serotoninsecreting

Serotonin-secreting refers to cells or tissues that produce and release serotonin (5-hydroxytryptamine, 5-HT) as part of their normal function. Serotonin is a monoamine neurotransmitter and local signaling molecule involved in a wide range of physiological processes.

In humans, the largest source of serotonin is the gastrointestinal tract, where enterochromaffin cells release 5-HT in response to luminal stimuli, influencing gut motility and secretion. In the central nervous system, serotonergic neurons in the raphe nuclei synthesize and project serotonin to widespread brain regions, modulating mood, sleep, appetite, and cognition. Platelets also store high levels of serotonin, taking it up from plasma and releasing it during hemostasis.

Biosynthesis begins with the amino acid tryptophan, converted to 5-hydroxytryptophan by tryptophan hydroxylase and then decarboxylated to serotonin by aromatic L-amino acid decarboxylase. Serotonin is stored in secretory vesicles in both enterochromaffin cells and neurons and is released by exocytosis in response to stimuli. Inactivation mainly occurs via reuptake through the serotonin transporter (SERT), followed by metabolism to 5-hydroxyindoleacetic acid (5-HIAA) by monoamine oxidase A and excretion in urine.

Physiological roles of serotonin-secreting systems include regulation of gut motility and secretion, vascular tone, and coagulation in the periphery, alongside mood, sleep, appetite, and cognitive functions in the brain. Clinical relevance includes dysregulation linked to mood disorders, irritable bowel syndrome, and carcinoid syndrome, as well as pharmacological modulation by SSRIs, SNRIs, MAO inhibitors, and other serotonergic agents.