精索静脉曲张对青春期大鼠睾丸中VEGF和Flt-1蛋白表达的影响

Effects of experimental left varicocele on VEGF and Flt-1 proteins in the testis of adolescent rats

目的研究血管内皮生长因子(VEGF)及其受体Flt-1蛋白在实验性左侧精索静脉曲张(ELV)大鼠睾丸中的表达和定位,探讨它们在精索静脉曲张(VC)致男性不育中的作用。方法建立青春期大鼠ELV模型,采用免疫组化法检测VEGF及Flt-1在ELV4周、8周组及相应对照组大鼠睾丸中的表达变化。结果 VEGF和Flt-1蛋白在大鼠睾丸中定位具有细胞特异性。VEGF蛋白表达于生精细胞、精子细胞发育中的顶体、Sertoli和Leydig细胞胞质内;Flt-1表达于精子细胞发育中的顶体及Leydig细胞胞质中。ELV4周组睾丸中VEGF蛋白的表达显著增加(P<0.01),8周时其表达量下降(P<0.01);ELV4周组与8周组睾丸中Flt-1蛋白的表达均比相应对照组下降(P<0.01),ELV8周组比4周组显著减少(P<0.01)。结论 ELV可影响青春期大鼠睾丸中VEGF和Flt-1蛋白的表达量,可能会影响精子的发生、发育,因而该变化可能是VC引起男性不育的原因之一。

Objective To investigate the effects of experimental left varicocele （ELV） on the expression of vascular endothelial growth factor （VEGF） and its receptor fms-like tyrosine kinase-1 （Fit-l） proteins in the testis of adolescent rats, and to explore the mechanism of infertility caused by varicocele. Methods The ELV model of male adolescent Sprague-Dawley （SD） rats was established, and the the changes in the expression of VEGF and Fit-1 proteins in the testis were detected by immunohistochemistry at 4 and 8 weeks after surgery. Results Cell-specific expressions of VEGF and Flt-1 were observed in the testis of the ELV and control groups. VEGF immunoreactive particles were localized in the cytoplasm of spermatogenic cells, the developing acrosome of spermatids, Sertoli cells and Leydig cells, while Flt-1 was ex pressed mainly in the developing acrosome of spermatids and in Leydig cells. Statistical analysis showed a notable increase in the VEGF protein expression in the hibateral testis of the 4-week ELV group compared with that of the controls （P〈0.01）While there was a remarkable reduction in the 8-week ELV group compared with that of the controls （P〈0.01）. An obvious reduction was seen in the Fit-1 protein expression in the testis of the 4-and 8-week ELV group pared with that of the corresponding controls （P〈0.01）. In addition, the reduction in the 8-week ELV group was much more distinct than that of the 4-week ELV group. Conclusion ELV can cause changes in the expressions of VEGF and Flt-1 proteins in the testis of ad olescent rats, and consequently affect spermatogenesis and spermiotelcosis, which may be one of the causes of varicocele-induced male infertility or subfertility.