title: Morphine enhancement of shuttle avoidance prevented by alpha-methyltyrosine.
abstract: Rats were given 6 days of training (180 trials) to make a two-way (shuttle) avoidance response. "Poor performers" making less than 50% avoidances in the 6th block of 30 tials were given drug treatments on the next 2 days. Both morphine sulfate (15 mg/kg) and d-amphetamine sulfate (1 mg/kg) increased the avoidance level by 70-100%. Prior treatment with alpha-methyltyrosine (50 mg/kg) prevented the effects of both drugs. Nalorphine hydrochloride (5 mg/kg) also blocked the effect of morphine. The action of alpha-methyltyrosine to block enhancement of avoidance is taken to indicate that this effect of morphine is attributable to a catecholamine-dependent excitatory component of its activity profile.
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D003216:Conditioning, Operant / Q000187:drug effects; D003913:Dextroamphetamine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology*; D009020:Morphine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D009269:Nalorphine / Q000494:pharmacology; D051381:Rats
chemical_list: D008781:Methyltyrosines; D009020:Morphine; D003913:Dextroamphetamine; D009269:Nalorphine