NICOTINE ENHANCES THE LEARNING AND MEMORY OF AGED RATS

The cognitive performance of young adult (2-3-month-old) and aged (22- 24 month-old) rats was characterized in one of three different behavio ral tasks, and the ability of daily nicotine treatment to alleviate ag e-related learning and memory deficits was evaluated. Aged rats receiv ed an IP injection of either nicotine (0.2 mg/kg) or saline vehicle 15 min prior to daily testing; young control rats received saline vehicl e injections. Compared to young control, aged control rats were severe ly impaired in the acquisition of one-way active avoidance pole jumpin g over 12 days of testing. Nicotine pretreatment of similar aged rats markedly improved overall learning and the rate of learning compared t o aged controls. In Lashley III maze performance, aged control rats ma de substantially more alternation errors than young controls; however, aged rats pretreated with nicotine made significantly fewer errors ov er the entire 20-day test period compared to aged controls. During 30 days of 17-arm radial maze testing, aged control animals were severely impaired in general learning and reference (long-term) memory, but on ly mildly impaired in working (short-term) memory. Nicotine pretreatme nt of similar aged rats induced a substantial enhancement in overall l earning and reference memory, but did not affect working memory. These results indicate that chronic nicotine administration can improve the impaired learning/memory abilities of aged rats in several tasks, and suggest that stimulation of central nicotinic receptors may be of con siderable therapeutic value to treat age-related memory impairment.