while VTA and SNc microglia were sparsely branched and displayed significantly reduced tissue coverage”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    At P6, nearly 100% of Iba1+ cells were EGFP+, and at P8, EGFP+Ki67+ cells could be observed.

    “At P6, nearly 100% of Iba1+ cells were EGFP+, and at P8, EGFP+Ki67+ cells could be observed”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    By P12, ramification of microglia has increased in all analyzed regions, but VTA and SNc microglia still exhibit comparatively sparse branching, while NAc and SNr microglia display heightened branching complexity, consistent with young adult mice.

    “By P12, ramification of microglia had increased in all analyzed regions, but VTA and SNc microglia still exhibited comparatively sparse branching, while NAc and SNr microglia displayed heightened branching complexity, consistent with observations in young adult mice”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    Genes involved in mitochondrial function, general cell metabolism, oxidative signaling/ROS homeostasis, and lysosome function are differentially expressed across regions, including notably low expression of cell metabolism genes in VTA microglia.

    “genes involved in mitochondrial function, general cell metabolism, oxidative signaling/ROS homeostasis, and lysosome function were differentially expressed, including notable low expression levels of cell metabolism genes in VTA microglia”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    SNr microglia display significantly more hyperpolarized resting potentials and larger membrane capacitance than VTA and SNc microglia.

    “SNr microglia displayed significantly more hyperpolarized resting potentials and larger membrane capacitance”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • The quote only partly states this claim.

    Findingown data

    VTA and SNc microglia exhibit passive responses when held at −70 mV and stepped to holding potentials ranging from −120 to 10 mV.

    “VTA and SNc microglia exhibited passive responses”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    Basal ganglia microglial density is uniform at P6 (205-259 cells/mm2) and varies significantly at P12, with the same pattern of relative abundance as in young adult mice.

    “BG microglial density was uniform at P6 (205–259 cells/mm2) and varied significantly at P12, with the same pattern of relative abundance as observed in young adult mice”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    In DT ablation/repopulation, greater mouse-to-mouse variability was observed, with some mice showing increased density of repopulated microglia across all basal ganglia nuclei relative to controls.

    “greater mouse-to-mouse variability was observed, with some mice showing increased density of repopulated microglia across all BG nuclei relative to control mice”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    In PLEX ablated/repopulated mice, repopulated SNr microglia possess significantly higher lysosome content than repopulated VTA microglia, consistent with observations in naïve mice.

    “repopulated SNr microglia possessed a significantly higher lysosome content than repopulated VTA microglia, consistent with observations in naïve mice”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.
    • Rests on an assumption: CD68 immunostaining marks microglial lysosomes.

  • May combine two claims.

    Findingown data

    VTA microglia show the largest differences in gene expression, implicating multiple functional families, including mitochondrial function, glycolysis, and gluconeogenesis.

    “VTA microglia showed the largest differences in gene expression, implicating multiple functional families, including mitochondrial function, glycolysis, and gluconeogenesis.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    At 6 weeks post-ablation in DT ablated/repopulated mice, EYFP+Iba1+ cells were abundant throughout the basal ganglia, and regional differences in microglial density and branching complexity were evident.

    “When 4HT-treated mice were examined at 6 weeks post-ablation (DT ablated/repopulated mice), EYFP+Iba1+ cells were abundant throughout the BG, and regional differences in microglial density and branching complexity were evident”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    Kv currents were detected in 65% of SNr microglia but only 3% of VTA and 0% of SNc microglia.

    “we detected Kv currents in 65% of SNr microglia but only 3% of VTA and 0% of SNc microglia”
    Quote in the paperSubstantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    Many genes are expressed at similar levels by basal ganglia and cortical microglia, consistent with the idea that all microglia share a core set of molecular markers and functional duties.

    “We found many genes expressed at similar levels by BG and Ctx microglia, consistent with the idea that all microglia share a core set of molecular markers and functional duties.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Findingown data

    By P12, BG microglia exhibited clear regional specialization, with cell density and branching patterns closely mirroring adult.

    “by P12, they exhibited clear regional specialization, with cell density and branching patterns closely mirroring those observed in the adult.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    At P6, most BG microglia were not amoeboid but had limited process branching that did not differ notably across regions.

    “At this stage, most cells were not amoeboid, but exhibited limited process branching that did not differ notably across regions.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    By P6, BG microglia were dispersed relatively evenly throughout analyzed nuclei at lower densities than in adult.

    “In the BG, we found that by P6, microglia were dispersed relatively evenly throughout analyzed nuclei at lower densities than those observed in the adult.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    For microglial RNAseq datasets from different brain regions, there were no significant differences in total reads, percent reads mapped, or dataset box plots.

    “For microglial RNAseq datasets generated from different brain regions, there were no significant differences in total number of reads (one-way ANOVA, P = 0.83), in the percent of reads mapped (ANOVA P = 0.03, individual comparisons not significant after Bonferroni correction, P > 0.05), or in the appearance of dataset box plots.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The data are sufficiently normal and group variances sufficiently similar to permit parametric tests.

  • May combine two claims.

    Findingown data

    During early repopulation, microglia exhibit similar density and morphology across BG nuclei, and later acquire region-specific morphological attributes.

    “during early phases of repopulation, microglia exhibit similar density and morphology across BG nuclei (data not shown), and then in later phases of repopulation acquire region-specific morphological attributes.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    ΔCt values were within ±2 for all target genes between pre-amplified and unamplified samples.

    “ΔCt values were within range of ± 2 for all target genes between the pre-amplified and unamplified samples,”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    RNA yields from such small numbers of cells were generally below the detection limit of the Bioanalyzer.

    “Yields of RNA from such small numbers of cells were generally below the limit of Bioanalyzer (Agilent, Santa Clara, CA) detection.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    The average yields of microglia collected with this gating strategy were 3989 ± 583 for Ctx, 916 ± 271 for NAc, 76 ± 11 for VTA, and 359 ± 51 for SN.

    “Average microglial cell yields collected using this gating strategy were the following: Ctx 3989 ± 583 cells, NAc 916 ± 271 cells, VTA 76 ± 11 cells, SN 359 ± 51 cells.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Greater sample-to-sample variability was observed within VTA microglia samples.

    “Greater sample-to-sample variability was observed within VTA microglia samples (Fig. S5C);”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    SPIA-generated cDNA from microglial samples of different brain regions gave highly similar Bioanalyzer profiles.

    “SPIA-generated cDNA from microglial samples from different brain regions yielded highly similar Bioanalyzer profiles (data not shown).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    Sequencing runs yielded about 10 gigabases each, resulting in 7-33 million reads mapped to the mouse mRNA transcriptome per sample.

    “3 libraries were sequenced per chip, with a yield of approximately 10 gigabases of sequence generated per run, resulting in 7–33 million reads mapped to the mouse mRNA transcriptome, per sample (Table S1).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    No significant effect of sex was observed in data analyses.

    “No significant effect of sex was observed in data analyses (data not shown).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Gene expression patterns from cortical microglia showed a high degree of overlap with previously published RNAseq data from cortical microglia.

    “gene expression patterns from our Ctx microglia showed a high degree of overlap with previously published RNAseq data from cortical microglia (Zhang et al., 2014)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Zhang et al., 2014 source

      Not checked in the free run.

    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Interpretationown data

    Microglia in distinct basal ganglia nuclei differ in phagocytotic activity or metabolic state.

    “Together, these observations suggest that microglia in distinct BG nuclei differ in their phagocytotic activity or metabolic state (Appelqvist et al., 2013).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Appelqvist et al., 2013 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Functional states of microglia in distinct basal ganglia nuclei differ from one another and from cortical and hippocampal counterparts.

    “support the conclusion that functional states of microglia in distinct BG nuclei differ from one another and from cortical and hippocampal counterparts”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Similar results were obtained regardless of the specific filtering criteria used to define expressed genes.

    “Similar results were obtained regardless of specific filtering criteria used to define expressed genes”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

  • May combine two claims.

    Interpretationown data

    Not all SNr microglia express Kv channels, indicating that cell-to-cell heterogeneity accompanies regional differences in microglial phenotype.

    “The observation that not all SNr microglia express Kv channels indicates that cell-to-cell heterogeneity accompanies the regional differences in microglial phenotype that we describe.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Regional differences in microglial anatomy are tightly regulated; the shift from low-density, sparsely branched VTA/SNc microglia to high-density, complex SNr microglia indicates that microglial phenotype is specified to within tens of microns.

    “the stark shift from low density, sparsely-branched VTA/SNc microglia to high density, complex SNr microglia indicates that microglial phenotype is specified to within 10’s of microns”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Substantial differences exist between the transcriptome of midbrain microglia and their cortical counterparts, supporting the conclusion that these cells exhibit region-specific phenotypes and functional states.

    “we also found substantial differences between the transcriptome of midbrain microglia and their cortical counterparts, supporting the conclusion that these cells exhibit region-specific phenotypes and functional states”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Spatial constraints imposed by tissue architecture do not account for regional differences in microglial density and branching, as shown by the relatively uniform density and branching complexity of OPCs across basal ganglia nuclei.

    “Spatial constraints imposed by tissue architecture do not account for these differences, as shown by the relatively uniform density and branching complexity of OPCs across BG nuclei.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    SNr microglial functional state differs from that of microglia in immediately adjacent basal ganglia nuclei, as well as higher brain structures.

    “these observations provide further direct evidence that SNr microglial functional state differs from that of microglia in immediately adjacent BG nuclei, as well as higher brain structures”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    RNAseq analysis showed dramatic differences in microglial gene expression between early postnatal periods (P3-9) and adulthood (2 months).

    “showing dramatic differences in microglial gene expression between early postnatal periods (P3–9) and adulthood (2 months) (Matcovitch-Natan et al., 2016).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Matcovitch-Natan et al., 2016 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Microglial maturation does not progress in a wave-like fashion outward from late embryonic/early postnatal hotspots; instead immature microglia disperse at low density throughout parenchyma and then proliferate and ramify in situ to attain mature distribution and morphology.

    “These observations suggest that microglial maturation does not progress in a wave-like fashion outward from late embryonic/early postnatal microglial “hotspots,” but, rather, that immature microglia disperse themselves at low density throughout the parenchyma and then proliferate and ramify in situ to attain a mature tissue distribution and morphology.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    Microglial-derived inflammatory and trophic signaling factors impact formation and elimination of dendritic spines.

    “which have been shown to impact formation and elimination of dendritic spines (Parkhurst et al., 2013)”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Parkhurst et al., 2013 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Patterns of in vivo neuronal activity could influence baseline microglial phenotype.

    “suggesting that patterns of in vivo neuronal activity could play a role in influencing baseline microglial phenotype.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Primitive macrophage progenitors from the yolk sac invade the developing neuroectoderm and give rise to resident CNS microglia.

    “primitive macrophage progenitors from the yolk sack invade the developing neuroectoderm and give rise to resident CNS microglia (Ginhoux and Prinz, 2015).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Ginhoux and Prinz, 2015

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    SNr neurons have high-frequency, tonic action potential firing.

    “One distinguishing feature of SNr neurons is their high-frequency, tonic action potential firing (Zhou and Lee, 2011)”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Zhou and Lee, 2011

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Death of SNc dopamine neurons is more pronounced than death of other midbrain dopaminergic neurons in Parkinson's disease.

    “Although dopaminergic neurons throughout the midbrain degenerate during Parkinson’s disease, death of SNc dopamine neurons is more pronounced (Gonzalez-Hernandez et al., 2010).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Gonzalez-Hernandez et al., 2010 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Reduced microglial capacity to support tissue homeostasis and lower microglial-derived trophic factors within VTA/SNc could contribute to neuronal susceptibility.

    “This observation suggests that reduced microglial capacity to support tissue homeostasis and lower levels of microglial-derived trophic factors within the VTA/SNc could also contribute to neuronal susceptibility.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Microglial-derived factors influence AMPA receptor trafficking.

    “influence AMPA receptor trafficking (Pribiag and Stellwagen, 2014)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Pribiag and Stellwagen, 2014 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Microglial-derived factors play key roles in responses to pathological insults.

    “play key roles in responses to pathological insults (Ransohoff and Perry, 2009).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Ransohoff and Perry, 2009 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Quality control tools, including total reads, percent reads mapped, box plots, and principal component analysis, were used to select viable datasets for further analysis.

    “Quality control assessment tools, including total number of reads, percent reads mapped to host genome, box plots and principle component analysis, were used to select viable datasets for further analysis”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Uniformity of the pre-amplification was verified by comparing cDNA templates from pre-amplified and unamplified cortex samples.

    “Uniformity of the pre-amplification was verified by comparing cDNA templates from the pre-amplified and unamplified cortex samples.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Only cDNA samples that produced a characteristic smear of 50-1500 bp fragments and microgram quantities were used for downstream processing.

    “Only those samples which yielded a characteristic smear of cDNA fragments from 50–1500 bp and quantities in the microgram range were used for downstream processing.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    For RT-PCR analyses, microglia were collected from an independent cohort of mice.

    “For RT-PCR analyses, microglia were collected from an independent cohort of mice and RNA was isolated as described above to obtain N = 5 samples per group.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Single cells were selected using a gating strategy based on forward and side scatter width and height.

    “A gating strategy based on FSC and SSC width and height was used to select only single cells.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Microglia-containing cells could be easily distinguished by their forward and side scatter properties.

    “The population of cells containing microglia could be readily identified based on forward scattering (FSC) and side scattering (SSC) properties.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Carrier tissue from a wildtype mouse was added to VTA and SNr samples to minimize tissue loss during processing.

    “To minimize tissue loss during processing, “carrier” tissue from a wildtype mouse was added to VTA and SNr samples.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Sample sizes for electrophysiology were selected to be in the upper range of published whole-cell patch clamp experiments.

    “Sample sizes were selected to be in the upper range of currently published whole-cell patch clamp electrophysiology experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Experimenters were not blind to source brain region during image analysis.

    “Experimenters were not blind to source brain region during image analysis.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductnone given

    Each sample used for downstream applications contained microglia from the basal ganglia nucleus of a single mouse, and tissues were not pooled.

    “Tissues were not pooled; each sample used for downstream applications represents microglia from the BG nucleus of an individual mouse.”
    • Also stated in: § METHOD DETAILS · plain
      “Tissues were not pooled; each sample was derived from microglia isolated from the BG nucleus of an individual mouse.”
    • Also stated in: § METHOD DETAILS · plain
      “Tissues were not pooled; each sample was derived from microglia isolated from the BG nucleus of an individual mouse.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    EDGE is similar to Fisher's Exact Test and was designed for count data with many features analyzed across few biological replicates.

    “Empirical analysis of Digital Gene Expression (EDGE) (Robinson et al., 2010) is similar to Fisher’s Exact Test and was developed specifically for count data where many features are analyzed simultaneously across few biological replicates.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Robinson et al., 2010 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Study design and conductnone given

    Sample sizes for immunohistochemistry were selected to be in the upper range of published experiments.

    “Sample sizes were selected to be in the upper range of published immunohistochemistry experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Wildtype cell suspensions served as a GFP-negative control to set GFP-negative gates.

    “Cell suspensions from wildtype tissue were used as a GFP-negative control for establishment of GFP-negative gates.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The RT-PCR sample sizes were selected to be at the upper end of currently published RT-PCR experiments.

    “These sample sizes were selected to be at the upper end of currently published RT-PCR experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The RNAseq sample sizes were chosen to be in the upper range of currently published RNAseq experiments.

    “These sample sizes were selected to be in the upper range of currently published RNAseq experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All experiments were performed in accordance with protocols approved by the Animal Care and Use Committee at NIDA.

    “All experiments were performed in strict accordance with protocols approved by the Animal Care and Use Committee at NIDA.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    The greater variability within VTA microglia is commonly seen in RNAseq of small cell numbers and does not reflect differences in sample quality.

    “this phenomenon is commonly observed in RNAseq analysis of small numbers of cells (Marinov et al., 2014) and does not reflect differences in sample quality”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Marinov et al., 2014 source

      Not checked in the free run.

    • Rests on an assumption: The addition of carrier tissue to VTA and SNr samples does not affect the microglial transcriptome or phenotype.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Primary antibodies were validated for immunohistochemistry in mouse tissue in published literature and manufacturer websites.

    “Primary antibodies have been validated for use in immunohistochemistry in mouse tissue in published literature and on the maunfacturer’s websites.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The order in which samples were sorted was systematically varied.

    “Sort order was varied systematically.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Local cues would need to be in place throughout the BG by the second postnatal week and remain present and active throughout adulthood.

    “Our data indicate that such cues would need to be in place throughout the BG by the second postnatal week of development and remain present and active throughout adulthood.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Primers and probes spanning target gene exon-exon junctions were chosen when possible to prevent amplification of genomic DNA contamination.

    “To avoid amplification of genomic DNA contamination, primers and probes that amplify across target gene exon–exon junctions were selected when possible.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductown data

    EGFP expression in the BG of CX3CR1EGFP/+ mice was specific to microglial cells, and 98 ± 1% of Iba1+ microglia were EGFP+.

    “EGFP expression in the BG of these mice was specific to microglial cells and 98 ± 1% of Iba1+ microglia were EGFP+ (Fig. 1B,C).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Both male and female mice were used, and sex distribution was balanced across analysis groups.

    “In all experiments, both male and female mice were used, and the number of males and females in each analysis group was balanced.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The progression of repopulation resembles developmental emergence of regional specialization and argues local cues within each nucleus direct maturation of repopulating cells.

    “This progression resembles the emergence of regional specialization observed during development and argues that local cues within each nucleus direct “maturation” of repopulating cells.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    The RD8 mutation was bred out of the colony, and all experimental mice were RD8 free.

    “The RD8 mutation, which results in retinal degeneration (Mattapallil et al., 2012), was bred out of our colony and all mice used for experiments were RD8 free.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Mattapallil et al., 2012 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Study design and conductnone given

    NMDG perfusion is a critical step for eliminating peripheral macrophages within vasculature and minimizing injury responses of CNS cells.

    “NMDG perfusion is a critical step for elimination of peripheral macrophages within the vasculature and to minimize injury responses of CNS cells.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationown data

    The greater variability within VTA microglia can reduce the ability to detect differentially expressed genes.

    “but can dampen the ability to detect differentially expressed genes.”
    Quote in the paperNot a substantial claim
73 of 73

  • The paper relies on this without support.

    Little is known about the basal features of basal ganglia microglia and their contributions to physiological basal ganglia function.

    “However, little is known about the basal features of these cells, their contributions to physiological BG functioning”

  • The paper relies on this without support.

    EGFP expression under the CX3CR1 promoter specifically labels microglia in adult basal ganglia.

    “cell density was examined in transgenic mice expressing EGFP under control of the endogenous fractalkine receptor promoter (CX3CR1EGFP/+ mice)”

  • The paper relies on this without support.

    CD68 immunostaining marks microglial lysosomes.

    “Three-dimensional reconstruction of EGFP+ microglia and CD68+ lysosomes from confocal images”

  • The paper relies on this without support.

    The addition of carrier tissue to VTA and SNr samples does not affect the microglial transcriptome or phenotype.

    “carrier” tissue from a wildtype mouse was added to VTA and SNr samples.”
    “GFP-negative cells were collected from Ctx and NAc, but not VTA and SN, due to the presence of carrier tissue in these samples.”

  • The paper relies on this without support.

    The data are sufficiently normal and group variances sufficiently similar to permit parametric tests.

    “Data are sufficiently normal and variance within groups is sufficiently similar for use of parametric tests.”
5 of 5

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Microglia are highly dynamic cells strongly influenced by environmental signals, resulting in distinct phenotypes and functions across brain regions.

    “Microglia are highly dynamic cells that are strongly influenced by different environmental signals which result in distinct phenotypes and functions across brain regions4–9.”

    From Genetic analysis of the human microglial transcriptome across brain regions, aging and disease pathologies (2022) · cites this paper as [7]

  • In animal stroke models, neuronal and microglial lysosomal functions are impaired by hypoxia, and induction of autophagy by rapamycin improves stroke outcomes by preventing neuronal death and improving microglial phagocytosis of damaged cell debris.

    “For example, in animal stroke models, neuronal and microglial lysosomal functions are impaired by hypoxia, and induction of autophagy by rapamycin, an mTOR inhibitor, improves stroke outcomes by both preventing neuronal death and improving microglial phagocytosis of damaged cell debris.45,46”

    From The lysosome and proteostatic stress at the intersection of pediatric neurological disorders and adult neurodegenerative diseases (2025) · cites this paper as [46]

    Split into 2 atoms — 0 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 2 unverifiable. Expand the claim to see per-atom verdicts.

    Experimental — accuracy not yet measured

  • Midbrain microglia have distinct gene expression profiles compared with cortical microglia.

    “For example, microglia in the midbrain have been shown to possess distinct gene expression profiles compared with cortical microglia (De Biase et al., 2017).”

    From Developmental Heterogeneity of Microglia and Brain Myeloid Cells Revealed by Deep Single-Cell RNA Sequencing (2019) · cites this paper as De Biase et al., 2017

  • Beyond gene transcription, microglial heterogeneity may be captured by other measures, including electrophysiological, epigenetic, or functional readouts.

    “Microglial heterogeneity can also be represented by measurements other than gene transcription, such as electrophysiological properties, epigenetic features or functional readouts (Ayata et al., 2018; De Biase et al., 2017).”

    From Developmental Heterogeneity of Microglia and Brain Myeloid Cells Revealed by Deep Single-Cell RNA Sequencing (2019) · cites this paper as De Biase et al., 2017

  • Microglia found in healthy reward circuitry are incredibly diverse.

    “Microglia found in healthy reward circuitry are incredibly diverse [196] and more work is needed to profile their function in pathologic states.”

    From The molecular and cellular mechanisms of depression: a focus on reward circuitry (2019) · cites this paper as [196]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Reported SNr recording count exceeds the stated per-region range

    Minor

    The results report recordings from 37 SNr microglia, but the methods state that no more than 31 cells were recorded per brain region.

  • Figure 3C is cited for two different measurements

    Minor

    Figure 3C is cited both for microglial process length and branch points and for total tissue content of microglial lysosomes. The same panel cannot show both measurements as described.

2 of 2

Cites

Flagged first, then by citations

1 of the 67 references couldn’t be matched to a known paper.

Cited by

Sorted by citations

Related

Authors
De Biase, L. M., Schuebel, K. E., Fusfeld, Z. H., Jair, K., Hawes, I. A., Cimbro, R., Zhang, H.-Y., Liu, Q.-R., Shen, H., Xi, Z.-X., Goldman, D., & Bonci, A.
Affiliations
  • National Institutes of Health (US)
  • Johns Hopkins University (US)
Corresponding author
Bonci, Antonello
ORCID
Venue
Neuron
Publisher
Elsevier BV
Published
2017-07
Volume
95
Issue
2
Pages
341-356.e6
ISSN
0896-6273 (ISSN-L)
DOI
10.1016/j.neuron.2017.06.020
PMC
PMC5754189
OpenAlex
W2725043130
Semantic Scholar
70166048bd33af0d3c3dc2c14c38a7ca20a43d29
Cited by
432
References
67
Citations by year
2026: 30 · 2025: 45 · 2024: 38 · 2023: 39 · 2022: 66 · 2021: 47 · 2020: 60 · 2019: 51 · 2018: 44 · 2017: 12
FWCI
22.75
Type
journal article
Language
en
Open access
Licence
Locations
  • Neuron (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • Intramural Research Program of NIDA and NIAAA
  • NIAMS (P30 AR-070254)
Topics
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
  • Life Sciences › Neuroscience › Developmental Neuroscience › Neurogenesis and neuroplasticity mechanisms
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
Keywords
microglia, basal ganglia, microglial heterogeneity, microglial development, membrane properties, microglial transcriptome, postnatal development
MeSH terms
Animals, Basal Ganglia, Cues, Mice, Transgenic, Neurons, Phenotype, Microglia

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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