-BETA-CARBOMETHOXY-3-BETA-(4-FLUOROPHENYL)TROPANE] BINDING TO RAT-BRAIN MEMBRANES - COMPARING DOPAMINE CELL BODY AREAS WITH NERVE-TERMINAL REGIONS

Potential differences between somatodendritic and axonal dopamine tran sporters were examined by comparing the binding constants of [H-3]WIN 35,428 [2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane] binding to membranes prepared from the rat ventral mesencephalon, containing A9 and A10 dopamine cell bodies, and from the nucleus accumbens. Saturati on analysis of [H-3]WIN 35,428 binding, in the presence of compounds t o occlude norepinephrine and serotonin transporters, was performed by both the ''unlabeled'' method (varying unlabeled ligand) and ''labeled '' method (varying radioligand). The density of binding was substantia lly lower in the ventral mesencephalon than in the nucleus accumbens, but the binding affinity was only slightly different. Likewise, the di fferences between the two regions in the inhibitory potency of cocaine and GBR 12909 nyl)-methoxy)-ethyl)-4-(3-phenylpropyl)piperazine] were not substantial. The results suggest that somatodendritic and axonal dopamine transporters in the Ventral mesencephalon and nucleus accumbe ns are not very different as far as their binding domains for uptake b lockers such as cocaine and GBR 12909 are concerned.