Ip Effects of Nicotine Infusion on Operant Self-admin1stration of Ethanol

Male Lister rats, 200 250g at start were used; n = 14 (controls) and 13 (nicotine treatments),. They were trained to press levers to obtain alcohol, using the "sucrose fading" method of Grant and Sampson (1985), in which the animals learn to press a lever to obtain sucrose, then the solution is gradually changed to sucrose plus alcohol, then alcohol alone. The operant schedule used was a variable interval (I 5s) with 30 min access per day, 5 days per week. The rats were trained to respond for 5% ethanol, then osmotic minipumps were implanted, which provided 28 days of either 1.25 or 5 mg/kg/24h nicotine; controls were implanted with sham pumps. After two days recovery time, followed by two weeks self-administration of 5% ethanol, the ethanol was replaced by water for two weeks so that the extinction of responding for ethanol could be studied. Results were analysed by two way analysis of variance.