Effect of aging on neurotransmitter receptor binding in rat and human brain

β-Adrenergic and GABA receptor binding were measured in brain areas of rats 3 to 24 months of age. While GABA receptor binding was not significantly different across age in any area, β-adrenergic receptor binding was significantly reduced in the cerebellum and brain stem, but not cerebral cortex, of 24-month-old animals. The loss in β-adrenergic receptor binding does not correlate in a temporal fashion with the reported decrease in norepinephrine-stimulated cyclic AMP accumulation in the cerebellum which occurs as early as 12 months of age. An age-related reduction in β-adrenergic binding was also noted in human cerebellar tissue obtained at autopsy, suggesting that the cerebellar dysfunction seen with aging may be related to a loss of cerebellar neurons which receive noradrenergic input.