Facilitation of responding for rewarding brain stimulation by a high dose of amphetamine when hyperthermia is prevented.

Rats given a 5 mg/kg injection of d-amphetamine did not respond for brain stimulation reward when tested under normal laboratory temperatures. In addition to the usual manifestations of stereotypy the rats were markedly hyperthermic. If the hyperthermia was prevented, however, by initially placing the rats in a cold room (10 degrees C) and subsequently testing for brain stimulation under a cool chamber temperature (14--16 degrees C), the rats responding for brain stimulation was facilitated. Thus, the occurrence of hyperthermia appears to be a critical factor responsible for this behavioral dysfunction produced by a high dose of amphetamine.