·AIM:To probe the relationship between the apoptosis of diabetic rats’ retinal neurons and change of caspase-3 expression in early diabetic rats.·METHODS:Eighteen male 8-week-aged SD rats were injected with a single dose of streptozotocin(60mg/kg)to induce the diabetic model,and then they were divided into 3 groups at 4,8 and 12 weeks(each group,n=6).Another 18 male 8-week-aged SD rats were the normal control group,and were raised at the same time without any intervertion,also divided into 3 groups at 4,8 and 12 weeks(each group,n=6).Apoptosis of retinal neurons was detected by TdT-mediated dUTP nick end label(TUNEL)assay.The protein expression of caspase-3 was detected by immunohistochemistry.Caspase-3 mRNA levels were determined by SYBR Green Realtime PCR Master Mix.·RESULTS:There were no apoptosis neurons in control groups’ retina at 4,8,12 weeks.Apoptosis of the retinal neurons occurred 4 weeks after the onset of diabetes,and the apoptosis degrees were significantly higher than that of age-matched control groups at 8 and 12 weeks.The apoptosis of the retinal neurons located in the rentinal ganglion cells layer(GCL)and the inner nuclear layer(INL).Caspase-3 protein expression was not observed in the control rats’ retina at 4,8,12 weeks.Positive staining of caspase-3 occurred 4 weeks after the onset of diabetes,and enhanced at 8 and 12 weeks.In control rats at 4,8 and 12 weeks,caspase-3 mRNA levels were 1.6±0.6,1.5±0.5,1.6±0.3 respectively.Caspase-3 mRNA levels in diabetic rats that had diabetes for 4,8 and 12 weeks were 5.7±1.2,12.6±2.3,14.3±2.1 respectively,which were greater than that in the control groups(P<0.05).·CONCLUSION:The apoptosis of the retinal neurons in diabetic rats may be related with the enhance of the caspase-3 expression.·