d-Amphetamine antagonizes prostaglandin E1-induced hyperthermia and suppression of fixed interval operant behavior in rats.

The experiments reported herein were designed to study the effects of prostaglandin F2 alpha (PGF2 alpha) and PGE1 on operant behavior and rectal temperature of rats. A solution containing PGF2 alpha or PGE1 was infused intracerebroventricularly into rats trained to press a lever for food reward on a fixed interval 75 second (FI 75 sec) schedule. PGF2 alpha (10, 100 or 1000 ng/min) had no effect on FI 75 sec operant behavior. Only the highest dose increased temperature. PGE1 (100 ng/min) had no effect, whereas higher doses (250 and 500 ng/min) produced a rate-dependent effect on behavior, increasing low rates and decreasing high rates. The two higher doses also produced convulsions after about 25 min or 20 min infusions, respectively. PGE1 also increased temperature in a dose-dependent manner. Systemic administration of a low dose of d-amphetamine (0.5 mg/kg IP) had little or no effect on behavior or temperature. d-Amphetamine did not alter hyperthermia induced by the highest dose of PGF2 alpha, but antagonized the PGE1-induced hyperthermia. d-Amphetamine also antagonized all of the behavioral effects of PGE1, including convulsions. The results are discussed in relation to the actions of PGs and d-amphetamine on catecholamine neurons in the central nervous system.