NITRIC-OXIDE PRODUCTION IS NOT INVOLVED IN THE EFFECTS OF INTERLEUKIN-1-BETA ON CAMP, THYROGLOBULIN AND INTERLEUKIN-6 IN TSH-STIMULATED HUMAN THYROID-CELLS

Interleukin (IL)-1 inhibits the function of insulin-producing rat panc reatic beta-cells in vitro and in vivo, and it has been postulated tha t the IL-1 effect is mediated through the cytokine inducable nitric ox ide (NO) synthase. IL-1 inhibits the function of cultured human thyroi d cells too, and in this study human thyroid cell production of NO in response to the TSH-stimulated influence of IL-1 beta (10(5) U/l) and TNF-alpha (10(6) U/1), alone or in combination was measured. IL-1 beta , but not TNF-alpha, induced an increase in nitrite production, which was significantly reduced by the competitive inhibitor of nitric oxide synthase L-N-G-monomethyl-arginine (L-NMMA) (0.1 mmol/L and 0.5 mmol/ L). However, the nitrite production was unrelated to the IL-1 beta-ind uced inhibition of thyroglobulin (Tg) and cyclic AMP (cAMP) and the IL -1 beta-induced IL-6 production. Thus, it is unlikely that NO is a sec ond mediator of the demonstrated effects of IL-1 beta and TNF-alpha on human thyroid cells in culture.