[Determination of the development of psychotic dependence to drugs in small animals. 4. Selective drinking of barbital and ethanol solutions by mice].

Using mice, preference for barbital or ethanol solution was examined in choice test between drug solution and tap water after pretreatment with the drugs for 6, 15 or 30 days under different conditions, a) forcedly given the drug solution as drinking liquid. b) ip injected the drug twice daily, c) combined treatment, forced drinking plus ip injection. Pretreatment with barbital induced aversion to the drug solution regardless the conditions of pretreatments mainly because the unpalatability of the drug solution and also the unpleasant effect of injected drug. In ethanol pretreated animals, pre-exposure to ethanol solution decreased the preference ratio for the drug solution n choice test but accustomed to the taste in parallel with the duration of the pretreatment. After treatment with injection, on the other hand, animals acquired preference for ethanol solution indicating the reinforcing effect of the injected drug. Six days pretreatment with the drugs developed tolerance to their suppressive effect and in barbital treated animals physical dependence was also developed. However, the degree of preference or drug solution was not parallel to the intensity of tolerance or physical dependence. Characteristics of the test drugs as reinforcer of drinking behavior was easily determined by this method and its validity for the screening of the drugs of psychic dependence liability was suggested.