Prostaglandins Leukotrienes and Essential Fatty Acids
نویسنده
چکیده
The incorporation of (n-3) versus (n-6) fatty acids into membrane lipids is regulated by a number of different processes within the cell. It is generally accepted that a common 6-desaturase uses both linoleate and linolenate as substrates. Desaturation of linoleate and linolenate are generally considered to be the rate limiting steps in the biosynthesis of arachidonate and 20:5(n-3) respectively (1). The addition of fatty acids to the diet, beyond the rate limiting 6-desaturation step, would thus appear to be a way to increase the amount of arachidonate or 20:5(n-3) that is produced and potentially made available for esterification into membrane lipids. In order to evaluate this hypothesis, we carried out a number of feeding studies with deuterium labeled (n-6) fatty acids using the following general protocol. Male weanling Sprague-Dawley rats were maintained on a modified AIN diet that contained 3.3% fat the composition of which was 2.1% oleate, 1.0% linoleate and 0.2% linolenate. After 4 weeks on this diet, the animals were changed to one in which all of the linoleate was replaced by 17,17,18,18-d4 linoleate. After 4 days the animals were sacrificed and it was observed that 34 mol % of arachidonate esterifed in liver phospholipids was derived from the deuterium labeled linoleic acid. Another group of animals was maintained on the AIN diet that contained 1.9% oleate, 1% linoleate, 0.2% linolenate and in addition 0.2% ethyl 18:3(n-6). Again, all of the linoleate
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