Dopamine

Dopamine (abbreviated as DA), a simple organic chemical in the catecholamine family, is a monoamine neurotransmitter which plays a number of important physiological roles in the bodies of animals. In addition to being a catecholamine and a monoamine, dopamine may be classified as a substituted phenethylamine. Its name derives from its chemical structure, which consists of an amine group (NH2) linked to a catechol structure, called dihydroxyphenethylamine, the decarboxylated form of dihydroxyphenylalanine (acronym DOPA). In the brain, dopamine functions as a neurotransmitter—a chemical released by nerve cells to send signals to other nerve cells. The human brain uses five known types of dopamine receptors, labeled D1, D2, D3, D4, and D5. Dopamine is produced in several areas of the brain, including the substantia nigra and the ventral tegmental area.

Dopamine plays a major role in the brain system that is responsible for reward-driven learning. Every type of reward that has been studied increases the level of dopamine transmission in the brain, and a variety of highly addictive drugs, including stimulants such as cocaine and methamphetamine, act directly on the dopamine system. There is evidence that people with extraverted (reward-seeking) personality types tend to show higher levels of dopamine activity than people with introverted personalities. Several important diseases of the nervous system are associated with dysfunctions of the dopamine system. Parkinson's disease, an age-related degenerative condition causing tremor and motor impairment, is caused by loss of dopamine-secreting neurons in the substantia nigra. Schizophrenia has been shown to involve elevated levels of dopamine activity in the mesolimbic pathway and decreased levels of dopamine in the prefrontal cortex. Attention deficit hyperactivity disorder (ADHD) and restless legs syndrome (RLS) are also believed to be associated with decreased dopamine activity.

Dopamine is available as an intravenous medication acting on the sympathetic nervous system, producing effects such as increased heart rate and blood pressure. However, because dopamine cannot cross the blood–brain barrier, dopamine given as a drug does not directly affect the central nervous system. To increase the amount of dopamine in the brains of patients with diseases such as Parkinson's disease and dopa-responsive dystonia, L-DOPA (the precursor of dopamine) is often given because it crosses the blood–brain barrier relatively easily.

Read more about Dopamine:  History, Chemistry, Receptors, Functions in The Brain, Links To Psychosis, Therapeutic Use, Toxicity

Other articles related to "dopamine":

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Biology Of Depression - Abnormalities By Brain Region - Ventral Tegmental Area (VTA)
... sends projections to the nucleus accumbens that use the neurotransmitter dopamine ... Addictive drugs universally increase the effects of dopamine in this system, whereas drugs that oppose dopamine produce anhedonia of the sort seen in depressed people ... Dopamine-enhancers such as cocaine often relieve the lack-of-pleasure in depression, but the effects only last as long as a drug is present in the body that is, they ...
Mephedrone - Pharmacology
... cathinones are determined by the differences in how they bind to noradrenalin, dopamine and serotonin transporters ... Dopamine and serotonin were collected using microdialysis, and increases in dopamine and serotonin were measured using HPLC ... Reward and drug seeking are linked to increases in dopamine concentrations in the nucleus accumbens, and drug half-life plays a role in drug seeking, as well ...
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