An ethopharmacological approach to the development of drug addiction.

In a rat model of alcoholism, different stages of the development towards a drug addiction can be discriminated. During the phase of "controlled" intake, drug consumption is reversibly modified by the social situation (housing conditions) and the individual's social role (in particular his dominance rank). In Wistar rats, this period lasts about half a year. During the next few months, the consumption of ethanol rises without a concomitant loss of its behavioral effects. After an abstinence period of nine months, the rats maintain a high preference for alcohol which cannot be suppressed by adulteration with (unpleasantly tasting) quinine. Ethanol-taking behavior can no longer be modified by external stimuli or by dominance rank. This irreversible state is called "behavioral dependence." It is drug-specific (i.e., other drugs like diazepam cannot substitute the alcohol) and not related to physical dependence. In behaviorally dependent rats, the effects of ethanol are altered; very low doses tranquillize the rats, higher ones stimulate them.