Abstract
Effects of aging on the lipid metabolism of the liver were studied in 8 early newborn rats (0-4 days after birth), 11 late newborn rats (5-10 days after birth), and 15 infant rats (11-28 days after birth). Respiratory quotient (R. Q. : Warburg Manometer) and the amount of acetone bodies (Conway's Diffusion method) in the rat liver were measured in fasting and in 1, 2, 3, and 4 hours after the oral administration of corn oil. At the same time, blood glucose concentration (glucose oxidase method) was measured in each rat. In fasting state, the acetone bodies contents of the liver were more increased in the early newborn rat than in the late newborn and infant rats, while the R. Q. was lower in the early newborn rats. The rise in the acetone bodies contents of the liver after the oil administration were the lowest in the early newborn rats and the highest in the infant rats. In the early newborn rats, the changes in the R. Q. after the oil loading were lower than the other group of rats at each times and were biphasic with the initial increase followed by rapid decrease. Changes of the blood glucose levels after the oil administration increased more significantly in the early newborn rats than in the infant rats. It is suggested that the gluconeogenesis from lipid and fatty acid oxidation in the liver after the oral oil administration are more enhanced in the early newborn rats than the infant rats.
