HORMONES AND AGING--PITUITARY-HYPOTHALAMIC FUNCTION IN EXPERIMENTAL ANIMALS

自动灌注系统中垂体组织的持续研究 证实了GnRH刺激的LH与年龄相关的减少 分泌，以前在单层培养中显示。无法逆转 GnRH重复灌注脉冲引起的体外LH分泌减少 与我们先前在重复体内施用 GnRH，并进一步表明，衰老与内在的 垂体促性腺激素分泌缺陷小学的最新研究 异质垂体细胞悬液的单层培养揭示了 给药后年龄相关的LH分泌减少 佛波酯，PMA，蛋白激酶C激活剂以及之后 硝苯地平，电压门控钙通道阻滞剂。这些观察结果 提示LH释放长期和短期刺激均可进行 通过不同的机制，这些机制受到衰老的不同影响。 检测细胞、生化和分子生物学的新技术 导致LH和PRL分泌年龄相关改变的事件 被引入我们的实验室。包括：离心 淘洗，反向溶血空斑试验，免疫细胞化学和 免疫荧光、G蛋白亚基RIA和PIP的HPLC测量 代谢物。体外雌激素刺激对LH-β和 PRL基因转录的研究是在单层培养的垂体 来自老年与成熟雌性大鼠的细胞。

Continuing studies of pituitary tissues in the automated perifusion system confirm the observations of an age-related decrease in GnRH-stimulated LH secretion, previously shown in monolayer cultures. The failure to reverse the in vitro LH hyposecretion by repetitive perfusion pulses of GnRH parallels our prior observations after repetitive in vivo administration of GnRH and further suggests that aging is associated with an intrinsic pituitary gonadotropic secretary defect. Recent studies in primary monolayer cultures of heterogeneous pituitary cell suspensions reveal age-related decreases in secretion of LH after administration of the phorbol ester, PMA, a protein-kinase C activator as well as after nifedipine, a voltage gated calcium channel blocker. These observations suggest that both long and short term stimulation of LH release may proceed through separate mechanisms which are differentially affected by aging. Newer techniques for examining the cellular, biochemical, and molecular events responsible for age-related alterations in LH and PRL secretion have been introduced into our laboratory. These include; centrifugal elutriation, reverse hemolytic plaque assay, immunocytochemistry and immunofluorescence, RIA of G-protein subunits, and HPLC measurement of PIP metabolites. The effects of in vitro estrogen stimulation on LH-beta and PRL gene transcription is being studied in monolayer cultures of pituitary cells from old vs mature female rats.