Serotonin, 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter synthesized from the amino acid tryptophan.
The functions of serotonin include mood stabilization, happiness, anxiety regulation, wound healing, nausea/vomiting, bone health, gastrointestinal motility, sleep-wake cycles, blood clotting, and sexual function.
Serotonin is primarily produced from the amino acid tryptophan. Enterochromaffin cells produce around 90% of serotonin in the gastrointestinal tract, with the remainder produced in the brain’s raphe nuclei. Gut bacteria also play a role in serotonin production in the GI tract.
Serotonin is released from presynaptic neurons into the synaptic cleft via exocytosis when an action potential reaches the terminal. The released serotonin then binds to and activates receptors on the postsynaptic cell. Serotonin release is potentiated by experience and underlies aversive learning.
Detoxification of serotonin involves its breakdown by the enzymes monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). The main metabolites are vanillylmandelic acid and conjugated MHPG, which are then excreted in the urine.
Serotonin is a neurotransmitter and hormone that modulates mood, emotions, appetite, digestion, sleep, and other bodily functions.
It is primarily found in the brain, bowels, and blood platelets. Serotonin modulates mood, emotions, appetite, digestion, sleep, and other bodily functions. In the central nervous system, serotonin plays a key role in mood regulation, while in the peripheral nervous system, it impacts gastrointestinal function and blood clotting.
According to Movassaghi & Andrews (2024) in their article “Call me serotonin,” serotonin has multiple roles in the body:
It maintains a sense of well-being and happiness; low levels are associated with mood disorders such as depression and anxiety.
Serotonin attunes the production of melatonin, a hormone that controls sleep patterns; promotes healthy sleep, and helps maintain the body’s circadian rhythm.
It regulates bowel movements and function, influencing appetite control, food intake, and satiety; imbalances induce gastrointestinal conditions like irritable bowel syndrome (IBS).
It Impacts memory, learning, and decision-making by modulating communication between neurons, affecting information processing and retention.
Stored in blood platelets and released during clot formation, serotonin promotes vasoconstriction to help stop bleeding by narrowing blood vessels.
Serotonin inflects pain perception and response, affecting pain pathways in the brain and spinal cord to either advance or diminish pain sensation.
It plays a role in regulating body temperature and helps maintain homeostasis in response to environmental changes.
Influences bone density and growth, serotonin receptors in bone tissue indicate a role in bone metabolism.
Stimulates the nausea reflex when irritants are present in the gut and activates receptors in the brain that trigger vomiting.
It affects heart rate and blood pressure and modulates vascular tone and blood vessel constriction.
Influences sexual desire and function, serotonin levels affect libido and sexual performance.
Regulates breathing patterns, maintains normal respiratory rhythm, and responds to environmental oxygen levels.
Modulates the release of various hormones and influences the hypothalamic-pituitary-adrenal (HPA) axis, affecting stress response.
Serotonin weighs upon social communication and behavior, emotional regulation and social bonding.
Modulates immune responses, and influences the activity of immune cells and inflammatory processes.
It’s critical in brain development and maturation, promoting neuronal growth, differentiation, and synaptic plasticity.
Regulates vascular smooth muscle contraction, and influences blood flow to various organs and tissues.
Serotonin is produced through a multi-step biochemical process, as outlined by Kossatz et al. (2024) in “G protein-specific mechanisms in the serotonin 5-HT2A receptor regulate psychosis-related effects and memory deficits”:
Serotonin is released through the synthesis from tryptophan, storage in synaptic vesicles, neuronal activation, the influx of calcium ions, vesicle fusion with the presynaptic membrane, release into the synaptic cleft, binding to receptors on the postsynaptic membrane, reuptake into the presynaptic neuron, and degradation by monoamine oxidase (MAO) as highlighted by Salvan et al. (2023) in “Serotonin regulation of behavior via large-scale neuromodulation of serotonin receptor networks”:
Detoxification of serotonin involves reuptake, enzymatic degradation, and excretion, as discussed by Lubman et al. (1983) in “Altered mood and norepinephrine metabolism following withdrawal from alcohol”:
The disorders associated with serotonin imbalance anxiety, depression, irritable bowel syndrome (IBS), schizophrenia, migraines, and anxiety disorders as noted by Chandley and Ordway (2012) in “The Neurobiological Basis of Suicide” detail disorders linked to serotonin imbalance:
Serotonin is involved in addiction via its influence on reward pathways, mood regulation, impulse control and decision-making, stress response, and craving and withdrawal symptoms as spotlighted by Müller and Homberg (2015) in “The Role of Serotonin in Drug Use and Addiction” explain serotonin’s role in addiction:
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Magnified Health Systems aims to improve the quality of life for people struggling with substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare providers.
Dr. Bickley graduated from U.C. Irvine with honors: Phi Beta Kappa, Golden Key International Honor Society, Cum Laude. He has been featured on national radio and print media. He is also a frequent lecturer at National Conferences. He holds an A.S. degree in Drug & Alcohol Studies, and two B.A. degrees in Criminology & Psychology, and masters and doctoral degree in Clinical Psychology. He is a licensed California Drug & Alcohol Counselor Level II, a licensed Clinical Supervisor and is certified in treating Eating Disorders.
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