PDE3 Inhibitors: Selective Blockers of Oocyte Maturation

说明(申请人提供)：避孕需求从未像现在这样强烈，世界人口超过60亿，目前处于最佳生育年龄段的年轻人超过10亿就是明证。人口过剩是一种有害的公共卫生问题，它破坏基础设施，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的艰苦成果。避孕还通过减少意外怀孕、堕胎和意外生育，提供显著的预防性健康益处。由于副作用、可获得性和文化或道德上的反对意见限制了人们对当前方法的普遍接受，因此有必要研究新的避孕方法。这笔赠款的目的是探索以下假设：灵长类卵巢中存在选择性表达磷酸二酯酶(POE)亚型，选择性阻断PDE3可以防止自发和促性腺激素诱导的卵母细胞成熟，以及长期使用PDE3抑制剂可以在不影响月经周期或黄体功能的情况下阻止灵长类动物怀孕。具体目的是：(1)描述PDE在灵长类卵巢中表达的基本生物学。这一目标的目的是确定猕猴卵巢中表达的PDE同工酶的特征。另一个目标是测试新型PDE3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高的选择性或效力。(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的卵母细胞成熟，但不能阻止排卵和黄体功能。这一目标的目的将是证明在体内可以有效和选择性地实现卵母细胞抑制，并在体内研究药物活性剂量的PDE3抑制剂的全身毒性。3)确定在配对交配情况下，PDE3抑制剂是否在定期骑自行车的猕猴中起到避孕剂的作用。这一目标的目的是通过长期观察，证明全身应用PDE3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：卵巢组织的体细胞和生殖细胞中PDE基因产物(mRNA和蛋白质)的特征(目标1)，未成熟卵母细胞和颗粒细胞与PDE3抑制剂的体外孵育(目标1)，在COS和自然月经周期期间体内给猴子注射PDE3抑制剂，然后抽吸卵泡以评估卵母细胞的体外成熟和受精能力，以及内分泌和毒性测量(目标2)，以及对关在笼子里的有生育能力的雌性猴子长期服用PDE3抑制剂，以评估避孕效果和长期毒性(目标3)。这一方法有望为未来PDE3抑制剂在人体上的第一阶段试验提供基础。

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.