Effects of centrally administered prostaglandin EP receptor agonists on febrile and adrenocortical responses in the prepubertal pig

Abstract

Febrile and adrenocortical responses to central (lateral ventricle) injections of prostaglandin E 2 (PGE 2) and E-series prostanoid receptor agonists (EP 1, EP 2, EP 3, subtypes) were investigated in prepubertal pigs. In Experiment 1, administration of PGE 2, (1.4, 5.6 nmol) produced dose-related increases in core temperature and plasma cortisol concentrations. In Experiment 2, approximately equimolar (1.2 to 1.4 nmol) amounts of EP 1, EP 2, and EP 2 EP 3 agonists were compared. The EP 2 and EP 2 EP 3 prostanoids raised core temperature, whereas the increase induced by the EP 1 agonist was not significant. Similarly, although all of the agonists appeared to stimulate cortisol release, these results were also not significant. In Experiment 3, pigs treatment with an EP 3 agonist (1.3 nmol) showed marked febrile and adrenocortical responses. The results of these experiments are compared with data from the rat using the same agonists and route of administration. The findings are also discussed in relation to the distribution of receptor populations in vascular and synaptosomal compartments of the porcine brain.