Dopamine molecule. Computer model of a molecule of the neurotransmitter and neurohormone dopamine. The atoms are represented as spheres and are colour-coded: carbon (red), hydrogen (white), oxygen (green) and nitrogen (orange). This is one of the most important of the neurotransmitters in the central nervous system (CNS). It plays a critical role in the way the brain controls movement. Underproduction of dopamine results in the movement disorder Parkinson's disease. Excess dopamine may contribute to psychotic illnesses, notably schizophrenia. Dopamine also acts as a hormone, inhibiting the release of the hormone prolactin, which stimulates and maintains lactation, from the pituitary gland.