Central cardiovascular and thermal effects of prostaglandin E2 in rats.

Prostaglandin E2 (PGE2) increased the blood pressure, heart rate and body temperature, when administered at the doses of 0.001-10 micrograms into the lateral cerebral ventricle (i.c.v.) of the urethane-anesthetised rat. The highest dose of 10 micrograms/rat induced a strong initial hypotensive effect. Intravenously (i.v.), PGE2 at the doses of 0.01-10 micrograms/rat caused a biphasic blood pressure response with dose-related initial decreases followed by slight increases in blood pressure. The heart rate and body temperature were slightly increased by i.v. administrations of PGE2. The highest i.v. dose of 10 micrograms/rat initially decreased also the heart rate. Central pretreatment with indomethacin (1 mg/rat i.c.v.) partly antagonised all of the recorded central effects of PGE2, while sodium meclofenamate (1 mg/rat i.c.v.) abolished the hypertensive response to i.c.v. administered PGE2 but failed to significantly affect the PGE2-induced rises of heart rate and body temperature. The results support the previous suggestions that PGE2 may participate in the central cardiovascular and thermoregulatory control. The results also suggest that indomethacin and sodium meclofenamate antagonize the effects of exogenous prostaglandins. Since sodium meclofenamate, unlike indomethacin, affected preferentially the hypertensive response to centrally administered PGE2, there may be differences in the sites and/or modes of action between these drugs.