Studies On Estrogen-Like Effects And Reproductive And Developmental Toxicity Of Arsenic Trioxide

The health risks of body exposured to environmental As is systemic and multi-system.As exposure has been link to skin damages,cardiovascular diseases, nervous system and reproductive and developmental problems.Also As has been considered a definitely human carcinogen.However,the exact mechanism has not been clear.Recently some studies suggested that As has estrogen-like effects and it is a candidate environmental endocrine disruptor(EEDs).To determine whether or not As has estrogen-like effects and if the estrogen-like effects is related to the health problems,The following studies were conducted.These studies focused on As estrogen-like effects and influence on reproductive and developmental toxicity from the cell culture and animal experiments.1,Study on estrogen-like effects and influence on the Hela cell growth of As₂O₃The Hela cells were cultured in improved RPMI-1640 supplemented respectively with E₂(lnM),Arsenic trioxide(0.5μM,1μM,5μM),ICI(500nM),E₂ (1nM) and ICI(500nM),As₂O₃(1μM) and ICI(500nM),respectively.The morphology was used to observe the situation of cell growth.The method of MTT was used to study the cell proliferation.The technique of flow cytometry was used to measure Hela DNA content.The results showed that the effects of 0.5μM As₂O₃ and 1nM E₂ was similar to the cell proliferation,it promote cell to enter the DNA synthesis phase(S),and the effect could be antagonized by ICI.As₂O₃ in 1.0μM affected the cell growth from proliferation to inhibition,Hela cells showed apoptosis in other groups.From the results it is suggested that As₂O₃ has estrogen-like effects and As₂O₃ in 1.0μM is a turning point for affected the growth of Hela cells.2,Study on ERα,PR mRNA expression of Hela cells exposured to As₂O₃The Hela cells were cultured in improved RPMI-1640 supplemented respectively with E₂(lnM),Arsenic trioxide(0.5μM,1μM,5μM),ICI(500nM),E₂ (1nM) and ICI(500nM),As₂O₃(1μM) and ICI(500nM).RT-PCR was used to detect the ERαand PRmRNA expression.The results showed that 1nM E₂ and 0.5μM As₂O₃ was similar to ER and PRmRNA expression of Hela cells,the effects could be antagonized by ICI.It demonstrated that ERαmRNA expression reduced and PRmRNA expression increased after Hela cells exposed to 0.5μtM As₂O₃,it further indicated that As₂O₃ has estrogen-like effects.3,Study on estrous cycle of mice exposed to chronic arsenicThe method of cervical mucus crystallization was used to examine estrous cycle of mice exposed to chronic different As₂O₃ drinking water.The results showed that the estrous cycle of mice was disorder,but there was no significant differences compared with control group,also the cycle was not regular(shortening or extension),particularly in estrus.The estrous cycle disorder is a sensitive marker responsed to the sex hormone metabolic disorders.This study proved that As₂O₃ has impact on body's endocrine,so it should be environmental endocrine disruptors.4,Study on genital uterus,ovary ERαand PR mRNA expression of female mice exposed to chronic arsenic ICP-MS wad used to analysis blood arsenic and RT-PCR was used to detect genital uterus,ovary ERαand PRmRNA expression of female mice exposed to chronic different As₂O₃ drinking water.The results showed that:â‘ The overall trend of ERαmRNA expression decreased with the blood As increasing.Uterus and ovary ERαexpression significantly lower in mice exposed to different As drinking water, the difference was significant(P<0.05) compared with control group.â‘¡In general, the trend of PRmRNA expression in uterus declined,PRmRNA expression in uterus was the lowest in mice exposed to 0.1-0.2μg/ml arsenic drinking water,and the difference of PRmRNA expression in these two groups was significant(P<0.05) compared with control group.Although PRmRNA expression in ovary was declined too but there was no significant difference(P>0.05) compared with control group.5,Study on genital testicular ERαand PRmRNA expression of male mice exposed to chronic arsenicICP-MS wad used to analysis blood arsenic and RT-PCR was used to detect genital testicular ERαand PRmRNA expression of male mice exposed to chronic different As₂O₃ drinking water.The results showed:â‘ Testicular ERαmRNA expression was higher of mice exposed to arsenic drinking water than control group. ERαmRNA expression increased with blood arsenic increasing,but the ERαmRNA expression declined in high As.Overall the changes were no significant differences (P>0.05).â‘¡Testicular PRmRNA expression increased of mice exposed to different arsenic drinking water,but in gerenal,the changes were not significant difference (P>0.05).6,Study on genital uterus,ovary and embryo ERαand PR mRNA expression of pregnant mice exposed to chronic arsenicICP-MS wad used to analysis blood arsenic and RT-PCR was used to detect genital uterus,ovary and embryo ERαand PRmRNA expression of pregnant mice exposed to chronic different As₂O₃ drinking water.The results showed that:â‘ ERαmRNA expression in pregnant uterus increased with the increased arsenic exposure,PRmRNA expression in pregnant uterus decreased with the increased arsenic exposure;â‘¡ERαmRNA expression declined and PRmRNA expression increased in pregnant ovary with the increased arsenic in blood.â‘¢ERαmRNA expression increased in embryo with maternal blood As increasing,there was significant differences(P<0.05) compared with control group;PRmRNA expression is also higher than the control group,but there was no significant difference(P>0.05).From above six experiments,we suggested that As₂O₃ has estrogen-like effects and the effects according to dose-response relationship.The reproductive and developmental toxicity of arsenic is related to its estrogen-like effects.Uterus and ovary ERαmRNA expression significantly lower and PRmRNA expression also declined totally in non-pregnant mice,Uterus ERαmRNA expression increased and PRmRNA expression declined.At the same time,experiments results indicated that it is not major to influence the ovarian function of mice exposed to chronic arsenic, the early reproductive toxicity is mainly due to uterine function conditions exposed to arsenic.The impact of the male testes exposured to arsenic need to be further study.