Estrogen is considered to be involved in duodenal function; however, the details of its receptor expression are largely unknown. The purpose of this study was to determine the expression and localization of estrogen receptors (ERs) in mouse duodenum. Male and female C57BL/6J mouse intestinal tissues were used to investigate the expression of ER alpha and ER beta by RT-PCR, western blotting, immunohistochemistry, and Southwestern histochemistry. ER beta, but not ER alpha, was expressed in proximal duodenal epithelium, but not in jejunum and ileum. The expression of ER beta mRNA and protein were confirmed by RT-PCR and western blotting, respectively. At postnatal day 20, the transit period of suckling to weaning, the distribution of ER beta-positive cells was changed in the crypt-villus axis, and cytoplasm/nuclear staining changed to only nuclear staining. Moreover, Southwestern histochemistry was used to detect estrogen response element (ERE)-binding proteins, and their expression pattern was highly similar to that of ER beta. These results suggested that ER beta is the predominant ER type in mouse small intestine, and the highly similar co-localization of ERE-binding proteins reveals that ER beta is functionally active in mouse duodenum. The ER beta expression changes during postnatal development indicate that ER beta may be involved in the differentiation of duodenal epithelium. (C) 2015 Elsevier Masson SAS. All rights reserved.
