Quantitative autoradiographic analysis of dopamine receptors, and DAT and DTBZ densities in the substantia nigra.

Autoradiograms show total binding of 1.44 nM [³H]SCH23390, 2.50 nM[³H]raclopride, 3.54 nM [³H]WC-10, 2.19 nM [³H]WIN35428, 4.53 nM [³H]DTBZ (A), and nonspecific binding in presence of 1 uM (+) butaclamol (for [³H]SCH23390), 1 µM S(-)-eticlopride (for [³H]raclopride and [³H]WC-10), 1 µM nomifensine (for WIN35428) and 1 µM S(-)-tetrabenazine (for DTBZ) (B) in the substantia nigra (SN) of aged human brain sections. [³H]Microscale standards (ranging from 0 to 36.3 nCi/mg) were also counted (C). Quantitative analysis of dopamine D₁, D₂ and D₃ receptors, and DAT and DTBZ densities (fmol/mg) and the dopamine D₂ ∶ D₃ receptor density ratio in human SN and red nucleus are shown in D and E respectively. The numbers 1 through 3 designate the following CNS anatomical regions: 1: Substantia nigra (SN); 2: Red nucleus (RN); 3: Thalamus.