Effects of Naltrexone on Alcohol and Nicotine Use in Female P Rats

Title: Effects of Naltrexone on Alcohol and Nicotine Use in Female P Rats Author: Usman Z. Hamid, Department of Psychology, University of Kentucky Faculty Mentor: Michael T. Bardo, Ph.D., Department of Psychology, University of Kentucky Alcohol is the most commonly abused substance worldwide. It is often co-abused with nicotine, which increases the difficulty of cessation of both alcohol and nicotine. Despite having similar mechanisms of action, there is no single medication to treat the co-abuse. The objective of the current study is to analyze the effects of the opiate antagonist naltrexone on alcohol consumption and the co-use of alcohol and nicotine in female alcohol-preferring (P) rats. Six female P rats were trained in two phases. During Phase 1 (ethanol access), subjects had 2-bottle choice sessions with 0% (water) and 15% ethanol. In Phase 2 (concurrent access), rats still had access to ethanol bottles, but were also given access to nicotine (0.3 mg/kg/infusion, i.v.) using a standard 2-lever procedure (active vs. inactive levers). Naltrexone (0.15, 0.3, or 0.6 mg/kg s.c.) treatments were administered to determine its effects on alcohol and nicotine consumption. Half the animals received naltrexone treatments during Phase 1, and half received treatments during Phase 2. During Phase 1 (ethanol access), naltrexone had no significant effect on ethanol or water consumption. Results from Phase 2 (concurrent access) showed that naltrexone dose-dependently reduced ethanol consumption, and reduced water consumption at the highest dose (0.6 mg/kg). Naltrexone did not have any significant effects on active lever presses for nicotine, but reduced inactive lever presses only at the lowest dose (0.15 mg/kg). Naltrexone is more effective in treating alcohol use when tested in combination with nicotine rather than when tested alone