Dopamine receptor agonists are a class of drugs with similar actions to dopamine, a neurotransmitter that occurs naturally in the brain. A neurotransmitter is a chemical that allows the movement of information from one nerve cell (neuron) across the gap between the adjacent neuron. Dopaminergic receptors are protein complexes on the surface of certain neurons of the sympathetic autonomic nervous system that bind to dopamine.
Dopamine stimulates the heart, increases the blood flow to the liver, spleen, kidneys, and other visceral organs, and controls muscle movements and motor coordination through an inhibitory action over stimuli response. Abnormal low levels of dopamine are associated withtremors, muscular rigidity, low blood pressure, and low cardiac input. Therefore, dopamine and dopaminergic agonist drugs are administered to treat shock and congestive heart failure and to improve motor functions in patients with Parkinson's disease and other movement disorders. The balance between two neurotransmitter levels, acetylcholine and dopamine, is essential for motor and fine movement coordination. The balance is frequently found altered in movement disorders, due to a dopamine deficiency that results in excessive stimulation of skeletal muscles. In Parkinson's disease, either dopamine levels or the number of dopamine receptors are progressively decreased, resulting in tremors, slowness of movements, muscle rigidity, and poor posture and gait (manner of walking). Symptoms of Parkinson's disease are treated with anticholinergic drugs and/or dopamine receptor agonists. Dopaminergic agonist drugs such as levodopa (L-dopa) along with carbidopa, bromocriptine mesylate, cabergoline, pergolide mesylate, pramipexole, and ropini-role hydrochloride are prescribed to treat the symptoms of Parkinson's disease, either alone or in combinations.
Sandra Galeotti, The Gale Group Inc., Gale, Detroit,