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

Febrile and adrenocortical responses to central (lateral ventricle) injections of prostaglandin E2 (PGE2) and E-series prostanoid receptor agonists (EP1, EP2, EP3, subtypes) were investigated in prepubertal pigs. In Experiment 1, administration of PGE2, (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 EP1, EP2, and EP2/EP3 agonists were compared. The EP2 and EP2/EP3 prostanoids raised core temperature, whereas the increase induced by the EP1 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 treated with an EP3 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.