The roles of Wnt5a and Frizzled-1 in the neuromuscular development of the anorectal unit in fetal rats with anorectal malformations induced by ethylenethiourea

Abstract

Objective To assess the roles of Wnt5a and Frizzled-1 (Fzd-1)in the neuromuscular development of the anorectal unit in fetal rats with anorectal malformations (ARM).Methods The ARM was induced by ethylenethiourea (ETU)in fetal rats.The RNA and protein expression level of Wnt5a and Fzd-1 were studied by immunohistochemistry,reverse transcription polymerase chain reaction (RT-PCR)and Western blotting.Results Immunohistochemical staining demonstrated Wnt5a and Fzd-1 expressed in myenteric nerve plexus (MP),smooth muscle layers and the mucosa of the rectum in the normal rat fetuses.From E17 to E21,the expression became stronger and stronger in normal fetuses.In the late fetal phase,Wnt5a and Fzd-1 expression was mostly found in the MP and smooth muscle layers.However,in ARM embryos,the expression of Wnt5a and Fzd-1 were only found in the rectum terminus.During gestational day 19 to 21,the mRNA and protein expression of Wnt5a and Fzd-1 significantly decreased in the rectum of ARM rat embryos comparing with normal rat embryos (E21:Wnt5amRNA:0.81 ± 0.14 vs 0.21 ± 0.03;Fzd-1mRNA..0.72 ± 0.11 vs 0.20 ±0.04;Wnt5a:1.12 ± 0.11 vs 0.48 ± 0.05;Fzd-1:0.91 ± 0.10 vs 0.32 ± 0.04,P<0.05).Conclusions The expressions of Wnt5a and Fzd-1 were downregulated in anorectal unit of fetal rats with ethylenethiourea induced anorectal malformations,which may play important roles in the pathogenesis of neuromuscular development. Key words: Anal canal,abnormalities; Enteric nervous system; Rats