Table 1.
Changes in body weights, muscle weights and liver weights in 8-month, 18-month, 29-month and 37-month old ad libitum (AL) and calorie restricted rats.
Figure 1.
Effect of aging and calorie restriction on gastrocnemius weights and non-heme iron content.
(A) Gastrocnemius muscle weights from ad libitum-fed and calorie-restricted rats at 8, 18, 29, and 37 months of age. (B) Total non-heme iron content of gastrocnemius muscle was calculated from non-heme iron concentrations and muscle weights. (C) Non-heme iron concentrations were measured colorimetrically after acid digestion of tissue. Values are means±SEM (n = 8–9). a,b,c,dDifferent letters indicate values are significantly different (p<0.05 by Tukey's Multiple Comparison Test).
Figure 2.
Effect of aging and calorie restriction on liver weights and non-heme iron content.
(A) The liver weights increased with age in AL rats, but not in CR rats. (B) Total amount of non-heme iron in liver increased with age in AL rats, but not in CR rats. (C) Liver non-heme iron concentrations did not change over time in CR rats, but they increased in AL rats. Values are means±SEM (n = 9). a,b,c,dDifferent letters indicate values are significantly different (p<0.05 by Tukey's Multiple Comparison Test).
Figure 3.
Effect of aging and calorie restriction on nucleic acid oxidation in gastrocnemius liver weights and non-heme iron content.
A) Total RNA oxidative damage in the gastrocnemius muscles increased with age in AL rats, which did not change over time in CR rats. B) Total DNA oxidative damage in the gastrocnemius muscle increased markedly after 29 months of age in both AL and CR rats. Values are means±SEM (n = 6). a,b,cDifferent letters indicate values are significantly different (p<0.05 by Tukey's Multiple Comparison Test).
Figure 4.
Effect of aging and calorie restriction on grip strength.
Grip strength in CR rats declined significantly at 37 months of age, while it decreased significantly at 29 months of age in AL rats, yet more pronounced in advanced age of 37 months. Values are means±SEM (n = 7–8). a,b,cDifferent letters indicate values are significantly different (p<0.05 by Tukey's Multiple Comparison Test).
Figure 5.
Calorie restriction attenuates iron accumulation and sarcopenia.
Reactive iron plays a major role in oxidative stress via Fenton chemistry, where homolytic cleavage by ferrous iron (Fe2+) of H2O2 generating hydroxyl radicals. In this regard, both H2O2 and superoxide radicals have been shown to promote the release of iron from iron-binding proteins. Iron accumulation therefore increases the risk for RNA and DNA damage, protein modification, lipid peroxidation, and can affect protein synthesis which contribute to the process of sarcopenia.