Enteroendocrine cells (EECs) are the primary sensory cells that sense the gut luminal environment and secret hormones to regulate organ function. Recent studies revealed that vagal afferent neurons are connected to EECs and relay sensory information from EECs to the brain stem. To date, however, the identity of vagal afferent neurons connected to a given EEC subtype and the mode of their gene responses to its intestinal hormone have remained unknown. Hypothesizing that EEC-associated vagal afferent neurons change their gene expression in response to the microbiota-related extracellular stimuli, we conducted comparative gene expression analyses of the nodose-petrosal ganglion complex (NPG) using specific pathogen-free (SPF) and germ-free (GF) mice. We report here that the Uts2b gene, which encodes a functionally unknown neuropeptide, urotensin 2B (UTS2B), is expressed in a microbiota-dependent manner in NPG neurons. In cultured NPG neurons, expression of Uts2b was induced by AR420626, the selective agonist for FFAR3. Moreover, distinct gastrointestinal hormones exerted differential effects on Uts2b expression in NPG neurons, where cholecystokinin (CCK) significantly increased its expression. The majority of Uts2b-expressing NPG neurons expressed CCK-A, the receptor for CCK, which comprised approximately 25% of all CCK-A-expressing NPG neurons. Selective fluorescent labeling of Uts2b-expressing NPG neurons revealed a direct contact of their nerve fibers to CCK-expressing EECs. This study identifies the Uts2b as a microbiota-regulated gene, demonstrates that Uts2b-expressing vagal afferent neurons transduce sensory information from CCK-expressing EECs to the brain, and suggests potential involvement of UTS2B in a modality of CCK actions.
Keywords: Gut-brain axis; Microbiota; Nodose ganglion; Uts2b; Vagal afferent neurons.
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