title: Late onset of dietary restriction reverses age-related decline of malate-aspartate shuttle enzymes in the liver and kidney of mice.
abstract: Dietary restriction (DR) influences several physiological processes, retards the incidences and severity of various age-related diseases and extends lifespan of various animal species. The effect of DR on the activities of malate-aspartate shuttle enzymes, viz. cytosolic and mitochondrial aspartate aminotransferase (c- and m-AsAT) and malate dehydrogenase (c- and m-MDH) was investigated in the liver and kidney of adult (5-months) and old (21-months) male mice. The results show that the activity (U/mg protein) of both c- and m-MDH and AsAT is decreased significantly in the liver and kidney of old mice compared to adult ones. However, DR in old mice reverses significantly the enzyme activities to a level closer to adult animals. Polyacrylamide gel electrophoresis (PAGE) and specific staining of c-AsAT, one of the selected isoenzymes of the shuttle, showed a similar pattern of activity expression as observed by activity measurements in both the tissues studied. Slot blot analysis of c-AsAT confirmed the lower protein content of this isoenzyme in old mice compared to adult ones and a higher level in old-dietary restricted mice. Thus, our results suggest that the late onset of DR in older mice reverses decline in malate-aspartate shuttle enzymes and that it may allow a better metabolic regulation in older animals.
authors.affiliation: Department of Biochemistry, North Eastern Hill University, Shillong, India.
authors.forename: Danswrang
authors.initials: D
authors.lastname: Goyary
authors.forename: Ramesh
authors.initials: R
authors.lastname: Sharma
mesh_terms: D000367:Age Factors; D000818:Animals; D001219:Aspartate Aminotransferases / Q000378:metabolism*; D001224:Aspartic Acid / Q000378:metabolism*; D031204:Caloric Restriction; D004591:Electrophoresis, Polyacrylamide Gel; D007668:Kidney / Q000201:enzymology*; D008099:Liver / Q000201:enzymology*; D008291:Malate Dehydrogenase / Q000378:metabolism*; D008293:Malates / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D008293:Malates; D001224:Aspartic Acid; C030298:malic acid; D008291:Malate Dehydrogenase; D001219:Aspartate Aminotransferases