Enhanced mitochondrial testicular antioxidant capacity in Goto-Kakizaki diabetic rats: role of coenzyme Q

Because diabetes mellitus isassociated with impairment of testicular function, ultimately leadingto reduced fertility, this study was conducted to evaluate theexistence of a cause-effect relationship between increased oxidativestress in diabetes and reduced mitochondrial antioxidant capacity. Thesusceptibility to oxidative stress and antioxidant capacity (in termsof glutathione, coenzyme Q, and vitamin E content) of testismitochondrial preparations isolated from Goto-Kakizaki (GK)non-insulin-dependent diabetic rats and from Wistar control rats, 1 yrof age, was evaluated. It was found that GK mitochondrial preparationsshowed a lower susceptibility to lipid peroxidation induced byADP/Fe²⁺, as evaluated by oxygen consumption and reactiveoxygen species generation. The decreased susceptibility to oxidativestress in diabetic rats was associated with an increase inmitochondrial glutathione and coenzyme Q9 contents, whereas vitamin Ewas not changed. These results demonstrate a higher antioxidantcapacity in diabetic GK rats. We suggest this is an adaptive responseof testis mitochondria to the increased oxidative damage in diabetes mellitus.