The regulation of Sertoli cell activin A and inhibin B secretion during inflammation was investigated in vitro. Adult rat Sertoli cells were incubated with the inflammatory mediators, lipopolysaccharide (LPS), interleukin-1β (IL-1β), IL-6 and the IL-1 receptor antagonist (IL-1ra) over 48 h in culture. Activin A, inhibin B and IL-1α were measured in the culture medium by specific two-site ELISAs. Both IL-1β- and LPS-stimulated activin A and inhibited inhibin B secretion. LPS also stimulated the

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... roduction of IL-1α in the cultures. In contrast to IL-1β, IL-6 had no effect on activin A, although it did have a significant inhibitory effect on inhibin B secretion. Ovine follicle-stimulating hormone (FSH) and the cAMP analogue dibutyryl cAMP opposed the actions of IL-1 and LPS by suppressing activin A and IL-1α secretion and by stimulating inhibin B. Blocking IL-1 activity in the cultures by addition of an excess of IL-1ra completely prevented the response of activin A to exogenous IL-1β, and reduced the response to LPS by 50%. In the presence of IL-1ra, basal secretion of inhibin B was increased, but IL-1ra was unable to reverse the suppression of inhibin B by LPS. These data indicate the importance of both IL-1 isoforms in regulating secretion of activin A and inhibin B by mature Sertoli cells during inflammation. The data also establish that inflammation exerts its effects on activin A and inhibin B secretion via other pathways in addition to those mediated by IL-1, and that hormonal stimulation by FSH and cAMP moderates the Sertoli cell response to inflammation. Interference with the complex interactions between these cytokines and hormones may contribute to the disruption of reproductive function that can accompany infection and illness in men.