D2 TANTYCYTES IN THE REGULATION OF HPT AXIS

描述(取自应用程序) 这项研究的长期目标是阐明其控制机制。 基础状态下下丘脑-垂体-甲状腺(HPT)轴 该监管系统受到环境应激源干扰的情况 或以低循环甲状腺激素为特征的疾病状态 促甲状腺激素过低(非甲状腺疾病综合征)。我们最近做了 证实存在高浓度的2型碘甲状腺原氨酸 脱碘酶(D2)mRNA在一组特殊的胶质细胞内排列在地板和 第三脑室的下侧壁，称为D2柔韧细胞。自D2开始 将甲状腺激素(T4)转化为更具生物活性的甲状腺激素， 三碘甲腺原氨酸(T3)，我们认为D2伸缩细胞由一个 以前未被认识的HPT轴的调节成分。我们进一步 提出通过与脑脊液和脑内神经元的相互作用 邻近的下丘脑弓状核，D2细胞调节 甲状腺激素对大鼠TRH基因表达的反馈调节 下丘脑室旁核。这款R21试验的目的是 可行性建议是开发动物模型来测试 D2细胞对HPT轴的调节并开始阐明 这一规定发生的机制。两种不同的方法来实现 柔韧细胞D2缺乏或过度表达动物模型的建立 将会被使用。在第一种模型中，表达反义或 立体定向后过表达正义D2基因将被用来感染松弛细胞 将病毒注入第三脑室或正中隆起。第二 模型将涉及使用DARPP-32基因的转基因小鼠的开发 作为靶向反义或正义D2转录本的工具。 D2反义和正义转录本在Tanycell中的表达效果 将通过测量中底栖动物提取物中的D2活性来确定 下丘脑，以及原位显示的伸缩细胞的特异性 杂交组织化学。D2耗竭和过度表达对血管内皮细胞生长的影响 HPT轴上的张力细胞将在基础条件下或在 甲状腺功能减退和禁食动物。由于DARPP-32的共存， 磷酸酶抑制剂和D2在柔韧细胞中，我们还将确定 DARPP-32通过测定循环甲状腺对D2的调节作用 甲状腺功能减退症和慢性甲状腺功能减退症患者松弛细胞的激素水平和D2活性 在DARPP-32基因敲除小鼠中禁食。

DESCRIPTION (taken from the application) The long term goals of this study are to elucidate the mechanisms of control of the hypothalamic-pituitary-thyroid (HPT) axis under basal conditions and during conditions when this regulatory system is perturbed by environmental stressors or disease states characterized by low circulating thyroid hormone and inappropriately low TSH (nonthyroidal illness syndrome). We have recently demonstrated the presence of large concentrations of type 2 iodothyronine deiodinase (D2) mRNA in a group of specialized glial cells lining the floor and infralateral wall of the third ventricle, termed D2 tanycytes. Since D2 converts thyroxine (T4) to the more biologically active thyroid hormone, triiodothyronine (T3), we propose that D2 tanycytes comprise part of a previously unrecognized regulatory component of the HPT axis. We further propose that via interactions with the cerebrospinal fluid and neurons in the adjacent hypothalamic arcuate nucleus, D2 tanycytes modulate the set point for feedback regulation of thyroid hormone on the gene expression of TRH in the hypothalamic paraventricular nucleus. The purpose of this R21 Pilot and Feasibility Proposal is to develop animal models to test the importance of the D2 tanycyte on the regulation of the HPT axis and begin to elucidate the mechanisms by which this regulation occurs. Two different approaches to developing animal models with D2 deficiency or D2 overexpression in tanycytes will be used. In the first model, adenovirus that express antisense or overexpress sense D2 mRNA will be used to infect tanycytes after stereotaxic injection of the virus into the third ventricle or median eminence. The second model will involve the development of transgenic mice, using the DARPP-32 gene as a tool to target antisense or sense D2 transcripts to the tanycytes. Efficacy of expression of the D2 antisense and sense transcripts in tanycytes will be determined by measuring D2 activity in extracts from the mediobasal hypothalamus, and the specificity for tanycytes demonstrated by in situ hybridization histochemistry. The effect of D2 depletion and overexpression in tanycytes on the HPT axis will then be studied under basal conditions or in hypothyroid and fasting animals. Due to the coexistence of DARPP-32, a phosphatase inhibitor, and D2 in tanycytes, we will also determine whether DARPP-32 exerts a regulatory function on D2 by measuring circulating thyroid hormone levels and D2 activity in tanycytes in response to hypothyroidism and fasting in the DARPP-32 knock-out mouse.