Dopamine is a neurotransmitter synthesized by your body from the dietary intake of an amino acid called tyrosine, found in protein-rich foods such as meats and cheeses. Dopamine is also a precursor molecule to two other important body chemicals--epinephrine and norepinephrine, sometimes called adrenaline and noradredaline. The brain and nervous system utilize neurotransmitters to send messages in the form of electrochemical impulses throughout your body and, thus, regulate all of your body's functions.
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Dopamine regulates a variety of functions within your brain and body. It helps to regulate blood flow through the arteries, modulates eating habits, contributes to learning and high cognitive functioning, reinforces behavior and regulates motor activity. It is also involved in regulating the secretion of hormones from the pituitary gland and contributes to the function of the autonomic nervous system.
Dopamine exerts different effects in different regions and pathways throughout the brain. In the mesolimbic pathway, dopamine is believed to be involved in motivation and addiction due to the feelings of reward and pleasure associated with dopamine release here. In the mesocortical pathway, dopamine is linked to emotional and motivational activities. In the nigrostriatal pathway dopamine is responsible for regulating and initiating motor activity. In the tuberoinfundibular pathway, dopamine regulates the release of hormones from the pituitary gland.
Degeneration of cells that release dopamine or dysfunction of this neurotransmitter system contribute to the pathology of neurological and psychiatric disease. Parkinson's disease, a movement disorder associated with muscle tremors and slowed movements, is the result of the degeneration of dopamine neurons in the nigrostriatal pathway. In the mesocortical and mesolimbic pathways, dopamine dysfunctions contribute to schizophrenia, depression and anxiety disorders.
Dopamine and Addiction
Dopamine is of particular interest to scientists studying addiction and addictive behaviors. Psychoactive drugs are believed to exert their euphoric effects by stimulating dopamine release. Release of the neurotransmitter results in feelings of pleasure and reward and contributes to reinforcement of the behavior that led to dopamine release. Chronic drug use is believed to decrease dopaminergic function and contribute to drug-seeking behavior.
REFERENCES & RESOURCES
- "Molecular Neuropharmacology" ; Nestler, Hyman and Malenka; 2009
- "Neurotransmitters and Neuromodulators: A Handbook of Receptors and Biological Effects"; Oliver von Bohlen und Halbach and Rolf Dermietzel; 2006
- ChangingMinds.org Dopamine Pathways
- AddictionScience.net Pleasure Systems in the Brain
- Psychology Today: Dopamine