Hyperglycemia exacerbates the effect of ischemia-reperfusion on peripheral nerve in rat.

Ischemia-reperfusion is known to induce generation of oxygen free radicals (OFRs), thereby resulting in tissue damage. To clarify the pathogenesis of diabetic neuropathy, we examined whether hyperglycemia exacerbates the effects of ischemia-reperfusion on peripheral nerves. Using light microscopy, characteristic pathological changes seen in myelin and axons of nerve fibers were classified into two types: "loose myelin" and "dark axon," respectively. After a 2-hour ischemia and 24-hour reperfusion of sciatic nerves of rats, the concentrations of lipid peroxide and "loose myelin" in the nerves were significantly increased in the diabetic rats, but not in the nondiabetic rats. Thereafter, "dark axon" was significantly increased in both diabetic and nondiabetic rats. "Loose myelin" may be increased as a result of the effects of OFRs produced by ischemia-reperfusion, which are exacerbated by hyperglycemia.