INTRODUCTION: The objective of this study was to evaluate the long-term effects of amino acids other than methionine in mitotic and postmitotic tissue of rats by measuring mitochondrial peroxide and superoxide production as well as oxidative protein and DNA damage in the liver and heart of rats fed with either a normal diet (ND) or a protein-restricted diet (PREMD).
METHODS: The study group comprised 4- and 12-month-old rats fed with either a ND or a PREMD for 4 months. The rate of mitochondrial peroxide and superoxide production, and the protein carbonyl (PC) and mitochondrial DNA (mtDNA) 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the liver and heart mitochondria were measured.
RESULTS: The mitochondrial peroxide and superoxide production rates of the liver and heart mitochondria of rats did not demonstrate any significant difference based on the diet provided. Similarly, diet did not have a significant effect on the PC level in the liver and heart mitochondria of either age group. In the 16-month-old rats, the mtDNA 8-OHdG level was significantly higher in the heart than the liver, regardless of the diet.
DISCUSSION AND CONCLUSION: Mitochondrial reactive oxygen species production, and oxidative protein and DNA damage increased in mitotic and postmitotic tissue with age; however, the increment was more prominent in the heart than the liver. Longterm PREMD consumption did not decelerate oxidative damage in the heart or in the liver with age.