Gonadotropin Binding and Activation of the Interstitial Cells of the Testis

Abstract

Tissue receptor sites with high affinity for luteinizing hormone (LH) and human chorionic gonadotropin (hCG) have been defined in the interstitial cells of the testis, and also in the normal and gonadotropin-luteinized rat ovary (1–8). Comparable binding sites have also been demonstrated in the bovine corpus luteum, and in porcine granulosa cells during maturation in vivo and in vitro (9). The common receptor site for LH and hCG in these tissues is highly specific, with binding affinity only for molecules with the conformation characteristics of LH and chorionic gonadotropin. The biological specificity of hormone binding is demonstrable with LH from a wide variety of species, and with the placental gonadotropins of man, primates and the horse (2). The properties of the testis LH/hCG receptors, and their applications to radioligand-receptor assay, have been previously described in detail (2). In this chapter, the characteristics and application of gonadotropin receptors will be briefly reviewed, and more recent studies on the analysis of hormone-receptor interactions and the target cell responses to gonadotropins will be described.