THE EFFECT OF WEEKLY EXPOSURES ON THE VOLUNTARY INTAKE OF ETHANOL IN INDIVIDUAL RATS

No pattern of ethanol exposure is at present known as a certainway to induce voluntary drinking of the drug in experimentalanimals. Based on an assurnptlon that humans who will ultimatelydevelop alcoholism do not start by drinking ethanol continuously,a chronic experiment was designed, where ethanol 2 g/kg intraperitoneally(i.p.) was injected in male rats once a week. Voluntary intakeof ethanol was tested in a two-bottle choice situation eitheron one day every week (restricted test) or continuously (continuoustest). During the first part of the intermittent treatment withethanol i.p., an inhibition of voluntary drinking in the restrictedtest was revealed. This inhibition could be overcome in mostrats if the treatment was pursued for more than 20 weeks. Rats,which during the treatment were exposed to ethanol in an intermittentfashion, had after the treatment a propensity to drink moreethanol in a continuous test. This intake was not influencedbv ethanol concentration and could at least In one rat givemeasurable blood ethanol concentration.