Effect of previous nutritional status on the formation of cholesterol gallstones in the prairie dog.

In the prairie dog model of cholesterol cholelithiasis, a high incidence of gallstones is achieved by feeding a semipurified lithogenic diet containing 0.4% cholesterol for 2 mo. On occasion, we noted a decrease in the percentage of animals with gallstones from 90-100% to 50-55%. To explain this phenomenon, we studied the effect of dietary history on gallstone formation. After weaning, animals were fed either rodent chow or alfalfa plus corn (mo 0-3) followed by a cross-over experiment at mo 4-6. Gallstone formation then was studied by feeding the lithogenic diet from mo 7 to 8. At sacrifice, the incidences of gallstones, biliary lipids and tissue cholesterol levels were correlated with dietary history. The incidence of gallstones was 100% only in animals fed the alfalfa-corn diet from weaning to 3 mo. In addition, the feeding of the alfalfa-corn diet at mo 4-6 increased gallstone incidence from 65% to 86%. The lithogenic index of all groups was highest when the animals received only alfalfa-corn prior to the lithogenic stimulus. The activity of hepatic HMG-CoA reductase was elevated in animals fed alfalfa-corn from weaning to 8 mo, suggesting that this diet stimulates hepatic cholesterol synthesis, leading to increased biliary cholesterol secretion. It is concluded that previous nutritional conditioning affects the incidence of gallstones. The prairie dog is a useful model of cholesterol cholelithiasis, but the dietary history of the animals plays an important role in lithogenesis.