Dietary restriction of amino acids other than methionine prevents oxidative damage during aging: involvement of telomerase activity and telomere length.

AIMS It has been suggested that variations in the proportions of some dietary amino acids can slow down aging. In this study, the influence of amino acids other than methionine on aging was investigated. MAIN METHODS Rats were fed either with normal (ND) or except methionine, protein restricted diet (PREMD) for 4 months and oxygen radical production, oxidative protein and DNA damage along with telomere length and telomerase activity were evaluated in the liver. KEY FINDINGS Except mitochondrial superoxide production rate, feeding with PREMD significantly decreased the oxygen radical production rate and protein carbonyl levels in the homogenate and mitochondria of 16-month-old rats. Feeding with PREMD prevented 8-OHdG formation in mitochondrial DNA but not in the genomic DNA. Although liver telomerase activities of rats receiving either ND or PREMD seemed to have some variations, these did not reach a statistical significance. Feeding with PREMD conserved the telomere length in the liver. The telomere length of 8- and 16-month-old rats fed PREMD was similar, 16-month-old rats fed ND had telomeres shortened by 36% (p<0.05). SIGNIFICANCE Long-term restriction of the amino acids other than methionine may decrease oxygen radical generation and oxidative damage of cellular constituents, and may also prevent telomere shortening in rat liver.