Altered sensitivity of forebrain neurones to iontophoretically applied noradrenaline in aging rats.

Responses of unidentified neurones in the rostral cerebral cortex to iontophoretically applied noradrenaline and GABA were compared in young (3-4 months old) and old (22-24 months old) albino rats. Depressant responses to noradrenaline were smaller in the older animals and this was manifested particularly as a decrease in response duration. Depressant responses to GABA did not differ significantly in the two groups. The results indicate that neurones in the cerebral cortex, as in the cerebellum, exhibit a decrease in postsynaptic responsiveness to noradrenaline with advancing age.