Rats Enriched with Odd-carbon Fatty Acids: Effect of Prolonged Starvation on Liver Glycogen and Serum Lipids, Glucose and Insulin

Abstract

Male rats were fed a complete diet containing 30 per cent of calories as fat, with corn oil exclusively in the controls and a 7:3 mixture of triundecanoin (C11) and corn oil in the experimental group. After six weeks, rats were sacrificed in the fed state and at 24, 48, 96 and 144 hours of starvation. In the experimental group, adipose tissue fatty acids were enriched with undecanoate to an average of 28 per cent of total fatty acids. Serum glucose was found to be significantly higher in the experimental group at all periods of starvation, and liver glycogen in the experimental rats was significantly higher at 48, 96 and 144 hours of starvation. Planimetry of the area circumscribed by values plotted from 24 to 144 hours of starvation gave mean values of immunoreactive insulin of 22.37 mU. hours per ml. for the experimental versus 13.55 mU. hours per ml. for the control group (P < .005), and mean values of free fatty acids of 967 mEq. hours/L. for the experimental versus 1,128 mEq. hours/L. for the control group (P < .05). Weight loss and nitrogen excretion were not significantly different among the two groups, nor were levels of serum cholesterol and triglycerides. The data suggest that during prolonged starvation, the odd chain, fatty acid-enriched animals are capable of maintaining liver glycogen and serum glucose better than even-chain-enriched control animals. These changes are reflected in concurrently higher serum immunoreactive insulin and lower free fatty acid levels. The odd-chain fatty-acid-enriched rat appears to be endowed with potentially glucogenic fatty acids.