Significance of Pituitary Leptin to Gonadotropes

垂体瘦素对促性腺激素的意义

• 批准号: 7660237
• 负责人: GWEN V CHILDS
• 金额: $ 7.25万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7660237
• 关键词: Ablation; Accounting; Activins; Adipocytes; Adult; Affect; Amenorrhea; Animal Model; Animals; Anterior Pituitary Gland; Cells; Child; Competence; Coupled; Development; Diet; Fasting; Female; Fertility; Food deprivation (experimental); Foundations; Future; Genes; Glucose; Gonadotropin Hormone Releasing Hormone; Gonadotropin-Releasing Hormone Receptor; Gonadotropins; Human; In Vitro; Infertility; Knock-out; LH Cell; Laboratories; Lead; Learning; Leptin; Link; Maintenance; Malnutrition; Mediating; Messenger RNA; Metabolic; Mus; Mutant Strains Mice; National Institute of Child Health and Human Development; Nutrient; Nutritional; Nutritional Support; Nutritional status; Oocytes; Organ; Peptides; Physiologic pulse; Pilot Projects; Pituitary Gland; Proestrus; Proteins; Puberty; Rattus; Recovery; Regulation; Reporting; Serum; Signal Pathway; Signal Transduction; Small Interfering RNA; Spermatocytes; Steroids; Stimulus; Technology; Testing; Time; Transgenes; Transgenic Mice; Ursidae Family; Water; Woman; cell type; design; feeding; female reproductive system; in vitro Model; in vivo; leptin receptor; male; men; model development; mouse model; neuropeptide Y; novel; prepuberty; promoter; public health relevance; recombinase; reproductive; reproductive hormone; response; restoration

DESCRIPTION (provided by applicant): Pituitary leptin changes in a cyclic manner that indicates it may facilitate or permit the secretion of gonadotropins. There are parallel reductions in pituitary leptin and LH during food deprivation and a parallel recovery mediated by glucose. This circumstantial evidence suggests that pituitary leptin may serve as a metabolic gateway to permit gonadotrope function, if the nutritional status is optimal. This proposed pilot study is designed to develop cellular and animal models that test the hypothesis that pituitary leptin from somatotropes is vital for the normal development and responses of gonadotropes to gonadotropin releasing hormone (GnRH). The studies will test the hypothesis with in vitro approaches in Aim 1 in which siRNA for leptin mRNA will be used to knock out pituitary leptin. In Aim 2, the hypothesis will be tested by in vivo studies, in which leptin expression is deleted in somatotropes by Cre-loxP technology. To ablate the leptin gene in somatotropes, mutant mice bearing the transgene rGHp-Cre will be crossed with mice that bear loxP flanking the leptin gene. In both sets of aims, gonadotrope responses to GnRH will be tested to determine if ablation of pituitary leptin in vitro or in vivo (in somatotropes) affects gonadotrope functions. Gonadotrope development and fertility will also be tested in the mutant mice that have leptin excised in somatotropes. This pilot study provides a focused approach to answer the question of the significance of pituitary leptin to gonadotrope functions, which avoids metabolic problems seen with global leptin knockouts that affect gonadotropes and confound interpretation of leptin functions. The pilot study will lay the foundation for the development of future studies that test the effect of pituitary leptin on gonadotrope responses to other regulators (steroids, neuropeptide Y and activin). Future in vivo studies with Cre-loxP technology can be proposed to test the significance of leptin produced by other pituitary cell types (corticotropes and gonadotropes). The ultimate aim of the study will be to determine how leptin supports reproductive competence and how information about malnutrition may be linked with infertility. PUBLIC HEALTH RELEVANCE: This proposed pilot study is focused on the significance of pituitary leptin to gonadotropes; testing the hypothesis that pituitary leptin is vital for gonadotrope development and/or functions. Aim 1 will develop an in vitro model; the studies will use siRNA for leptin mRNA to ablate pituitary leptin to determine its effects on gonadotrope function. Aim 2 will develop an in vivo transgenic mouse model in which leptin is ablated specifically in somatotropes by Cre-loxP technology. Transgenic mice, in which leptin is knocked out in somatotropes, will be tested for the time of onset of puberty, fertility, and responses by gonadotropes to stimuli. These studies focus on basic regulatory mechanisms that link nutritional status to fertility.

描述（由申请人提供）：垂体瘦素以循环方式变化，表明它可以促进或允许促性腺激素的分泌。在食物匮乏期间，垂体瘦素和 LH 会平行减少，而葡萄糖介导的平行恢复。这一间接证据表明，如果营养状况最佳，垂体瘦素可以作为促进促性腺激素功能的代谢途径。这项拟议的试点研究旨在开发细胞和动物模型，以测试以下假设：生长激素中的垂体瘦素对于促性腺激素的正常发育和对促性腺激素释放激素 (GnRH) 的反应至关重要。这些研究将通过目标 1 中的体外方法检验这一假设，其中瘦素 mRNA 的 siRNA 将用于敲除垂体瘦素。在目标 2 中，该假设将通过体内研究进行检验，其中通过 Cre-loxP 技术删除生长激素中的瘦素表达。为了消除生长激素中的瘦素基因，携带转基因 rGHp-Cre 的突变小鼠将与携带瘦素基因侧翼 loxP 的小鼠杂交。在这两组目标中，将测试促性腺激素对 GnRH 的反应，以确定体外或体内（生长激素）垂体瘦素的消除是否会影响促性腺激素功能。促性腺激素的发育和生育力也将在生长激素被切除的突变小鼠中进行测试。这项试点研究提供了一个有针对性的方法来回答垂体瘦素对促性腺激素功能的重要性问题，避免了整体瘦素敲除中出现的影响促性腺激素和混淆瘦素功能解释的代谢问题。该试点研究将为未来测试垂体瘦素对促性腺激素对其他调节剂（类固醇、神经肽 Y 和激活素）反应的影响的研究奠定基础。未来可以利用 Cre-loxP 技术进行体内研究，以测试其他垂体细胞类型（促肾上腺皮质激素和促性腺激素）产生的瘦素的重要性。该研究的最终目的是确定瘦素如何支持生殖能力以及有关营养不良的信息如何与不孕不育相关。 公共健康相关性：这项拟议的试点研究的重点是垂体瘦素对促性腺激素的重要性；检验垂体瘦素对于促性腺激素的发育和/或功能至关重要的假设。目标1将开发体外模型；该研究将使用瘦素 ​​mRNA 的 siRNA 来消除垂体瘦素，以确定其对促性腺激素功能的影响。 Aim 2 将开发一种体内转基因小鼠模型，其中生长激素中的瘦素通过 Cre-loxP 技术被特异性消除。转基因小鼠的生长激素中的瘦素被敲除，将测试其青春期开始时间、生育能力以及促性腺激素对刺激的反应。这些研究重点关注将营养状况与生育力联系起来的基本调节机制。