Pronunciation: (dō'pu-mēn"),[key] —n. 1. Biochem.a catecholamine neurotransmitter in the central nervous system, retina, and sympathetic ganglia, acting within the brain to help regulate movement and emotion: its depletion may cause Parkinson's disease. Cf. dopa. 2. Pharm.a dopamine preparation used to increase the force of contraction of the heart in the treatment of shock. Cf. levodopa.