PITUITARY CELLS TO STUDY MALE INFERTILITY

多达15%的夫妇在某个时候被评估为生育障碍。其中，40%是男性因素导致的不育症，另外20%是无法解释的不育症。精子数量在20世纪大幅下降的证据进一步增加了男性生殖健康研究的重要性。该项目的长期目标是通过分析睾丸控制促性腺激素分泌的机制来了解人类男性不育的内分泌方面。大多数关于促性腺激素分泌的细胞和分子生物学的知识是来自大鼠和大鼠垂体细胞的实验。但我们的研究表明，调节雄性大鼠促性腺激素分泌的控制机制可能并不总是适用于男性。在此，我们建议使用来自非人雄性灵长类动物的垂体细胞培养物作为人类下丘脑-垂体单元的模型，以了解正常和不育男性的促性腺激素分泌。实验将使用单层培养以及经GnRH脉冲刺激的周围垂体细胞进行。要检查的主要终点包括促性腺激素分泌和亚基基因表达，GnRH受体和卵泡抑素mRNA。本建议的目的是：1)研究在激活素- a存在或不存在的情况下重组抑制素- b和重组抑制素- a对灵长类垂体细胞促性腺激素分泌和亚基基因表达的影响；2)确定GnRH脉频对周围灵长类垂体细胞FSH和LH分泌的调节是否存在差异，并探讨激活素、抑制素和卵泡抑素在这一调节中的作用。3)确定雌二醇而非雄激素抑制灵长类垂体细胞促性腺激素分泌的原因。从这些研究中获得的信息应该能够深入了解人类男性不育症的内分泌异常，这是无法从细胞系或大鼠的研究中或通过人体调查中了解到的。

As many as 15 percent of couples are evaluated at some time for a fertility disturbance. Of these, 40 percent are male factor infertility, and in another 20 percent the infertility is unexplained. Evidence that sperm counts have declined substantially in the twentieth century adds further significance to research in male reproductive health. The long term goal of this project is to understand the endocrine aspects of human male infertility by analyzing the mechanisms involved in the testicular control of gonadotropin secretion. Most of what is known about the cellular and molecuar biology of gonadotropin secretion is from experiments using rats and rat pituitary cells. But our research indicates that the control mechanisms regulating gonadotropin secretion in male rats may not always be applicable to men. Herein we propose the use of pituitary cell cultures from the nonhuman male primate as a model of the human hypothalamic-pituitary unit in an effort to understand gonadotropin secretion in normal and infertile men. Experiments will be conducted using monolayer cultures as well as perifused pituitary cells stimulated with pulses of GnRH. The major endpoints to be examined include gonadotropin secretion and subunit gene expression, GnRH receptors and follistatin mRNA. The aims of the current proposal are: 1) To examine the effects of recombinant inhibin-B and recombinant inhibin-A in the presence or absence of activin-A on gonadotropin secretion and subunit gene expression in primate pituitary cells, 2) To determine whether GnRH pulse frequency differentially regulates the secretion of FSH and LH in perifused primate pituitary cells, and to probe the role of activin, inhibin and follistatin in this regulation, and 3) To determine why estradiol but not androgens inhibit gonadotropin secretion in primate pitutiary cells. The information to be derived from these studies should provide insight into the endocrine abnormalities in human male infertilty which cannot be learned from studies in cell lines or rats, or through human investigation.