BENZODIAZEPINE RECEPTOR AND ADRENAL DEVELOPMENT

苯二氮卓受体和肾上腺发育

• 批准号: 6381540
• 负责人: ERIC P. WIDMAIER
• 金额: $ 24.55万
• 依托单位: BOSTON UNIVERSITY (CHARLES RIVER CAMPUS)
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2003-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6381540
• 关键词: SDS polyacrylamide gel electrophoresis; adrenal glands; adrenocorticotropic hormone; benzodiazepine receptor; cholesterol; cyclic AMP; growth /development; hormone regulation /control mechanism; hormone sensitivity /resistance; in situ hybridization; laboratory rat; lipid transport; mitochondrial membrane; newborn animals; northern blottings; protein structure function; receptor binding; receptor expression; steroid hormone biosynthesis; tissue /cell culture; transfection; western blottings

The objectives of this application are to elucidate the role of the peripheral-type benzodiazepine receptor (PBR) in maturation of the adrenal glands, and to determine mechanisms of regulation of this receptor. PBR is expressed in all steroidogenic cells, including gonads, adrenals, placenta, and brain (glia), where it is believed to mediate transport of cholesterol to the inner mitochondrial membrane, the site of enzymes needed to convert cholesterol to pregnenolone. Inability to transfer cholesterol to the inner membrane is associated with decreased steroidogenesis. Since this is the rate-limiting step in steroidogenesis, it is critical that this process be fully understood if new and better therapeutic approaches to disorders of adrenal pathology (e.g., adrenal insufficiency or hypertrophy) are to be developed. Studies on regulation of this important receptor in have been hindered by the lack of a normal cell or animal model in which the receptor is expressed at low levels. The neonatal rat is a model of ACTH-insensitivity, since during this period adrenocortical cells respond weakly to ACTH (10 percent of adult levels). Insensitivity to ACTH is also observed in fetuses of larger mammals, and prevents neurotoxic effects of high levels of glucocorticoids on developing brain cells. Because adrenal insufficiency is the primary cause of morbidity and mortality in premature infants (glucocorticoids are required for induction of surfactant expression in fetal lungs), the process by which the developing adrenal gland matures is of great significance. Recent findings demonstrate that neonatal rat adrenals express PBR at 10 percent the level in adult adrenals. Thus, it is proposed to characterize the complete developmental profile of PBR and other factors suggested to be important in cholesterol transport, and correlate this with changes in adrenocortical sensitivity to ACTH in vivo and in vitro. PBR expression will be determined by immunoblot, Northern blot, in situ hybridization, and ligand binding assays from fetal life through weaning. The effects of chronic treatment with ACTH or cAMP on cholesterol transport, PBR expression, and steroidogenesis in vivo and in cultured neonatal adrenal cells will be examined. The ability of transfected PBR to restore ACTH sensitivity in cultured neonatal cells will also be examined. The ontogenic appearance of PBR ligands will be determined by radioimmunoassay. These studies, therefore, will simultaneously address two important questions: What are the factors that limit steroidogenesis in immature adrenal glands, and which factors regulate expression of PBR?

此应用程序的目标是阐明 外围型苯二氮卓受体（PBR）在成熟的成熟 肾上腺，并确定调节的机制 受体。 PBR在所有类固醇生成细胞中均表示 性腺，肾上腺，胎盘和大脑（神经胶质），被认为是 介导胆固醇向内部线粒体膜的转运， 酶的部位需要将胆固醇转化为妊娠烯醇酮。 无法将胆固醇转移到内膜是相关的 类固醇生成降低。 因为这是限制步骤 在类固醇生成中，至关重要 理解是否为疾病的新方法和更好的治疗方法 肾上腺病理学（例如肾上腺功能不全或肥大）是 被开发。 研究该重要受体的调节 由于缺乏正常细胞或动物模型所阻碍 受体以低水平表达。新生大鼠是 ACTH的敏感性，因为在此期间肾上腺皮质细胞 对ACTH的反应较弱（成人水平的10％）。 对 在较大哺乳动物的胎儿中也观察到ACTH，并预防 高水平糖皮质激素对发展的神经毒性作用 脑细胞。因为肾上腺功能不全是 早产婴儿的发病率和死亡率（糖皮质激素是 在胎儿肺中诱导表面活性剂表达所必需的） 发育中的肾上腺成熟的过程很棒 意义。 最近的发现表明新生儿大鼠肾上腺 在成年肾上腺中以10％的水平表达PBR。因此，是 建议表征PBR和 建议在胆固醇运输中很重要的其他因素，并且 将其与对ACTH的肾上腺皮质敏感性的变化相关 体内和体外。 PBR表达将由免疫印迹确定， 北印迹，原位杂交和配体结合测定 通过断奶的胎儿生活。 ACTH慢性治疗的影响 或在胆固醇转运，PBR表达和类固醇生成上进行营地 将检查体内和培养的新生儿肾上腺细胞。 这 转染PBR在培养的 还将检查新生儿细胞。 PBR的个体生成外观 配体将由放射免疫测定法确定。 这些研究， 因此，将同时解决两个重要问题：什么是 限制未成熟肾上腺中类固醇发生的因素，以及 哪些因素调节PBR的表达？