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

Because diabetes mellitus is associated with impairment of testicular funct ion, ultimately leading to reduced fertility, this study was conducted to e valuate the existence of a cause-effect relationship between increased oxid ative stress in diabetes and reduced mitochondrial antioxidant capacity. Th e susceptibility to oxidative stress and antioxidant capacity (in terms of glutathione, coenzyme Q, and vitamin E content) of testis mitochondrial pre parations isolated from Goto-Kakizaki (GK) non-insulin-dependent diabetic r ats and from Wistar control rats, 1 yr of age, was evaluated. It was found that GK mitochondrial preparations showed a lower susceptibility to lipid p eroxidation induced by ADP/Fe2+, as evaluated by oxygen consumption and rea ctive oxygen species generation. The decreased susceptibility to oxidative stress in diabetic rats was associated with an increase in mitochondrial gl utathione and coenzyme Q9 contents, whereas vitamin E was not changed. Thes e results demonstrate a higher antioxidant capacity in diabetic GK rats. We suggest this is an adaptive response of testis mitochondria. to the increa sed oxidative damage in diabetes mellitus.