Effects of psychoactive drugs on the conflict behavior under operant situation in Mongolian gerbils (Meriones unguiculatus).

Effects of diazepam, pentobarbital, morphine, ethanol, caffeine, and nicotine on the conflict behavior established under a MULT FR 20/FR 20 punishment schedule of food reinforcement were investigated in Mongolian gerbils. Fourteen out of 17 gerbils learned lever-press response for food within 15 sessions of training under FR 20 schedule. Although high voltage of electric shock (125-225 V) was required for attaining lever-press suppression, all 14 gerbils exhibited stable conflict behavior, i.e., showing high response rate of 20-30 responses/min in the safety period and low response rate of 0-3 responses/min in the alarm period. Diazepam, a prototype of the antianxiety drugs, increased the response rate in the alarm period. The anticonflict effect was also observed after administration of either pentobarbital or ethanol. On the other hand, morphine suppressed lever-pressing in a nonspecific manner. Caffeine tended to attenuate the conflict behavior, but nicotine had no such effect. These results suggest that the effects of psychoactive drugs on the conflict behavior of gerbils are almost identical with those in mice and rats.