Changes in the myelin sheath of the peripheral nerve in experimental diabetes mellitus

The aim of the present study was to examine morphometric changes of myelin sheath of the peripheral nerve in the early stages of experimental streptoz otocin diabetes mellitus. Adult male Wistar rats aged 17 wks were used in t his study. Diabetes mellitus was induced by streptozotocin. Samples of the common peroneal nerve from diabetic rats (4 and 8 wks after induction of di abetes mellitus) and from age-matched control animals were removed and proc essed. The semi-thin cross sections were stained with toluidine blue and us ed for a computer-aided morphometric analysis of the myelinated fiber. No s ignificant changes were found in diabetic animals after a 4 wk duration of the disease. There were significant reductions in the thickness of the myel in sheath and in the myelin sheath area in diabetic rats 8 wks after the in duction of diabetes, in comparison with age-matched control animals. It can be concluded that the concomitant diminution of fiber area of the myelinat ed fibers of the peripheral nerve was caused predominantly by a reduction o f the myelin sheath area because no significant reduction of the axonal are a was observed in this group of diabetic rats. The present study demonstrat es that the induction of diabetes mellitus in rat by streptozotocin is acco mpanied by early changes in the thickness of the myelin sheath and in the m yelin sheath area indices of myelinated nerve fibers of the peripheral nerv e.