Regional and maturation-associated expression of endothelin 2 in rat gastrointestinal tract

Endothelin 2 (ET2), also referred to as vasoactive intestinal contractor peptide, is a member of a family of vasoactive peptides. ET2 is a potent constrictor of intestinal smooth muscle, and the mRNA that encodes it has been detected in murine intestinal extracts. To further investigate the potential physiological roles of ET2, we characterized the cellular distribution of ET2 gene expression in adult rat gastrointestinal tract. Using an RNAse protection assay, an overall proximal to distal gradient of increasing ET2 gene expression was observed from stomach to colon. In situ hybridization studies confirmed this finding and demonstrated ET2 mRNA localized in lamina propria stromal cells. Moreover, ET2 gene expression in stromal cells increased from crypt to villous tip. The results demonstrate that ET2 is produced by stromal cells in villi throughout the intestine. Increased ET2 gene expression at the villous tip is associated with more mature overlying epithelial cells, suggesting a possible role for this vasoactive peptide in intestinal epithelial differentiation or secretory activity.