番石榴叶总三萜改善糖尿病大鼠视网膜损伤的作用机制研究

The effect of total triterpenoids in guava leaves on retinal injury in diabetic rats

目的探讨番石榴叶总三萜(TTPGL)对糖尿病大鼠视网膜损伤的影响及相关机制。方法雄性SD大鼠50只,按55 mg/kg腹腔一次性注射链脲佐菌素(STZ)诱导糖尿病模型。模型诱导成功后,大鼠编号后按照随机数字表法分成5组:糖尿病组(DM组,生理盐水灌胃)、TTPGL低剂量组(TTPGL-L组,50 mg/kg灌胃)、TTPGL中剂量组(TTPGL-M组,100 mg/kg灌胃)、TTPGL高剂量组(TTPGL-H组,200 mg/kg灌胃)及二甲双胍组(Met组,10 mg/kg灌胃,阳性对照),另取10只正常雄性SD大鼠作为对照组(CON组,生理盐水灌胃)。每日1次连贯干预12周后,免疫荧光染色检测视网膜神经胶质酸性蛋白(GFAP)表达,Western blot检测视网膜核转录因子-κB(NF-κB)、肿瘤坏死因子(TNF)-α蛋白相对表达量,HE染色检测视网膜神经节细胞(RGC)密度。结果干预12周后,与CON组相比,DM组血糖明显升高,视网膜GFAP、NF-κB及TNF-α蛋白表达明显增加,RGC密度明显降低(均P<0.05)。与DM组相比,TTPGL-M组、TTPGL-H组及Met组GFAP、NF-κB及TNF-α蛋白表达明显降低,RGC密度明显增加(均P<0.05),而DM组与TTPGL-L组之间上述指标差异无统计学意义(P>0.05)。结论 TTPGL对糖尿病状态下RGC损伤具有保护作用,其机制可能与降血糖、下调视网膜GFAP表达和抑制炎症反应有关。

Objective To investigate the effect and its mechanism of total triterpenoids in guava leaves(TTPGL)on retina injury in diabetic rats.Methods The diabetes mellitus(DM)rat model was induced by intraperitoneal injection(IP)of streptozotocin(STZ,55 mg/kg)in fifty male rats.After the model was induced successfully,the rats were numbered and divided into 5 groups according to the random number table method:diabetes group(DM group,intragastric administration of normal saline),TTPGL low-dose group(TTPGL-L group,50 mg/kg intragastric administration),TTPGL medium-dose group(TTPGL-M group,100 mg/kg intragastric administration),TTPGL high-dose group(TTPGL-H group,200 mg/kg intragastric administration)and metformin group(Met group,10 mg/kg,intragastric administration,positive control).Ten normal male SD rats were taken as control group(CON group,intragastric administration with normal saline).After twelve weeks,the expression of glial fibrillary acidic protein(GFAP),NF-κB and TNF-αin retina were detected by immunofluorescence or Western blot assay,and the density of RGC was detected by HE staining.Results After 12 weeks of intervention,compared with CON group,the blood glucose,the protein expression levels of GFAP,NF-κB and TNF-αwere significantly higher,and the density of RGC was significantly lower in DM group(all P<0.05).Compared with DM group,the protein expression levels of GFAP,NF-κB and TNF-αwere decreased significantly,the density of RGC was increased significantly in TTPGLM group,TTPGL-H group and Met group(all P<0.05).There were no significant differences in the above indexes between DM group and TTPGL-L group(P>0.05).Conclusion TTPGL has protective effect on RGC injury in diabetes state,and its mechanism may be related to the lowering blood glucose,down-regulating the expression of GFAP in retina and inhibiting inflammatory reaction.