Brain benzodiazepine binding in aged rats.

Membrane [3H]flunitrazepam binding to central and peripheral benzodiazepine binding sites was studied in four brain areas (cerebellum, cortex, striatum and midbrain) of young (age 2-4 months) and aged (> 24 months) rats. A generalized reduction in the density of central binding sites (Bmax) was observed in all brain areas examined in aged rats. This reduction is irrelevant of the brain area and, according to literature, may correspond to cell loss and/or differential expression of mRNAs coding for the subunits of the GABA/benzodiazepine receptor complex during ageing. In the case of the peripheral binding sites, there was a decrease of Bmax in all brain areas with the exception of the cerebellum. However, the percent reduction of peripheral binding sites varied significantly among the different brain areas. These data suggest a differential effect of ageing on brain benzodiazepine binding which may reflect the special role for each brain area during ageing.