CAT and Insulin resistance: On the other hand, the antioxidant enzyme activities such as glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD) as well as non-enzymatic antioxidants including reduced glutathione (GSH) were reduced in the brains of insulin resistance rats [9]–[13], suggesting that a declined antioxidant ability is induced by insulin resistance.