Circadian Disruption Elicits Sex-Specific Gut Microbiota, Endocannabinoidome and Lipid Mediator Responses

Abstract

Circadian disruption is a pervasive environmental stressor that increases susceptibility to metabolic and inflammatory diseases, yet sex-specific adaptive strategies remain poorly understood. Here, we show that constant light (LL) exposure alters gut microbial communities and triggers sex- and tissue-specific host adaptations in the endocannabinoidome and other bioactive lipids. Using 16S rRNA sequencing, short chain fatty acid (SCFA) quantification, LC-MS/MS lipidomics, and cytokine profiling, we identified divergent coping strategies across brain, metabolic and intestinal tissues and reproductive organs. In females, LL induced microbial restructuring, with enrichment of Rikenellaceae, Butyricicoccaceae, and Alistipes, but these changes were uncoupled from short-chain fatty acids (SCFA) output. Also, they engaged N-acylethanolamine (NAE)-driven endocannabinoidome signaling in the brain (AEA, DHEA, OEA, PEA, SEA), accompanied by omega-6 prostaglandin upregulation and increased cytokines (IL-5, IFN-{gamma}, MIP-2). The 2-monoacyl glycerols (2-MAGs) increased selectively in liver and skeletal muscle, reflecting tissue-specific lipid remodeling. In males, microbial shifts were limited (e.g., Ruminococcaceae depletion, Tuzzerella enrichment), yet LL triggered robust metabolic adaptation resulting in elevated SCFA levels (isobutyric, butyric, isovaleric, valeric acids) in faeces and elevation of several DHA-derived bioactive lipids in different intestinal tissues Few alterations in brain bioactive lipids were found, while several 2-MAGs were elevated skeletal muscles and testes. In contrast, several oxylipins were decreased within subcutaneous but not other adipose tissue depots. Together, the data shows that changes in bioactive lipid levels in response to circadian rhythm disruption are organ- and sex-specific as are alterations in microbiota populations, positioning sex as a key determinant of responses to circadian stress.