Nicotine in alcohol deprivation increases alcohol operant self-administration during reinstatement

Tobacco and alcohol are highly co-abused by humans. Most experimental studies have evaluated ethanol consumption in animals exposed concomitantly to nicotine. However, little is known regarding the effects of nicotine administered during periods of alcohol deprivation. In the present study, adult male Wistar rats with an extended background of operant self-administration of ethanol were alcohol-deprived and treated with nicotine (0.1, 0.2, 0.4 and 0.8 mg/kg) or saline during five consecutive days in one chamber of a place conditioning apparatus. Nicotine-induced changes in locomotion were monitored daily, whereas the expression of place conditioning was studied the day after the last nicotine injection. Forty-eight hours after testing for conditioning, the animals resumed operant self-administration of ethanol and their alcohol intake was evaluated during the next 14 days. We observed that alcohol consumption was increased in animals treated with nicotine at doses of 0.2, 0.4 and 0.8 mg/kg but not in animals treated with the dose of 0.1 mg/kg or saline. Additionally, the dose of 0.8 mg/kg of nicotine not only induced persistent changes in alcohol self-administration but also produced conditioned place aversion and depressed locomotor activity. These results indicate that nicotine administration during the ethanol deprivation period can exacerbate the maintenance of alcohol consumption. (C) 2004 Published by Elsevier Ltd.