邻苯二甲酸二丁酯诱导雄性大鼠发生尿道下裂的分子作用机制

Molecular mechanisms of hypospadias in male rats exposed to di-n-butyl phthalate during late gestation

目的探讨邻苯二甲酸二丁酯(DBP)孕晚期染毒诱导雄性大鼠发生尿道下裂的分子作用机制。方法雌鼠怀孕(GD)第14～18天,每天分别灌胃予大豆油,DBP 500或每日800 mg/kg体重,雄性仔鼠出生后(PND)第1天,鉴别出DBP染毒组中发生尿道下裂的雄性仔鼠,分组为雄性仔鼠对照组(A组),每日500 mg/kg体重(H)(B组)和每日800 mg/kg体重(H)(C组)。用实时定量逆转录景合酶链反应(RT-PCR)方法检测阴茎组织中Shh,骨形态发生蛋白4(Bmp4)和雄激素受体(Ar)mRNA表达水平。用Western blot测量阴茎组织中Ar蛋白表达水平。用放射免疫分析法测定血清睾酮(T)水平。结果B组在mRNA(Shh,Ar)表达水平和血清睾酮水平较对照组有明显的降低(P<0.05),C组在mRNA(Shh,Bmp4,Ar)和蛋白(Ar)表达水平以及血清睾酮水平都较对照组有明显的降低(P<0.05)。结论DBP通过对生殖结节(GT)生长发育早期的Shh信号系统,以及晚期的雄激素信号系统发生作用而影响GT的生长发育,诱导尿道下裂的发生。

Objective To investigate the molecular mechanisms of hypospadias in male rats exposed to di-n-butyl phthalate （DBP） during late gestation. Methods Timed pregnant rats were given DBP by gastric intubation at a dose of 0 ,500 or 800 mg/kg every day from gestation day （GD） 14 to 18. On postnatal day （PND） 1,male offspring were allocated to three groups： control male offspring （group A） ,500 mg/kg/day （H） （group B） and 800 mg/kg/day （H） （group C） after identifying control male offspring not exposed to DBP and hypospadiac male offspring exposed to DBP. Real-time quantitative RT- PCR and Western blot were used to quantify mRNA of sonic hedgehog （Shh） ,bone morphogenetic protein 4 （Bmp4） and androgen receptor （Ar） and protein of Ar expression in rat penises of above three groups on PND 1. Serum testosterone （T） concentration of male offspring in above three groups on PND 1 was de- termined by using T radioimmunoassay （RIA） kit. Results mRNA （Shh,Ar） expression in rat penises and serum T level in group B were significantly decreased as compared with those in control group （ P 〈 0.05 ）. mRNA （Shh, Bmp4, Ar）, protein （Ar） expression in rat penises and serum T level in group C were significantly decreased as compared with those in control group （ P 〈 0.05 ）. Conclusion DBP affects the development of the genital tubercle （GT） by regulating Shh signaling in early development of GT and androgen signaling in late development of GT,inducing the occurrence of hypospadias in male rats.