Effects of growth hormone on male reproductive functions.

This brief review will summarize evidence that growth hormone (GH) plays a physiological role in the control of male reproductive development and function, while excessive release of GH can interfere with male sexual behavior and fertility. An attempt will also be made to put this information in the broader context of interactions between the somatotropic and the hypothalamic-pituitarytesticular (H-P-T) axis. Appreciation of the existence of such an interaction dates back to the pioneering studies of the impact of GH deficiency or resistance on testicular development and fertility in the human and in experimental animals (Laron and Sorel, 1970; Arsenijevic et al, 1989) and to early demonstration of synergistic interactions between GH and gonadotropins in hypophysectomized animals (Woods and Simpson, 1961; Swerdloff and Odell, 1977). In more recent years, availability of recombinant GH, identification of new GH-deficient mutants, and development of various transgenic and knock-out mouse models for the study of GH led to renewed interest in the role of GH in reproduction and accumulation of new data relevant to this topic.