INTRODUCTION: The objective of this study was to evaluate the long-term effects of amino acids other than methionine in mitotic and postmitotic tissues of rats by measuring mitochondrial peroxide and superoxide production, oxidative protein and DNA damage in the liver and heart of 16-month-old rats which fed either with normal diet (ND) or protein restricted-except methionine diet (PREMD).
METHODS: 4- and 12-month-old rats were fed with either ND or PREMD for 4 months. Mitochondrial peroxide and superoxide production rates, the protein carbonyl and mtDNA 8-OHdG levels of liver and heart mitochondria were measured.
RESULTS: Mitochondrial peroxide and superoxide production rates of the liver and heart mitochondria in 16-month-old rats fed either ND or PREMD did not show any significant difference. Neither feeding with PREMD nor ND has any significant effect on protein carbonyl levels between the liver and heart mitochondria of rats at any age. In 16-month-old rats, mtDNA 8-OHdG levels were significantly higher in heart than the liver regardless of the diet.
DISCUSSION AND CONCLUSION: Mitochondrial ROS production, oxidative protein and DNA damages increase both in mitotic and postmitotic tissues with age however the increment is more prominent in heart than liver. Long term feeding with PREMD could not decelerate oxidative damage during aging neither in the heart nor in the liver.