The Role of Gut Microbiota in Regulating Serotonin Production and Its Connection to the Gut-Brain Axis

The gut microbiota is increasingly recognized as a pivotal regulator of host physiology, particularly in the synthesis of serotonin (۵-hydroxytryptamine, ۵-HT), a critical neurotransmitter implicated in gastrointestinal motility, mood, and cognition. This review synthesizes current evidence on direct microbial production of serotonin, the identification of key bacterial consortia, and the subsequent physiological and neurological implications via the microbiota-gut-brain axis (MGBA). Experimental models utilizing germ-free (GF) and Tph۱-deficient mice demonstrate that colonization with specific Lactobacillus species (Limosilactobacillus mucosae and Ligilactobacillus ruminis) restores intestinal serotonin levels, enhances enteric nervous system (ENS) innervation, and normalizes gut transit. Clinically, depletion of these taxa is associated with altered serotonin metabolism and symptom severity in irritable bowel syndrome (IBS) patients. Mechanistic studies reveal microbial decarboxylase activity capable of converting tryptophan to serotonin precursors. These findings underscore the microbiome as an active endocrine organ within the MGBA, with direct therapeutic implications for probiotic and microbiome-targeted interventions in serotonin-related disorders.

کلیدواژه ها:

Gut microbiota ، Serotonin ، Irritable bowel syndrome ، Probiotics ، Microbial metabolism ، Dysbiosis