Analysis and treatment of visual pathway disturbance in diabetes mellitus

链脲佐菌素(STZ)诱导大鼠糖尿病模型。观察到体重减轻和血糖水平显著升高。经链脲佐菌素治疗后，视网膜内GABA含量较对照组降低。糖尿病组谷氨酸脱羧酶(GAD)活性和GABA转氨酶(GABA-T)活性降低。上丘(SC)和大脑皮层的GABA含量较对照水平降低。糖尿病动物皮质和SC的GAD和GABA-T活性也降低。糖尿病组GAD活性明显降低。GAB含量的降低依赖于对GAD活性的抑制。用形态计量学方法研究STZ诱导的糖尿病大鼠视神经纤维的结构损伤。电子显微镜形态计量学显示轴突和髓鞘横截面积明显缩小，但有髓纤维数量无明显变化。在较大的纤维中，有髓纤维大小的减少尤其显著。ARI治疗改善了结构异常，而体重和血糖水平没有任何变化。这些发现表明，结构损伤可能是糖尿病患者心理、生理和电生理测量异常的原因之一。此外，ARI治疗可改善多元醇代谢，对糖尿病患者的视神经损害有一定的治疗作用。

Streptozotocin (STZ) was administrated to rats to induce diabetes. Loss of body weight and significantly elevated level of serum glucose were observed. After treatment of STZ,the GABA content in retina decreased compared to that of control animals. The glutamic acid decarboxylase (GAD) activity and the GABA transaminase (GABA-T) activity of diabetic group was decreased. The GABA content in the superior colluiculus (SC) and the cerebral cortex decreased compared to the control level. The GAD and GABA-T activity of SC and conrtex in DM animals also reduced. The GAD activity of diabetic group was markedly decreased. Decreases of GAB content were dependent on the inhibition of the GAD activity.Structural impairments of optic nerve fibers in STZ-induced diabetic rat were investigated using morphometric analysis. Electron microscopic morphometry showed significantly smaller cross-sectional size of axons and myelin but no change of myelinated fiber number. Reductions of myelinated fiber size was especially remarkable in the larger fibers. ARI treatment improved structural abnormalities without any changes in body weight and blood glucose level. These findings suggest that structural impairment may contribute to the abnormalities of psychophysical and electrophysiological measurement detected in diabetes. Moreover, ARI treatment, which can improve the polyol metabolism, may have a beneficial effect on optic nerve impairment in diabetes.