Regulation of types I, III, and IV procollagen mRNA synthesis in glucocorticoid-mediated intestinal development

Administration of dexamethasone (0.8 mg/kg) to 9-day-old rats once daily for 3 consecutive days caused precocious induction of adult specific disaccharidase activity in the small intestine. Maturation-specific disaccharidase activity was accompanied by decreased amounts of types I and III collagen and decreased procollagen type I and III mRNA levels. Conversely, type IV procollagen, fibronectin, and laminin amounts and their respective mRNA levels were increased. In vitro transcription of nuclei isolated from small intestine and colon of suckling rats indicated a decreased rate of synthesis of procollagen types I and III mRNAs and an increased rate of synthesis of procollagen type IV mRNAs and laminin mRNAs after dexamethasone treatment. The data suggest that glucocorticoids mediate a differential regulation of interstitial and basement membrane collagen gene expression in the developing rat intestine.