Effects of dietary fats on fatty acid composition and Δ5 desaturase in normal and diabetic rats |
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Authors: | A Q Dang K Kemp F H Faas W J Carter |
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Affiliation: | (1) John L. McClellan Memorial Veterans Hospital, 72205 Little Rock, AR;(2) University of Arkansas for Medical Sciences, 72205 Little Rock, AR |
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Abstract: | We have studied the effect of various diets on the phospholipid fatty acid composition andin vitro Δ5 desaturase activity of hepatic microsomes derived either from the normal or streptozotocin-induced diabetic rat. The diets
studied were the standard rat chow diet and a basal fat-free diet supplemented either with 20 percent saturated fat, 20 percent
unsaturated fat, or 20 percent menhaden oil. Phospholipid fatty acid composition analysis revealed that the normal rat fed
the saturated fat or menhaden oil diet had significantly decreased arachidonate levels, consistent with decreased Δ5 desaturase
activities and decreased 18∶2n−6 intake. On the contrary, the unsaturated fat diet decreased dihomo-γ-linolenate and increased
arachidonate levels, without increased Δ5 desaturase activity. Streptozotocininduced diabetes resulted in decreased arachidonate
and Δ5 desaturase activity. The unsaturated fat diet fed to the diabetic rat also failed to correct this decreased Δ5 desaturase
activity. The unsaturated fatty acids in this diet also displaced a substantial amount of n−3 fatty acids in both normal and
diabetic microsomes, due to the competition between these two fatty acid families for incorporation into the membrane phospholipids.
Conversely, the menhaden oil diet fed to the normal and diabetic rats displaced n−6 fatty acids, reduced Δ5 desaturase activity,
and enhanced 22∶6n−3 incorporation into diabetic microsomes. |
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