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

异质垂体细胞的原代单层培养显示年龄- PMA是一种蛋白质， 激酶C激活剂以及钙通道阻滞剂硝苯地平。 观察结果表明，长期与短期LH释放可能会继续进行 通过不同的机制，这些机制受到衰老的不同影响。 研究细胞、生物化学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 被介绍。 这些包括;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RIA 亚基和PIP代谢物的HPLC测量。 我们已经发现 可以获得高度富集的促性腺细胞群， 少量老鼠。 来自另一个分离垂体的旁腺效应 细胞对于GnRH介导的LH分泌似乎不是必需的， 以这种方式富集的促性腺激素是有功能的。 初步 LH释放的测量结果证实， 和促性腺激素释放激素刺激的LH分泌。 在 垂体匀浆制剂从年轻和老年大鼠，我们已经表明， ADP-核糖基化，即G α水平不变。 结果，在 与之前的发现相结合，绕过质膜 逆转了与年龄相关的LH分泌缺陷，这表明， LH分泌缺陷涉及转导机制。 水平 膜肌醇1，4，5-三磷酸在刺激后确实增加， GnRH，但肌醇1，3，4，5-四磷酸似乎也参与 LH的释放。 这一结果可以解释为什么在以前的研究中，IP 3 单独使用并不能改变LH释放的年龄缺陷。

Primary monolayer cultures of heterogeneous pituitary cells have shown age- related decreases in LH secretion after administration of PMA, a protein- kinase C activator as well as after nifedipine, a calcium channel blocker. Observations suggest that long vs. short term LH release may proceed through separate mechanisms which are differentially affected by aging. New techniques for examining the cellular, biochemical, and molecular events responsible for age-related alterations in LH and PRL secretion have been introduced. These include; centrifugal elutriation, reverse hemolytic plaque assay, immunocytochemistry and immunofluorescence, RIA of G-protein subunits, and HPLC measurement of PIP metabolites. We have found that it is possible to achieve highly enriched gonadotropic cell populations using small number of rats. Paracine effects from the other separated pituitary cells do not appear necessary for GnRH mediated secretion of LH so that gonadotropes enriched in this manner are functional. Preliminary measurements of LH release confirm an age-related decrease in both basal and GnRH-stimulated LH secretion in enriched gonadotrope populations. In pituitary homogenate preparations from young and old rats, we have shown by ADP-ribosylation, that G alphas levels do not change. This result, in conjunction with the previous finding that bypassing the plasma membrane reverses the age related LH-secretion deficit, suggests that a signal transduction mechanism is involved in the LH secretion deficit. Levels of membrane inositol 1, 4, 5-triphosphate do increase upon stimulation with GnRH, but inositol 1,3,4,5-tetrakisphosphate also appears to be involved in the release of LH. This result may explain why, in previous studies, IP3 alone did not alter the age-deficit in LH release.