| Polychlorinated biphenyls(PCBs)are a type of environmental estrogens,with a total of 209 homologs,including dioxin-type and non-dioxin-type PCBs.PCB118(2,3',4,4',5-penta chlorobiphenyl)belongs to the dioxin type polychlorinated biphenyls,which is highly toxi c and can cause damage to the nervous system and reproductive system of mammals.A dolescence and pregnancy are critical periods of mammalian growth and development.PC B118 can accumulate in pregnant mouse,and then transmit the toxicity to the offspring t hrough the placenta and breast milk,thereby causing irreversible damage to the offspring's reproductive system.PCB118 also directly affects the reproductive organs of animals d uring puberty(The critical period in the development of the reproductive organs).At pre-sent,there are little literatures to explore the specific effects of PCB118 exposure on th e mechanism of the effect.In this study,ICR mice were exposed to PCB118 during ado lescence and pregnancy to explore the effects of PCB118 exposure on male testis and sp ermatogenesis.Part 1: The mice in the control group and the dose groups received 0,20,and 100 ?g/kg/day PCB118 gavage treatments from 8.5 days to 13.5 days of gestation.The testes and sperm were taked when the F1 generation were 7 to 8 weeks old at sexual maturity.We explore the effect of parental exposure to PCB118 on offspring male mice by using real-time fluorescent quantitative PCR,immunohistochemistry,western blotting and other molecular biological methods(Compared with the control group).(1)Exposure to PCB118 during pregnancy did not affect the weight gain of the mice(P>0.05).But the testis weight of the mice in the dose groups were significantly reduced(P<0.05).(2)Exposure to PCB118 during pregnancy had an effect on the diameter of seminiferous tubules and the thickness of seminiferous epithelium of F1 mice(P< 0.05),which mainly manifested in the increased thickness of the seminiferous epithelium and the increased diameter of the seminiferous tubules.(3)Exposure of the PCB118 during pregnancy caused the sperm deformity rate have a significant increased and the sperm motility have a significant decreased in the F1 generation mice(P<0.05).(4)Exposure of the PCB118 during pregnancy caused the expression of PCNA and STRA8 showed a dose-dependent trend(P<0.05).Part 2: The mice in the control group and the dose groups were given 0,50,and 500?g/kg/day PCB118 for 5 consecutive weeks.The drug was administered by gavage from the onset of puberty to the end of week 7.Starting from the 7th week,when the ICR mice reached sexual maturity,their organs,testes and epididymis were taken.Then we using real-time fluorescent quantitative PCR,immunohistochemistry,western blotting and other molecular biological methods,to explore the effects of exposure to PCB118 during adolescence on the reproductive organs of sexually mature mice(Compared with the control group).(1)Exposure to PCB118 during puberty did not affect the weight gain of the mice(P>0.05),but the liver weight and testis weight of the mice in the treated groups were significantly reduced(P<0.05).(2)Exposure to PCB118 during puberty in mice decreased the diameter of seminiferous tubules in the testes(P<0.05),and vacuolation in the histological sections of the testes.(3)Exposure of mice to PCB118 during puberty caused a significant increase in the rate of sperm deformity and a significant decrease in sperm motility(P<0.05).(4)Exposure of the PCB118 during puberty caused the expression of PCNA and STRA8 showed a dose-dependent trend(P<0.05).The above results indicate that exposure of the PCB118 during the two sensitive periods cause damage to the internal structure of the mouse testis,impaired sperm quality,increased sperm deformity rate,and changes the expression of genes related to spermatogenesis. |
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