ANALYSIS OF GROWTH-HORMONE RELEASE FROM RAT ANTERIOR-PITUITARY-CELLS BY REVERSE HEMOLYTIC PLAQUE-ASSAY - INFLUENCE OF INTERLEUKIN-1

Interleukin-1 (IL-1) has been suggested to directly affect pituitary g rowth hormone (GH) release, although other investigators have failed t o observe this effect. We examined the effects of IL-1 beta on GH secr etion from single somatotrophs by means of reverse hemolytic plaque as say (RHPA). Anterior pituitary cells of adult male rats were enzymatic ally dispersed and subjected to RHPA. IL-1 beta at 100 pM and 1 nM, in creased both the mean plaque area and the fraction of somatotrophs for ming large plaques. IL-1 beta did not increase the mean plaque area in the presence of the IL-1 receptor antagonist (IL-1ra) IL-1 beta (1 nM ) added together with GH-releasing hormone (GHRH;10 nM), showed no add itive effect on GHRH-induced GH release. The stimulatory action of IL- 1 beta on the release of GH was,suppressed by somatostatin. In conclus ion, our data show that IL-1 beta stimulates GH-secretion through dire ct action on the pituitary.