Mucosal gastrin receptor. VI. Induction by corticosterone in newborn rats

Serum and antral gastrin levels as well as specific binding of [125I]gastrin-17 to a 270-30,000 g oxyntic gland mucosa crude membrane preparation were measured in rats between 5 and 40 days of age. Rats were normally weaned at day 18, although weaning was prevented in some animals until day 25. The results of these studies confirmed our previous data showing that mucosal gastrin receptors and antral gastrin levels begin to increase at the time of normal weaning and reach adult levels within a few days. Although the shift from liquid to a solid diet enhances the response, it is not essential for it and does not trigger it. In addition, the current studies demonstrated that injection of corticosterone caused a premature increase in both gastrin receptor and antral gastrin levels. Once maturation had occurred, however, corticosterone had no further effect. Adrenalectomy delayed but did not prevent the maturational changes in gastrin receptors and antral gastrin levels. Normal serum gastrin concentrations were necessary for the number of gastrin receptors and the amount of antral gastrin to reach normal levels.