壬基酚聚氧乙烯醚对斑马鱼精巢组织的影响

Alterations in Testicular Histology in the Zebrafish( Danio rerio) Exposed to Nonylphenol Ethoxylates

采用半静态水体暴露的方式研究了非离子表面活性剂对成熟雄性斑马鱼精巢组织的影响。用荧光定量PCR(qRT-PCR)方法检测试验鱼精巢雌激素受体α(ERα)、雄激素受体(AR)基因以及性激素合成相关细胞色素P450酶类基因(CYP17和CYP19a)的表达,通过组织学观察研究受试鱼精巢结构的变化。结果表明,壬基酚聚氧乙烯醚(NPEO)暴露可以引起雄性斑马鱼精巢组织结构的改变,并影响成年雄性斑马鱼ERα、AR基因和性激素合成相关细胞色素P450酶类基因的表达水平,且10.0mg·L^-1的NPEO暴露可以显著上调CYP19a、ERα和AR基因的表达量,可显著下调斑马鱼精巢中CYP17基因的表达量。在组织学上,0.1mg·L^-1组斑马鱼生精小管内不仅生精小囊数目减少,且管腔中精子数量减少,出现非细胞区域;1.0和10.0mg·L^-1组可见部分个体精子凝聚于生精小管管腔中央,管腔内空隙明显增大,表现出严重的精子浓缩效应。由此表明,NPEO暴露通过抑制CYP17基因的表达干扰睾酮的合成;同时,NPEO暴露通过诱导CYP19a和ER基因的表达增加内源雌激素的合成,导致斑马鱼精巢中性激素紊乱,最终损伤斑马鱼精巢组织。

In the present study,the effects of nonionic surfactant on testicular histology of adult male zebrafish (Danio rerio) were studied by the semi-static exposure test.The expressions of estrogen receptor α(ERα),androgen receptor (AR) and CYP450 enzymes related to sex steroid synthesis (CYP17,CYP19a) were measured using realtime polymerase chain reactions (qRT-PCR) method.Histological alterations of testicular structure of fish were also investigated after exposure.The results indicated that the NPEO exposure could cause histological alterations in the testicular structure and affect the mRNAs expressions of ERα,AR and CYP450 enzymes related to sex steroid synthesis in the adult male zebrafish.The exposure to the 10.0 mg·L^-1 NPEO could significantly up-regulate the expression of CYP19a,ERα and AR genes and down-regulate the expression of CYP17 gene in the testis of zebrafish. The number of both the spermatocysts and spermatozoans was found to be decreased,and some acellular zones appeared in the seminiferous tubule of fish exposed to the 0.1 mg·L^-1 NPEO.The congregated sperms in the lumen of seminiferous tubules and enlarged acellular zones were shown in the fish exposed to the 1.0 and 10.0 mg·L^-1 NPEO. Therefore,NPEO exposure could interfere the synthesis of testosterone by inhibiting the expression of CYP17 gene.Moreover,NPEO exposure could increase the synthesis of endogenous estrogen by inducing the expression of CYP19a and ERα genes and ultimately result in the alterations in the structure of zebrafish testis.