DOPAMINE

The Role of Dopamine in Depression

The Role of Dopamine in Depression

Introduction

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 nervous system signaling, it also acts as a hormone in an area of the brain called the hypothalamus, regulating release of the hormone prolactin, which is involved in parenting behavior and milk production. 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 signalling 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 centre 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 (Everitt, 1997).

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.

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. 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. The nigrostriatal pathway connects the dopamine-producing nigrostriatal area with the striatum and plays a high-profile role in the development (Everitt, 1997).

Role of Dopamine

The exciting discoveries began in the spring of 1977. They had discovered effective tools. Tools that allow scientists to penetrate into the brain's nerve cells. Important discoveries made daily on the inner workings of the brain. Now we know that there are certain vital chemicals that carry messages between brain cells (Everitt, 1997). In essence, these chemicals allow the brain nerve cells “Talk” to each other.

On a typical day in the brain, trillions of messages sent and received. The messages are happy or positive, carried by the “Happy messengers” (technically known as biogenetic amine system / endorphin). Other messages are somber and depressing. These were driven by “Sad messengers”. Most nerve centers receive both types of messages. While transmission is in balance, it all works normally.

Stress causes problems with the Happy Messengers. When life is calm and smooth, the messengers can meet their ...