Dopamine is a natural chemical substance that is produced from the amino acid tyrosine by a mid-brain structure called the substantia nigra. As a neurotransmitter, dopamine transmits chemical signals from the dopamine-containing neurons to target cells that contain dopamine receptors. In the brain, dopamine controls physical movement, memory, alertness, attention, emotions and perception of pain and pleasure. As a synthetic medication, dopamine is administered intravenously to increase cardiac output during cardiogenic or hypovolemic shocks.
Schizophrenia and Psychosis
According to the "British Journal of Nursing," increased dopamine in the limbic system is linked to suspicious personality, paranoia and withdrawal from social situations. Drugs, such as amphetamines and cocaine, cause buildup of dopamine, which leads to drug-induced psychosis or schizophrenia. In Parkinson's disease, dopamine-containing cells in the substantia nigra degenerate and die out. Parkinson's disease patients who are treated with too much L-dopa, a precursor of dopamine, may experience psychosis similar to psychosis seen in schizophrenia.
Increased Impulsive Behavior
High levels of dopamine in the brain are found in patients with attention deficit/hyperactivity disorder and Parkinson's patients treated with L-dopa, who exhibit impulsive behavior. Individuals with boosted brain dopamine levels were more likely to act impulsively with need for instant gratification. Dopamine plays a major role in motivation, learning through reinforcement and addictions, such as drug, food, alcohol, tobacco, sex and gambling, according to the "Journal of Neuroscience."
As a hormone, dopamine is secreted by the hypothalamus to inhibit prolactin hormone secretion by the pituitary gland. Too much dopamine and abnormal inhibition of prolactin have been associated with menstrual disorders, delayed puberty, infertility and decreased immunity, says the "Journal of Immunology."
Minor Side Effects
The Merck Manual describes minor side effects of intravenous dopamine administration, which include nausea, vomiting, headache, fast heart beat, and irritation or skin necrosis at the site of injection. According to the "Journal of the Royal Society of Medicine," prolonged dopamine administration at high doses may result in gangrene of fingers and toes. Patients, such as diabetics, with blood circulation problems or peripheral vascular disease are at an increased risk for dopamine gangrene.
Life-threatening side effects are related to anaphylactic symptoms, such as difficulty breathing, chest tightness, blue skin discoloration, swelling of face, tongue or throat, and decreased or increased heartbeat with or without arrhythmia.