Lh. Chen et al., EFFECTS OF AGE AND DIETARY RESTRICTION ON LIVER ENDOGENOUS ANTIOXIDANT DEFENSES IN MALE LOBUND-WISTAR RATS, Age, 19(3), 1996, pp. 101-109
Dietary restriction (DR) of 30% in caloric intake extends both median
and maximum life span by about 30%. DR retards the aging process, but
the mechanism of action is not clearly understood. The effects of DR o
n major endogenous antioxidant defenses were studied in 80 male Lobund
-Wistar (LW) rats at various ages throughout the life span. Two groups
of rats were fed ad libitum (AL) or restricted diet (DR) from 6 weeks
of age. Adult DR rats received 30% less diet with regard to calories
per day when compared to adult AL rats. Eight rats in each diet group
were killed at 6, 12, 18, 24 and 30 months of age. The livers were exc
ised and prepared for the determinations of major endogenous antioxida
nt defense parameters. Hepatic reduced glutathione (GSH) levels were d
ecreased at old age in the AL group, however, DR eliminated this decre
ase. Activities of glutathione reductase (GR) and Se-dependent glutath
ione peroxidase (GPx) were not affected by age nor by DR. Superoxide d
ismutase (SOD) activity decreased from 6 to 12 months of age and catal
ase activity decreased with aging in the AL group, while DR maintained
the enzyme activities at similar levels for all ages. Quinone reducta
se (QR) activity increased with increasing age in the AL group, and DR
further increased the enzyme activity at all ages. The results sugges
t that 30% DR may contribute to the delaying of the aging process by i
mproving endogenous antioxidant defense capability which decreases by
20 to 30% during aging.