Protective role of tea polyphenols in oxidative stress damage of the rat articular cartilage tissue caused by brick-tea fluorosis

Abstract

Objective To explore the protective mechanism of tea polyphenols (TPs) ion oxidative stress damage of the rat articular cartilage tissue caused by brick-tea fluorosis. Methods One hundred and twenty wistar male rats were randomly divided into 6 groups according to body mass: fluoride group with drinking water containing 100.00 mg/L F-, fluoride plus TPs group treated with 100.00 mg/L F- and 10.0 g/L TPs, fluoride plus aluminum group fed with 100.00 mg/L F- and 200.00 mg/L Al3+, fluoride plus aluminium and TPs group treated with 100.00 mg/L F-,200.O0 mg/L Al3+ and 10.0 g/L TPs;brick-tea group treated with drinking water containing 100.00 mg/L F-,215.00 mg/L Al3+ and 9.2 g/L TPs, which was steeped by the brick-tea;control group treated with tap water. The animals were bred for three months and then sacrificed. The level of SOD,T-AOC and MDA in blood serum were detected,also the level of NO and cytokine IL-1β and IL-6, the expression of iNOS mRNA and protein in articular cartilage were respectively analyzed by RT-PCR and immunohistochemistry. Results Blood serum SOD level in the fluoride plus aluminum and TPs group[(664.009 ± 29.589)kU/L] was higher compared with that in the fluoride group[(625.328 ± 27.199)kU/L], fluoride plus aluminum group[(652.282±13.926)kU/L], although no statistically significant differences was found(P > 0.05) ;blood serum T-AOC level of the fluoride plus TPs, fluoride plus aluminum and TPs group, brick tea group[(10.874 ± 0.721), (11.871 ± 0.941), (10.380 ± 2.747)kU/L] was higher compared with fluoride group, fluoride plus aluminum group [(8.849 ± 1.887), (8.210 ± 1.740)kU/L], the differences all being statistically significant(P 0.05);the blood serum IL-6 level of fluoride plus aluminum and TPs group, brick-tea group[(7.231 ± 0.596), (7.325 ± 0.290)ng/L] had statistical differences compared with fluoride plus aluminum[(8.256 ± 0.635)ng/L, P < 0.05]. The iNOS mRNA correspondent expression content of fluoride plus Tps group, fluoride plus aluminum and TPs group, brick-tea group(0.482 ± 0.021,0.447±0.021,0.491 ± 0.022) had statistical differences compared with fluoride group, fluoride plus aluminum group (0.562 ± 0.025,0.591 ± 0.020, all P < 0.05). Cells with positive iNOS protein expression of control group were mainly distributed at the surface layer of joint, while the cells of experiment groups were distributed both at the surface layer and the intermediate layer. Conclusions Tea polyphenols could alleviate oxidative stress damage on the articular cartilage, exerting protection against brick-tea fluorosis on rats through cleaning up free radicals, elevating total anti-oxidation capability, diminishing the generation of lipid peroxide. Key words: Tea; Fluorosis; Tea polyphenols; Oxidative stress