SOD1 and infectious otitis media: As shown in Figure 2C, the expression of GPx1 mRNA, which encodes an antioxidant enzyme, was reduced by AOM injection (P < 0.05), but astaxanthin significantly increased the expression of GPx1, as well as of SOD1 and CAT, both of which encode antioxidant enzymes, in the colonic mucosa of db/db mice treated with AOM (P < 0.05).