Diabetic peripheral neuropathy is the most common complica¬tion of long-standing diabetes mellitus. The objective of this study was to investigate the fatty acids composition abnormalities of sciatic nerve in streptozotocin (STZ)-induced diabetic neuropathy (DNP) in male rats. Six groups of 20 rats were studied. Group I (control group): received no drugs, Group II (diabetic group) A single dose of streptozotocin (STZ) (50mg/kg i.p.) was used for the induction of diabetes in rats, Group III (normal α-Lipoic acid-treated group), Group IV (diabetic alpha-Lipoic acid -treated group), Group V (diabetic insulin- treated group), Group VI (diabetic alpha-Lipoic acid and insulin-treated group). Eight weeks after diabetes induction therapeutic treatment with alpha-lipoic acid (54 mg/kg body weight i.p daily) and insulin (2U s.c daily) were given either alone or in combination and continued for six weeks. Equivalent volumes of saline were given subcutaneously to the rats in the other diabetic and non diabetic control groups. Blood samples and sciatic nerve tissues were collected from all animal groups two times at 4 and 6 weeks from the onset of treatment which begin after eight weeks of diabetic neuropathy (DNP) induction for determination of serum glucose and sciatic nerve triacylglycerols, non esterified fatty acids (NEFA) and membrane fatty acids composition of sciatic nerve. The obtained results revealed that, a significant increase in serum glucose and sciatic nerve NEFA concentrations with marked decrease in triacylglycerols and fatty acids composition percentage including palmitic acid, palmitoleic acid, oleic acid and arachidic acid were observed in sciatic nerve of STZ-induced DNP in rats. Administration of α -lipoic acid with insulin significantly lowered serum glucose and sciatic nerve NEFA concentrations as well as several fatty acids contents including myristic, palmitic, palmitoleic, oleic, cis-vaccenic, linoleic, alpha linolenic, arachidic, and godoleic acid with increase in margaric, stearic, and eicosadienoic acid percentage in addition to triacylglycerols level in sciatic nerve. The results suggest that, treatment with α-lipoic acid combined with insulin administrations could ameliorate the altered myelin of sciatic nerve lipids induced by diabetes and attenuate the changed fatty acid composition membrane in sciatic nerve and improved the metabolic control of diabetic neuropathy. The results indicated that the beneficial effect of α- lipoic acid treatment in diabetic neuropathy.
Key words: diabetic neuropathy, sciatic nerve, fatty acids composition, alpha-Lipoic acid
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