PRIMING OF THE ANTERIOR-PITUITARY WITH CORTICOTROPIN-RELEASING HORMONE IN-VITRO DOES NOT FACILITATE AN ACTH RESPONSE TO INTERLEUKIN-1-BETA

Stimulation of the hypothalamo-pituitary-adrenal axis by the cytokine interleukin-1 beta (IL-1 beta) is an important facet of the functional interaction between the endocrine and immune systems. IL-1 beta can a ct by releasing corticotropin-releasing hormone (CRH) from the hypotha lamus, but it has also been proposed to act directly at the anterior p ituitary when the pituitary has been primed with CRH. We tested this h ypothesis using in vitro experiments in which anterior pituitaries wer e primed with low doses of CRH. We were unable to demonstrate a direct effect of IL-1 beta on the release of ACTH from freshly harvested ant erior pituitary tissue. Neither continuous nor discontinuous priming o f the cells with CRH or arginine vasopressin, at concentrations by the mselves insufficient to cause ACTH release, facilitated an ACTH respon se to IL-1 beta. Therefore our data do not support the hypothesis that IL-1 beta can have a direct effect upon ACTH release from the anterio r pituitary primed with CRH.