Effects of Growth Hormone on Adult Human Gonads: Action on Reproduction and Sexual Function

Figure 1

GH/IGF-1 roles in reproduction of adult males and potential mechanisms. GH secreted by the anterior pituitary, which is the main source of systemic GH, induces the liver to produce IGF-1. Systemic GH/IGF-1 reaches the testis and improves the production of local GH/IGF-1. In response to systemic GH/IGF-1 and/or local GH/IGF-1, FSH action on the Sertoli cell is improved to ameliorate the sperm development environment, and LH action on the Leydig cell is promoted to increase the levels of T. The effect of GH/IGF-1 on spermatogenesis is not clear and is not shown in the figure. GHR: growth hormone receptor; IGF-1R: insulin-like growth factor-1 receptor; LHCGR: luteinizing hormone/choriogonadotropin receptor; FSHR: follicle-stimulating hormone receptor.