Specific linoleate deficiency in the rat does not prevent substantial carbon recycling from [C-14]linoleate into sterols

Compared with classic essential fatty acid deficiency or the feeding of a f at-free diet, little is known about specific linoleate deficiency in the ra t. Carbon recycling into de novo lipogenesis has been reported to be an obl igatory feature of Linoleate metabolism in the liver, even in extreme linol eate deficiency (LA-D). The present study had two objectives: 1) to report a brief summary of the tissue n-6 polyunsaturated fatty acid (PUFA) profile s in specific LA-D, and 2) to quantify whole body carbon recycling from [C- 14]linoleate in specific LA-D. Rats consumed a linoleate-deficient diet for 12 weeks and then received a bolus of [l-C-14]linoleate by gavage, In lino leate-deficient rats, the triene/tetraene ratio in several organs increased by 18- to 100-fold. The amount of C-14 appearing in organ sterols (dpm/g) of linoleate-deficient rats tvas 2- to 10-fold higher than in the controls and equaled 16.3% of the [C-14]linoleate dose given, compared with 7.4% in the controls. We conclude that a similar amount (about 10%) of the carbon s keleton of linoleate is normally recycled into lipids synthesized de novo, as remains in the whole body pool of n-6 polyunsaturates.