虫草菌丝对2型糖尿病大鼠胰岛内质网应激和胰岛细胞凋亡的影响

Effects of cordyceps sinensis on endoplasmic reticulum stress and islets apoptosis in rats with type 2 diabetes mellitus

目的 观察虫草菌丝（cordyceps sinensis，CS）对2型糖尿病（T2DM）大鼠胰岛细胞的保护作用及机制。方法采用链脲佐菌素联合高脂饮食建立T2DM大鼠模型，成模后大鼠分为T2DM组、虫草菌丝低剂量组（2ml·kg＾-1·d＾-1，CS1组）、虫草菌丝高剂量组（5ml·kg＾-1·d＾-1，CS2组），同时设置正常对照组。CS1组、CS2组用CS干预12周。观察CS对大鼠糖代谢的影响，进行各组大鼠空腹血糖（FBG）、空腹胰岛素水平（FINS）的比较，并计算胰岛素敏感指数（ISI）。胰岛细胞中凋亡的变化采用TUNEL方法测定，测定胰岛内质网应激蛋白（CHOP、JNK）的表达，其表达水平采用免疫组化进行检测。本实验多个样本均数间比较，采用F检验，组间两两比较采用SNK-q法检验，同一组干预前后比较用t检验。结果（1）FBG、FINS和ISI变化：CS干预12周后，CS1、CS2组FBG{（15．8±2．6）、（13．1±2．3）mmol/L]低于T2DM组[（20．5±3．7）mmol／L；q=8．56、10．20，均P〈0．0l]；CS1、CS2组FINS[（19．7±3．3）、（15．5±1．9）mU/L]低于T2DM组【（22．3±3．7）mU/L；q=5．28、7．44，均P〈0．01]；CS1、CS2组ISI[（-5．43±0．32）、（-4．35±O．24）】高于T2DM组[（-5．94±0．41）；q=6．38、8．52，均P〈O．01]。（2）大鼠胰岛凋亡指数：T2DM组显著高于正常对照组[（O．583±0．137）比（0．154±0．042）；q=12．02，P〈0．01]和CS1、CS2组[（0．369±0．032）、（0．241±0．024）；q=4．58、9．87，P〈0．05和P〈0．01]。（3）大鼠胰岛CHOP、JNK的表达：T2DM组[（0．362±0．064）、（1．35±0．15）]高于正常对照组[（0．063±O．021）、（0．12±0．03）；q=18．87、26．28，均P〈O．01]、CS1组[（0．268±0．038）、（0．56±0．07）；q=4．26、6．75，P〈0．05，P〈0．01]和CS2组[（0．152±0．035）、（0．33±0．06）；q=7．84、8．97，均P〈0．01]。结论CS能够保护T2DM大鼠胰岛细胞的功能，其机制可能与减轻胰岛细胞凋亡的发生，抑制胰岛内质网应激水平．降低CHOP、JUN的表达有关。

Objective To investigate the protective effects and mechanism of cordyceps sinensis （CS） on the islets cells of rats with type 2 diabetes mellitus. Methods Streptozotocin combined with highfat diet was used to induce T2DM rats＇ model. The rats were randomly divided into three groups： model control group （MOR）, low dose group （CS1, 2 ml·kg^-1·d^-1, i.p.） and high dose group （CS2, 5 ml·kg^-1. d^-1, i.p.）. Two treatment groups （CS1 and CS2） were given CS for 12 weeks and a normal control group （NOR） was set to observe the effects of CS on rats＇ glucose metabolism. The following parameters were measured： the fasting blood glucose （FBG）, the fasting insulin level （FINS） and the insulin sensitivity index （ISI）. TUNEL was used to detect the islets apoptosis. Immunohistochemistry was used to assess the expression level of islet CHOP and JNK stress proteins. Results （1）Rats were given CS for 12 weeks, FBG of CS1 and CS2 group,respectively（15.8 ± 2.6）, （13.1± 2.3） mmol/L, were obviously lower than that of MOR group （20.5±3.7） mmol/L, with q values respectively 8.56, 10.20, P values all below 0.01. ISI of CS1 and CS2 group, respectively （-5.43±0.32）, （-4.35±0.24）, were obviously higher than that of NOR group （-5.94±0.41）, with q values： 6.38, 8.52, P〈O.O1. （2）AI of MOR group （0.583±0.137） was obviously higher than that of NOR group （0.154±0.042）, （q=12.02, P〈0.01 ）. AI of CS1 and CS2, respectively （0.369±0.032）, （0.241±0.024）, were obviously lower than that of MOR, with q values： 4.58, 9.87, P values below 0.05, 0.01. （3）The expression levels of CHOP and JNK in MOR group, respectively （0.362±0.064）, （1.35±0.15）, were obviously higher than those of NOR group, respectively （0.063±0.021）, （0.12±0.03）, with q values： 18.87, 26.28, P〈O.O1. The expression levels of CHOP and JNK in CS1 were （0.268±0.038） and （0.56±0.07）, obviously lower than those of MOR group, with q values： 4.26, 6.75, P values below 0.05, 0.01. CHOP and JNK expression levels of CS2. respectively （0.152±0.035） and （0.33±0.06）, were obviously lower than those of MOR group, with q values： 7.84, 8.97 （P〈O.O1）. Conclusion CS can protect the function of T2DM rats＇ islet cells; the mechanism may relate to reducing apoptosis, decreasing the level of ERS and the expression level of CHOP and JUN.