EVALUATION OF LIPID PEROXIDE METABOLISM IN NEONATAL RATS DURING SUCKLING - DEVELOPMENTAL-CHANGES IN WHOLE-BODY LIPID PEROXIDES

To evaluate lipid peroxide metabolism in neonatal rats during suckling , we studied developmental changes in whole body lipid peroxidation by measurement of thiobarbituric acid-reactive substances (TBARS) determ ined as malondialdehyde. Whole body TBARS contents were very low immed iately after birth but increased sharply at 3-9 days, peaked at 9-15 d ays, and then remained unchanged until 21 days. The feeding of a skimm ed milk diet to neonates between 17 and 20 days old sharply decreased their whole body TBARS contents at 20 days as compared with those at 1 6 days, however, this was not observed by the feeding of an artificial milk diet containing 3 g of soybean oil/100 g diet. In vitro ethane p roduction by liver and brain homogenates and in vivo breath ethane lev els in expired air were higher at 20 or 21 days than at 10 days after birth. These results suggest that lipid peroxide formation in neonatal rats increases shortly after birth and that its degradation and/or ex cretion may increase during the latter period of suckling.