Mesolimbic dopaminergic neurones and somatodendritic mechanisms.

The concept that a neurone may release transmitter from both dendritic and axonal sites was investigated by studying mesolimbic dopaminergic neurones. The rat ventral tegmentum (containing dendrites and somata of mesolimbic dopaminergic neurones) possessed high levels of dopamine and tyrosine hydroxylase. Slices of ventral tegmentum accumulated [3H]dopamine (15 or 60 nM) and stimulus-induced release of [3H]dopamine was observed after elevated potassium (44 mM). The potassium-induced release was calcium-dependent. These dopaminergic parameters were compared to those found for nucleus accumbens (containing terminals of mesolimbic dopaminergics neurones). Thioridazine and clozapine elevated 3,4-dihydroxyphenylacetic acid (DOPAC) concentration in ventral tegmentum.