[Changes in the saccharase and lactase activities of the small intestine in suckling rats prematurely weaned from the nursing dam].

In suckling rats prematurely weaned on the 15th, 17th, 19th or 21st day of life, the body weight and the weight of small intestine were studied as well as the activity of enteral sucrase and lactase. A delay in the gain of body weight and small intestine weight was the greater the earlier the sucklings had been weaned. The sucrase activity did not depend on the term of weaning. Whereas weaning on the 15th or 17th days of life considerably delayed the decrease in lactase activity. The latter seems to be due to the changes in the suckling's thyroid state because of thyroid depression under these conditions and absence of thyroid hormones intake from maternal milk.