Effect of sympathetic blockade on central prostaglandin E2-induced hyperthermia

The mechanisms by which intracerebroventricular (i.v.t.) prostaglandin E2 (PGE2) produce hyperthermia in the rat were investigated. I.v.t. PGE2 produced dose-related increases in blood pressure, heart rate and rectal temperature which were significant with a dose of 0.5 ng. Oxygen consumption also increased and remained above baseline over an hour with 50 and 500 ng PGE2 doses. Ganglionic blockade with hexamethonium (20 mg/kg) attenuated the blood pressure and heart rate response to PGE2 but metabolic rate and rectal temperature increases were unchanged. Propranolol (2 mg/kg i.v.) decreased the heart rate response to PGE2 but had no significant effect on blood pressure, metabolic rate and rectal temperature responses. These results suggest a similar sensitivity of central receptors for mediating cardiovascular and metabolic rate/temperature increases but suggest that the mechanisms mediating these effects are separate.