根皮素对糖尿病小鼠光感受器视杆细胞的保护作用

Protective effects of phloretin on rod photoreceptors in diabetic mice

目的观察根皮素对糖尿病小鼠视网膜视杆细胞功能和形态的影响。方法 健康8周龄C57BL/6小鼠随机分为正常对照组、糖尿病对照组和根皮素治疗组,每组6只。采用腹腔注射链脲佐菌素50mgkg-1连续5d建立糖尿病小鼠模型,成模后根皮素治疗组予以根皮素100mgkg-1灌胃,连续12周,正常对照组和糖尿病对照组予以等量生理盐水。成模18周后3组小鼠行暗适应视网膜电图检查视杆细胞功能,并测量视网膜含糖量以及行HE染色切片测量距离视盘上下方048mm、096mm、1.44mm、1.92mm处视网膜外核层厚度检查视杆细胞形态学变化。结果 糖尿病模型成模后18周糖尿病对照组视网膜含糖量为（142.25±6.92）nmolglucose/mgprotein、根皮素治疗组视网膜含糖量为（97.82±4.12）nmolglucose/mgprotein,均高于正常对照组（39.43±2.17）nmolglucose/mgprotein,但根皮素治疗组视网膜含糖量比糖尿病对照组低,差异有显著统计学意义（P〈0.01）。暗适应视网膜电图发现糖尿病对照组a波及b波振幅为（125.6±19.6）μV、（264.3±21.5）μV,根皮素治疗组为（226.7±23.2）μV、（515.3±36.4）μV,均低于正常对照组（359.3±32.3）μV、（830.8±45.2）μV,但根皮素治疗组比糖尿病对照组高,差异均有显著统计学意义（均为P〈0.01）。根皮素治疗组和糖尿病对照组小鼠视网膜外核层厚度较正常对照组下降（628～16.05）%和（20.41～35.38）%,然而根皮素治疗组视网膜外核层厚度较糖尿病对照组小鼠厚（661～2992）%,差异有统计学意义（P〈0.05）。结论 根皮素通过抑制葡萄糖转运蛋白1转运葡萄糖进入视网膜,限制视网膜局部含糖量,从而对光感受器视杆细胞的功能和形态均产生保护作用。

Objective To investigate the effects of phloretin on morphous and function of rod photoreceptors under diabetic condition. Methods Healthy 8-week- old C57BL/5 mice were randomly divided into normal control group, diabetic control group and phloretin treatment group, 5 cases in each group. Diabetic models were established by intraperitoneal injection of streptozotocin （50 mg · kg^-1 ）. Phloretin treatment group received intragastric administration of phloretin （ 100 mg · kg^-1 ） for 12 weeks, and same volumes of NS were given in normal control group and diabetic control group. In 18 weeks after diabetic induction, the glucose concentration was calculated, scotopic electroretinogram （ERG） was conducted to evaluate rod photoreceptors function, and outer nuclear layer thickness at 0.48 mm, 0.95 ram, 1.44 mm and 1.92 mm distant to optic disc was measured to determine the density and morphology changes of rod photoreceptors. Results At 18 weeks after diabetic induction, retinal glucose concentration of diabetic control and phloretin treatment groups were （ 142.25 ± 5.92 ）nmol glucose/mg protein and （ 97.82 ± 4. 12 ） nmol glucose/mg protein, respectively, which were both higher than that of normal control （39.43 ± 2. 17 ）nmol glucose/mg protein, but phloretin treatment group was lower than diabetic control group （P 〈 0.01 ）. The amplitude of a-wave and b-wave in scotopic ERG of diabetic control group were （125.5 ± 19.5）μ V and （254.3 ± 21.5 ） μV, respectively,phloretin treatment group were （ 225.7 ± 23.2 ） μV and （515.3 ± 35.4 ） μV, respectively, both lower than normal control,which were （359.3±32.3 ） μV and （830.8 ± 45.2 ） μV, respectively, but phioretin treatment group were higher than diabetic control group （all P 〈 0.01 ）. The outer nuclear layer thickness of diabetic control group and phloretin treatment group were both lower than that of normal control group, decreased （6.28 - 16.05 ）% and （20.41 -35.38 ）% , respectively, but phloretin treatment group was thicker about （6.61 - 29.92 ） % compared with diabetic control group （P 〈 0.05 ）. Coaelusion By means of limiting the glucose transport into retina, phloretin plays a protective role on rod photoreceptors function and morphology under diabetic condition.