NEUROTENSIN SYNTHESIS IN ARCUATE NEUROSECRETORY CELLS

弓形神经分泌细胞中的神经降压素合成

• 批准号: 2655480
• 负责人: MARK J ALEXANDER
• 金额: $ 11.61万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-02-01 至 2000-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2655480
• 关键词: estrogen receptors; estrogens; estrus; female; follicle stimulating hormone; gender difference; gene expression; genetic transcription; hormone regulation /control mechanism; hypothalamus; in situ hybridization; laboratory rat; luteinizing hormone; median eminence; messenger RNA; neuroendocrine system; neurohormones; neuropeptide receptor; neurotensin; ovariectomy; peptide hormone biosynthesis; progesterone; prolactin; secretion; tyrosine 3 monooxygenase

The broad objective of this proposal is to clarify the function of neurotensin (NT) synthesis and-release by neurosecretory cells located in the dorsomedial division of the hypothalamic arcuate nucleus in the rat. Regulation of NT synthesis in this region follows a pattern that implies NT involvement in female-specific, estrogen-dependent secretion of one or more adenohypophysial hormones, particularly prolactin and the gonadotropins. To test this hypothesis, NT antiserum will be used to selectively interfere with endogenously released NT in conscious, freely moving females at proestrus, and the effect of this intervention on circulating levels of prolactin, luteinizing hormone, and follicle- stimulating hormone will be determined. A primary aim of this proposal is to determine in the female the extent to which estrogen-inducible synthesis of NT occurs in tuberoinfundibular dopaminergic neurons under physiological conditions. To that end, a double-label method of in situ hybridization will be used to determine the number and distribution of dorsomedial arcuate neurons that coexpress mRNA encoding NT and neuromedin N (NT/N mRNA) and tyrosine hydroxylase mRNA under different endocrine conditions. The same technique will also be used to investigate likely coexpression of NT/N mRNA with either estrogen receptor mRNA or NT receptor mRNA in this region and thus to identify NT neurons subject to direct regulation by estrogen or NT itself. A basic premise of these studies is that heterogeneous coexpression of the NT/N gene with certain other genes in dorsomedial neurons will reveal functional subgroups of NT-synthesizing neurons in this region. Hormonal regulation of NT/N mRNA expression in these neurons will be investigated to obtain additional clues to their function. In situ hybridization will be used to assess the possibility that prolactin or progesterone influence NT/N mRNA expression in the dorsomedial arcuate nucleus. Also, in situ hybridization with an intron-specific probe will be used to determine whether estrogen increases NT/N mRNA levels through increased transcription of the NT/N gene. The time course over which estrogen increases levels of NT/N primary transcript and mature NT/N mRNA will indicate whether estrogen- induced synthesis of NT could plausibly mediate specific neuroendocrine events. Steady-state levels of NT and neuromedin N will be measured to determine whether estrogen alters their ratio in the median eminence or neurointermediate lobe. Finally, in situ hybridization will be used to determine whether adult sex differences in plasma estrogen levels account for sexually differentiated expression of NT/N mRNA in dorsomedial arcuate neurons. By clarifying the role of NT in normal neuroendocrine function, these studies will provide a basis for future investigation of NT involvement in human neuroendocrine disorders.

这项建议的主要目标是澄清 神经降压素（NT）的合成和释放的神经分泌细胞位于 在下丘脑弓状核的背内侧区， 大鼠该区域NT合成的调节遵循一种模式， 提示NT参与雌性特异性雌激素依赖性分泌 一种或多种腺垂体激素，特别是催乳素， 促性腺激素为了检验这一假设，NT抗血清将用于 选择性地干扰内源性释放的NT在有意识的，自由的 在发情前期移动的女性，以及这种干预对 催乳素、促黄体生成素和卵泡的循环水平- 刺激激素将被确定。这项提案的主要目的是 是为了确定雌激素诱导的 NT的合成发生在结节漏斗多巴胺能神经元， 生理条件。为此，采用原位双标记方法， 杂交将被用来确定数量和分布 背内侧弓状神经元共表达编码NT的mRNA， 神经介肽N（NT/N）mRNA和酪氨酸羟化酶mRNA在不同条件下 内分泌条件。同样的技术也将用于调查 NT/N mRNA可能与雌激素受体mRNA或 NT受体mRNA在此区域，从而确定NT神经元受 通过雌激素或NT本身直接调节。一个基本前提是， 研究表明，NT/N基因与某些 背内侧神经元中的其他基因将揭示 NT合成神经元在这个区域。NT/N mRNA的激素调节 将研究这些神经元中的表达以获得额外的 它们功能的线索原位杂交将用于评估 催乳素或孕酮影响NT/N mRNA表达的可能性 背内侧弓状核此外，原位杂交与一个 内含子特异性探针将用于确定雌激素是否 通过增加NT/N的转录增加NT/N mRNA水平 基因雌激素增加NT/N水平的时间过程 初级转录物和成熟NT/N mRNA将指示雌激素- NT的诱导合成可能介导特异性神经内分泌 事件将测量NT和神经介肽N的稳态水平， 确定雌激素是否改变了它们在正中隆起的比例， 神经中间叶最后，原位杂交将用于 确定血浆雌激素水平的成人性别差异是否可以解释 NT/N mRNA在背内侧核的性分化表达 弓状神经元通过阐明NT在正常神经内分泌中的作用， 功能，这些研究将为未来的调查提供基础， NT参与人类神经内分泌紊乱。