The role of serotonin and its pathways in gastrointestinal disorders

Gut-derived serotonin and its emerging roles in immune function, inflammation, metabolism and the gut–brain axis

“…The gut-brain axis serves as a platform for continuous reciprocal communication between the brain and the gut. This axis integrates information from the hypothalamic-pituitary-adrenal (HPA) axis, the limbic system, the autonomic nervous system, endogenous pain regulation systems, and ascending aminergic pathways, as well as the endocrine system and the gut microbiota [34]. 5-HT, acting as a neurotransmitter in the gut-brain axis, exerts effects locally in the gut and systemically, which is both physiologically and clinically relevant.…”

“…Bellini et al summarized several studies supporting the coexistence of psychological/psychiatric disorders, such as stress, anxiety, and depression in patients with functional gastrointestinal disorders (FGID). Moreover, they presented the evidence that patients diagnosed with FGID, in coexistence with psychiatric disorders, often show more severe symptoms, have longer recovery times, and have a worse prognosis suggesting the probability of common genetic tendency involving alteration in 5-HT signalling [34].…”

“…As 5-HTR 4 is expressed in the gut (in enterochromaffin cells and enteric neurons) and limbic system, the authors suggest the involvement of 5-HTR 4 in psychiatric diseases and gastrointestinal disorders, referring to the case of depression-induced IBS [49]. Moreover, the authors added that 5-HT can activate the HPA axis and alter gastrointestinal functions in patients with depression, leading to symptomatic IBS [34,49]. Recently, selective serotonin reuptake inhibitors (SSRIs) have been proposed as a possible common therapy for depression and IBD [50].…”