A GENETIC COMPARISON OF BEHAVIORAL ACTIONS OF ETHANOL AND NICOTINE INTHE MIRRORED CHAMBER

Human alcoholics are almost invariably heavy users of tobacco, perhaps because both ethanol and nicotine may have anxiolytic activity. Howev er, studies in humans have not uniformly detected anxiolytic effects b ecause significant individual differences in anxiolytic actions of the se agents seem to exist. One factor that seems to contribute to these individual differences is tolerance to ethanol. Individuals who are mo re sensitive to depressant actions of alcohol seem to show anxiolytic actions more readily. Consequently, we examined the relative sensitivi ties of the ethanol-sensitive (to the anesthetic actions of ethanol) l ong-sleep (LS) and ethanol-resistant short-sleep (SS) mouse lines to d iazepam, ethanol, nicotine, and ethanol-nicotine combinations in the m irrored chamber test. This test measures approach-conflict behavior. E thanol and nicotine evoked changes in mirrored chamber activities that resembled those elicited by diazepam. These effects were seen at dose s that did not markedly affect locomotor activity, thereby suggesting that these changes in behavior represent anxiolytic actions. The LS-SS mice did not differ in sensitivity to diazepam, but the SS were more uniformly responsive to the other drugs. Only the SS showed clear evid ence for interactions between ethanol and nicotine. If the changes in mirrored chamber behavior elicited by ethanol, nicotine, and combinati ons of the two drugs occur because of anxiety reduction, it seems that the SS mouse line is more responsive to anxiolytic actions of these d rugs.