The effect of taurine on Nrf2/HO-1 signaling pathway on diabetic neuropathy in rats

Eliminating the adverse effects of diabetic neuropathy, which is one of the secondary complications of diabetes mellitus, is an important objective to improve the life quality of patients. Taurine; is a free amino acid, which has endogenous antioxidant properties derived from the metabolism of methionine and cysteine. The aim of this study is; to investigate the possible effects of taurine on nuclear factor-E2-related factor 2 (Nrf2) and the heme oxygenase 1 (HO-1) signaling pathway in the brain tissue of diabetic neuropathy induced rats with streptozotocin (STZ). In addition, the effect of taurine on glucose transporter protein 1 (GLUT1), glucose transporter protein 3 (GLUT3) levels and serum malondialdehyde (MDA) levels were also examined. Male Wistar albino rats (180±20 g, n=40, 8 weeks old) were used in this study. The animals were assigned randomly to 4 groups and each group contained 10 animals; (i) control group (single dose intraperitoneally (i.p.) saline injected group). (ii) Taurine group; Saline injected and taurine received (2 % w/v, dissolved in water). (iii) STZ group; 60 mg/kg, (i.p.) injected with a single dose STZ. (iv) STZ+Taurine group; 60 mg/kg, (i.p.) injected with a single dose STZ and taurine received (2 % w/v, dissolved in water) group. Study finished after 8 weeks. At the end of this study; MDA levels increased in STZ group compared to control group (P<0.001), and it was decreased significantly in STZ+Taurine group in comparison to STZ group (P<0.05). In brain tissue; the protein levels of GLUT1 and GLUT3 were significantly decreased in STZ group (P<0.001) and increased conversely in STZ+Taurine group when compared to STZ group (P<0.05). When Nrf2 and HO-1 protein levels considered; the STZ group levels were distincly lower in comparison to control group (P<0.001) and Nrf2 and HO-1 protein levels were higher in STZ+Taurine group compared to STZ group (P<0.001). In conclusion; taurine supplementation on diabetic neuropathy induced rats, enhances Nrf2 protein levels and activates Nrf2/HO-1 signaling pathway, thus; improves prevention of oxidative stress that plays a major role in the development of diabetic neuropathy.