Decreased Measures of Experimental Anxiety in Rats Bred for High Alcohol Preference

Authors

  • Christian Möller,

    1. Department of Clinical Neuroscience (C.M., L. W, A. T., M.H.), Karolinska Institute, Stockholm, Sweden, and the Department of Alcohol Research (P.H.), National Public Health Institute, Helsinki, Finland.
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  • Lisa Wiklund,

    1. Department of Clinical Neuroscience (C.M., L. W, A. T., M.H.), Karolinska Institute, Stockholm, Sweden, and the Department of Alcohol Research (P.H.), National Public Health Institute, Helsinki, Finland.
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  • Annika Thorsell,

    1. Department of Clinical Neuroscience (C.M., L. W, A. T., M.H.), Karolinska Institute, Stockholm, Sweden, and the Department of Alcohol Research (P.H.), National Public Health Institute, Helsinki, Finland.
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  • Petri Hyytiá,

    1. Department of Clinical Neuroscience (C.M., L. W, A. T., M.H.), Karolinska Institute, Stockholm, Sweden, and the Department of Alcohol Research (P.H.), National Public Health Institute, Helsinki, Finland.
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  • Markus Heilig

    Corresponding author
    1. Department of Clinical Neuroscience (C.M., L. W, A. T., M.H.), Karolinska Institute, Stockholm, Sweden, and the Department of Alcohol Research (P.H.), National Public Health Institute, Helsinki, Finland.
      Reprint requests: Markus Heilig, Ph.D., Magnits Huss Clinic, Karolinska Hospital, S-17176 Stockholm, Sweden.
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Reprint requests: Markus Heilig, Ph.D., Magnits Huss Clinic, Karolinska Hospital, S-17176 Stockholm, Sweden.

Abstract

A prevalent notion holds that acute anti-anxiety actions of ethanol are important for the reinforcing properties of this drug, and might predispose individuals with pre-existing anxiety disorders for developing ethanol dependence. This notion remains controversial, and human studies have yielded conflicting results. Ethanol dependence is likely a heterogenous disorder, and the discrepancies might be explained by a different relationship between anxiety and alcohol reinforcement in different subtypes of alcoholism. Recent results in experimental animals suggest that antianxiety actions of ethanol are important reinforcers of voluntary ethanol consumption in heterogeneous rats. Here, we examined whether the relationship is different in the AA line of rats bred for high voluntary ethanol intake. Behavior was studied in two established animal models of anxiety, a punished drinking conflict test, and the elevated plus maze. In the conflict test, the AA line displayed a markedly disinhibited behavior over a range of shock intensities, compared both with their counterpart, the ANA line, and with regular Wistar rats. On the plus maze, both AA and Wistar rats showed lower measures of experimental anxiety than ANA subjects. The phenotype of the animals was confirmed using a two-bottle free choice alcohol drinking procedure. The disinhibited behavior and spontaneous ethanol preference of the AA line differs from what has been found in heterogeneous rats, and displays similarities to genetically transmitted type II alcoholism according to the nomenclature of Cloninger.

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