Neonatal intestinal metabolism

in the presence of glutamine, glucose, and 3-hydroxybutyrate, glutamine is the preferred oxidative substrate in enterocytes of suckling and weaned rats. The oxidation of substrates that enter the citric acid cycle in the form of acetyl-CoA such as glucose, fatty acid, and lipids is low during the suckling period and increases after weaning. The control of the citric acid cycle appears to be the intramitochondrial [NADH]/[NAD(+)] ratio which is high during the suckling period and low in the intestine of weaned rats. The changes in substrate oxidation during weaning is not controlled by the endogenous steroid burst that occurs at 16 days of age. Substrate oxidation only changes after weaning suggesting that a change in diet is a significant factor in intestinal substrate oxidation.