Pharmacological characterization and anatomical distribution of the dopamine transporter in the mouse cerebellum

We studied the binding parameters, the pharmacological profile and the anatomical distribution of the dopamine transporter in the mouse cerebellum by using the specific dopamine uptake antagonist [(3)H]GBR12935 and an antidopamine transporter monoclonal antibody. Competition experiments in cerebellar and striatal membrane preparations showed that [(3)H]GBR12935 binds to a specific binding site, sensitive to dopamine and low concentrations of mazindol. The affinity of dopamine for the cerebellar binding site was one order of magnitude lower than the affinity for the striatal binding site. Saturation experiments in cerebellar membrane preparations and thin frozen sections showed that the affinity of [(3)H]GBR12935 for this binding site is similar to its affinity for the striatal dopamine transporter. Saturable binding was lobule specific and in general was higher in the molecular layer compared to the granule cell layer. The immunohistochemical signal was mostly concentrated in the Purkinje cell layer and the cerebellar nuclei. The results suggest that the cerebellar dopamine transporter is similar but not identical to the striatal dopamine transporter and that it is present in the mouse cerebellum in a lobule and lamina specific pattern.