Reversal of learning and memory impairments following lesion of the nucleus basalis magnocellularis (NBM) by concurrent noradrenergic depletion using DSP4 in the rat

Abstract

In the following study the behavioural effects of simultaneous lesion of the nucleus basalis magnocellularis (NBM) using ibotenic acid and noradrenergic depletion following a single i.p. administration of DSP4 (50 mg/kg) were examined in the rat. NBM lesion induced a deficit in acquisition of a reinforced T-maze alternation task, a working memory adaptation of a spatial navigation task in a water maze and 24 h retention in a passive avoidance task compared to sham controls. No effect of the lesion on a reference memory version of spatial navigation in a water maze task was found. Animals that received a combination of NBM lesion and DSP4 treatment showed no impairment on any of the tasks that were impaired by NBM lesion alone. This indicates a reversal of the learning and memory deficits consequent to NBM lesion by simultaneous noradrenergic depletion. NBM lesion induced a significant reduction in cholineacetyltransferase activity in the frontal cortex, and DSP4 induced a significant decrease in noradrenaline concentration in occipital cortex and hippocampus, confirming the effects of these treatments. These results suggest an interaction between central noradrenergic and cholinergic systems in learning and memory processes.