有机磷农药对胎鼠酪氨酸激酶受体基因转录和突变作用的研究

The relationship between organophosphorus (trichlorfon) and RET gene expression and mutation in embryonic rats

目的 探讨有机磷农药 (敌百虫 ,LD50 )在先天性巨结肠症发病中的作用。方法 4 0只妊娠Wistar大鼠随机分为 4组。在大鼠妊娠期 8～ 14d ,Ⅰ组每日以生理盐水灌胃作为阴性对照 ;Ⅱ组每日以 5 0mg/kg敌百虫 (LD50 的 1/ 10 )灌胃 ;Ⅲ组给予 10mg/kg敌百虫 (LD50 的 1/ 5 0 ) ;Ⅳ组给予 2mg/kg敌百虫 (LD50 的 1/ 2 5 0 )。分娩前处死母鼠 ,取出胎鼠 ,每只母鼠取 4只体重相似的胎鼠 ,取其远段 1cm结肠组织 ,提取DNA和RNA。采用RT PCR方法检测RET基因表达 ,采用PCR SSCP对RET基因第 15外显子 (E15 )进行基因突变检测 ,阳性PCR产物进行直接测序。结果 RET基因在所有的标本中均稳定表达。在Ⅲ组 (10mg/kg敌百虫 )的 2只胎鼠 (由不同母鼠所产 )和Ⅱ组 (5 0mg/kg敌百虫 )的 1只胎鼠的DNA标本在PCR SSCP分析时发现泳动变位 ,经测序证实均为V90 6密码子存在GTG→GTT的同义突变。

Objective To investigate the potential role of trichlorfon in pathogenesis of Hirschsprung's disease.Methods Forty pregnant Wistar rats were divided randomly into 4 Groups: Group 1 were fed saline daily between days 8 to 14 of gestation, as negative controls. Group 2 were fed with 50mg/kg (1/10 of LD50) trichlorfon, Group 3 were fed with 10?mg/kg (1/50 of LD50)trichlorfon and group 4 were fed with 2?mg/kg (1/250 of LD50)trichlorfon. Pregnant rats were killed before delivery and fetuses were removed. Four fetuses with similar weight were chosen from each pregnant rat. DNA and RNA were extracted from 1?cm of the distal colon. RT PCR assay was performed to study the RET gene expression. PCR SSCP method was used to detect the RET gene mutation in exon 15. The positive PCR products were sequenced.Results RET gene expressions were detected in every sample. However, 2 fetuses from group 3 (from different mothers) and 1 fetus from group 2 were found to develop mutations of RET gene in exon 15. Sequencing analysis showed a silent mutation at codon V906 (GTG→GTT).Conclusions Trichlorfon may responsible for the RET gene mutation.