EFFECTS OF INTERLEUKINS ON SECRETION OF LUTEINIZING-HORMONE FROM OVINE PITUITARY-CELLS

Objective-To determine whether cytokines of homologous species might m ediate the stimulatory effects of endotoxin on release of luteinizing hormone (LH) from pituitary cells. Sample Population-Cells from pituit ary glands collected from 8- to 14-month-old wethers. Procedure-Cells from the anterior pituitary gland were cultured in the presence of rec ombinant ovine or bovine cytokines (interleukin [IL]-1 alpha, IL-1 bet a, and IL-2), tumor necrosis factor-alpha (TNF), and interferon-gamma (IFN-gamma). Luteinizing hormone that was released into the medium was measured. Cells were also cultured with modulators of signal transduc tion pathways to evaluate the second messenger system used by IL-1 alp ha and IL-1 beta. Results-Similar to effects of endotoxin, IL-1 alpha and IL-1 beta stimulated release of LH. Interleukin 2, TNF, and IFN-ga mma did not have a detectable effect on release of LH. Stimulation of LH release by IL-1 alpha and IL-1 beta required activation of voltage- dependent Ca2+ channels and appeared to involve protein kinase C. Conc lusions-IL-1 alpha and IL-1 beta may mediate the direct stimulatory ef fect of endotoxin on release of LH in vitro. Interleukin 2, TNF, and I FN-gamma do not have a direct effect on release of LH; therefore, they do not mediate this effect of endotoxin. Clinical Relevance-Stressors , including infection, are often associated with reduced fertility. In fection resulting in endotoxin release, production of interleukins, or both, can lead to direct stimulation of LH release from the pituitary gland. Inopportune release of LH via cytokines may interfere with nor mal pulsatile release of LH, thereby suppressing gonadal function.