A comparison of the hypothermic effects of methylphenidate and d-amphetamine.

Methylphenidate is a central nervous system stimulant with a spectrum of action similar to the effects of d-amphetamine. d-Amphetamine-induced hypothermia is mediated via release of dopamine in the DA mesolimbic pathway. Methylphenidate causes hypothermia among rats kept at 4 degrees C, but d-amphetamine is twice as potent as methylphenidate. Dose-response relationship of methylphenidate thermal effects exhibits a U-shape curve. The hypothermic effects of 5-15 mg/kg methylphenidate are mediated by central dopaminergic neurons, as pretreatment with haloperidol inhibits these effects. The hypothermia produced by larger doses of methylphenidate is not blocked by pretreatment with haloperidol and hypothermia induced by d-amphetamine is blocked by pretreatment with haloperidol.