Differential effects of nucleus basalis lesions in young adult and aging rats

To characterize age-related changes in frontal cortical plasticity, we asse ssed maze learning and frontal cortical pharmacology in young adult, middle -aged, and aged rats. Rats received either ibotenic acid or sham lesions of the nucleus basalis magnocellularis (NBM) and were then trained on a radia l maze task. After training, we assessed [H-3]desmethylimipramine (DMI), [H -3]muscimol, [H-3]AMPA, and [H-3]QNB binding using quantitative autoradiogr aphy. Both middle-aged and aged rats were impaired on the radial maze task. DMI binding was increased in both middle-aged and aged rats, while QNB bin ding was decreased in aged rats. While lesions impaired maze performance at all ages, middle-aged and aged rats showed more profound lesion-induced de ficits. Lesions increased GABA, and AMPA receptor binding in young adult ra ts only. These lesion-induced changes may reflect a compensatory response t hat is lost with advancing age. (C) 1999 Elsevier Science Inc. All rights r eserved.