Studies of endotoxin-dependent fever in pre-pubertal pigs following acute activation of the pituitary-adrenocortical axis: towards a new hypothesis of fever regulation

The possibility that adrenocortical activation might alter the pyretic effe cts of bacterial lipopolysaccharide endotoxin in growing pigs was investiga ted. In a series of four experiments, animals received increasing doses of porcine adrenocorticotrophic hormone ACTH (1.5, 4.5, 13.5 IU kg(-1)) or CRH (7 mu g kg(-1)), all of which markedly affected cortisol release. Unexpect edly, these treatments tended to increase body temperature during the early and middle stages of the febrile response, although they did appear to ind uce an earlier deferscence. These results suggest that acute stress may not modify fever induced by immunological challenge, although a different situ ation could obtain during chronic stress. Furthermore, a hypothesis of feve r regulation is proposed which attempts to reconcile the present findings w ith those from previous studies in swine.