Mahood I Kim, Hallmark Nina, McKinnell Chris, Walker Marion, Fisher Jane S, Sharpe Richard M
Medical Research Center Human Reproductive Sciences Unit, Centre for Reproductive Biology, The University of Edinburgh Academic Centre, 49 Little France Crescent, Edinburgh EH16 4SB, United Kingdom.
Endocrinology. 2005 Feb;146(2):613-23. doi: 10.1210/en.2004-0671. Epub 2004 Nov 11.
Fetal exposure of male rats to di (n-butyl) phthalate (DBP) induces testicular changes remarkably similar to testicular dysgenesis syndrome in humans; these include induction of focal areas of dysgenetic tubules in otherwise normal testes. In searching for the fetal origins of the latter, we used image analysis to show that exposure to 500 mg/kg DBP [embryonic day (E)13.5-20.5)] caused abnormal aggregation of Leydig cells centrally in the fetal testis. This aggregation was not due to increase in Leydig cell number, and Leydig cell size was significantly reduced in DBP-exposed animals, as were testosterone levels and immunoexpression of P450 side-chain cleavage enzyme. The Leydig cell aggregates did not exhibit evidence of focal proliferation at E17.5-19.5. Using confocal microscopy and Leydig (3beta-hydroxysteroid dehydrogenase) and Sertoli (anti-Mullerian hormone) cell-specific markers, we show that fetal Leydig cell aggregates in DBP-exposed animals trap isolated Sertoli cells within them at E21.5. These areas of intermingled cells are still apparent on postnatal d 4, after cessation of DBP treatment, when they may form misshapen seminiferous cords that trap (intratubular) Leydig cells within them. These centrally located dysgenetic tubules contain germ cells in early puberty, but by adulthood they are Sertoli cell only, implying that presence of intratubular Leydig cells interferes with spermatogenesis. It is concluded that DBP-induced fetal Leydig cell aggregation may be a key event in formation of focal dysgenetic areas in the testis, and identification of the mechanisms underlying these events may give new insights into the fetal origins of testicular dysgenesis syndrome disorders in the human.
雄性大鼠在胎儿期暴露于邻苯二甲酸二（正丁基）酯（DBP）会引发睾丸变化，这些变化与人类的睾丸发育不全综合征极为相似；其中包括在原本正常的睾丸中诱导发育异常的小管形成局灶性区域。在探寻后者的胎儿起源时，我们运用图像分析表明，暴露于500 mg/kg DBP（胚胎期第13.5 - 20.5天）会导致胎儿睾丸中Leydig细胞在中央异常聚集。这种聚集并非由于Leydig细胞数量增加，并且在暴露于DBP的动物中，Leydig细胞大小显著减小，睾酮水平以及细胞色素P450侧链裂解酶的免疫表达也降低。在胚胎期第17.5 - 19.5天，Leydig细胞聚集体未表现出局灶性增殖的迹象。利用共聚焦显微镜以及Leydig细胞（3β - 羟基类固醇脱氢酶）和支持细胞（抗苗勒管激素）特异性标记物，我们发现，在胚胎期第21.5天，暴露于DBP的动物中的胎儿Leydig细胞聚集体会将孤立的支持细胞捕获其中。在停止DBP处理后的出生后第4天，这些细胞混合区域仍然明显，此时它们可能形成畸形的生精小管，将（管内）Leydig细胞捕获其中。这些位于中央的发育异常的小管在青春期早期含有生殖细胞，但到成年时仅含有支持细胞，这意味着管内Leydig细胞的存在会干扰精子发生。得出的结论是，DBP诱导的胎儿Leydig细胞聚集可能是睾丸中局灶性发育异常区域形成的关键事件，确定这些事件背后的机制可能会为人类睾丸发育不全综合征疾病的胎儿起源提供新的见解。
