Quantitative autoradiographic distribution of γ-hydroxybutyric acid binding sites in human and monkey brain

g-Hydroxybutyric acid (GHB), a naturally occurring metabolite of GABA, is present in micromolar concentrations in various areas of the mammalian brain. Specific GHB binding sites, uptake system, synthetic and metabolizing enzymes have been identified in CNS. The present study shows the anatomical distribution of GHB binding sites in sections of primate (squirrel monkey) and human brain by radioligand quantitative autoradiography. In both species the highest densities of binding sites were found in the hippocampus, high to moderate densities in cortical areas (frontal, temporal, insular, cingulate and entorhinal) and low densities in the striatum; no binding sites were detected in the cerebellum. High density of GHB binding was found in the monkey amygdala. In addition the binding characteristics 3 of [ H]GHB to membrane preparations of human brain cortex were examined. Scatchard analysis and saturation curves revealed both a high (K 9264.4 nM; B 10276110 fmol/mg protein) and a low-affinity binding site (K 916642 nM; B 87706159 fmol/mg d1 max1 d2 max2 protein). The present study is the first report on the autoradiographic distribution of specific GHB binding sites in the primate and human brain: such distribution is in both species in good agreement with the distribution found in the rat brain.