Flaxseed protects against diabetes-induced glucotoxicity by modulating pentose phosphate pathway and glutathione-dependent enzyme activities in rats

Abstract

This study investigated the effects of flaxseed (Linum usitatissimum L.) intake on general metabolism, pentose phosphate pathway (PPP) and glutathione-dependent enzymes in diabetic rats. Diabetes was induced by streptozotocin injection (40 mg/kg, i.p.) and the enzyme activities were determined spectrophotometrically. Diabetic and control rats were divided in two subgroups, one untreated, and one treated with flaxseed (0.714 g/kg body weight/day; orally) for 12 weeks. Flaxseed ameliorated decreased body weight (p <.05) and increased blood glucose (p <.001), triglyceride (p <.001), ALT (p <.001) and AST (p <.001) in diabetic rats. Diabetes resulted in increased glucose-6-phosphate dehydrogenase (G6PD) (p <.05) and decreased glutathione-S-transferase (GST) (p <.01), but unchanged 6-phosphogluconate dehydrogenase (6PGD) and glutathione reductase (GR) in the brain of rats. These alterations were partially improved by flaxseed in comparison to diabetic untreated group (p <.05). G6PD, 6PGD, GR were elevated (p <.001), while GST unchanged in the lung of diabetic untreated group compared to control. Flaxseed partially prevented the increase in 6PGD (p <.05) and GR (p <.01), but unaffected G6PD in the lung of diabetic rats. G6PD (p <.001), 6PGD (p <.05), GR (p <.001) were augmented, while GST showed a significant (p <.001) depletion in the pancreas of diabetic untreated rats compared to control. Diabetic alterations observed in pancreatic enzyme activities were significantly prevented by flaxseed. Furthermore, a remarkable decrease in 6PGD (p <.001) and an increase in G6PD (threefold of control) were found in the lens of diabetic untreated group that were completely prevented by flaxseed (p <.001). Flaxseed has beneficial effects against diabetes-induced glucotoxicity by modulating G6PD, 6PGD, GR and GST activities in tissues.