Apomorphine hypothermia: interaction with serotonergic agents

Apomorphine (APO, 0.25 to 16 mg/kg) induced a dose dependent hypothermia in mice. Haloperidol, a dopamine antagonist, antagonized APO hypothermia due to lower doses. Clozapine and phenoxybenzamine, on the other hand, failed to modify APO hypothermia. Similarly, levopropranolol and cyproheptadine, which modify serotonergic responses, also failed to modify APO hypothermia. But fluxetine which selectively inhibits serotonin uptake, reversed APO induced hypothermia due to higher doses but not that induced by low dose of APO. The behavioral stereotypy was, however, not modified by fluoxetine pretreatment. It is concluded that APO hypothermia due to lower and higher doses are mediated by different receptors and the latter action involves the interaction of more than one type of receptor.