[Anti-oxidative effects of dexamethasone on mice with experimental autoimmune encephalomyelitis]

To investigate the effects of dexamethasone (DXM) on the level of oxidative stress and antioxidant enzymes in mice with experimental autoimmune encephalomyelitis (EAE).

C57BL/6 mice were immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG35-55) to induce EAE. The mice were randomly divided into control group, EAE group, DXM group, and their clinical symptoms were observed. On day 13, 20 and 30 post immunization, the content of malondialdehyde (MDA) in the brain was assayed by thiobarbituric acid method; the expression levels of nuclear factor-erythroid 2-related factor 2 (Nrf2) and NADP(H):quinine oxidoreductase 1 (NQO1) in the brain were detected by immunohistochemistry and Western blotting.

The morbidity and neurological deficit score of DXM group were significantly lower than those of EAE group (P<0.05). On day 13, 20 and 30 post immunization, the content of MDA in the EAE group was obviously higher than that in the control group (P<0.05); the content of MDA in the DXM group was obviously lower than that in the EAE group (P<0.05). Compared with the control group, the expression levels of Nrf2 and NQO1 in the EAE and DXM groups significantly increased on day 13, 20 and 30 post immunization (P<0.05). Compared with the EAE group, the expression levels of Nrf2 and NQO1 in the DXM group notably increased on day 13, 20 and 30 post immunization (P<0.05). In addition, DXM promoted the nuclear translocation of Nrf2.

DXM could mitigate oxidative insult by up-regulation of Nrf2 and antioxidant enzymes, which may be an important mechanism involved in its protective effects on EAE.