升清降糖合剂对1型糖尿病小鼠胰岛细胞形态功能及凋亡相关基因的影响

Effects of SQ on Morphology and Function of Islet Cell and Apoptosis-Related Gene in Islet Cell of Type 1 Diabetic Mice

目的:探讨升清降糖合剂(简称SQ)对1型糖尿病小鼠胰岛细胞形态功能及凋亡相关基因Bcl-2、Bax mRNA表达的影响。方法:小剂量连续多次腹腔注射链脲佐菌素(STZ)诱导建立1型糖尿病小鼠模型。根据不同的干预方式将1型糖尿病小鼠分为模型组、SQ低剂量组、SQ高剂量组。每周测小鼠体质量和血糖,于干预第6周末,各组小鼠麻醉后心脏取血,ELISA法测定血清C肽水平,取胰腺组织HE染色观察病理学改变,免疫组化法观察胰岛素表达情况,RT-QPCR法检测胰腺组织凋亡相关基因Bcl-2、Bax mRNA的表达。结果:平均体质量:正常对照组(26.32±0.91)>SQ高剂量组(24.40±1.42)>SQ低剂量组(23.01±1.70)>模型组(22.81±1.61),SQ高剂量组与模型组相比,差异具有显著性(P<0.01)。空腹血糖:模型组(18.69±2.21)>SQ低剂量组(15.92±3.35)>SQ高剂量组(14.13±4.19)>正常对照组(6.51±0.70),SQ低、高剂量组相较于模型组血糖明显降低,差异有显著性(P<0.05、P<0.01)。血清C肽:正常对照组(0.72±0.09)>SQ高剂量组(0.69±0.07)>SQ低剂量组(0.60±0.06)>模型组(0.33±0.08),SQ低、高剂量组血清C肽与模型组相比均明显升高,差异有显著性(P<0.01)。Bcl-2mRNA、BaxmRNA、Bcl-2/Bax比值:Bcl-2mRNA正常对照组(1.03±0.28)>SQ高剂量组(0.66±0.20)>SQ低剂量组(0.39±0.17)>模型组(0.29±0.05);BaxmRNA模型组(5.73±0.80)>SQ低剂量组(2.80±1.11)>SQ高剂量组(1.68±0.90)>正常对照组(1.04±0.31);Bcl-2/Bax比值正常对照组(1.09±0.56)>SQ高剂量组(0.50±0.26)>SQ低剂量组(0.15±0.08)>模型组(0.05±0.01),与模型组相比,SQ低、高剂量组Bcl-2mRNA、Bcl-2/Bax比值均显著升高,BaxmRNA均明显降低,差异有统计学意义(P<0.01)。胰岛病理切片HE染色形态学观察发现:模型组小鼠胰岛明显萎缩,轮廓不规则,胰岛细胞数量明显减少,排列紊乱,分布稀疏,胞质染色浅呈空泡状,部分胞核固缩,伴有炎症细胞浸润,SQ低、高剂量组小鼠胰岛细胞受损程度较轻。胰岛素免疫组化染色:模型组小鼠胰岛素染色阳性面积仅占胰岛较小部分,SQ低、高剂量组染色较深,在胰岛内分布较广泛均匀。结论:SQ能明显增加糖尿病小鼠的体质量,降低空腹血糖水平,提高血清C肽水平,具有保护胰岛细胞功能,促进胰岛素分泌的作用。其机制可能与其上调1型糖尿病模型小鼠胰腺组织Bcl-2mRNA表达、抑制BaxmRNA表达,调节Bcl-2/Bax比值,抗胰岛细胞凋亡有关。

Objective ： To investigate the influence of SQ on the morphology and function of islet cell and the mRNA ex- pression of genes （Bcl -2, Bax） associated with apoptosis in islet cell in type 1 diabetic mice. Methods：To establish type 1 diabetic models by multiple intraperitoneal injection with low dose STZ（40 mg/（kg ·d） · 5 d）. The Type 1 diabetic mice were divided into model group,SQ low dose group and SQ high dose group according to the means of intervention. The fasting blood glucose （FBG） and the body weight were measured every week. After six -week intervention,the blood was collected from the heart under an anaesthetic condition. Serum C - peptide levels were analyzed by ELISA. Take a part of the pancreas tissue, the pathological changes of pancreatic islets were observed by HE staining and the expressions of insulin in islets were characterized by immunohistochemistry. Another part of the pancreas tissue would be used to de- tect the expressions of Bcl - 2 and Bax mRNA by RT - QPCR. Results ： Average body weight ： normal group （26.32 ± 0.91 ） 〉 SQ high dose group（24.40 ± 1.42） 〉 SQ low dose group（23.01 ± 1.70） 〉 model group （22.81 ± 1.61 ）. The average body weight of SQ high dose group was significantly higher than the model group＇ s（ P 〈 0.01 ）. FBG： model group（ 18.69 ± 2.21 ） 〉 SQ low dose group（ 15.92 ± 3.35 ） 〉 SQ high dose group（ 14.13 ± 4.19 ） 〉 norm group（6.51 ±0.70）. The FBG of SQ low and high dose groups was significantly decreased compared to that of the model group（ P 〈 0.05,P 〈 0.01 ）. Serum C - peptide ： normal group （ 0.72 ±0.09 ） 〉 SQ high dose group （ 0.69± 0.07 ） 〉 SQ low dose group（0. 60 ±0.06） 〉 model group（0. 33 ±0.08）. The serum C - peptide of SQ low and high dose groups was obviously increased compared to that of the model group （ P 〈 O. 01 ）. Bel - 2mRNA： normal group （ 1.03 ＋ 0.28 ） 〉 SQ high dose group （ 0.66 ± 0.20 ） 〉 SQ low dose group （ 0.39 ± 0.17 ） 〉 model group （ 0.29 ± 0.05 ）. BaxmRNA ： model group （ 5.73 ±0.80） 〉 SQ low dose group（2.80 ± 1.11 ） 〉 SQ high dose group（ 1.68 ±0.90） 〉 normal group（ 1.04 ±0.31 ）. Bel - 2/Bax ： normal group （ l. 09 ± 0.56 ） 〉 SQ high dose group （ 0.50 ± 0.26 ） 〉 SQ low dose group （ 0.15 ± 0.08 ） 〉 model group（0.05 ±0.01 ）. Compared to model group, the expression of Bcl -2mRNA and Bcl -2/Bax in SQ low and high dose groups ascended significantly（P 〈 0. Ol ） and the expression of Bax mRNA descended obviously（P 〈0.01 ）. Patho- logical observation：in model group, pancreatic islets were significantly atrophied and irregular contour. The cell amount of pancreatic islets obviously decreased coupled with disorganization, sparse - distribution, vacuolar change, pyknosis and inflammatory cell infiltration. In SQ low and high dose groups ,pancreatic islets cells had mild damage in mice. Immuno- histochemical staining of insulin：in model group, the insulin - positive areas occupied just a small part of pancreatic is- lets. The insulin -positive areas in SQ low and high dose groups were distributed widely with dark staining. Conclusion： SQ has effects on increasing average body weight, decreasing FBG, increasing serum C - peptide and protecting the islet cell and promoting the release of insulin. The mechanism is probably correlated with the regulation of Bcl - 2/Bax ： the ex- pression of Bcl -2mRNA was up -regulated and the expression of BaxmRNA down -regulated by SQ. Consequently, the islet cell was preserved and the apoptosis was inhibited.