Action of Lithocholic Acid in the Germ-Free Chick. ∗ †

Abstract

Feeding of lithocholic acid to chicks and hens caused a rise in their serum cholesterol in work of Edwards(1) and Edwards et al. (2). When this compound was fed to mice or rats it caused a depression in serum cholesterol in the work of Beher et al.(3), Howe et al.(4) and Portman and Bruno (5). Recently Howe and Bosshardt(6) demonstrated that in the presence of a mixture of succinyl-sulfathiazole and oxytetracycline in the diet of mice, lithocholic acid no longer had a serum cholesterol-depressing effect while hyodeoxycholic acid was still effective. They interpreted these findings to mean that lithocholic acid was active by virtue of conversion to an unidentified compound under the influence of the intestinal bacteria. The investigation reported here was carried out to determine if the cholesterol elevating action of lithocholic acid in the chick might also be due to some other compound produced from lithocholic acid in the chicken's gastrointestinal tract.

Experimental. Four plastic canopy germ-free isolators (American Sterilizer Co.) were used for the experiment. The isolators were sterilized by spraying with 30% beta-propiolactone solution; each air filter (Fiber-glass 50) was sterilized with 1 ml methyl bromide; water bottles, cages and other equipment were autoclaved; feed was sterilized with ethylene oxide.

Eggs of Single Comb White Leghorns were obtained from a local hatchery after 18 days of incubation. The eggs were washed in detergent and passed through 2% HgCl₂ solution into the isolators. Twelve eggs were placed in each isolator. After hatching, 6 chicks were placed in each of 2 wire cages in each isolator. The basal ration was fed to the chicks in one cage and the lithocholic ration to the chicks in the other cage.

Cultures were taken daily for 3 days and each 3 days thereafter.