Nerve cells, or neurons, function as the communication system in the brain, similar to the way utility wires transmit electricity. The gap between two nerve cells is called a synapse, according to the University of Washington. The body produces substances called neurotransmitters to communicate between the nerve cells. Dopamine exists as one such neurotransmitter. Neurotransmitters play a part in the behavior changes in depression.
Neurotransmitters and Mood
"Integrative Psychiatry" describes dopamine as one of four neurotransmitters in the brain that influences the expressions of mood. The four neurotransmitters consist of serotonin, norepinephrine, dopamine and GABA. These substances act at the synapse to alter feelings in humans. Dopamine, an excitatory neurotransmitter, works by increasing the speed of a signal from the brain to other areas of the body.
Dopamine and Depression
"World Psychiatry" reported a decrease of the monoamine dopamine in the brain in depressed individuals. The depression theory of monoamine-deficiency posits that the underlying rationale for depression involves the depletion of dopamine, serotonin or norepinephrine in the central nervous system. "Progress in Neurobiology" reports that the research on dopamine and depression is in an infant stage of development, with few studies published.
Dopamine Agonists
According to "World Psychiatry," a dopamine agonist drug that is available is pramipexole, or Mirapex, but the medication remains limited to therapy for difficult-to-treat depression as an off-label medication. The drug stimulates dopamine receptors in the brain. Similar to serotonin and norepinephrine drugs, pramipexole takes as long as six weeks to produce an effect on mood.
Side Effects of Dopamine Agonists
Pramipexole has several side effects. According to "Davis' Drug Guide for Nurses," pramipexole produces mainly mild to moderate side effects of amnesia, dizziness, drowsiness, weakness, constipation, dry mouth, nausea and dyspepsia. On rare occasions, individuals report life-threatening reactions of sleep attacks.
Dopamine Agonist Drug Interactions
Pramipexole produces an increased risk of hallucinations and dyskinesia when given at the same time as levodopa, a drug for Parkinson's disease, according to "Davis' Drug Guide for Nurses." The drug cimetidine may increase the effect of pramipexole. Providers advise patients to bring a list of their medications to every office visit so that drugs can be reviewed for possible interactions.
References
- University of Washington: Neuroscience for Kids
- Integrative Psychiatry: Neurotransmitters
- "World Psychiatry"; Pathophysiology of Depression; Gregor Hasler; 2010
- "Davis' Drug Guide for Nurses"; Dulexotine; J. H. Deglin et al.; 2011
- "Progress in Neurobiology"; Depression and the role of genes involved in dopamine metabolism and signaling; Opmeer, E. M., Kortekaas, R. & Aleman A.; 2010
