Fig. 1
From: Male contraception: narrative review of ongoing research
Overview of the hypothalamic-pituitary-testicular (HPT) axis and targets of male contraception. The HPT axis consists of the hypothalamus, pituitary gland, and testes. The hypothalamus releases gonadotropin-releasing hormone (GnRH) in a pulsatile fashion which signals for release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary. LH and FSH drive testosterone (T) production and spermatogenesis in the testes. T and the hormonal contraceptives exert negative feedback on the hypothalamus to inhibit GnRH, LH, and FSH release, therefore suppressing spermatogenesis. Non-hormonal methods focus on distinct targets to inhibit spermatogenesis, sperm motility, or transit through the vas deferens. Pointed arrows indicate activation; red broad-tipped arrows indicate inhibition. NES/T, Nestorone/testosterone; DMAU, dimethandrolone undecanoate; 11β-MNTDC, 11β-methyl-19-nortestosterone dodecylcarbonate; RARA, retinoic acid receptor alpha; BRDT, bromodomain testis-specific protein; TSSK, testis-specific serine/threonine kinase; sAC, soluble adenylyl cyclase; CatSper, cation channel of sperm; SLO3, slowpoke homolog 3; RISUG, reversible inhibition of sperm under guidance. Figure created by EJL using BioRender.com