Authors
Beier K. Volkl A. Fahimi HD.
Institution
Institut fur Anatomie und Zellbiologie II, Heidelberg, Germany.
Title
The impact of aging on enzyme proteins of rat liver
peroxisomes: quantitative analysis by immunoblotting and
immunoelectron microscopy.
Source
Virchows Archiv. B, Cell Pathology Including Molecular Pathology.
63(3):139-46, 1993.
Abstract
The alterations of hepatic peroxisomes and their enzymes
during aging were investigated in male rats.
Peroxisomes in the livers of young (2 months) and old (39
months) male Wistar rats were analyzed by morphometry and quantitative
immunocytochemistry, as well as by immunoblotting of highly purified
peroxisomal fractions. Immunoblots showed that catalase and acyl-CoA oxidase
were decreased in peroxisomes of old animals but the
trifunctional enzyme, thiolase, and urate oxidase were increased. The
morphometrical analysis revealed a heterogeneous distribution of
peroxisomes in the liver lobule of the old animals, with a
significant elevation of peroxisomal volume density in pericentral over
periportal hepatocytes, in contrast to the uniform pattern in the young rats.
Furthermore, age-related lobular gradients were also observed by quantitative
immunocytochemistry in the peroxisomal concentrations of trifunctional enzyme
(central > portal) and, inversely, for catalase (portal > central). Whereas
acyl-CoA oxidase was diminished across the liver lobule, the enzyme
3-ketoacyl-CoA thiolase was elevated. These observations show that
peroxisomes are significantly altered in aged animals and
suggest that these alterations may contribute to the disturbance of lipid
metabolism in aged animals. Moreover, the diminution in catalase and the
elevation of urate oxidase could contribute to the oxidative stress which is
considered to be of fundamental importance in the aging
process.