PDE3 Inhibitors: Selective Blockers of Oocyte Maturation

描述（由申请人提供）：世界人口超过60亿，目前处于生育黄金期的年轻人超过10亿，这证明避孕的需求从未如此之大。人口过剩是一种有害的公共卫生问题，它破坏基础设施，并通过威胁人类的基本基础设施，限制在总体健康状况方面取得来之不易的进展。避孕还通过减少意外怀孕、堕胎和意外生育提供了显著的预防性健康益处。由于副作用、获取途径以及文化或道德上的反对限制了对当前方法的普遍接受，因此有必要对新型避孕药进行研究。本基金的目的是探索以下假设：在灵长类动物卵巢中存在磷酸二酯酶（POE）亚型的选择性表达，可以利用PDE 3的选择性阻断来防止自发性和促性腺激素诱导的卵母细胞成熟，以及用PDE 3抑制剂长期治疗可以防止灵长类动物怀孕而不影响月经周期或黄体功能。具体目的是：（1）描述PDE在灵长类动物卵巢中表达的基础生物学。本研究的目的是表征猕猴卵巢中表达的PDE同工酶。另一个目标是测试新型PDE 3抑制剂在体外防止减数分裂自发恢复的能力，以了解是否可以实现更大的选择性或效力。(2)确定PDE3抑制剂是否能阻止接受控制性卵巢刺激（COS）方案或体内自然周期的恒河猴卵母细胞成熟，但不能阻止排卵和黄体功能。该目的的目标是证明卵母细胞抑制可以在体内有效地和选择性地实现，并研究PDE3抑制剂在体内以非活性剂量的全身毒性。 3)确定PDE3抑制剂是否作为避孕药在定期循环的恒河猴配对交配的情况下。本研究的目的是通过长期观察记录全身给予PDE 3抑制剂作为潜在避孕药的有效性和实用性。实验设计将包括：PDE基因产物的表征（mRNA和蛋白质），未成熟卵母细胞和颗粒细胞与PDE 3抑制剂的体外孵育（Aim 1），在COS和自发月经周期期间向猴体内施用PDE 3抑制剂，随后进行卵泡抽吸以评估卵母细胞的体外成熟和受精能力，加上内分泌和毒性测量（目标2），以及向与能生育的雄性关在一起的能生育的雌性长期施用PDE 3抑制剂以评估避孕功效和长期毒性（目标3）。这种方法有望为未来人体PDE3抑制剂的I期试验提供基础。

DESCRIPTION (provided by applicant): The need for contraception has never been greater, as evidenced by a world population of over 6 billion, and greater than one billion young people currently in the prime reproductive years. Overpopulation is a pernicious public health affliction that ravages infrastructure and limits the achievement of hard fought gains in overall health status by threatening the basic infrastructure of humanity. Contraception also provides significant preventative health benefits by reducing unintended pregnancy, abortions, and unwanted births. As side effects, access, and cultural or moral objections limit the universal acceptance of current methods, research into novel contraceptives is warranted. The purpose of this grant is to explore the hypotheses that selective expression of phosphodiesterase (POE) isoforms exists in the primate ovary, that selective blockade of PDE3 can be exploited to prevent spontaneous and gonadotropin induced oocyte maturation, and that chronic treatment with a PDE3 inhibitor can prevent pregnancy in primates without affecting menstrual cyclicity or luteal function. The Specific Aims are to: (1) Describe the basic biology of PDE expression in the primate ovary. The goal of this aim is to characterize the PDE isoenzymes expressed in the macaque ovary. An additional goal will be to test novel PDE3 inhibitors for their ability to prevent spontaneous resumption of meiosis in vitro to learn if greater selectivity or potency can be achieved. (2) Determine if PDE3 inhibitors prevent oocyte maturation, but not ovulation and function of the corpus luteum in rhesus monkeys undergoing controlled ovarian stimulation (COS) protocols or during natural cycles in vivo. The goals of this aim will be to document that oocyte inhibition can be effectively and selectively achieved in vivo, and to investigate the systemic toxicity of PDE3 inhibitors at pharmacologically active dosages in vivo. 3) Determine whether PDE3 inhibitors function as contraceptive agents in regularly cycling rhesus monkeys in paired mating situations. The goal of this aim is to document the efficacy and practicality of systemic administration of a PDE3 inhibitor as a potential contraceptive through longer-term observation. Experimental designs will include: characterization of PDE gene products (mRNA and protein) in somatic and germ cells from ovarian tissue (Aim 1), in vitro incubation of immature oocytes and granulosa cells with PDE3 inhibitors (Aim 1), in vivo administration of a PDE3 inhibitor to monkeys during COS and spontaneous menstrual cycles, followed by follicular aspiration to assess oocyte maturation and fertilizability in vitro, plus endocrine and toxicity measurements (Aim 2), and chronic administration of a PDE 3 inhibitor to fertile females caged with fertile males to assess contraceptive efficacy and long term toxicity (Aim 3). This approach is expected to provide a foundation for future Phase 1 trials of PDE3 inhibitors in humans.