银杏叶提取物对2型糖尿病大鼠睾酮水平、LHR和StAR mRNA表达的影响

目的： 探讨银杏叶提取物(EGB)在2型糖尿病大鼠睾酮合成中的作用及其对黄体生成素受体(LHR)、类固醇激素合成急性调节蛋白(StAR)基因表达的影响。方法: 雄性SD大鼠30只，随机均分成3组：正常对照组、2型糖尿病组、EGB 治疗组。后2组给以高脂饮食加小剂量(30 mg/kg)链脲佐菌素(STZ)诱导2型糖尿病大鼠模型，EGB治疗组予EGB50mg·kg^-1·d^-1灌胃12周，正常对照组及2型糖尿病组灌服等容积生理盐水。测定各组大鼠血葡萄糖、血胰岛素、血LDL-c含量；称各组大鼠睾丸重量，并用光镜和透射电镜观察大鼠睾丸组织的形态学改变； ELISA法检测血清黄体生成素(LH)、睾酮(T)水平；RT－PCR检测睾丸组织中LHR、StAR mRNA表达水平。结果: 与正常组相比，糖尿病组大鼠血清T、LH含量及睾丸组织的StAR mRNA含量明显降低，血糖、血胰岛素、LDL-c及LHR mRNA含量显著升高，睾丸重量明显减轻；光镜下主要表现为睾丸曲细精管内生精细胞数量减少及生精阻滞，透射电镜下主要见到间质细胞(Leydig cell)及支持细胞内线粒体、内质网等细胞器空泡样变及扩张。EGB治疗组睾丸组织病理改变较轻，血清T 、LH含量及睾丸组织StAR mRNA含量明显高于糖尿病组，血糖、血胰岛素、LDL-c及睾丸组织LHR mRNA含量低于糖尿病组。结论: EGB可提高2型糖尿病大鼠T的合成，其机制可能与改善糖脂代谢紊乱，调节LHR、StAR mRNA表达有关。

Effect of EGB on pituitary-testicular axis and expressions of LHR and StAR in type II diabetic rats

AIM: To observe the effect of the extract of Ginkgo biloba(EGB) on pituitary-testicular axis and the mRNA expressions of luteinizing hormone receptor (LHR) and steroidogenic acute regulatory protein (StAR). METHODS: Thirty male Sprague-Dauley rats were divided into three groups randomly: normal control group, type II diabetic group and EGB treatment group. After fed with high-fat diet for 4 weeks, the later two groups were injected with strepozotocin intraperitoneally to induce type II diabetes mellitus. The EGB treatment group was given EGB at the dose of 50 mg/kg once a day for 12 weeks by intragastric administration. The normal control and diabetic group were given normal saline of equal volume per day for 12 weeks. The indices of blood glucose, insulin and low-density lipoprotein-cholesterol (LDL-c) were measured. The morphologic change of testicular tissue was observed under light microscopy (LM) and transmission electron microscopy (TEM) respectively. The concentrations of blood luteinizing hormone (LH) and testosterone (T) were assayed by the technique of enzyme linked immunosorbent assay (ELISA). The mRNA expressions of LHR and StAR from Leydig cells were detected by RT-PCR. RESULTS: The concentrations of blood glucose, insulin and LDL-c increased obviously, and the testis weights lessened obviously in type II diabetic groups compared to those in normal control groups. Rare spermatogenic cells of seminiferous tubule and germinal arrest were observed in diabetic group under LM. Ultrastructural analysis of testicular tissue by TEM showed dilation of the endoplasmic reticulum and mitochondrial swelling in Leydig cell and sertoli cell in diabetic group. The level of blood LH and T decreased in type II diabetic groups in comparison with that in the normal control group. Compared to normal groups, the mRNA expression of StAR in type II diabetic groups decreased, while the mRNA expression of LHR increased. After the treatment of EGB, the pathological change of testis was relieved, the concentrations of blood glucose, insulin and LDL-c were decreased, the level of blood LH and T, and the mRNA expression of StAR were increased, and the mRNA expression of LHR descended compared to type II diabetic groups. CONCLUSION: EGB may increase the LH-induced testosterone production by correcting metabolic disorder of glucose and lipid, improving the function of pituitary-testicular axis and regulating the expression of LHR and StAR mRNA.