DEVELOPMENTAL-CHANGES IN THE PHOSPHO(ENOL)PYRUVATE CARBOXYKINASE GENE-EXPRESSION IN SMALL-INTESTINE AND LIVER OF SUCKLING RATS

The cytosolic enzyme phospho(enol)pyruvate carboxykinase (PEPCK) is ma rkedly expressed in the intestinal mucosa of suckling rats. The expres sion is located in the small intestine, but there is no expression in stomach, colon, or cecum. The expression changes with age. The mRNA le vels at birth are very low, increase after the first lactation, reach maximum levels between 3 and 9 days after birth, and then decrease smo othly. At weaning, when animals begin to feed on a solid chow diet, th e expression falls to adult levels, which are hardly detectable. Mothe r's milk may influence the intestinal expression, since in rats weaned at Day 18, 3 days before normal weaning the mRNA levels decreased dra matically. mRNA levels for PEPCK in liver present a rather different d evelopmental pattern from that of intestine, remaining high at weaning and in adult rats. On the ninth day after birth, the mRNA levels are the same in intestine and liver. (C) 1996 Academic Press, Inc.