单纯性肥胖儿童中生长激素生物活性变化及其机制研究

Grows Hormone (GH) is a kind of hormone which excreted by antehypophysis, it's the pivotal factor of regulating the growth and development of human. With the further research of GH function in recent years, a large number of evidence proved that GH has some other functions, it is a role in a wide range and plays important role in the regulation of metabolism and the proliferate and aging. With the widely used of the GH determination in clinical practice and the continuous updating of diagnostic code of correlative ailment of GH. The clinical laboratory must reply the different demand of determination of GH. The usual methods of GH determination are based on immunologic determination method. Because of the technology limit of GH bioactivity determination and experimental procedure are complicated. Have not extended to clinical determination and become a hindrance to the progress of GH bioactivity determination research in many kinds of disease. This research intends to use our original extracorporeal GH determination method, which called BAF- GM cell strain determination method. Determinate serum in different form of endocrine disease, the result shows that there are close correlation GH between immunoactivity and bioactivity in obese children, GH bioactivity in obese children is obviously lower than normal children, this study intends to expand the sample, the Xinjiang Han, Uygur, kazak simple obese children, serum samples of growth hormone bioassay and immunoradiometric assay, comparing GH bioactivity between normal children and simple obese children, Verify the previous experimental results, and according to the previous studies provide clues, as the object of study in rats, inject recombinant human growth hormone to the simple obese rats sample, Determinate indicators of the obese rats, Determinate lipase activity in the liver, determinate JAK2 in rats by using Semi - quantitative RT-PCR technology and STATS gene mRNA expression level, Exploration of GH bioactivity and signaling pathways regulating lipid metabolism in rats role to play, To further reveal the molecular mechanism of GH regulation of bioactivity provided the theoretical foundation, for the rational selection and use of appropriate drug control and treatment of human obesity and related metabolic disorders provided a new target.

生长激素（growth hormone ,GH）不仅参与调解生长发育过程，而且还能参与调解脂肪代谢，有报告称存在有免疫活性但无生物活性的GH，由于GH生物活性检测方法尚不成熟，目前鲜有GH生物活性检测的报道。本课题组之前采用我们独创的BAF - GM细胞株检测法，对不同内分泌疾病状态下的血清样本进行检测，结果显示肥胖儿童GH生物活性较正常儿童明显减低。 本研究拟扩大样本量，通过对新疆不同民族单纯性肥胖儿童进行血清GH生物活性测定验证既往试验结果，并进一步以小鼠为研究对象，采用重组人GH注射治疗单纯性肥胖小鼠模型，监测各项肥胖指标, 用半定量RT-PCR技术检测小鼠体内JAK2、STATS 基因的mRNA表达水平，探索JAK2 、 STATS参与GH调控脂代谢作用的分子机制，为深入阐明GH活性作用机制提供依据，为深入研究单纯性肥胖的病因学及治疗对策提供一定的实验依据。

生长激素参与调节生长发育过程，生长激素生物活性与免疫活性是否存在差异尚待研究，目前鲜有生长激素生物活性的研究报道。BAF-GM细胞株检测法为课题负责人米热古丽日本旭川医科大学博士研究课题，本课题为该研究的进一步延伸。新疆为多民族聚集地，因其特殊的饮食结构导致肥胖高发，本课题研究利用BAF-GM细胞株检测法，研究比较单纯性肥胖儿童血清生长激素生物活性及免疫活性的差异。同时建立单纯性肥胖小鼠模型，检测各项肥胖指标，并探索生长激素调控脂代谢的分子机制，为生长激素治疗肥胖提供新的思路。研究结果显示：1. 基于BAF/GM细胞株法是潜在的检测生长激素生物活性的良好方法,且具有一定的抗干扰能力。2.单纯性肥胖儿童瘦素水平较正常儿童增高,可能存在瘦素抵抗现象。单纯性肥胖儿童与正常儿童比较生长激素生物活性明显减低。对正常组、超重组、肥胖组的性早熟患儿研究发现，各组骨龄、子宫容积、促黄体生成素峰值均存在统计学差异。3.使用生长激素作用于肥胖小鼠后，在注射后1周、2周后甘油三酯、总胆固醇、低密度脂蛋白出现明显的下降，随着时间的增长，下降幅度增加(P<0.05)；并且随着生长激素的浓度增加而下降幅度增加，提示明显的剂量反应关系。4.生长激素慢性刺激可抑制小鼠肝细胞的JAK／STATS信号转导通路,且随着刺激剂量的提高其抑制作用有上升趋势。肥胖小鼠机体正常分泌GH情况下，长期注射生长激素显著抑制肥胖小鼠JAK和STATS的基因表达水平，同时通过对比处死前半小时注射1IU/g的生长激素组和处死前未处理组的JAK和STATS基因表达水平发现长期注射生长激素降低了机体对处死前注射生长激素刺激的敏感性，如果将处死前注射生长激素视为机体分泌生长激素的峰值，则进行长期注射生长激素刺激或许能够抑制机体对内源性生长激素的敏感程度，提示长期注射生长激素能够抑制JAK/STATS信号通路，并使机体对生长激素敏感性降低。