Effects of Flaxseed Oil on Anti-oxidative System and Membrane Deformation of

The erythrocyte membrane lesion is a serious diabetic complication. A number of studies suggested that n3 fatty acid could reduce lipid peroxidation and elevate alpha or gamma tocopherol contents in membrane of erythrocytes. However, evidence regarding the protective effects of flaxseed oil, a natural product rich in n3 fatty acid, on lipid peroxidation, antioxidative capacity and membrane deformation of erythrocytes exposed to high glucose is limited. Human peripheral blood erythrocytes were isolated and treated with 50 mM glucose to mimic hyperglycemia in the absence or presence of three different doses of flaxseed oil (50, 100 or 200 muM) in the culture medium for 24 h. The malondialdehyde (MDA) and L-glutathione (GSH) were measured by HPLC and LC/MS respectively. The phospholipids symmetry and membrane fatty acid composition of human erythrocytes were detected by flow cytometry and gas chromatograph (GC). The morphology of human erythrocyte was illuminated by ultra scanning electron microscopy. Flaxseed oil attenuated hyperglycemia induced increase of MDA and decrease of GSH in human erythrocytes. Human erythrocytes treated with flaxseed oil contained higher C22:5 and C22:6 than those in the 50 mM glucose control group, indicating that flaxseed oil could reduce lipid asymmetric distribution and membrane perturbation. The ultra scanning electron microscopy and flow cytometer have also indicated that flaxseed oil could protect the membrane of human erythrocytes from deformation at high glucose level. The flaxseed oil supplementation may prevent lipid peroxidation and membrane dysfunction of human erythrocytes in hyperglycemia. (Authors Abstract)
Oxidative stress is considered as a common cause of diabetes mellitus (DM). At high blood glucose level, erythrocytes could easily deform into acanthoid cells (acanthocytes) which is difficult to flow through the blood vessels or microvessels. This kind of cellular deformation was probably related to hyperglycemia, protein glycation, sorbitol accumulation or dyslipidemia [8]. The hyperglycemia or dyslipidemia easily induce serious oxidative stress that causes serious cellular dysfunction as well as hematic and vascular complications in diabetic patients. Studies regarding the effect of flaxseed oil on antioxidation and protecting membrane of erythrocytes at high glucose level are limited. Therefore, this study aimed to use human peripheral blood erythrocytes to test the hypothesis that flaxseed oil supplement can reduce oxidative stress and protect membrane of erythrocytes exposed to high glucose level in vitro.  Hyperglycemia induces oxidative stress because of excessive oxygen radical production caused by the auto-oxidation of glucose or stimulation of cytochrome P450 like activity, which results from excessive NADPH production by glucose metabolism. This study indicated that flaxseed oil could reduce the lipid peroxidation level (MDA) and GSSG, and maintain the GSH contents in erythrocytes. Flaxseed oil maintains the normal cellular shape in human erythrocytes exposed to high glucose model. MDA is an oxidative modification of cellular macromolecules, which can induce cell apoptosis, cell necrosis, as well as tissue damage.  In the present study, flaxseed oil reduced MDA level in human erythrocytes at high glucose level. Membrane incorporation of n3 PUFAs such as ALA in flaxseed oil may reduce cellular susceptibility to lipid peroxidation, alter membrane fluidity, enhance receptor function, elevate enzyme activity and influence the production of lipid mediators,  GSH is the most abundant antioxidant in human body. In this study, flaxseed oil reduced GSSG level and maintained GSH level in erythrocytes, suggesting it may enhance antioxidant capacity in human erythrocytes. The  results indicated that flaxseed oil could counteract lipid peroxidation to enhance fluidity or prevent phosphatidylserine externalization on membrane.  Overall, the results suggest that  flaxseed oil could protect against deformability of human erythrocytes which may occur in DM. (Editors comments)