ROLE OF PROSTAGLANDINS E(1), E(2) AND F2-ALPHA IN THE BRAIN IN INTERLEUKIN 1-BETA-INDUCED ADRENOCORTICOTROPIN SECRETION IN THE RAT

It is well known that interleukin (IL)-1 is a potent activator of the hypothalamo-pituitary-adrenal axis in the rat, Many studies have reported that prostaglandins (PGs), especially PGE(2), in the brain may mediate the IL-1 stimulation of corticotropin-releasing hormone release, which then leads to adrenocorticotropin (ACTH) secretion, However a general consensus has yet to emerge regarding whether PGE(2) is the only or the most important PG in the brain mediating IL-1-induced ACTH secretion in the rat. To address this question, we examined the effect of intracerebroventricular (icy) administration of antisera against PGE(1), PGE(2) or PGF(2) alpha, or normal rabbit serum on the ACTH response induced by an icy injection of IL-1 beta in the rat, Each antibody or normal rabbit serum (as the control) was given icy 15 min before an icy administration of human recombinant IL-1 beta (50 ng), IL-1 beta produced a significant rise in plasma ACTH levels, and this response was significantly suppressed by either of the three PG antibodies, Interestingly, the inhibitory effect of anti-PGE(2) antibody seemed to be somewhat weaker than those of the other two antibodies, We conclude that not only PGE(2) but also PGE(1) and PGF(2) alpha in the brain may mediate the IL-1 beta stimulation of ACTH secretion in the rat. (C) 1995 Academic Press Limited.