Intrahepatic glucose: a requirement for neonatal ODC induction by specific hormones

Abstract

We have shown previously that short-term nutritional deprivation causes a tissue-specific loss of liver ornithine decarboxylase (ODC) induction after isoproterenol, phenylephrine, or glucagon administration in rat pups. To examine the role of nutrition in the regulation of hepatic ODC, we tested the ability of intragastric nutrient administration to reverse nutritionally related deficits in the ODC response to hormonal challenge. Intragastric whole milk was effective in restoring ODC induction and accumulation of its immediate product, putrescine, in response to isoproterenol administration. Glucose was shown to mediate this effect by the ability of intragastric skimmed milk, lactose, galactose, or D-glucose to return ODC induction, and the inability of casein, sucrose, fructose, L-glucose, or pyruvate plus lactate to do so. D-Glucose also reestablished ODC induction by phenylephrine and glucagon. Parenteral administration of D-glucose produced results comparable to those obtained after intragastric administration. Isoproterenol induction of ODC was prevented when hepatic glucose uptake was blocked by phlorizin but not by blockade of central nervous system glucose uptake with 2-deoxyglucose. We conclude that intrahepatic glucose is an absolute requirement for hepatic ODC induction by isoproterenol, phenylephrine, or glucagon in preweanling rats.