PITUITARY CELLS TO STUDY MALE INFERTILITY

多达15%的夫妇会在某个时间接受生育障碍评估。在这些人中，40%是男性因素不育，另有20%的人不育原因不明。有证据表明，精子数量在20世纪大幅下降，这进一步增加了男性生殖健康研究的意义。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。大多数已知的促性腺激素分泌的细胞和分子生物学来自于使用大鼠和大鼠脑垂体细胞的实验。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，我们建议使用非人类男性灵长类动物的垂体细胞培养作为人类下丘脑-垂体单位的模型，以努力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GnRH脉冲刺激的灌流垂体细胞进行。检查的主要终点包括促性腺激素分泌和亚单位基因表达、促性腺激素释放激素受体和卵泡抑素mRNA。本研究的目的是：1)检测重组抑制素-B和重组抑制素-A在激活素-A存在或不存在的情况下对灵长类细胞促性腺激素分泌和亚单位基因表达的影响；2)确定促性腺激素释放激素(GnRH)脉冲频率是否对周围灌流的灵长类细胞FSH和LH的分泌有不同的调节作用，并探讨激活素、抑制素和卵泡抑素在这一调节中的作用；以及3)确定雌二醇而不是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为人类男性不育的内分泌异常提供洞察，这是从细胞系或大鼠的研究中无法了解的，也不是通过人类研究得出的。

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.