Richburg J H, Boekelheide K
Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island 02912, USA.
Toxicol Appl Pharmacol. 1996 Mar;137(1):42-50. doi: 10.1006/taap.1996.0055.
Mono-(2-ethylhexyl) phthalate (MEHP) is a widely studied Sertoli cell toxicant. Here we describe alterations in Sertoli cell vimentin filament distribution and the incidence of testicular germ cell apoptosis in young (28-day-old) Fischer rats that were treated with MEHP (2 microgram/kg, po) and killed 0, 3, 6, or 12 hr after exposure. A collapse in vimentin filaments was observed 3 hr after MEHP exposure without accompanying changes in the pattern of Sertoli cell tubulin or actin. A progressive increase in the perinuclear condensation of the vimentin filaments was observed from 6 to 12 hr after exposure. To evaluate the consequences of these Sertoli cell changes on germ cells, the role of apoptosis in MEHP-induced testicular toxicity was examined. DNA isolated from testis of rats 6 and 12 hr after MEHP exposure showed a marked increase in low-molecular-weight DNA resulting from internucleosomal cleavage. In addition, DNA fragmentation visualized in frozen testis cross sections by terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick end label (TUNEL) staining demonstrated a progressive increase in germ cell apoptosis from 6 to 12 hr after MEHP exposure. However, 3 hr after MEHP exposure, the incidence of TUNEL-positive germ cells was significantly decreased compared to that seen in controls. Taken together, the early collapse in Sertoli cell vimentin filaments and the concurrent decrease in germ cell apoptosis suggests that MEHP engenders Sertoli cell dysfunction resulting in the disruption of the physiological mechanism of germ cell apoptosis.
邻苯二甲酸单（2-乙基己基）酯（MEHP）是一种经过广泛研究的支持细胞毒物。在此，我们描述了用MEHP（2微克/千克，经口给药）处理的年轻（28日龄）Fischer大鼠支持细胞波形蛋白丝分布的改变以及睾丸生殖细胞凋亡的发生率，这些大鼠在暴露后0、3、6或12小时被处死。MEHP暴露3小时后观察到波形蛋白丝塌陷，而支持细胞微管蛋白或肌动蛋白的模式没有伴随变化。暴露后6至12小时观察到波形蛋白丝在核周的凝聚逐渐增加。为了评估这些支持细胞变化对生殖细胞的影响，研究了凋亡在MEHP诱导的睾丸毒性中的作用。从MEHP暴露后6小时和12小时的大鼠睾丸中分离的DNA显示，由于核小体间裂解，低分子量DNA显著增加。此外，通过末端脱氧核苷酸转移酶介导的地高辛配基-dUTP缺口末端标记（TUNEL）染色在冷冻睾丸横切片中观察到的DNA片段化表明，MEHP暴露后6至12小时生殖细胞凋亡逐渐增加。然而，MEHP暴露3小时后，TUNEL阳性生殖细胞的发生率与对照组相比显著降低。综上所述，支持细胞波形蛋白丝的早期塌陷和生殖细胞凋亡的同时减少表明，MEHP导致支持细胞功能障碍，从而破坏生殖细胞凋亡的生理机制。
