ABSTRACT
Dopamine neurons are widely distributed in the nervous system, being found in the retina, olfactory bulb, adjacent to the ventricles of the brain and in autonomic ganglia. Most dopaminergic neurons, however, are confined to a few nuclei in the brainstem but send their axons to many regions of the forebrain including the cerebral cortex. Vesicular monoamine transporters (VMAT) are blocked by the drug reserpine which, by preventing vesicular storage, drastically impairs monoamine neurotransmission. Dopamine is taken into vesicles by a VMAT which actively transport catecholamines and serotonin using the efflux of protons from the vesicle to provide the energy. Firstly, the mesocortical neurons have no autoreceptors which means they lack the normal regulation of synthesis and release of dopamine. In addition, D2 receptors are autoreceptors on dopamine neurons in the substantia nigra and ventral tegmentum where they help to regulate dopamine synthesis.
