Tetrahydroaminoacridine facilitates passive avoidance learning in rats with nucleus basalis magnocellularis lesions

The effect of bilateral ibotenic acid lesions of the nucleus basalis magnocellularis (NBM) on performance in a step-through passive avoidance task and the ability of tetrahydroaminoacridine (THA) to enhance learning were evaluated. Fischer 344 rats were used in a passive avoidance task in which footshock was replaced by ultrasound (30-62 K Hz, 125 dB) as the aversive training stimulus. THA was given immediately after each single daily training trial and retention was tested 24 hr later for 10 consecutive days. Although NBM lesions alone did not impair passive avoidance learning, THA at 5 mg/kg (i.p.), but not 1 mg/kg, significantly facilitated latency performance in NBM-lesioned rats.