Certain aspects of tocopherol and tocotrienol absorption, plasma transport, and tissue distribution were examined in humans and hamsters. Plasma transport differed in that tocopherols were found primarily in low density lipoprotein and high density lipoprotein in association with plasma surface components, whereas tocotrienols disappeared from plasma with chylomicron clearance. In keeping with transport by triglyceride-rich lipoproteins, tocotrienols were deposited in conjunction with triglycerides in the adipose tissue of hamsters. In hamsters, tocopherols were the only tocol readily detected in all tissues, except adipose during tocotrienol supplementation. In fasting humans, the plasma tocotrienol concentration was not significantly increased after tocotrienol supplementation, whereas the platelet concentration of delta-tocotrienol doubled. Furthermore, tocotrienol intake did not appear to modulate the plasma cholesterol concentration in normolipemic hamsters. Thus, the transport, tissue concentration, and relative biologic function of tocopherol and tocotrienol appear somewhat disparate and possibly unrelated.

Because different strains of hamsters vary in their susceptibility to gallstones, the relationship between plasma lipoproteins, hepatic cholesterol, bile lipids and bile acid profile was examined during gallstone induction in strains of male Syrian hamsters from Charles River Lakeview (CHR), Biobreeder F1B (BIO) and Harlan Sprague-Dawley (HAR). Gallstones were induced by feeding a purified diet containing 0.4 or 0.8% cholesterol for 5 wk. Basal plasma total cholesterol was similar, but the hypercholesterolemia induced by dietary challenge was significantly lower in CHR than in HAR and BIO hamsters. Cholesterol-fed CHR hamsters transported cholesterol mainly in HDL (47%), whereas VLDL-C + IDL-C predominated in BIO and HAR hamsters, and their HDL transported only 28 and 38%, respectively. HAR hamsters accumulated the most hepatic cholesterol, revealed the highest cholate/cheno ratio, the lowest glycine/taurine ratio and hydrophobicity index. HAR also developed the fewest cholesterol gallstones (23%), while 64% of CHR and 58% of BIO hamsters had cholesterol gallstones and 34% of BIO hamsters developed pigment stones. Doubling dietary cholesterol from 0.4 to 0.8% doubled the incidence of cholesterol gallstones but exerted minimal impact on other parameters compared to strain differences. Thus, different strains of hamsters vary considerably with respect to biliary cholesterol, bile acid profile and formation of cholesterol gallstones associated with differences in plasma lipoprotein profiles.

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