The Effect of Gestational Diabetes Mellitus on Sciatic Nerve in Adult Offspring Rats

Gestational diabetes mellitus (GDM) is one form of diabetes affect approximately 7 % of pregnancies. Diabetic peripheral neuropathy (DPN) is a common complication of diabetes that is associated with loss of nerve fibers, myelin abnormalities and significant decrease in the expression of myelin basic protein (MBP) in peripheral nerves. This study was done to determine the effect of induced diabetes during pregnancy on sciatic nerve in adult rat offspring. In this study, wistar rats' dams were allocated to control and diabetic groups. Diabetic rats were received 40 mg/kg/body weight of streptozotocin (STZ) on the first day of gestation. Six offspring of each group were randomly selected on 12 weeks postnatal and histopathological changes in their nerve tissue were examined through H&E staining and transmission electron microscopy. Furthermore, the expression of MBP in sciatic nerve was examined by immunohistochemistry. We found that the myelinated fiber number of sciatic nerve in offspring of diabetic rats was reduced compared to the controls, but this difference was not significant. The average thickness of the myelin sheath of sciatic nerve fibers in the control and GDM was 97.1±0.1and 94.1±0.2 µm, respectively that the difference was not statistically significant. The expression of MBP protein in the myelin sheath of both groups was similar. TEM results showed that myelin sheath of diabetic offspring had not any changes compared to control. Atrophy of axons and schwannocytus (Schwann cells) alterations were not observed in diabetic offspring. Induction of diabetes during pregnancy reduced the number of nerve fibers and thickness of the myelin sheath. But it has no effect on MBP expression and schwannocytus morphology.