The roles of serotonin in human body

Serotonin is the best known as a neurotransmitter that modulates neural activity and a wide range of neuropsychological processes. It is a chemical that carries messages between nerve cells in the brain and throughout the human body.

Serotonin (5-hydroxytryptamine, 5-HT) was isolated and characterized in 1948 by Maurice Rapport and Irvine Page. The isolation of serotonin came after decades of investigation to characterize a vasoconstrictor substance that was suspected to be contained in platelets. It was discovered in blood, peripheral tissues and central nervous system.

In the human body serotonin is synthesized in two independent compartments that are separated by brain-blood barrier. The majority of serotonin is synthesized in enterochromaffin cells of the gastrointestinal tract, released in the blood stream and stored in blood platelets.

Serotonin regulates numerous biological processes including cardiovascular function, bowel motility, ejaculatory latency, and bladder control.

Serotonin is implicated in many physiological (body temperature, sleep, vomiting, sexuality, appetite), behavioral (aggression, mood) and cognitive (learning, memory) functions.

New work and research suggest that serotonin may regulate some processes, including platelet aggregation, by receptor independent, transglutaminase-dependent covalent linkage to cellular proteins.

The biological function of serotonin plays several roles in the human body, such as influencing learning, memory, happiness, and reward, as well as physiological processes such as regulation of sleep, behavior, and appetite.

Serotonin plays a significant role in the pharmacodynamic activities of antidepressants, such as SSRIs and SNRIS. Lack of enough serotonin is thought to play a role in depression, anxiety, mania and other health conditions.

When serotonin is at normal levels, people feel more focused, emotionally stable, happier and calmer. Low levels of serotonin are associated with depression.

The behavioral and neuropsychological processes modulated by serotonin include mood, perception, reward, anger, aggression, appetite, memory, sexuality, and attention, among others.
The roles of serotonin in human body

Biochemical reaction in depression

The biological factors that might have some effect on depression include: genes, hormones, and brain chemicals. Depression often runs in families, which suggests that individuals may inherit genes that make them vulnerable to developing depression. There is strong epidemiological evidence for a genetic contribution, especially for bipolar disorders, and heritability is estimated to be as high as 80%

Depression can be triggered by traumatic life events, poor diet, genetic conditions, blood sugar imbalances, medical illness, hormone imbalance, lack of exercise, medications, drug and alcohol use, and digestive difficulties. These triggers are known to cause or contribute to neurotransmitter imbalances.

Neurotransmitters are chemical messengers in the brain. The nerve cells of the brain use neurotransmitters to communicate with each other. The messages they send are believed to play a role in mood regulation.

Neurotransmitters in the brain — specifically serotonin, dopamine, or norepinephrine — affect feelings of happiness and pleasure and may be out of balance in people with depression. Dopamine creates positive feelings associated with reward or reinforcement that motivate us to continue with a task or activity. Norepinephrine helps human bodies to recognize and respond to stressful situations. Researchers suggest that people who are vulnerable to depression may have a norepinephrinergic system that doesn't handle the effects of stress very efficiently.

Another neurotransmitter is serotonin or the "feel good" chemical. In addition to helping regulate human mood, serotonin has a number of different jobs throughout the body from your gut to blood clotting to sexual function. Serotonin is produced by serotonergic neurons. Current research suggests that a decrease in the production of serotonin by these neurons can cause depression in some people, and more specifically, a mood state that can cause some people to feel suicidal.

The main symptoms of depression are due to a functional deficiency of the brain monoaminergic transmitters norepinephrine (NE), 5-HT, and/or dopamine (DA), whereas mania is caused by functional excess of monoamines at critical synapses in the brain.
Biochemical reaction in depression