Uts2b is a microbiota-regulated gene expressed in vagal afferent neurons connected to enteroendocrine cells producing cholecystokinin

Research progress on intestinal microbiota regulating cognitive function through the gut-brain axis

The intestinal microbiota community is a fundamental component of the human body and plays a significant regulatory role in maintaining overall health and in the management disease states.The intestinal microbiota-gut-brain axis represents a vital connection in the cognitive regulation of the central nervous system by the intestinal microbiota.The impact of intestinal microbiota on cognitive function is hypothesized to manifest through both the nervous system and circulatory system. Imbalances in intestinal microbiota during the perioperative period could potentially contribute to perioperative neurocognitive dysfunction. This article concentrates on a review of existing literature to explore the potential influence of intestinal microbiota on brain and cognitive functions via the nervous and circulatory systems.Additionally, it summarizes recent findings on the impact of perioperative intestinal dysbacteriosis on perioperative neurocognitive dysfunction and suggests novel approaches for prevention and treatment of this condition.

Gut/rumen-mammary gland axis in mastitis: Gut/rumen microbiota-mediated "gastroenterogenic mastitis"

BACKGROUND

Mastitis is an inflammatory response in the mammary gland that results in huge economic losses in the breeding industry. The aetiology of mastitis is complex, and the pathogenesis has not been fully elucidated. It is commonly believed that mastitis is induced by pathogen infection of the mammary gland and induces a local inflammatory response. However, in the clinic, mastitis is often comorbid or secondary to gastric disease, and local control effects targeting the mammary gland are limited. In addition, recent studies have found that the gut/rumen microbiota contributes to the development of mastitis and proposed the gut/rumen-mammary gland axis. Combined with studies indicating that gut/rumen microbiota disturbance can damage the gut mucosa barrier, gut/rumen bacteria and their metabolites can migrate to distal extraintestinal organs. It is believed that the occurrence of mastitis is related not only to the infection of the mammary gland by external pathogenic microorganisms but also to a gastroenterogennic pathogenic pathway.

AIM OF REVIEW

We propose the pathological concept of "gastroenterogennic mastitis" and believe that the gut/rumen-mammary gland axis-mediated pathway is the pathological mechanism of "gastroenterogennic mastitis".

KEY SCIENTIFIC CONCEPTS OF REVIEW

To clarify the concept of "gastroenterogennic mastitis" by summarizing reports on the effect of the gut/rumen microbiota on mastitis and the gut/rumen-mammary gland axis-mediated pathway to provide a research basis and direction for further understanding and solving the pathogenesis and difficulties encountered in the prevention of mastitis.

Vagal interoception of microbial metabolites from the small intestinal lumen

The vagus nerve is proposed to enable communication between the gut microbiome and brain, but activity-based evidence is lacking. Herein, we assess the extent of gut microbial influences on afferent vagal activity and metabolite signaling mechanisms involved. We find that mice reared without microbiota (germ-free, GF) exhibit decreased vagal afferent tone relative to conventionally colonized mice (specific pathogen-free, SPF), which is reversed by colonization with SPF microbiota. Perfusing non-absorbable antibiotics (ABX) into the small intestine of SPF mice, but not GF mice, acutely decreases vagal activity, which is restored upon re-perfusion with bulk lumenal contents or sterile filtrates from the small intestine and cecum of SPF, but not GF, mice. Of several candidates identified by metabolomic profiling, microbiome-dependent short-chain fatty acids, bile acids, and 3-indoxyl sulfate stimulate vagal activity with varied response kinetics, which is blocked by co-perfusion of pharmacological antagonists of FFAR2, TGR5, and TRPA1, respectively, into the small intestine. At the single-unit level, serial perfusion of each metabolite class elicits more singly responsive neurons than dually responsive neurons, suggesting distinct neuronal detection of different microbiome- and macronutrient-dependent metabolites. Finally, microbial metabolite-induced increases in vagal activity correspond with activation of neurons in the nucleus of the solitary tract, which is also blocked by co-administration of their respective receptor antagonists. Results from this study reveal that the gut microbiome regulates select metabolites in the intestinal lumen that differentially activate chemosensory vagal afferent neurons, thereby enabling microbial modulation of interoceptive signals for gut-brain communication.

HIGHLIGHTS

Microbiota colonization status modulates afferent vagal nerve activityGut microbes differentially regulate metabolites in the small intestine and cecumSelect microbial metabolites stimulate vagal afferents with varied response kineticsSelect microbial metabolites activate vagal afferent neurons and brainstem neurons via receptor-dependent signaling.

Pcgf1 gene disruption reveals primary involvement of epigenetic mechanism in neuronal subtype specification in the enteric nervous system

The enteric nervous system (ENS) regulates gut functions independently from the central nervous system (CNS) by its highly autonomic neural circuit that integrates diverse neuronal subtypes. Although several transcription factors are shown to be necessary for the generation of some enteric neuron subtypes, the mechanisms underlying neuronal subtype specification in the ENS remain elusive. In this study, we examined the biological function of Polycomb group RING finger protein 1 (PCGF1), one of the epigenetic modifiers, in the development and differentiation of the ENS by disrupting the Pcgf1 gene selectively in the autonomic-lineage cells. Although ENS precursor migration and enteric neurogenesis were largely unaffected, neuronal differentiation was impaired in the Pcgf1-deficient mice, with the numbers of neurons expressing somatostatin (Sst+ ) decreased in multiple gut regions. Notably, the decrease in Sst+ neurons was associated with the corresponding increase in calbindin+ neurons in the proximal colon. These findings suggest that neuronal subtype conversion may occur in the absence of PCGF1, and that epigenetic mechanism is primarily involved in specification of some enteric neuron subtypes.