The expression and localization of neuregulin-1 (Nrg1) in the gastrointestinal system of the rhesus monkey.

Although Neuregulin-1 (Nrg1) and its cognate receptors have been found at the mRNA level in human gastrointestinal (GI) tract and their functional roles have been evaluated in vitro, their morphological distribution in higher mammals are not fully elucidated. The present research focused on morphological distribution of Nrg1 and its receptors, ErbB2 and ErbB4, in main GI tissues of the non-human primate rhesus monkey. The morphological expression of Nrg1 and its ErbB2 and ErbB4 receptors as well as their potential colocalization were determined by double immunofluorescence staining in esophagus, stomach, small intestine and colon tissues derived from the rhesus monkey tissue microarray. The Nrg1 level on each sample was indexed by the fold of integrated fluorescence intensity (IFI) relative to that of one brain cortical tissue from the rhesus monkey. Differential expression of Nrg1 and its receptors ErbB2 and ErbB4 was found in the GI structures, with higher expression levels detected in stomach and small intestine. Co-localization of Nrg1 with ErbB2 and/or ErbB4 receptors was most apparently detected in the stomach, followed by small intestine, colon, and esophagus. This investigation morphologically profiles the differential expression of Nrg1 and its receptors in main GI structures, suggesting an autocrine or paracrine loop-directed Nrg1/ErbB receptor signaling pathway in these organs of higher mammals.