Studies on the mechanism of avoidance facilitation by nicotine

A series of experiments were conducted to determine whether nicotine facilitates avoidance acquisition by enhancing consolidation or merely by stimulating performance. Sprague-Dawley albino rats were trained for 15 one-hour sessions in a discriminated leverpress avoidance situation with buzzer as a conditioned stimulus. More rats receiving nicotine, 0.4 mg/kg, i.p. immediately before each one-hour daily session (presession) reached a preset learning criterion than did saline controls, and rats receiving 0.1 mg/kg of nicotine performed better than controls but not as well as those receiving the higher nicotine dose. Rats given similar doses of quaternary nicotine bismethiodide in an identical presession experiment did not learn more proficiently than controls. Other groups of rats were given four doses of nicotine in photocell activity cages and the doses of nicotine which facilitated avoidance acquisition actually depressed spontaneous motor activity. Later studies in which rats were given 0.1 and 0.4 mg/kg nicotine or saline i.p. immediately after each session (postsession) showed that the drug also facilitates avoidance acquisition by this method; however, only the lower dose produced significant facilitation in this instance. Finally, rats were again trained with precession nicotine, but saline was substituted for nicotine beginning on session 16. No drug dissociation effect was seen. Thus the results of these studies strongly suggest that small doses of nicotine permanently facilitate the consolidating neural memory trace and do not enhance avoidance acquisition merely by stimulating performance.Supported by grant No. 629 from the Council for Tobacco Research, U.S.A. A major portion of this work was presented at the 116th Annual Meeting of the American Pharmaceutical Association, Pharmacology and Biochemistry Section, Montreal, Canada (May, 1969).