Endogenous hyperprolactinaemia enhances amphetamine- and apomorphine-induced stereotypy.

Rats with endogenous hyperprolactinaemia induced by pituitary homografts under the kidney capsule were more sensitive to amphetamine and apomorphine with respect to drug-induced stereotypy, while a normal response was noted in drug-induced changes of locomotor activity, rearing and grooming. It is suggested that postsynaptic dopaminergic receptors, probably in the nigro-striatal system, may become selectively supersensitive in the endogenous hyperprolactinaemic animals.