The Correlation between the Binding of the Human Chorionic Gonadotropin to Luteal Cells and Plasma Membrane of Luteal Cells

Abstract

Granulosa cells as well as luteal cells maintained in tissue culture require a low but constant level of LH or hCG to stay differentiated (1,2).It can therefore be assumed that all factors regulating the appearance or disappearance (modulation) of the receptor sites for gonadotropins are of importance for the luteotrophic function and the differentiation of luteal cells. To study the modulation of the receptor sites in luteal cells maintained in tissue culture, one needed a binding technique specific enough to detect small variations in receptor concentration under different culture conditions. Also, since luteal cells are obtained by enzymatic digestion, and since it had been shown that proteolytic enzymes can destroy receptors (3–7), one must be assured that such a treatment does not significantly alter the characteristics of the binding of gonadotropins to their receptors. In this communication we compare the binding characteristics of hCG to bovine luteal membranes and bovine luteal cells obtained by enzymatic treatment (7). We have been able to show that the binding was identical and that the enzyme treatment needed to dissociate the luteal cells before putting them into culture did not affect the receptor site for gonadotropins.