Cerebellar GABAA and benzodiazepine receptor characteristics in young and aged mice

Age-related differences in GABAA and benzodiazepine receptors were investigated in cerebella of young (1-month-old), mature adult (3 months old), older (8 months old) and aged (20 months old) mice. In cerebellar membranes of aged mice, [3H]muscimol binding was significantly higher as compared to those from all three younger age groups. Binding was the same in these younger age groups. Scatchard analysis of binding isotherms in cerebellum of young and aged mice showed the presence of two components (with different affinities and binding capacities). In aged mice, a significantly lower KD of low affinity sites and a significantly higher Bmax of high affinity sites were noted as compared to those in young mice. However, [3H]flunitrazepam binding to benzodiazepine receptors in cerebellar membranes was the same in both age groups. These results suggested that GABAA receptor binding was increased during senescence in cerebella without altering benzodiazepine binding.