Effect of tea polyphenols on diabetic nephropathy mice by regulating Nrf-2/ARE signaling pathway / 国际生物医学工程杂志

ABSTRACT

Objective To investigate the effects of tea-polyphenols on diabetic nephropathy (DN) mice by regulating nuclear factor E2-related factor 2/antioxidant response element (Nrf-2/ARE) signaling pathway. Methods A total of ten male 9-week-old normal (db/m) mice were randomly and equally divided into blank control group and tea-polyphenol control group, and ten male 9-week-old homologous type 2 diabetes (db/db) mice were randomly divided into model group and tea polyphenol treatment group. The animals in the tea-polyphenol control group and the treatment group were given 50 mg/(kg·d) tea-polyphenols by oral gavage, and the animals in the blank control group and model group were given same volume of double distilled water. The administration was once a day for 8 weeks. The blood glucose and 24-hour urine protein quantization (24 h-UP) were measured and recorded at 0, 4, and 8 weeks. After 8 weeks of the treatment, the mice were sacrificed. The intraocular blood stasis samples were collected for renal function indicators (serum creatinine and urea nitrogen), and kidney tissue samples were also collected for the tests of superoxide dismutase (SOD), reactive oxygen species, and malondialdehyde. Periodic acid Schiff reaction (PAS) staining was used to observe glomerular injury and scored. Western blot was used to detect the expression of Nrf-2 and hemeoxygenase-1 (HO-1) protein. Results Compared with the blank control group, the blood glucose and 24 h-UP of the mice in the model group and the tea-polyphenol treatment group increased after 4 and 8 weeks of the treatment (all P<0.01). Compared with the blank control group, after 8 weeks of the treatment, the serum creatinine and blood urea nitrogen of the model group and the tea-polyphenol treatment group increased (all P<0.01), the content of SOD in the renal tissue decreased (all P<0.01), the content of active oxygen and malondialdehyde, the relative expression of Nrf-2 and HO-1 protein increased (all P<0.01), and the glomerular injury aggravated (all P<0.01). However, there were no significant differences in all the indexes between the tea-polyphenol control group and the blank control group (all P>0.05). Conclusions Renal tissue of DN mice will undergo significant oxidative stress injury. Tea-polyphenols may reduce the oxidative stress injury in DN mice by regulating the Nrf-2/ARE signaling pathway, and play a protective role in the kidney.