Effect of postnatal undernutrition on ketone metabolism and its relation to metabolic changes in brain and liver of rats.

The effects of undernutrition on ketone metabolism and its relation to brain growth in developing rats were studied. In the first series of experiments, undernutrition was induced by increasing the litterr size from 4 to 16 pups. Body weight of pups was inversely related to litter size. Increasing the litter size lowered brain weight by 6-16% and liver weight by 20-46%. The ratio of brain weight:body weight was greater by 16 to 39% in the larger litters. Increasing the litter size did not alter concentration of brain lipid. liver glycogen or plasma ketone bodies. In the second series of experiments, undernutrition was induced by restricting maternal dietary intake to 40% of that of the control dam. This undernutrition caused a more pronounced growth retardation than that resulting from increasing litte size. At 14 days of age, the mean body weight of the undernourished group was 44% lower than the control value. The dietary restriction lowered brain weight by 19%, liver weight by 38%, liver glycogen by 47%, brain lipid by 11%, plasma ketone bodies by 30%, glucose by 37% and the rate of hepatic ketogenesis by 28%. The results suggest that brain-growth retardation is related to low brain lipids and impaired ketone metabolism.