FASTING-INDUCED REMODELING OF HEPATIC TRIACYLGLYCEROLS

Rat liver triacylglycerol species are known to respond differentially to metabolic and nutritional manipulation but changes in triacylglycerols containing 20-22 carbon polyunsaturates have been difficult to determine. Liver total triacylglycerols were separated by high performance liquid chromatography into subclasses to determine whether their remodelling by fasting induced changes consistent with reacylation causing enrichment by long-chain polyunsaturated fatty acids. Triacylglycerol subclasses and their fatty acid composition were quantitatively determined. The fasting-induced changes in liver triacylglycerols were characterized by the appearance of new subclasses containing 20-22 carbon polyunsaturates at 18-30% but relative and quantitative depletion of more saturated subclasses. Previous studies have not been able to identify whether changes in the polyunsaturated fatty acid content of triacylglycerols during fasting were mainly a function of depletion of saturates and monounsaturates or whether extensive reacylation of subclasses/species specifically enriched in polyunsaturated fatty acids also occurred; our present data suggest that the latter is a significant component of the fasting-induced triacylglycerol remodelling process.