BDADs for Male Contraception

描述（由申请人提供）：大约50年前，口服双氯乙酰二胺（BDADs）如WIN 18446被证明可以安全、完全和可逆地抑制男性精子的发生。然而，这些化合物并没有作为男性避孕药进入市场，因为它们与酒精一起摄入会引起“双硫仑反应”，其特征是脸红、恶心和呕吐。由于缺乏对BDADs引起这些作用的机制的了解，这一领域的进一步研究停滞不前。现在已知双硫仑反应是由肝酶醛脱氢酶（ALDH2）的抑制引起的，该酶通常参与酒精的代谢。当BDADs和酒精混合时触发双硫仑反应表明BDADs也抑制ALDH2。似乎BDADs还通过抑制醛脱氢酶介导其对精子发生的影响。在睾丸的精小管中，一种名为ALDH1a2的睾丸特异性醛脱氢酶生物合成维甲酸，维甲酸是一种维生素a衍生物，已知对精子形成至关重要。因此，我们假设bdad如WIN 18446通过抑制睾丸精管内ALDH1a2合成维甲酸来抑制精子发生。在本提案的具体目标#1中，我们将努力证明BDADs（如WIN 18446）抑制精子发生的机制涉及抑制睾丸内维甲酸的形成。这将在体外使用新生儿精原细胞培养物，以及在体内使用维生素a缺乏小鼠模型和正常兔子来完成。在特定目标#2中，我们将努力证明WIN 18446使用编码该酶的cDNA稳定转导的细胞系特异性抑制ALDH1a2。接下来，在具体目标#3中，我们将合成新的win18446衍生物，特异性抑制ALDH1a2，同时最大限度地减少对aldh2介导的酒精代谢的抑制。然后，我们将研究这些新化合物在体外和体内抑制精子发生的能力。这项工作将深入了解精子发生的生理学，并在开发一种安全有效的口服、非激素、可逆的男性避孕药方面取得实质性进展。

DESCRIPTION (provided by applicant): Almost fifty years ago, oral administration of Bis-dichloroacetyl-diamines (BDADs) such as WIN 18,446 was shown to safely, completely and reversibly inhibit spermatogenesis in men. These compounds were not brought to market as male contraceptives, however, because they caused a "disulfiram reaction" characterized by flushing, nausea and vomiting when co-ingested with alcohol. Further research in this area was stalled by lack of knowledge regarding the mechanism by which BDADs caused these effects. The disulfiram reaction is now known to be caused by the inhibition of the liver enzyme aldehyde dehydrogenase (ALDH2), normally involved in the metabolism of alcohol. The triggering of a disulfiram reaction when BDADs and alcohol are mixed suggests that BDADs also inhibit ALDH2. It seems plausible that BDADs also mediate their effects on spermatogenesis via inhibition of an aldehyde dehydrogenase. Within the seminiferous tubules of the testes, a testes-specific aldehyde dehydrogenase called ALDH1a2 biosynthesizes retinoic acid, a vitamin-A derivative known to be essential for spermatogenesis. Therefore, we hypothesize that BDADs such as WIN 18,446 suppress spermatogenesis by inhibiting the biosynthesis of retinoic acid by ALDH1a2 within the seminiferous tubules of the testes. In specific aim #1 of this proposal, we will endeavor to demonstrate that the mechanism by which BDADs such as WIN 18,446 suppress spermatogenesis involves inhibition of the formation of intratesticular retinoic acid. This will be accomplished in vitro using primary cell cultures of neonatal spermatogonia, as well as in vivo using the vitamin-A deficient mouse model and normal rabbits. In specific aim #2, we will endeavor to demonstrate that WIN 18,446 specifically inhibits ALDH1a2 using cell lines stably transduced with a cDNA encoding this enzyme. Next, in specific aim #3, we will synthesize novel derivatives of WIN 18,446 that specifically inhibit ALDH1a2 while minimizing inhibition of ALDH2-mediated alcohol metabolism. We will then examine the ability of these novel compounds to inhibit spermatogenesis both in vitro and in vivo. This work will provide insight into the physiology of spermatogenesis and result in substantial progress towards the development of a safe and effective oral, non-hormonal, reversible contraceptive for men. PUBLIC RELEVANCE: Despite currently available contraceptives, the world's population exceeds six and a half billion and is increasing by 80 million yearly. Much of this population growth is unintended and is due to inadequate contraception. Currently, male-directed contraceptive options are particularly limited. The research described in this proposal may eventually allow for the development of a safe and effective oral approach to male contraception, which will serve to greatly decrease the risk of unintended pregnancy and population growth.