Morphormetric changes of optic nerve in experimentally induced type 2 diabetic rats

Abstract

Purpose To investigate the morphometric changes of optic nerve and evaluate the effect of restriction of diet in experimentally‐induced type 2 diabetic rats. Methods Thirty Strague‐Dawley(S.D.) rats were divided into three groups. At 13‐week old age, control group (group A) was performed to just open and close the abdominal cavity and partial pancreatectomy was done in group B and C. Group B(ad libitum) was admitted to intake normal diet and group C(restriction) was restricted to intake from 6 week post‐operation until to be sacrificed at 24‐week old age. We measured the size of optic nerve, axon, the thickness of the myelin sheath, the ratio of axon per myelin, the histologic findings of the optic nerve in electron microscopy. Results From the 19th week to 24th week‐old‐age mean blood glucose (mg/dl) was 99.9±11.10 in group A, 399.8±108.42 in group B and 197 ±83.48 in group C(p<0.05). Mean axon size (µm2) was 0.699±0.094 in group A, 0.579±0.089 in group B and 0.672±0.023 in group C(p>0.05). The mean ratio of myelin to axon was 1.155 ±0.121 in group A, 1.667±0.075 in group B and 1.070±0.324 in group C(p<0.05). Disappearance of regular axonal shape was found in group B and lamellar separation of myelin sheath was found in group C. Conclusion Experimentally‐induced type 2 diabetic rats showed morphometric changes of optic nerve during early diabetes even if strict control of blood glucose was performed.