Studies on the mode of action of gonadotrophin-inhibiting material (anti-LH) isolated from human urine.

Gonadotrophin-inhibiting material (GIM) was able to inhibit the binding of 125I-hCG to rat Leydig cells, suggesting that its inhibiting properties are due to its ability to complete for the hCG binding sites on Leydig cells. Binding of fluorescein isothiocyanate-tagged GIM to Leydig cells was also seen. The effect of GIM on hCG-induced adenylate cyclase activation and testosterone production was also studied. It was found that there was a dose-dependent inhibition of both these effects.