Occurrence of sulfatide as a major glycosphingolipid in WHHL rabbit serum lipoproteins.

Glycosphingolipids in serum and lipoproteins from Watanabe hereditable hyperlipidemic rabbit (WHHL rabbit), which is an animal model for human familial hypercholesterolemia (FH), were analyzed for the first time in this study. Chylomicrons and very low density, low density, and high density lipoproteins contained sulfatide as a major glycosphingolipid (12nmol/μmol total phospholipids (PL) in chylomicrons, 19nmol/μmnol PL in VLDL, 18nmol/μmol PL in LDL, and 14nmol/μmol PL in HDL) with other minor glycosphingolipids such as glucosylceramide, galactosylceramide, GM3 ganglioside, lactosylceramide, and globotriaosylceramide. The concentration of sulfatide as a major glycosphingolipid in WHHL rabbit serum (121nmol/ml) was much higher than that in normal rabbit serum (3nmol/ml). Fatty acids of the sulfatides comprised mainly nonhydroxy fatty acids (C22, 23, and 24) and significant amounts of hydroxy fatty acids (about 10%), whereas long chain bases of the sulfatides comprised mostly (4E)-sphingenine with a significant amount of 4D-hydroxysphinganine (about 10%). Furthermore, sulfatides in the liver and small intestine from normal and WHHL rabbits (where serum lipoproteins are produced) were determined to amount to 260nmol/g liver in WHHL rabbit, 104nmol/g liver in control rabbit, 99.6nmol/g small intestine in WHHL rabbit, and 31.2nmol/g small intestine in control rabbit. Ceramide portions of the sulfatides in the liver were mainly composed of (4E)-sphingenine and nonhydroxy fatty acids, while those in the small intestine were mainly composed of 4D-hydroxysphinganine and hydroxy fatty acids. These results indicated that the sulfatides of serum lipo-proteins were mostly derived from the liver (90% of the total), and that the remaining sulfatides (10% of the total) might be derived from the small intestine. These two sulfatides, which have different ceramide portions, could be useful markers for metabolic and biosynthetic studies of various lipoproteins in WHHL rabbit, and thus would be helpful to further elucidate the relationship between hypercholesterol-emia and atherosclerosis in the rabbit.