角膜电刺激对糖尿病大鼠前部缺血性视神经病变模型的影响

目的:观察并评估角膜电刺激对糖尿病大鼠前部缺血性视神经病变(AION)模型的影响。方法:实验研究。健康雄性Sparague-Dawley大鼠40只,随机分组后抽出8只作为正常大鼠组。余下32只先予以链脲佐菌素腹腔注射建立糖尿病大鼠模型,将造模成功的大鼠随机抽出8只作为糖尿病组,余下24只糖尿病大鼠采用孟加拉玫瑰红联合532nm激光方法建立AION大鼠模型。将24只造模成功的AION大鼠随机分成3组,每组8只,分别为AION模型组,不予任何处理;电刺激组,予以角膜电刺激(刺激参数为:电流1mA,频率20Hz,波宽1ms/phase,刺激时间1h,隔日1次,刺激2周);假电刺激组,电极安放位置与电刺激组相同,仅不接通电源。2周后5组大鼠进行眼底照相、光学相干断层扫描和视觉诱发电位,然后处死,行视网膜及视神经冰冻切片,苏木精伊红染色观察。数据采用单因素方差分析和LSD-t检验进行分析。结果:正常大鼠组视盘上半部视网膜厚度为(211±13)μm,糖尿病大鼠组为(206±16)μm,AION模型组为(240±54)μm,假电刺激组为(216±11)μm,电刺激组为(198±4)μm,5组视盘上半部视网膜厚度差异有统计学意义(F=2.854,P=0.038)。其中AION模型组视盘上半部视网膜厚度高于正常组、糖尿病组、电刺激组,差异均有统计学意义(P<0.05);正常组与糖尿病组差异无统计学意义,AION模型组与假电刺激组未见明显差异。视觉诱发电位示AION模型组N1潜伏期较电刺激组延长,差异有统计学意义(t=4.1,P<0.001);AION模型组P1潜伏期较正常组、糖尿病组、假电刺激组、电刺激组延长,差异均有统计学意义(t=4.1、2.5、2.6、3.2,P<0.05);电刺激组N1-P1波幅大于假电刺激组,差异有统计学意义(t=4.0,P<0.001)。结论:角膜电刺激能促进糖尿病大鼠前部缺血性视神经病变模型肿胀的视盘变薄,加速视盘水肿的消退,同时在一定程度上改善视功能。

Effects of Corneal Electrical Stimulation on the Anterior Ischemic Optic Neuropathy in Diabetic Rats

To observe and evaluate the effect of corneal electrical stimulation on anterior ischemic optic neuropathy (AION) in diabetic rats. Methods: In this experimental study, 40 healthy male Sprague-Dawley rats were randomly grouped, and 8 of them were selected as the normal group. For the remaining 32 rats,the diabetic rat model was established by intraperitoneal injection of streptozotocin, and 8 of the rat models were randomly selected as the diabetic group. Meanwhile, the remaining 24 diabetic rats were treated with rose bengal combined with 532 nm laser to construct the AION rat model. Afterwards, the above-mentioned AION rat models were randomly divided into three groups with 8 in each group, including the AION rat group (received no treatment), the electrical stimulation group and the sham electrical stimulation group. The electrical stimulation group was given corneal electrical stimulation with the followingparameters: Current of 1 mA, frequency of 20 Hz, wave width of 1 ms/phase, and stimulation time of 1 hour once every other day for 2 weeks. Thesham electrical stimulation group had an electrode placed in the same position as that of the electrical stimulation group, but the power was notconnected. After 2 weeks, rats in the 5 above-mentioned groups were analyzed with fundus color photography, optical coherence tomography (OCT) and visual evoked potentials (VEP). Moreover, after the rats were sacrificed, the retina and optic nerve were frozen and sectioned, and hematoxylin and eosin stains were applied to the tissues. LSD-t tests and one-way analysis of variance were used to analyze the data. Results: The average retinal thickness of the superior optic disc was 211±13 μm in the normal rat group, 206±16 μm in the diabetic rat group, 240±54 μm in the AION rat group, 216±11 μm in the sham stimulation group, and 198±4 μm in the electrical stimulation group. There were significant differences in the average retinal thickness of the superior optic disc among the five groups (F=2.854, P=0.038). Of them, the average retinal thickness of the superior optic disc in the AION group was greater than the retinal thickness in the normal group, the diabetic group and the electrical stimulation group, and the differences were statistically significant (P<0.05).However, no significant difference was found between the normal group and the diabetic group (P>0.05), or between the AION group and the sham stimulation group (P>0.05). VEP revealed that the N1 latency of the AION group was longer than that of the electrical stimulation group, and the difference was statistically significant (t=4.1, P<0.001). The P1 latency of the AION group was extended compared to latencies in the normal group, the diabetic group, the sham electrical stimulation group and the electrical stimulation group, and the differences were statistically significant (t=4.1, 2.5, 2.6, 3.2, P<0.05). In addition, the amplitude of N1-P1 in the electrical stimulation group increased relative to that in the sham electrical stimulation group, and the difference was statistically significant (t=4.0, P<0.001). Conclusions: Corneal electrical stimulation can promote optic disc thinning in AION rats under hyperglycemia status, accelerate the regression of optic disc edema, and partially improve visual function.