Inhibiting vitamin A metabolism as an approach to male contraception.

Although oral contraceptives have been available to women since the 1960s, contraceptive options for men have remained limited. Spermatogenesis relies on the active metabolite of vitamin A, retinoic acid, to drive spermatogonial differentiation and to allow the production of normal numbers of sperm. Recent evidence describes how the enzymes which control vitamin A metabolism in the testis could be targeted to generate effective male contraceptives; however, the detailed mechanism(s) regarding how vitamin A regulates normal spermatogenesis are still unknown. The essential nature of vitamin A to male germ cell development and the prospects of developing the proteins responsible for the generation, transport, and storage of retinoic acid as targets for male contraceptive development are discussed in this review.