AGE, SEX AND SOURCE OF HAMSTER AFFECT EXPERIMENTAL CHOLESTEROL CHOLELITHIASIS

In the present study, we examined the effect of the following factors on a hamster model of cholesterol cholelithiasis: (i) the source of th e golden Syrian hamsters (Sasco, Omaha, NE or Charles River, Wilmingto n, MA), (ii) the sex of the experimental animals and (iii) their age ( 4 wk vs. 8 wk of age). All hamsters were fed a semipurified diet which contained cholesterol (0.3%) and palmitic acid (1.2%). No cholesterol gallstones formed in any of the female hamsters regardless of age or source. The 4-week-old male hamsters from Sasco had the greatest incid ence of gallstones (93%). The 8-week-old male hamsters tended to have a lower incidence of cholesterol gallstones than the younger ones, reg ardless of the commercial supplier (67 vs. 93% for Sasco and 27 vs. 40 % for Charles River). Female hamsters had higher liver and serum chole sterol levels than the male hamsters; Charles River hamsters had lower serum cholesterol concentrations than the Sasco animals. Total biliar y lipid concentrations were highest in Sasco male hamsters, but biliar y cholesterol (mol%) was lower in the males than in the females (4.2-4 .5% vs. 6.1-7.1%) regardless of age. The cholesterol saturation indice s were higher in the Sasco females than the corresponding males; these values were lower in the Sasco hamsters than the Charles River animal s, regardless of age or sex. The male Sasco hamsters had a higher tota l biliary bile acid concentration (98.9 mg/mL) than the Sasco females (58.9 mg/mL) and the Charles River animals (24.6 mg/mL for males and 3 8.2 mg/mL for females). The percentage of chenodeoxycholic acid in bil e was significantly lower, and the percentage of cholic acid was highe r in all females as compared to males. We conclude that there is a sex , age and ''strain'' difference in cholesterol cholelithiasis in hamst ers; it is important to consider these factors when working with the h amster model of gallstone disease. All female hamsters were markedly r esistant to the induction of cholesterol gallstone disease.