GH早期干预对SGA大鼠糖代谢影响及胰岛Pdx1基因表达调控机制研究

发布时间：2018-11-04 19:57

【摘要】：研究背景近年来众多流行病学研究和临床试验结果均提示,由宫内环境改变导致的小于胎龄儿(SGA)与成年后代谢综合征(MS),2型糖尿病(T2DM)密切相关。SGA如何导致成年期代谢疾病的机理尚未明确,胰岛功能障碍是其中重要环节,可能与胰岛相关转录因子表达密切相关。胰十二指肠同源盒1(Pdx1)是胰腺定向发育成熟过程中一个重要转录因子,能抑制胰岛细胞凋亡,促进其分化与增生；同时在转录水平通过与胰岛素基因启动子和增强子区域的转录因子结合位点结合介导胰岛素基因的表达,是决定胰腺分化和胰岛功能的主要调节基因,对于探讨SGA者发生胰岛功能障碍的发病机理具有十分重要的意义。部分SGA儿童不能实现生长追赶,需要生长激素(GH)治疗。GH具有保持胰岛p细胞数量、刺激胰岛素合成与分泌,参与和维持正常的胰岛素敏感性和血糖动态平衡的作用。GH治疗是否影响SGA儿童代谢是一个重要临床问题,目前可见有关GH干预对SGA者代谢的临床研究,但罕见GH对胰岛功能影响的机制探讨。研究目的明确早期GH干预能否影响SGA大鼠成年后血糖代谢,探讨甲基转移酶家族成员Set7/9与组蛋白去乙酰化酶(HDAC)是否参与GH干预的SGA大鼠胰岛p细胞Pdxl基因组蛋白修饰过程。研究方法采用孕鼠全程饥饿法,建立SGA大鼠模型。生后第21天随机分为GH千预组或生理盐水(NS)对照组；适于胎龄儿(AGA)随机分为GH干预组或NS对照组；SGA、AGA大鼠GH干预组每日清晨腹腔注射5mg/kg/d重组人生长激素至生后第35天,NS对照组同时注射等量生理盐水。子鼠在0、21、35、70天分别测量体质量、鼻肛长；于21、35、70天行腹腔糖耐量测试、测定空腹血清胰岛素水平、血清IGF-1水平、血清IGFBP-3水平；并在第0、21、35、70天测定胰腺组织中Pdx1mRNA、蛋白水平,第21、35、70天时胰岛中Set7/9蛋白水平与HDAC活性变化。研究结果生后第21天SGA大鼠的体重、身长均未能追赶上AGA组大鼠,有统计学意义(P0.01)；21天时SGA大鼠空腹血糖高于AGA大鼠,空腹血清胰岛素低于AGA组,有显著性差异(P0.05)。至35天GH治疗结束时,SGA+GH组体重追赶上AGA对照组(P＞0.05), SGA+NS组体重及生长均未追赶上AGA对照组(P0.05)。各组大鼠糖耐量测试无显著性差异(P0.05),但SGA+NS组大鼠空腹胰岛素水平低于AGA+NS组(P0.05)。70天大鼠成年期时,SGA+GH组与AGA+NS组体重及身长均无明显差异；但SGA+NS组体重仍落后于AGA+NS组(P0.05)。与AGA+NS组相比,SGA+GH组无糖耐量测试显著差异(P0.05),SGA+NS组空腹血糖不升高,但糖耐量测试30分钟、60分钟时血糖升高,与AGA+NS组比较有显著性差异(P0.05)。GH干预能提高SGA大鼠Pdx1mRNA表达及蛋白含量,且作用持续至成年期。第21天GH干预前,SGA组大鼠胰岛中HDAC活性显著高于AGA组(P0.05)。第35天干预结束时,与SGA+NS组比较,SGA+GH组HDAC活性下降(P0.05),至成年期时仍保持较低水平；21天时,SGA组大鼠SET7/9蛋白水平显著低于AGA组(P0.05),GH干预后SGA+GH组SET7/9蛋白含量增高,与SGA+NS组比较有显著性差异(P0.05),成年时SGA+GH组仍高于SGA+NS组。结论GH早期干预有利于SGA大鼠血糖调控,提高SGA大鼠胰岛素转录因子Pdxl表达,可能与组蛋白修饰有关。
[Abstract]:The results of many epidemiological studies and clinical trials in recent years suggest that less than gestational age (SGA) caused by intrauterine environmental change is closely related to postadult metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM). How SGA results in the pathogenesis of adult metabolic diseases is not clear, and islet dysfunction is an important link, which may be closely related to the expression of islet-related transcription factors. Pancreaticoduodenal homeobox 1 (Pdx1) is an important transcription factor in the development of pancreatic orientation, which can inhibit the apoptosis of pancreatic islet cells and promote the differentiation and proliferation of pancreatic islet cells. At the same time, the expression of the insulin gene is mediated by binding the transcription factor binding site of the promoter and the enhancer region of the insulin gene at the transcription level, so as to determine the main regulating gene of the pancreatic differentiation and the islet function, It is very important to investigate the pathogenesis of pancreatic islet dysfunction in SGA. Some SGA children can't achieve growth chase, and growth hormone (GH) therapy is needed. GH has the function of keeping the number of islet p cells, stimulating insulin synthesis and secretion, participating in and maintaining normal insulin sensitivity and blood glucose homeostasis. GH treatment is an important clinical problem for the metabolism of SGA children, and the clinical study of GH intervention on the metabolism of SGA is currently seen, but the mechanism of GH on the function of islet function is discussed. Objective To study the effect of early GH intervention on blood glucose metabolism in adult rats of SGA rats, and to explore the expression of Paxl genomic proteins in islet p cells of SGA rats with GH intervention by the group members of methyltransferase family Set7/ 9 and histones. Process. The study method adopts the full-course starvation method of pregnant mice to establish SG A rat model was randomly divided into GH group or normal saline (NS) control group on the 21st day after birth; it was randomly divided into GH intervention group or NS control group for gestational age (AGA). At the 35th day of the day, the NS control group was injected simultaneously The levels of fasting serum insulin, serum IGF-1 and IGFBP-3 were measured at 0, 21, 35 and 70 days respectively, and the levels of serum insulin, serum IGF-1 and IGFBP-3 in serum were measured at 0, 21, 35 and 70 days. Protein levels, levels of Set7/ 9 protein in pancreatic islets on Days 21, 35, 70 and HDA The results showed that the weight of SGA rats was higher than that of AGA rats at 21 days after the study, and the fasting blood glucose was higher than that in AGA rats at 21 days. At the end of GH treatment at 35 days, the weight and growth of SGA + GH group after GH treatment did not catch up with AGA control group. There was no significant difference in glucose tolerance test in group (P0.05). However, the fasting insulin level in SGA + NS group was lower than that of AGA + NS group (P0.05). Compared with AGA + NS group, SGA + GH group had no significant difference in glucose tolerance test (P0.05). The fasting blood glucose in SGA + NS group was not increased, but the glucose tolerance test was 30 min, and the blood sugar increased in 60 min. Compared with AGA + NS group, there was significant difference (P <0.05). GH intervention could improve the expression of Pdx1mRNA and protein content in SGA rats. The action lasted to adulthood. The HDAC activity was significantly higher in the SGA group than in the AGA group before the 21-day GH intervention. At the end of the 35-day intervention, the HDAC activity of SGA + GH group decreased (P0.05), and the level of SET7/ 9 protein in SGA group was significantly lower than that of AGA group (P0.05). There was a significant difference in protein content (P <0.05) compared with that of SGA + NS group (P0.05). Conclusion GH early intervention was beneficial to the regulation of blood glucose in SGA rats, and the expression of Paxl in the insulin transcription factor of SGA rats was increased.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R725.8

【共引文献】