Beta-adrenoceptor density and subtype distribution in cerebellum and hippocampus from patients with Alzheimer's disease

Abstract

beta-Adrenoceptor density and beta 1- and beta 2-subtype distribution were examined in hippocampi and cerebella from patients with Alzheimer's disease (AD/SDAT). Tissues from age-, sex and post-mortem delay matched non-demented patients served as controls. The total beta-adrenoceptor density as evaluated in saturation experiments with the hydrophilic radioligand [3H]CGP 12177 was higher in hippocampal (36-39 fmol/mg protein) than cerebellar tissues (20-21 fmol/mg), however, no differences were found in either brain region between AD/SDAT patients and controls. Subtype distribution using the highly selective beta 1-adrenoceptor antagonist CGP 20712A revealed a slightly higher proportion of beta 1-adrenoceptors in hippocampus (26%-27%) than in cerebellum (20%-21%) with, again, no difference between AD/SDAT and controls. We recently described a 40% reduction in basal and stimulated adenylyl cyclase activity in post-mortem hippocampus of AD/SDAT patients, a brain region greatly affected by the disease, the present data now demonstrate that this disease-related effect is not mirrored by a similar change in beta-adrenoceptor density nor in subtype distribution.