EFFECTS OF PSYCHOTROPIC-DRUGS ON IMPAIRMENT OF ACQUISITION OF SHUTTLEAVOIDANCE PRODUCED BY PRETREATMENT WITH PAIRS OF TONE SIGNAL AND SHOCK IN MICE

The acquisition of discrete shuttle avoidance of mouse was significant ly impaired by presentation of 120 pairs of a tone signal and an unavo idable/unescapable shock at 30 sec intervals for 3 consecutive days pr ior to the training session. Caffeine (3 and 10 mg/kg s.c.) reduced su ch an impairment of the avoidance acquisition, whereas diazepam (0.5-2 mg/kg s.c.), imipramine (30 mg/kg i.p.) and chlorpromazine (2 mg/kg s .c.) enhanced it, when these drugs were administered 10 min before eac h shock-presenting session, Ethanol (0.8-2.4 g/kg p.o.), nicotine (0.1 -1 mg/kg s.c.), methamphetamine (0.1-1 mg/kg s.c.) and morphine (1-10 mg/kg s.c.) did not modify the avoidance acquisition. These results in dicate that the nature of impairment of the avoidance acquisition caus ed by this condition is different from learned helplessness, and elici ts different responses to psychotropics.