褪黑素对糖尿病大鼠早期视网膜神经细胞凋亡的影响

Effects of melatonin on early retinal neurons apoptosis in diabetic rats

目的研究褪黑素对糖尿病大鼠早期视网膜神经细胞凋亡的影响。方法将54只健康雄性8周龄SD大鼠,随机分为正常对照组、糖尿病组及褪黑素组各18只,各组再按4周、8周、12周3个时间点随机分为3小组,每组各6只大鼠。正常对照组不进行干预;糖尿病组大鼠给予一次性腹腔注射链脲佐菌素60mg·kg-1,以诱导糖尿病大鼠模型;褪黑素组在成功建立糖尿病大鼠模型后给予褪黑素(10mg·kg-1·d-1)灌胃进行干预。每只大鼠取左眼眼球,制作石蜡组织病理学切片,应用TUNEL法检测视网膜神经细胞凋亡情况。结果正常对照组4周、8周、12周均未见视网膜神经细胞凋亡。糖尿病组4周可见视网膜神经细胞凋亡,糖尿病组8周和12周视网膜神经节细胞凋亡指数较同期正常对照组大鼠均明显升高,糖尿病组4周、8周、12周凋亡指数分别为(0.48±0.53)%、(5.66±2.10)%和(11.83±1.58)%,8周及12周与同期正常对照组相比差异有统计学意义(均为P=0.000)。褪黑素4周组与同期糖尿病组神经细胞凋亡情况无明显差异,褪黑素组8周及12周较同期糖尿病组神经细胞凋亡情况有不同程度的减轻,视网膜神经节细胞凋亡指数有所下降,褪黑素组4周、8周、12周凋亡指数分别为(0.30±0.74)%、(1.67±0.54)%和(7.73±0.95)%,褪黑素组8周及12周时与同期糖尿病组相比差异有统计学意义(均为P=0.000)。结论褪黑素能够通过减轻糖尿病大鼠早期视网膜神经细胞的凋亡,达到神经保护的目的。

Objeetive To observe the effects of melatonin on early retinal neu- rons apoptosis in the diabetic rats. Methods Fifty-four healthy male SD rats with 8 weeks old were randomly divided into control group, diabetic group and melatonin treatment group, 18 cases in each group, and then each group were re-divided into 4 weeks,8 weeks and 12 weeks groups,5 cases in each group. The rats in control group received no any treatment, and the rats in diabetic group were injected with a single dose of streptozotocin （60 mg ·kg^-1 ） to induce the diabetic model, and the diabetic rats were treated with melatonin （ 10mg·kg^-1·d^-1 ）, gastric perfusion） in melatonin treatment group. The left eyeballs of each group were enucleated to make the paraffin section,the retinal neurons apoptosis was detected by TUNEL assay. Results There were no retinal neurons apoptosis in control group at 4 weeks,8 weeks and 12 weeks. The apoptosis of the retinal neurons happened at 4 weeks in diabetic group, the apoptot- ic index of retinal ganglion cells at 4 weeks, 8 weeks and 12 weeks in diabetic were （0.48 ± 0.53 ） % , （ 5.65 ± 2. 10 ） % and （ 11.83 ± 1.58 ） % , respectively, compared with that in control group,there were significant differences at 8 weeks and 12 weeks in dia- betic group （ both P = 0.000）. There was no difference in retinal neurons apoptosis at 4 weeks between diabetic group and melatonin treatment group ,but which at 8 weeks and 12 weeks in melatonin treatment group were less than that in diabetic group,and the ap- optotic index of retinal ganglion cells was also decreased, which at 4 weeks, 8 weeks and 12 weeks were （0.30 ±0.74） % , （ 1.67 ± 0.54 ） % and （ 7.73± 0.95 ） % , respective-ly, there were more higher in 8 and 12 weeks than age-matched control groups （P = 0.000）. The apoptosis ratio of the retinal ganglion cells in rats with melatonin treatment for 4,8 and 12 weeks were （0. 30±0. 74）% ,（1.57 ±0. 54）% and （7. 73 ± 0. 95）% ,respectively,compared with that in diabetic group,there were significant differences at 8 weeks and 12 weeks in melatonin treatment group （both P = 0.000）. Conclusion Melatonin can decrease the early apoptosis of retinal neurons to protect retinal nerve in diabetic rats.