Lipofuscin and Mitolipofuscin in the Organs of Young and Adult Rats

Abstract

The levels of lipofuscin (aging pigment) were compared in four organs (liver, kidney, heart, brain) of young and adult rats, as well as in the suspension of hepatic mitochondria. Mitochondrial lipofuscin—mitolipofuscin fluorescing in the blue region—was seen to make the major contribution to hepatic lipofuscin. It is clear that mitolipofuscin also makes a significant contribution in other organs. The age-related accumulation of lipofuscin was shown to occur in all rat organs, but in the brain least of all. In addition to fluorescent lipofuscin, non-fluorescent protein aggregates were found in all organs, mostly in the heart. A considerable portion is covalently cross-linked aggregates not destroyed by detergents. Their number also increases with age.