HORMONAL-REGULATION OF GLYCOSYLATION PROCESS IN RAT SMALL-INTESTINE - RESPONSIVENESS OF FUCOSYL-TRANSFERASE ACTIVITY TO HYDROCORTISONE DURING THE SUCKLING PERIOD, UNRESPONSIVENESS AFTER WEANING

The aim of this study was to examine the possible role of certain hormones (especially hydrocortisone) in the developmental variations of intestinal fucosyl-transferase activity in rats. Thyroxine and insulin, injected into suckling rats, did not induce significant modifications of the fucosyl-transferase activity, under the conditions used, whereas this enzyme activity was highly enhanced after administration of glucocorticoids (cortisone and hydrocortisone). Hydrocortisone administration to suckling rats induced a precocious and progressive activation of the fucosyl-transferase activity up to adult level as a function of the duration of treatment. The responsiveness of suckling rats to hydrocortisone, as shown by increased fucosyl-transferase activity, disappeared at the end of the third week (corresponding to the weaning time). These physiological periods of responsiveness and unresponsiveness to hydrocortisone could be related to the binding of the hormones to receptors since the antiglucocorticoid RU 38486 counteracted the effect of hydrocortisone in suckling rats but did not prevent the developmental rise of the fucosyl-transferase activity, when administered in the third week of life. These results suggest that the normal developmental rise of the fucosyl-transferase activity is independent of glucocorticoids.