神经病靶酯酶在TOCP诱导小鼠睾丸Leydig细胞自噬和凋亡中的作用及机制研究

Tri-ortho -cresyl phosphate (TOCP) has been widely used as plasticizers, plastic softeners, and flame-retardants in the industry. It has been shown that inhibition of neuropathy target esterase (NTE) activity leads to decrease of cauda epididymal sperm density, suggesting that NTE might play a role in spermatogenesis. Our preliminary results found that TOCP could inhibit spermatogenesis, decrease testosterone concentration and induce autophagy of mice Leydig cells. Inasmuch as inhibition of NTE activity can increase lysophosphatidylcholine (LPC) content, and LPC can induce apoptosis, and Leydig cells play an important role in spermatogenesis. These results indicate that TOCP might induce autophagy and apoptosis of mice Leydig cells via NTE/LPC signal. Therefore, we will test this hypothesis by the following approaches: (1) we will employ flow cytometry, transmission electron microscopy (TEM), monodansylcadaverine (MDC) staining, a specfic autophagolysosome marker, and western blotting to investigate whether TOCP induces autophagy and apoptosis of mice Leydig cells, (2) phenyl valerate hydrolysis and western blotting will be used to assess the effect of TOCP on NTE activity and LPC content in these cells and (3), we will determine whether TOCP induces autophagy and apoptosis of mice Leydig cells via NTE/LPC signal. The present study will provide a novel insight into the mechanism for the regulation of mice Leydig cells.

三邻甲苯磷酸酯（TOCP）常作为增塑剂、软化剂及阻燃剂等，在工业中使用非常广泛。研究显示，神经病靶酯酶（NTE）活性被抑制后，精子发生明显受抑制，提示NTE在精子发生中起着非常重要的作用。我们的初步结果发现，TOCP可抑制精子发生和睾酮的含量并诱导睾丸Leydig细胞自噬；鉴于NTE活性降低可增加溶血卵磷脂（LPC）含量，LPC可诱导细胞凋亡以及Leydig细胞在精子发生中的重要作用；提示TOCP很可能通过NTE/LPC而诱导Leydig细胞自噬和凋亡。本课题通过分离的小鼠Leydig细胞，首先用流式细胞仪、透射电镜、MDC染色和免疫印迹等方法确定TOCP诱导Leydig细胞自噬和凋亡，然后用戊酸苯酯水解法及免疫印迹等方法确定TOCP对细胞内NTE活性及LPC含量的影响，并最终确定TOCP可通过NTE/LPC而诱导细胞自噬和凋亡。为深入探讨Leydig细胞的调控机理提供理论基础和实验依据。

三邻甲苯磷酸酯（TOCP）常作为增塑剂、软化剂及阻燃剂等，在工业中使用非常广泛。研究显示，TOCP 可抑制神经病靶酯酶（NTE）活性并抑制精子发生，提示NTE 很可能参与精子发生。该课题通过体外培养的小鼠睾丸间质TM3细胞，发现TOCP可抑制小鼠睾丸间质细胞活性并显著增加细胞内LC3-II的含量及LC3-II/LC3-I的比例，细胞内Atg5和Beclin1的含量也显著增加；透射电子显微镜显示，TOCP可显著增加细胞内自噬泡的数量，提示TOCP可诱导小鼠睾丸间质细胞自噬。然而TOCP对细胞周期和凋亡并无明显影响。用免疫组织化学方法发现NTE在小鼠睾丸Leydig细胞上表达，并且TOCP可抑制小鼠睾丸Leydig细胞内NTE活性和增加LPC的含量。敲减小鼠睾丸Leydig细胞内NTE后，细胞内LPC含量显著增加，细胞自噬也显著增加，然而对细胞凋亡无明显影响；通过本课题的研究，提示NTE/LPC途径很有可能参与了TOCP诱导小鼠睾丸间质Leydig细胞自噬。本课题的研究为深入探讨TOCP对男性生殖毒性机理提供理论基础和实验依据。