The Down-Regulation of Neuroligin-2 and the Correlative Clinical Significance of Serum GABA Over-Expression in Hirschsprung’s Disease

The goal of this study was to investigate the expression level of neuroligin-2 in different colon tissue segments of children with Hirschsprung’s disease (HSCR) and the correlative clinical significance of serum Gamma-Aminobutyric Acid (serum GABA) in HSCR. Neuroligin-2 was assessed by Immunohistochemistry staining method on routine paraffin section from different colon tissue segments of HSCR (ganglionic colonic segment, transitional colonic segment and aganglionic colonic segment). Western-blot analysis and real-time fluorescence quantitative PCR(qRT-PCR) were applied to compare and evaluate the expression levels of neuroligin-2 from three segments of HSCR, and we used Enzyme-linked Immunosorbent Assay (ELISA) method to detect and compare the serum GABA between HSCR and non-HSCR. Immunohistochemistry staining demonstrated that intensive neuroligin-2 staining was detected in the ganglion cells in the ganglionic colonic and transitional colonic segments from the HSCR children; however, neuroligin-2 staining was down-regulated significantly in the aganglionic colonic segments. The expression levels of neuroligin-2 mRNA and protein in the aganglionic colonic segment were decreased compared to the ganglionic colonic segment and transitional colonic segment (P < 0.05). And the level of serum GABA was significantly higher in HSCR than that in non-HSCR. The expression of neuroligin-2 varies from different segments of HSCR. The down-regulation of neuroligin-2 in aganglionic colonic segments may be correlated with the excessive intestine contraction and further result in HSCR. The over-expression of serum GABA may be considered as a new diagnostic method of HSCR.