To investigate the effect and mechanism of Qianggu Tongbi capsules on oxidative stress in rats with osteoarthritis.

Twenty-four SD rats were randomly divided into two groups, 6 of which were used for control group and 18 were used for modeling. After modeling, the 18 rats were randomly divided into model group, Qianggutongbi capsules group, and glucosamine group. Hematoxylin eosin staining (HE) was used to observe the changes of cartilage. Superoxide dismutase (SOD) kit, malondialdehyde (MDA) kit, and nitric oxide (NO) kit were applied to detect the levels of SOD, MDA and NO in serum, respectively. Real time-polymerase chain reaction (RT-PCR) was applied to detect the expressions of nuclear factorerythroid 2-relaxed factor (Nrf2), Kelch-like ECH-associated protein 1 (Keap1), macrophage activation factor (Maf), heme oxygenase-1 (HO-1), and NADPH quinone oxidoreductase 1 (NQO1) in each group. Western blot was used to detect the expressions of Nrf2, Keap1, Maf, HO-1, and NQO1 in each group.

HE staining results showed that there was obvious infiltration of dense inflammatory cells in the cartilage tissue of the model group, while the inflammatory cells in the Qianggu Tongbi capsules group and glucosamine group were significantly reduced compared with the blank control group. Compared with the model group, the levels of antioxidant indexes of Qianggu Tongbi capsules group and glucosamine group increased significantly, while the free radical concentrations decreased significantly (P<0.05). Compared with the model group, the mRNA and protein expression levels of Nrf2, Maf, HO-1, and NQO1 in Qianggu Tongbi capsules group and glucosamine group were significantly up-regulated (P<0.05), while the mRNA and protein expression levels of Keap1 were down-regulated (P<0.05).

Qianggu Tongbi capsules can change the antioxidant indexes in serum by activating the expression of Nrf2-Keap1/ARE pathway-related proteins and mRNA, so as to restore the function of antioxidant stress in rats with osteoarthritis.