Apomorphine-induced stereotypy: function of age and rearing environment.

Rats of different age groups ("young" vs. "old"), reared in isolation and social groups were tested for differences in apomorphine-induced stereotypy. Sensitivity to apomorphine (2 mg/kg SC) was found to be a function of an interaction between rearing environment and age. The "younger" isolated animals displayed greater stereotypy than group-reared and "older" isolated animals. Rearing environment and age, as main factors, did not have significant influence on drug-induced stereotypy.