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Cited by 281

The DOI matches its Crossref record; 56 of the 56 references it cites were found in a registry or an index.

Microglia inflammatory responses are controlled by an intrinsic circadian clock

Open access
Fonken, Laura K., Frank, Matthew G., Kitt, Meagan M., Barrientos, Ruth M., Watkins, Linda R., Maier, Steven F.·2015·Brain, Behavior, and Immunity

Abstract

The circadian system regulates many physiological functions including inflammatory responses. For example, mortality caused by lipopolysaccharide (LPS) injection varies depending on the time of immunostimulation in mammals. The effects of more subtle challenges on the immune system and cellular mechanisms underlying circadian differences in neuroinflammatory responses are not well understood. Here we show that adult male Sprague-Dawley rats injected with a sub-septic dose of LPS during the light phase displayed elevated sickness behaviors and hippocampal cytokine production compared to rats injected during the dark phase. Microglia are the primary central nervous system (CNS) immune cell type and may mediate diurnal differences in sickness response, thus we explored whether microglia demonstrate temporal variations in inflammatory factors. Hippocampal microglia isolated from adult rats rhythmically expressed inflammatory factors and circadian clock genes. Microglia displayed robust rhythms of TNFα, IL1β and IL6 mRNA, with peak cytokine gene expression occurring during the middle of the light phase. Microglia isolated during the light phase were also more reactive to immune stimulation; such that, ex vivo LPS treatment induced an exaggerated cytokine response in light phase-isolated microglia. Treating microglia with corticosterone ex vivo induced expression of the circadian clock gene Per1. However, microglia isolated from adrenalectomized rats maintained temporal differences in clock and inflammatory gene expression. This suggests circadian clock gene expression in microglia is entrained by, but oscillates in the absence of, glucocorticoids. Taken together, these findings demonstrate that microglia possess a circadian clock that influences inflammatory responses. These results indicate time-of-day is an important factor to consider when planning inflammatory interventions such as surgeries or immunotherapies.

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Metadata

Authors
Fonken, L. K., Frank, M. G., Kitt, M. M., Barrientos, R. M., Watkins, L. R., & Maier, S. F.
Venue
Brain, Behavior, and Immunity
Publisher
Elsevier BV
Published
2015-03
Volume
45
Pages
171-179
ISSN
0889-1591 (ISSN-L)
OpenAlex
W1967727674
Cited by
281
References
56
FWCI
4.53
Type
journal article
Language
en
Open access
green

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CoChat. (2026). Citation check: Microglia inflammatory responses are controlled by an intrinsic circadian clock. https://app.cochat.ai/papers/10.1016/j.bbi.2014.11.009
The paper
Fonken, L. K., Frank, M. G., Kitt, M. M., Barrientos, R. M., Watkins, L. R., & Maier, S. F. (2015). Microglia inflammatory responses are controlled by an intrinsic circadian clock. Brain, Behavior, and Immunity. https://doi.org/10.1016/j.bbi.2014.11.009

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Contains information from the Semantic Scholar Academic Graph Datasets, made available under the ODC Attribution License (ODC-BY 1.0).

Semantic Scholar’s data is described in: Kinney, R., et al. (2023). The Semantic Scholar Open Data Platform. arXiv:2301.10140.