Neuregulin 1 is required for the development of enteric neurons and vagus in zebrafish

Hirschsprung’s disease (HSCR) is a congenital malformation of the colon characterised by the absence of enteric ganglion in the submucosal and myenteric plexuses. Recently genome-wide association studies have identified that neuregulin 1 (nrg1) gene might be a susceptibility locus for HSCR. This study aimed to investigate whether nrg1 is involved in the development of the enteric nervous system. By in situ hybridization, we revealed that nrg1 was mainly expressed in the mucous layer of the adult zebrafish gut. After been injected with nrg1 morpholino antisense oligonucleotides, zebrafish embryos showed delayed hatching, small head, pericardial edema, shortened- twisted trunk, and impaired motor ability. Some of these defects could be partially ameliorated by the injection of nrg1 mRNA. Further, we observed that knock down of nrg1 resulted in reduced number of enteric neurons (29.5 ± 5.8 vs 51.5 ± 8.3, P<0.01) and aganglionosis (an HSCR-like phenotype), and also affected the development of the vagal innervation of the gut. Taken together, our findings indicated that nrg1 played a critical role in the development of the enteric neurons as well as vagus nerve. Therefore, this work provides an evidence of nrg1 in the pathogenesis of HSCR.