Expression And Significance Of Neurexin Ⅱ In Enteric Nervous System Of Rats And Rats At Different Embryonic Day

Objective The enteric nervous system (ENS), an extensive network of neurons and glia within the wall of gut, provides the intrinsic innervation of the bowel and is capable of autonomous regulation of gastrointestinal functions although receive the nerve impulse from the central nervous system (CNS). The ENS arises from the enteric neural crest-derived cells (ENCDCs) and certain genes such as RET, SOX10, GDNE are play important roles during the colonization of ENCDCs and the development of the ENS. Neuronal intestinal malformations (NIM), a common congenital disorder, clinically manifests as abnormal the intrinsic innervation of the gut wall, such as the quantity, quality of ganglion cells, due to abnormal ENS development. NIM represents a spectrum of developmental disorders including Hirschsprung’s disease (HD), Immaturity of ganglion cells (IGC), Intestinal neuronal dysplasia (IND), Hypoganglionosis (HG), Combinations and Not classifiable dysganglionosis. Researchs confirm that Neurexins, a family of presynaptic neuronal cell-adhesion proteins, express in the CNS and play an important role in the formation, differentiation, maturation and plasticity of functional synapses. Our previous studies revealed that neurexins coupling to neuroligins, one of interaction partners of neurexins, and their relative neurotransmitters Glu and y-GABA express in the ENS and may be involved in the pathogenesis of HD. Therefore, we elucidate the expressions of Neurexin Ⅱ in ENS in rat at embryonic day 16,18,20 and the newborn within 24 hours (E16, E18, E20 and EpO) to explore the correlation of the expressions with the development of ENS and the potential significance to NIM.Methods The cleaning and healthy Wistar rats were fed by 1 male to 1 female randomly at similar environment. After pregnancy, the female rats were fed separately. Then the rats at pregnant days 16,18,20 and the newborns within 24 hours were put to death after anaesthesia. Dissect and harvest the colon specimens, proximal to the ileocecal junction and 1.0 cm approximately, of the rats at embryonic day 16,18,20 and the newborns within 24 hours and some adult rats. Immunohistochemical staining of the colon specimens of adult rats was employed to explore the histological appearance. Then, Immunohistochemical staining, Western-blotting and qRT-PCR were performed to detect the expression levels of Neurexin II a protein and Neurexin II mRNA.Results Immunohistochemical staining revealed that the positive cells of Neurexin II a can be observed in the myenteric nerve plexus of colon specimens mostly and the expression levels of Neurexin II a increased gradually as the growth of embryon. Western-blotting also revealed a similar tendency that the Neurexin II a protein expression levels of E16, E18, E20 and EpO were 0.054±0.009、0.106±0.020、 0.215±0.013、0.280±0.030, respectively, increasing from lowest to highest as the growth of embryon rat (P<0.05). The Neurexin II mRNA expression levels detected by qRT-PCR were 0.390±0.029、0.552±0.054、0.748±0.065、1.000±0.000, respectively at E16, E18, E20 and Ep0 (P<0.05). The increasing tendency was consist with the tendency at protein.Conclusion Neurexin II is expressed at ENS and has a temporal correlation with the development of ENS during which NIM may occur due to dysplasia.