The metabolism of [1-¹§4C] linoleate in linoleate deficient rats

grantor: University of TorontoThe purpose of this study was to characterize the metabolism and quantitative partitioning of (1-$\sp{14}$C) -linoleic acid (LA) among its metabolic endpoints which include (i) accumulation in structural and storage lipids, (ii) conversion to long chain products and (iii) $\beta$-oxidation, during pure LA deficiency (LAD) and subsequent LA supplementation. LA-deficient rats retain significantly more $\sp{14}$C in the liver (10% vs 4%) and brain (0.05% vs 0.01%) than the controls. During pure LAD, a greater proportion of (1-$\sp{14}$C) LA was retained in the liver n-6 PUFA pool, but as much as 14% was found in de novo synthesized non n-6 fatty acids and sterols. Within the n-6 PUFA pool LA-deficient rats incorporated a smaller proportion of $\sp{14}$C into arachidonic acid and retained a greater proportion in LA. Specific activity data showed that both the anabolic and catabolic pathways of LA metebolism are operating during pure LAD, but as a proportion of total activity, these metabolic routes are attenuated. Thus, there is a significant conservation of LA and a proportional reduction in carbon recycling during pure LAD. Furthermore, LA deficient rats respond rapidly and favourably to short-term LA supplementation as indicated by partial correction of fatty acid profiles of tissue lipids and $\sp{14}$C incorporation and turnover in tissue and liver lipids.M.Sc