Hyperthermic and endocrine effects of intravenous prostaglandin administration in the pig

Experimentally induced fever is accompanied by a variety of hormonal changes, and there is evidence to suggest that some of these responses may be mediated by prostaglandins. However, little is known about the endocrine effects of peripherally administered prostaglandins, especially in domesticated species. In this study, the effects of intravenous prostaglandin E2 (PGE2; 20 micrograms/kg) on deep body temperature and plasma concentrations of cortisol, lysine vasopressin (LVP), and growth hormone were investigated in prepubertal pigs (n = 6) prepared with venous catheters and sampled at 10-min intervals for 3 hr. PGE2-induced hyperthermia, which lasted for the duration of the study, was accompanied by a 70-min increase in cortisol and LVP concentrations. Moreover, this hyperthermic response was checked when LVP levels were high. These results indicate that a fever-inducing intravenous injection of PGE2 produced a marked anterior and posterior pituitary hormone response in growing pigs. Also, the transient increase in LVP may be correlated with a central action of the hormone, limiting the extent of the fever. In addition, because the majority of the animals exhibited mild hyperthermia (0.5 degrees C) under control conditions, the results suggest that, in a given population of pigs, there may be some animals that exhibit stress-induced hyperthermia.