The effect of aging on rat tissue content of moisture, protein, zinc, copper, and manganese with partial food deprivation: II. Middle stages of aging

Abstract

Underfeeding (50% ad libitum) resulted in marked retardation of growth which was nearly a 50% reduction at 12 months of age for males and a 34% reduction for females. The retardation of female growth was not as severe as that of male. Various organ weights showed a pattern similar to total body growth. Moisture content tends to decrease with age but it is statistically insignificant. Protein concentration of male showed a gradual increase up to eight months, then remained constant throughout the test period. Unlike protein content in the male, female protein concentration remained fairly constant from one to twelve months in ad libitum feeding. However, protein levels in 50% ad libitum female tissues tended to decrease with age. Zinc content in liver, kidney, and brain showed a gradual increase to 8 months then decreased. Zinc content in bone showed a rapid increase before leveling off. The zinc level in the bone was consistently higher than any other tissues examined. A gradual increase was observed in copper content of liver and kidney in the ad libitum fed groups whereas a rapid increase was observed in the 50% ad libitum fed group before leveling off to relatively constant concentrations. Manganese levels in all tissues remained constant except in the brain. Brain manganese content tended to increase with age. Among the parameters studied, there was a significant retardation of organ and body growth with diet manipulation. Supplementation of trace minerals (Cu, Mn, Zn) in the diet reduced mortality rate. Protein content was the only significant difference observed between sexes or dietary groups.