The age-related accumulation of protein carbonyl in rat liver carbonyl in rat liver correlates with the age-related decline in liver proteolytic activities

Increases ofprotein carbonylin animal tissues have been associatedwith the agingprocess. Sofar, the accumulation of oxidizedproteins,highly susceptibleto proteolysis, hasbeen attributedto age-relatedchangesin proteasomalalkalineproteases. Carbonylin protein wasmonitored in six differenttissuesofmale Sprague-Dawley ratsfed ad libitum up to the age of27 months, and of24- and 27-month-oldrats subjectedto anti-agingdiet restriction (every-other-day feeding ad libitum). Alkaline protease activitiesand liver lysosomalproteolysiswerestudied. The levelsofprotein carbonyl weresignificantly different in differenttissues,and quite stablethroughoutlife;accumulationwasrestricted to livertissue verylate in life~ betweenages24 and 27 months; wasfuUypreventedby diet restriction; wasnot accompaniedby any diet-restriction-sensitive declineofalkalineproteaseactivity;and wasaccompanied by a dramaticage-relateddeclinein lysosomalproteolysisthat waspartiallypreventedby anti-agingdiet restriction. No correlation wasfound betweenlevelsofalkaline proteaseactivity and levelsofproteincarbonylin the different tissuesfrom youngeranimals. It is concludedthat the processofautophagy, a well-knownmechanismfor cellmaintenance,may deserve moreinterestin aging studies