Serotonin, or 5-hydroxytryptamine (5-HT), is a key neurotransmitter involved in many physiological processes in both the central and peripheral nervous systems. While often associated with brain function and mental health, most serotonin is produced in the gastrointestinal tract. It regulates intestinal motility, secretion, vascular activity, inflammation, and platelet aggregation, and disruptions in serotonin signalling have been linked to neurological and psychiatric conditions. The gut microbiota plays a central role in serotonin production and gut-brain communication. The gastrointestinal tract hosts a diverse microbial community that influences the production of signalling molecules such as neurotransmitters and hormones. Alterations in microbiota composition may disrupt gut-brain communication and are associated with gastrointestinal disorders as well as mental health conditions like depression and anxiety. This study is a narrative literature review examining the relationship between probiotics, gut microbiota, and serotonin. The authors reviewed serotonin synthesis and metabolism, mechanisms by which gut microbes influence serotonin production and transport, and evidence from experimental and animal studies showing how microbiota changes can affect gut-derived serotonin. They also explored communication between the microbiota and the brain via neural, immune, and endocrine pathways. A focus was the potential for probiotics to modulate serotonin. Evidence suggests certain probiotic strains can alter gut microbiota composition, increase serotonin transporter expression, modulate immune responses, and influence cell activity, all contributing to changes in gut-derived serotonin. Several animal studies reported that specific probiotics increased serotonin gene expression, enhanced intestinal motility, and affected serotonin signalling pathways. The review also highlighted that modulating serotonin through probiotics could benefit conditions involving disrupted gut-brain communication, such as irritable bowel syndrome or mood disorders. Overall, the literature supports the role of gut microbiota in regulating serotonin and suggests that probiotics may offer promising interventions for gastrointestinal and neurological health.
Abstract:
Modulatory effects of serotonin (5‐Hydroxytryptamine [5‐HT]) have been seen in hepatic, neurological/psychiatric, and gastrointestinal (GI) disorders. Probiotics are live microorganisms that confer health benefits to their host. Recent research has suggested that probiotics can promote serotonin signaling, a crucial pathway in the regulation of mood, cognition, and other physiological processes. Reviewing the literature, we find that peripheral serotonin increases nutrient uptake and storage, regulates the composition of the gut microbiota, and is involved in mediating neuronal disorders. This review explores the mechanisms underlying the probiotic‐mediated increase in serotonin signaling, highlighting the role of gut microbiota in the regulation of serotonin production and the modulation of neurotransmitter receptors. Additionally, this review discusses the potential clinical implications of probiotics as a therapeutic strategy for disorders associated with altered serotonin signaling, such as GI and neurological disorders. Overall, this review demonstrates the potential of probiotics as a promising avenue for the treatment of serotonin‐related disorders and signaling of serotonin.
Article Publication Date: 7/12/2023
DOI: 10.1002/fsn3.3826
