Alterations in beta 1- and beta 2-adrenergic receptor density in the cerebellum of aging rats

The densities of beta 1 and beta 2-adrenergic receptors were determined in homogenates of cerebral cortex and cerebellum of rats between 3 and 14 mo of age. No change in either receptor population occurred in the cortex during this period. In the cerebellum, a 20--25% decrease in the density of beta 2 receptors and a 350% increase in the density of beta 1 receptors occurred. The increase in beta 1 receptors in the cerebellum may be the result of a decrease in the function of the noradrenergic projections from the locus coeruleus which synapse on cerebellar Purkinje cells.