褪黑素通过Müller细胞保护糖尿病视网膜神经节细胞的机制

Protective effects of melatonin on diabetic retinal ganglion cell via Müller cell

目的探讨褪黑素对糖尿病视网膜Müller细胞的影响及其对视网膜神经节细胞的保护作用。方法 SD大鼠54只随机分为对照组、糖尿病组和褪黑素治疗组,糖尿病组和褪黑素治疗组制造糖尿病模型。造模后,对照组和糖尿病组大鼠腹腔注射体积分数10%乙醇溶液,褪黑素治疗组大鼠腹腔注射褪黑素溶液(10 mg·kg^-1)。3个月后,试剂盒检测视网膜中丙二醛(malondialdehyde,MDA)和还原型谷胱甘肽(reduced glutathione,GSH)的含量,Western blot检测视网膜中神经胶质酸性蛋白(glial fibrillary acidic protein,GFAP)及谷氨酰胺合成酶(glutamine synthetase,GS)的表达变化,免疫组织化学染色观察GFAP阳性染色的空间分布并进行定量分析,高效液相色谱检测视网膜中谷氨酸含量变化,HE染色计数视网膜神经节细胞密度。结果对照组及褪黑素治疗组GFAP免疫阳性染色主要局限于视网膜神经纤维层,而糖尿病组GFAP阳性染色几乎贯穿视网膜全层。与对照组相比,糖尿病组视网膜MDA含量增加而GSH含量减少,GFAP表达增加而GS表达减少,谷氨酸含量增加,视网膜神经节细胞密度明显下降(均为P<0.01)。褪黑素治疗组与对照组各指标相比差异均无统计学意义(均为P>0.05)。结论褪黑素能抑制糖尿病视网膜的氧化应激反应,恢复视网膜Müller细胞功能酶GS的含量,减少视网膜内谷氨酸堆积,保护视网膜神经节细胞。

Objective To explore the effect of melatonin(MLT) on diabetic retinal Müller cell,and the protective effect on retinal ganglion cell(RGC).Methods Totally 54 Sprague-Dawley rats were assigned into control group,diabetic group and MLT-treated group.Rats in diabetic group and MLT-treated group were administered with streptozotocin to induce diabetic models.After diabetes onset,rats in control group or diabetic group were administered with 10% ethanol,and rats in MLT-treated group were administered with MLT(10 mg·kg^-1).Three month later,we observed the content of retinal malondialdehyde(MDA) and reduced glutathione(GSH) by kits,the expression of retinal glial fibrillary acidic protein(GFAP) and glutamine synthetase(GS) by Western blot,the alteration of retinal GFAP positive staining with immunohistochemistry,the level of retinal glutamate with high efficiency liquid chromatography,and the density of RGC with HE staining.Results GFAP positive staining was restricted located in retinal nerve fiber layer in control group and MLT-treated group,but nearly throughout the retina in diabetic group.Compared with control group,diabetic group showed increased MDA,decreased GSH,increased GFAP,decreased GS,increased glutamate as well as decreased RGC density(all P<0.01), while MLT-treated group showed no alterations to control group(all P>0.05).Conclusion MLT inhibits oxidative stress in diabetic retina,reversing the expression of GS in Müller cell and inhibiting the accumulation of glutamate,and protects RGC.