AGE
, Volume 11, Issue 4, pp 120-127

Age-related electrophysiological changes in cerebellar noradrenergic receptors

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Abstract

Noradrenergic transmission in the central nervous system declines early in the aging process. This decline can be demonstrated as subsensitivity to the depressant effects of norepinephrine on cerebellar Purkinje neurons of aged rats. In young rats alpha1 alpha2 and beta adrenergic receptors are present and functional in the cerebellar cortex. The purpose of this study was to determine which of these receptor subtypes alter their response with age. Inhibition of the spontaneous activity of Purkinje neurons by selective noradrenergic agonlsts was compared in young (3-month-old) and aged (18-and 26–28-month-old) Fischer 344 rats. These agonists were applied to Purkinje neurons by pressure microejection from multi-barreled micropipettes and the change in neuronal action potential discharge rate was recorded. Purkinje cells of both groups of aged rats were significantly less sensitive to locally-applied isoproterenol, a beta-adrenerglc agonist, than Purkinje cells of young rats. Subsensitivity to the alpha, agonist phenylephrine and the alpha2 agonist clonidine was not observed in the aged rats. These results suggest an age-related functional decline in an adenylate cyclase-linked beta receptor system with no concomitant functional change in receptor systems linked to other second messengers.