Objectives: Diabetic polyneuropathy is a serious complication of diabetes mellitus and the most frequent neuropathy worldwide. Evening primrose oil (EPO) is rich in omega-6 essential fatty acid component and gamma-linolenic acid. Alpha lipoic acid (ALPA) has a protective effect against lipid peroxidation and helps in scavenging free radicals. Data regarding the effect of treatment with EPO on diabetic parameters and neuropathic manifestations are conflicting. This study aimed to determine the therapeutic efficacy of EPO and ALPA in correcting diabetic parameters and functional and structural neuropathic manifestations in streptozotocin (STZ) induced diabetic rats.
Materials and methods: In this study, the effects of two week oral treatment with EPO (1.25 g/kg) was compared to that of ALPA (100 mg/kg) and insulin (2 IU/day), utilized singly or in combination.
Results: Compared with untreated diabetic rats, EPO and ALPA resulted in reduction of serum levels of glucose (p<0.05), total cholesterol (p<0.01), triglycerides (p<0.01), low density lipoprotein cholesterol (p<0.01), thiobarbituric acid reactive substance (a marker of oxidative stress) (p<0.05), and increased in levels of high density lipoprotein cholesterol (p<0.05) and total antioxidant capacity (p<0.05). Enhanced positive effect was observed with combination therapy.
Conclusion: This work indicates that EPO and ALPA, particularly when used in combination, improve glycemic control, lipid abnormalities and antioxidant capacity, thus restore the impaired functional properties of peripheral nerves to a great extent.