Is a dopaminergic system involved in thyrotropin releasing hormone induced hyperthermia and in its potentiation by amphetamine?

1. A dose-related hyperthermia is obtained in mice with TRH administered intraperitoneally. 2. This hyperthermia is reinforced by amphetamine given at doses which usually cause hypothermia. 3. p-Chloroamphetamine and L-Dopa also reinforce TRH hyperthermia. Apomorphine is not significantly active. 4. TRH hyperthermia is lowered significantly by alpha-methyl-tyrosine and haloperidol but not significantly by pimozide and chlorpromazine. TRH + Amph hyperthermia is not lowered by any of the DA antagonists tested even at doses reversing Amph hyperthermia. Direct participation of DA receptors is then doubtful. 5. All these variations of temperature have their acme a 15 min except for reserpine which, given 22 hours before, potentiates TRH + Amph hyperthermia after 30 min.