EFFECT OF 3-THIA FATTY-ACIDS ON THE LIPID-COMPOSITION OF RAT-LIVER, LIPOPROTEINS, AND HEART

To investigate the importance of factors influencing the fatty acid co mposition, lipid and lipoprotein metabolism in the rat, the effect of 3-thia fatty acids of chain-length ranging from octyl-to hexadecylthio acetic acid were studied. In liver, very low density lipoprotein (VLDL ), and low density lipoprotein (LDL), the hypolipidemic 3-thia fatty a cids, namely C12-S-acetic acid to C14-S-acetic acid increased the amou nt of monoenes, especially oleic acid (18: 1n-9). In contrast, the con tent of polyunsaturated fatty acids in liver, VLDL, and LDL decreased, mostly attributed to a reduction of eicosapentaenoic acid (EPA, 20:5n -3). Noteworthy, the hypolipidemic 3-thia fatty acids reduced the amou nt of arachidonic acid (AA, 20:4n-6) in LDL and HDL. 3-Thia fatty acid s accumulated in the liver. In heart, as in liver, 3-thia fatty acids replaced fatty acids of chain-length homologues. In contrast to liver, we were unable to detect any changes in 18:1n-9. However, the n-3 pol yunsaturated fatty acid content increased, particularly 20:5n-3 and do cosahexaenoic acid (DHA, 22: 6n-3) leading to an increased n-3/n-6 rat io. In conclusion, this study demonstrates that hypolipidemic 3-thia f atty acids change the fatty acid composition of organs and lipoprotein s. These changes are linked to the expression and activity of hepatic Delta(9)-desaturase, fatty acid oxidation, and displacement of normal fatty acids by 3-thia fatty acids. The fatty acid composition is regul ated differently in liver and heart after administration of hypolipide mic 3-thia fatty acids.