Reserpine affects differentially the density of the vesicular monoamine transporter and dihydrotetrabenazine binding sites.

We have studied the effect of a single injection of reserpine (5 mg/kg, s.c.) on the synaptic vesicle monoamine transporter (VMAT) density in the rat striatum, using two labelling procedures: radioimmunolabelling with an antibody against VMAT, and binding of the specific ligand [(3)H]dihydrotetrabenazine ([(3)H]TBZOH). In the rostral and medial striatum, the distribution of VMAT immunoreactivity displayed the highest density in the lateral subregions. In the caudal part of the striatum, VMAT immunoreactivity showed increasing density from dorsal to ventral subregions. The VMAT immunoreactivity was not altered 2 and 30 days after the reserpine injection, whereas [(3)H]TBZOH binding site density, measured on adjacent slices, showed a dramatic decrease at day 2 and a moderate recovery at day 30, suggesting that despite a persistent blockade of [(3)H]TBZOH binding sites, VMAT protein density was unchanged.