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目的研究不同月龄大鼠胰腺促性腺激素释放激素(GnRH)mRNA的表达及其与糖代谢的关系。方法按月龄将Wistar大鼠分为:幼龄组(1～2个月),中龄组(7～8个月),老龄组(14～16个月),每组7或8只。对各组大鼠进行OGTT实验,测定空腹及糖负荷后30min、60min、120min的血糖和胰岛素水平。实时定量PCR测定各组大鼠GnRH的mRNA表达水平。结果 (1)OGTT实验结果表明,老龄组糖负荷后60min和120min血糖和胰岛素水平、胰岛素抵抗指数(HOMA-IR)、糖负荷后30min净增胰岛素与净增葡萄糖的比值(△I_(30)/△G_(30))、糖负荷后120min净增胰岛素与净增葡萄糖的比值(△I_(120)/△G_(120))均高于其余两组(P<0.01)。(2)RT PCR结果表明,GnRH mRNA的相对表达量分别为幼龄组0.66、中龄组0.75、老龄组0.26,老龄组存在低表达(P<0.05)。(3)所有大鼠GnRH mRNA表达水平与FBG(r=-0.628,P<0.01)、2hBG(r=-0.889,P<0.05)均呈负相关,与FIns(r=-0.636,P<0.05)、2hIns(r=-0.874,P<0.01)亦呈负相关,与△I_(30)/△G_(30)(r=-0.573,P<0.05)、△I_(120)/△G_(120)(r=-0.600,P<0.05)、HOMA-IR(r=-0.718,P<0.05)均呈负相关。结论老龄大鼠胰腺GnRHmRNA表达水平下降,且与血糖、胰岛素及胰岛素分泌指数呈负相关,提示胰腺GnRH表达的改变可能与老年性糖代谢异常的发生有关。
Objective To study the expression of gonadotropin-releasing hormone (GnRH) mRNA and its relationship with glucose metabolism in rats of different months. Methods Wistar rats were divided into three groups: young group (1-2 months), middle age group (7-8 months) and aging group (14-16 months), with 7 or 8 rats in each group. OGTT experiments were carried out on the rats in each group, blood glucose and insulin levels were measured at 30 min, 60 min and 120 min after fasting and glucose loading. Real-time quantitative PCR was used to determine the mRNA expression of GnRH in each group. Results (1) The results of OGTT showed that the glucose and insulin levels, insulin resistance index (HOMA-IR) at 60 min and 120 min, the ratio of net insulin to net glucose increased 30 min after the glucose load (△ I_ (30) / △ G_ (30)), and the ratio of net insulin and net increase of glucose at 120min after glucose load (△ I_ (120) / △ G_ (120)) were higher than the other two groups (P <0.01). (2) RT-PCR results showed that the relative expression of GnRH mRNA was 0.66 in young group, 0.75 in middle-aged group and 0.26 in aged group, respectively. There was a low expression of GnRH mRNA in aging group (P <0.05). (3) The expression of GnRH mRNA in all the rats was negatively correlated with FBG (r = -0.628, P <0.01), 2hBG (r = -0.889, P < ), And 2hIns (r = -0.874, P <0.01). There was also a negative correlation between △ h_ (0) and 2hIns (r = -0.874, 120) (r = -0.600, P <0.05) and HOMA-IR (r = -0.718, P <0.05). Conclusion The expression of GnRHmRNA in the pancreas of aged rats is decreased, and it is negatively correlated with the index of blood glucose, insulin and insulin secretion, suggesting that the change of GnRH expression in the pancreas may be related to the occurrence of abnormal glucose metabolism in senile rats.