DOPAMINE

Dopamine

Dopamine

What Is Dopamine?

Dopamine is a neurotransmitter. It is a chemical that transmits nerve impulses (or electrical signals) across the gaps between nerve cells. In this way, dopamine carries information between nerve cells (Iversen & Iversen, 2007). Dopamine, identified as a central nervous system agent in 1959, is a neurotransmitter (nerve-signaling molecule) the body makes from the amino acid tyrosine. Dopamine, in turn, serves as the molecule the body uses to make adrenaline and noradrenaline. In addition to operating in the nervous system signaling, it also acts as a hormone in an area of the brain called the hypothalamus, regulating the release of the hormone prolactin, which is involved in parenting behavior and milk production (Wittmann et al, 2005). The body regulates dopamine' activity in the brain in part by using proteins called dopamine transporters, which can take up dopamine and dump it back into a cell, preventing the signaling molecule from exerting its activity. The body also has five types of proteins, called dopamine receptors, responsible for recognizing the dopamine molecule, binding to it, and transmitting its signal to the cell. Dopamine is at the center of the development of a number of psychiatric disorders, including addiction and schizophrenia, and it also plays a prominent role in the manifestations of Parkinson's disease (Smith-Roe & Kelley, 2000) (Koob, 2006).

Description

The brain produces dopamine in three primary areas: the substantia nigra, the ventral tegmental area, and the arcuate nucleus. The first two are of interest in terms of psychiatric disorders; the arcuate nucleus is associated with dopamine's role as a neurohormone in prolactin regulation. Disorders associated with dopamine signaling have a biological basis in the brain that appears to be site-specific. The brain has four major dopamine-signaling pathways (Wittmann et al, 2005) (Koob, 2006).

The mesocortical pathway connects the ventral tegmental area to the cortex, the part of the brain involved in cognition, and that may play a role in motivation. This pathway features in hypotheses of dopamine's association with schizophrenia (Missale et al, 1998).

The mesolimbic pathway also begins in the ventral tegmental area, which is linked to the nucleus accumbens, the largest component of the ventral striatum. Much research has associated the nucleus accumbens and the mesolimbic pathway with brain reward processes and addiction also with different aspects of schizophrenia (Koob, 2006).

The nigrostriatal pathway connects the dopamine-producing nigrostriatal area with the striatum and plays a high-profile role in the development of Park-sinon's symptoms. The ...