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

激素与衰老--实验动物的垂体-下丘脑功能

• 批准号: 3802185
• 负责人: S MITCHELL HARMAN
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3802185
• 关键词: ADP ribosylation; G protein; aging; animal old age; biological signal transduction; gonadotropin releasing factor; high performance liquid chromatography; hormone regulation /control mechanism; hypothalamic pituitary axis; immunocytochemistry; immunofluorescence technique; inositol phosphates; juvenile animal; laboratory rat; luteinizing hormone; nifedipine; phorbols; pituitary gland; prolactin; radioimmunoassay; tissue /cell culture

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.

异种垂体细胞的原代单层培养已经显示出年龄- 服用PMA后，黄体生成素分泌相关减少。 激酶C激活剂以及钙通道阻滞剂硝苯地平之后。 观察表明，长期与短期促黄体生成素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。 检测细胞、生化和分子的新技术 与年龄相关的黄体生成素和催乳素分泌改变的事件有 被介绍给了。包括：离心洗脱、反向溶血 空斑分析、免疫细胞化学和免疫荧光、G蛋白放射免疫分析 亚基，以及PIP代谢物的高效液相测定。我们发现它 是有可能获得高度丰富的促性腺细胞群体使用 老鼠的数量很少。分离出的其他脑垂体区的旁腺效应 细胞似乎不需要GnRH介导的促黄体生成素分泌，因此 以这种方式浓缩的促性腺激素是有功能的。初步 促黄体生成素释放的测量证实了这两个基础的年龄相关性下降 促性腺激素释放激素刺激促性腺激素的分泌。在……里面 来自幼年和老年大鼠的脑垂体匀浆制剂，我们已经通过 ADP-核糖化，即Gα水平不变。这个结果，在 与之前的发现相结合，绕过质膜 逆转与年龄相关的促黄体生成素分泌缺陷，表明一种信号 促黄体生成素分泌缺陷与信号转导机制有关。级别 膜上的1，4，5-三磷酸肌醇在刺激下确实增加 GnRH，但肌醇1，3，4，5-四氢磷酸似乎也参与了 促黄体生成素的释放。这一结果可能解释了为什么在以前的研究中，IP3 单独使用并不能改变黄体生成素释放的年龄缺陷。