Localization of Na,K-ATPase alpha/beta isoforms in rat sciatic nerves: Effect of diabetes and fish oil treatment

The localization of the Na,K-ATPase isoenzymes in sciatic nerve remains con troversial, as well as diabetes-induced changes in Na,K-ATPase isoforms. So me of these changes could be prevented by fish oil therapy. The aim of this study was to determine by confocal microscopy the distribution of Na,K-ATP ase isoforms (alpha 1, alpha 2, alpha 3, beta 1, and beta 2) in the sciatic nerve, the changes induced by diabetes, and the preventive effect of fish ail in diabetic neuropathy. This study was performed in three groups of rat s. In the first two groups, diabetes was induced by streptozotocin and rats were supplemented daily with fish oil or olive oil at a dosage of 0.5 g/kg of body weight. The third one was a control group that was supplemented wi th olive oil. Five antibodies against specific epitopes of Na,K-ATPase isoe nzymes were applied to stained dissociated nerve fibers with fluorescent se condary antibodies. The five isoenzymes were documented in nonspecific regi ons, Schwann cells (myelin), and the node of Ranvier. The localization of t he alpha 1, alpha 2, and beta 1 isoenzymes was not affected by diabetes. In contrast, diabetes induced a decrease of the alpha 2 subunit (p < 0.05) an d an up-regulation of the beta 2 subunit (p < 0.05). These modifications we re noted in both regions for alpha 2 and were localized at the myelin domai n only for the beta 2. Fish oil supplementation prevented the diabetes-indu ced changes in the alpha 2 subunit with an additional up-regulation. The be ta 2 subunit was not modified. A phenotypic change similar to nerve injury was induced by diabetes. Fish oil supplementation partially prevented some of these changes.