Comparison of the subregional distributions of the monoamine vesicular transporter and dopamine uptake complex in the rat striatum and changes during aging.

We have studied the heterogeneous distribution of the vesicular monoamine transporter, labelled with 3H dihydrotetrabenazine (3H TBZOH) and the dopamine uptake complex, labelled with 3H GBR12783 in the rat striatum. The ratio TBZOH/GBR12783 was higher in the anterior part of the striatum than in the caudal part. This discrepancy could not be explained by the contribution of serotoninergic innervation to 3H TBZOH binding, since the ratio TBZOH/citalopram was also higher in the anterior striatum than in the caudal striatum. The monoamine vesicular transporter and the dopamine uptake complex were more abundant in the lateral regions than in the regions situated near the midline. In the caudal striatum, the ventral part was richer in vesicular transporter than the dorsal part. In aged rats (30 months), a significant decrease in the density of both transporters was noticed in the middle part of the striatum. In the anterior part of the striatum, the ratio TBZOH/GBR12783 was elevated in aged rats compared to adult ones. This could participate in a functional adaptation of the partially diminished population of dopaminergic neurons during aging.