Intestinal disaccharidase activities in the growing germfree and conventional rats

Abstract

Disaccharidase (maltase, invertase, trehalase, lactase, and cellobiase) activities have been studied in homogenates of small intestine of the germfree and conventional rats from birth through 120 days of age. The pH optimum values for germfree and conventional rats were comparable. In adult germfree rats, the pattern of distribution of disaccharidase activities in different sections of small intestine was similar to that of conventional rats. Lactase and cellobiase activities were substantial at birth, reached maximum at 7 days of age, and then decreased gradually to a plateau at 30 days of age in both groups. Maltase activity was low at birth, whereas no invertase and trehalase activities could be detected up to 7 days of age, and these activities developed rapidly during the third week of life in both groups. Differences in activity of these disaccharidases between germfree and conventional rats were not apparent until after weaning (21 days) when the germfree animal showed a higher activity than the conventional rat. When the germfree rats were conventionalized by the introduction of cecal contents from the conventional rats, the disaccharidase activities were reduced to normal conventional levels. These results indicate that intestinal disaccharidases are synthesized by the animal itself, and that the intestinal microorganisms do not contribute to any major extent to their production.