Gut microbe-derived trimethylamine shapes circadian rhythms through the host receptor TAAR5.

Jan 29, 2026eLife

Gut microbe chemical trimethylamine may influence daily body rhythms through a specific host receptor

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Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

Mice lacking the host TMA receptor (TAAR5) exhibit altered circadian rhythms, metabolic hormone levels, gut microbiome composition, and various behaviors.

Elevated levels of the gut microbe-derived metabolite trimethylamine-oxide (TMAO) are linked to increased cardiometabolic disease risk.
Dietary choline is converted to trimethylamine (TMA) by gut bacteria, which can then be oxidized by the host to form TMAO.
Mice without the TMA receptor (TAAR5) demonstrate changes in gene expression related to circadian rhythms.
Alterations in circadian rhythms are also observed in mice that lack either bacterial TMA production or the host's ability to oxidize TMA.
These findings suggest that gut bacterial production of TMA and the host's TMA receptor play a role in regulating circadian rhythms.

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Elevated levels of the gut microbe-derived metabolite trimethylamine-oxide (TMAO) are associated with cardiometabolic disease risk. However, the mechanism(s) linking TMAO production to human disease are incompletely understood. Initiation of the metaorganismal TMAO pathway begins when dietary choline and related metabolites are converted to trimethylamine (TMA) by gut bacteria. Gut microbe-derived TMA can then be further oxidized by host flavin-containing monooxygenases to generate TMAO. Previously, we showed that drugs lowering both TMA and TMAO protect mice against obesity via rewiring of host circadian rhythms (Schugar et al., 2022). Although most mechanistic studies in the literature have focused on the metabolic end product TMAO, here we have instead tested whether the primary metabolite TMA alters host metabolic homeostasis and circadian rhythms via trace amine-associated receptor 5 (TAAR5). Remarkably, mice lacking the host TMA receptor () have altered circadian rhythms in gene expression, metabolic hormones, gut microbiome composition, and diverse behaviors. Also, mice genetically lacking bacterial TMA production or host TMA oxidation have altered circadian rhythms. These results provide new insights into diet-microbe-host interactions relevant to cardiometabolic disease and implicate gut bacterial production of TMA and the host receptor that senses TMA (TAAR5) in the physiologic regulation of circadian rhythms in mice. N Taar5 -/ -