577 LIPID INTAKE DURING THE SUCKLING PERIOD REGULATES GLUCOSE METABOLISM IN THE DEVELOPING RAT INTESTINE

Abstract

The oxidation of glucose in developing rat intestine changes dramatically during suckling and weaning. The rate of glucose oxidation to CO₂ by intestinal slices increased 3-fold after weaning and subsequently declined by half to an adult level. The steady state concentration of pyruvate decreased from 45 μM in suckling animals to 20 μM after weaning suggesting a change in pyruvate metabolism during this period without a change in lactate production. Studies with 1-¹⁴C-pyruvate suggested increased pyruvate dehydrogenase (PDH) activity after weaning: production of ¹⁴CO₂ increased from 3.52 to 4.48 n moles/mg/hr after weaning. High levels of fatty acid esters present during the suckling period may be responsible for PDH inhibition. To investigate this possibility, palmitoylcarnitine (400 μM) was added to assays using intestinal slices from post-weaning animals. This resulted in a decrease in glucose oxidation from 2.23 to 1.35 n moles/mg/hr while steady state levels of pyruvate increased from 28 to 42 μM. Oxidation of 1-¹⁴C-pyruvate to ¹⁴CO₂ decreased from 4.32 to 2.38 n moles/mg/hr, again indicating decreased PDH activity. These results mimic those found in tissues from suckling animals. These studies demonstrate an influence of fatty acids on intestinal glucose metabolism during development probably at the level of PDH and emphasize the importance of diet in regulating intestinal metabolism.

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