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 trials 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 α-methyltyrosine (50 mg/kg) prevented the effects of both drugs. Nalorphine hydrochloride (5 mg/kg) also blocked the effect of morphine. The action of α-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.
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Davis, W.M., Smith, T.P. Morphine enhancement of shuttle avoidance prevented by α-methyltyrosine. Psychopharmacologia 44, 95–97 (1975). https://doi.org/10.1007/BF00421191
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DOI: https://doi.org/10.1007/BF00421191