Study On Apoptosis Of Germ Cells In Male Mice Induced By MeHg And Regulative Process

Methylmercury(MeHg) is an important environmental pollutant which seriously threaten the ecological environment and the people's health. The study has shown that MeHg could induce the DNA damage of somatic cells and germ cells. It has effects on female and male reproductive system and affects the growth of the offspring. We used the techniques of toxicology and molecular biology to study the DNA damage and the apoptosis of germ cells in male mice induced by MeHg. The results showed as follows: 1. The effects of MeHg on DNA damage of germ cells in male mice in vitro DNA dmage was observed in 0.001mmol/L group with SCGE. There was a positive correlationship between the exposure doses of MeHg and rate of DNA migration(P＜0.05). But there were no significant differences among exposed groups. It indicated that MeHg could induce the DNA damage of germ cell to some degree. 2. The effects of MeHg on apoptosis of testis germ cell by HE Dispersed apoptotic cells in testis tissues were observed in all of groups treated with MeHg by hematoxylin-eosin dyeing, the plasm of these cells took on light red, the nuclei shrinked and took on dark blue. These suggested that MeHg could induce apoptosis of testis germ cell. 3. The effects of MeHg on apoptosis of testis germ cell by TUNEL TUNEL is a convenient method to assess apoptosis. We found apoptotic cells dispersed in testis, the nuclei or plasm of them took on brownish-yellow or yellow by staining. The results of image analysis showed that the apoptotic index of the groups treated with MeHg was higher than that in the control group, the apoptotic index was significantly elevated in the 1/50LD50 and 1/10 LD50 MeHg treatment groups compared with that in the control group. All above further confirmed MeHg could induce apoptosis of testis germ cell, and with increasing dose of MeHg, apoptotic index increased gradually.4. The expression of Fas/FasL by immunohistochemical study Fsa/FasL is an important death receptor in the process of cell apoptosis. We found that the membrane or plasm of the cells which expressed positively Fsa/FasL of the groups treated with MeHg took on brownish-yellow or dark brownish-yellow by staining. The results of image analysis showed that the expression of Fsa/FasL wasn't significant difference compared with that in the control groups. But the expression of the group treated with 1/100LD50 MeHg was more than that in the control groups. With the increasing dose of MeHg, the average value of gray scale of every group increased gradually, which represent that the expression of Fsa/FasL decreased.5. The expression of caspase-3 by immunohistochemical study Caspase-3 is a main enzyme which can trigger cell apoptotic cascade reaction. The results of this study showed that the membrane or plasm of the cells which expressed caspase-3 positively of the groups treated with MeHg took on brownish-yellow by staining. The results of image analysis showed that when treated with 1/100LD50 MeHg, the expression of caspase-3 was significant difference compared with that in the control group. With the increasing dose of MeHg, the average value of gray scale of every group increased gradually. Which represent that the expression of caspase-3 decreased.The above-mentioned results had a very significant effect on revealing the regulatory mechanism of apoptosis of testis germ cell by MeHg, and the mechanism of MeHg poisoning. At the same time, they provided new thinking for prevention and cure of MeHg poisoning.