The Australian High and Low avoidance rat strains: differential effects of ethanol and alpha-methyl-p-tyrosine.

Two new lines of rats have been selectively bred for high or low active avoidance responding--the Australian High (AHA) and Low (ALA) Avoiders. Ethanol (1-1.5 g/kg body weight, i.p.) improved acquisition of active avoidance responding only in ALA, whereas alpha-methyl-p-tyrosine (AMPT; 80 mg/kg body weight, i.p.) seemed to selectively impair acquisition of responding in AHA. The combination of ethanol and AMPT caused a general depression of behaviour. The 2 lines did not differ consistently in the latency to escape from shock, locomotor activity, 'emotionality' or passive avoidance responding. Ethanol had no effect on locomotor activity or 'emotionality', but increased the latency to escape from shock and impaired passive avoidance responding in both lines.