Palmitic acid enhances cholesterol gallstone incidence in sasco hamsters fed cholesterol enriched diets |
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Authors: | Nariman Ayyad Bertram I Cohen Erwin H Mosbach Shigeo Miki |
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Affiliation: | (1) Department of Surgery, the Mount Sinai School of Medicine of the City University of New York, 10003 New York, New York;(2) Department of Surgery, Beth Israel Medical Center, First Avenue at 16th Street, 10003 New York, NY |
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Abstract: | In an established hamster model of cholesterol cholelithiasis, a semipurified lithogenic diet containing 4% butterfat and
0.3% cholesterol leads to the production of cholesterol gallstones in only 50–60% of animals after a 6-wk feeding period.
The purpose of this study was to investigate whether gallstone incidence could be increased while feeding a nutritionally
adequate diet of moderate cholesterol content. The semipurified lithogenic diet was modified as follows: (i) substitution
of 1.2% palmitic acid for 4% butterfat, and (ii) varying the amount of dietary cholesterol from 0.0 to 0.3% with either butterfat
or palmitic acid as the lipid component of the diet. Substitution of palmitic acid for butterfat produced a significantly
higher incidence of cholesterol gallstones (94%vs. 53%). Palmitic acid also raised the incidence of gallstones when added to the 0.1% and 0.2% cholesterol diets as compared
to butterfat: 0%vs. 44% and 50%vs. 81%, respectively. Gallstone incidence increased from 0% to nearly 100% when the cholesterol content of the palmitic acid
diets was raised from 0.0% to 0.3%, indicating a dose response effect with respect to dietary cholesterol. Hamsters fed cholesterol-free
diets did not form gallstones. Increased dietary cholesterol led to increased liver weight associated with a significant increase
in liver cholesterol concentration. However, the palmitic acid groups had significantly lower liver cholesterol values than
the corresponding butterfat groups. Serum and biliary cholesterol concentrations increased with increasing dietary cholesterol
intake, but there were no differences between the butterfat and palmitic acid groups. The cholesterol saturation index increased
from 0.56 to 1.32 in the butterfat groups and from 0.56 to 1.30 in the palmitic acid groups upon raising the dietary cholesterol
from 0.0 to 0.3%. Biliary total bile acid concentration did not vary significantly within all groups; however, the addition
of cholesterol produced an increase in the ratio of chenodeoxycholic acid to cholic acid. It is concluded that in Sasco hamsters
the saturated fatty acid, palmitic acid, when substituted for butterfat in a nutritionally adequate lithogenic diet, is capable
of increasing gallstone incidence to almost 100% during a 6-wk feeding period. |
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