Time course of postmortem modifications in synaptosomal [3H]dopamine uptake and [3H]GBR 12783 binding to the dopamine uptake complex in the rat striatum.

The present study focuses on the changes of two biochemical markers of the striatal dopaminergic innervation evaluated after different postmortem storage periods of rat heads either at room temperature (21 degrees C) or at 4 degrees C: (i) the uptake of [3H]dopamine (DA) into striatal synaptosomes and (ii) the specific binding of [3H]GBR 12783, a selective ligand for the neuronal dopamine uptake sites, to a striatal membrane fraction. The uptake of [3H]DA was completely abolished after 24 and 72 h storage of the tissue at 21 degrees C and 4 degrees C, respectively, whereas in the same conditions, the binding of [3H]GBR 12783 was slightly decreased. The Km and Kd of these two processes were virtually unchanged after the different storage periods considered, whereas the Vmax and Bmax were markedly decreased.