Lipid peroxidation and antioxidants in rat liver during development.

The concentration of lipid peroxidation was extensively high in rat fetuses and early newborns. However, it declined sharply thereafter. Superoxide dismutase (SOD) activity was approximately 10% of the adult level during 5 days postpartum. The enzyme activity began to increase after the 10th day to 60% of the adult level at the 20th day. Catalase activity was low in the fetal period, corresponding to approximately 20% of the adult level, but increased rapidly after birth reaching approximately 50% of the adult level at 5-7 days postpartum. Glutathione peroxidase (GSH-Px) activity was measured to amount to only 7% of the adult level in the fetal and early newborn period. The level of this activity was approximately 20% of the adult level at the 20th day. The difference in GSH-Px activity became wide between sexes after the first 30 days of life; the male adult level was 61% of the female adult level. The concentration of vitamin E was low in the fetus. It increased by a factor of 10 times within a few days after birth, and thereafter it decreased gradually. Fetal and early newborn livers have low enzymatic defense capabilities against possible deleterious effects of lipid peroxidation processes.