[Determination of the development of psychotic dependence to drugs in small animals. 2. Selective drinking of morphine and cocaine solutions and its reinforcement in mice].
To develop a screening method for psychic dependence liability of the drugs, morphine- and cocaine-directed drinking behavior was studied in mice. Using automatic drinkometer the intake of drug solution from the paired sucking tube connected to tap water and/or drug solution was estimated. The drinking pattern showed a diurnal rhythm and large portion of the total intake was done during dark period. When the animals were forcedly given drugs as drinking solution total intake and the gain of body weight was suppressed in proportion to the concentration of the drugs. In the choice test between tap water and drug solution, mice can distinguish the concentration of drug solution and avoid it in high concentrations. Animals experienced drug solution before the choice test showed a tendency to intake more drug solution than the untreated control animals depending on the length of pretreatment. Pretreatment of the animals with twice daily injections of the drugs failed to develop high grade of preference to drug solution in the succeeding choice test. Thus, the positive reinforcing properties of morphine and cocaine was demonstrated in mice and the validity of this animal species for the screening of the drugs of psychic dependence was suggested.
D000818:Animals; D002755:Choice Behavior / Q000187:drug effects*; D002940:Circadian Rhythm; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D004326:Drinking / Q000187:drug effects; D006801:Humans; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D012996:Solutions; D019966:Substance-Related Disorders / Q000523:psychology*
D012996:Solutions; D009020:Morphine; D003042:Cocaine