The Effect of Food Deprivation on In Vivo Gluconeogenesis in the Suckling Rat

Abstract

Radioactive pyruvate was administered in trace or substrate concentrations to fed or 24 hr food deprived male and female Wistar rats of 5, 10, 20 and 30 days of age and adults. The formation of glucose-¹⁴C 30 min after the administration of pyruvate was higher in fed suckling rats than in adults. Food deprivation increased the rate of glucose-¹⁴C synthesis in all groups given a trace concentration of pyruvate and in the adults and 30 days old rats given a substrate concentration of pyruvate. Food deprivation failed to significantly elevate glucose formation in 5, 10 and 20 days old rats given substrate concentrations of pyruvate. The formation of glycogen-¹⁴C in the liver was slightly reduced in 5 and 10 days old rats and augmented in 20 days old rats compared to adults. Food deprivation increased liver glycogen formation in 20 and 30 days old rats and in adults, but not in younger animals. The relationship between the rate of gluconeogenesis and the availability of lipids in the rats is discussed. An explanation for the lack of a gluconeogenic response to food deprivation in suckling rats is given based on the level of citrate synthesis from oxalacetate.

Key words

Suckling-Food Deprivation - Gluconeogenesis - Liver Glycogen