Effect of calorie restriction on liver and kidney glutathione in aging emory mice

Increases in antioxidant defense capacity have been associated with increases in the health and life span of calorie restricted animals. Emory mice develop late-life cataract, a lesion associated with oxidative damage and loss of lens glutathione (GSH). The effect of calorie restriction on GSH in liver and kidney in this model has not been explored. GSH and oxidized GSH (GSSG) were measured by HPLC in liver and kidney of Emory mice fed a control diet (C; 85% calories of ad-lib fed mice) or 60% calorie intake of C (R; 40% calorie restriction relative to C mice) for up to 22 mo age. Liver GSH concentration increased significantly in C and R mice from 4.5 to 12 mo old with no difference observed between the two groups. At 22 mo of age, liver GSH was lower than that of 12 mo old in both groups. As compared with GSH at 12 mo old, this decrease was almost twice as greater in C (70%, p=0.001) than in R mice (36%, p=0.02), so that R mice had a significantly higher concentration of GSH in liver than C mice at 22 mo of age (R = 32.8+5.1, C= 22.1+8.3 imol GSH/g protein, p<0.01). Liver GSSG was similar in C and R mice at 12 mo of age (4.45+1.35 vs. 4.75+1.83 imol GSSG/g protein), but increased in R mice at 22 mo (R=5:43±1.48; C=3.22±1.02, p<0.01). Therefore, at 22 mo old, total liver glutathione (GSH+GSSG) was higher in R than in C mice. There was no significant difference in GSH, GSSG and total GSH in kidney from C and R mice at these ages. Thus, calorie restriction reduces the age-related loss of GSH antioxidant capacity in liver but not kidney of Emory mice.