Caloric restriction diminishes the age-associated loss of immunoreactive catalase in rat prostate.

Abstract

Caloric restriction (CR) retards aging and diseases in mice, rats, and other animals by unknown mechanisms. A popular hypothesis is that CR acts by opposing age-associated increases in oxidative stress. Because influences of CR on antioxidant enzymes in the prostate have not been previously investigated, immunohistologic methods (light and electron microscopy) were used to determine the prostatic localization of catalase (CAT) in rats of diverse ages (3-32 months) fed either normally or subjected to CR from age 16 months. In 20-month-old rats fed either diet, CAT appeared as dense deposits at the apical poles of the epithelium in the lateral lobes, and within the ductular lumens, suggesting that CAT is secreted. Confirmation of both liver peroxisomal and prostatic apical cytoplasmic localization of CAT was provided by electron microscopic immunogold staining. The amount of CAT was reduced at 30 months in normally fed rats but not in those on CR. CAT appears to be a secretory product of the epithelial cells in the lateral lobes of the rat prostate. Further, CR from late-middle age opposed the age-associated loss of this intracellular enzyme activity.