| Objective To study the oxidative stress and the protein level changes of mitochondrialapoptosis pathway Cytochrome C released induced by decabromodiphenylether（BDE-209） in liver of mice for providing the basis for in-depth study of liver toxicitymechanism induced by BDE-209.Methods Twenty eight male BALB/c mice which3-week-old were randomizedlydivided into four groups with seven mice in each group: saline group, solvent group,low （200mg/kg） and high （500mg/kg） dose groups. All the groups were exposed withoral gavage and administered6times every week. The mice were sacrificed after6weeks BDE-209treatment. Morphological and ultrastructural changes of liver wereobserved using optical microscope and electron microscope. The levels of alanineaminotransferase（ALT）, glutamic-oxalacetic transaminase（AST） in Serum andmalonyldialdehyde （MDA）, total supemxide dismutase （T-SOD） and glutathione （GSH）in liver were analysised. The protein expression was assayed by Western blot in liverincluding Bax, Bcl-2, Cyt-C, caspase-9and caspase-3.Results There was no significant difference among the groups in liver weight/bodyweight. In the high and low dose groups, the active of serum ALT were （95.9243±10.8066） U/L and （87.7352±7.9656） U/L, both of them were higher than that in thesaline group （62.0655±8.3967U/L） and the solvent group （62.5168±8.3400U/L）, thedifference was statistically significant （P <0.05）; In the high and low dose groups, theactive of serum AST were （176.8746±12.3145） U/L and （167.3821±8.4494） U/L, bothof them were higher than that in the saline group （130.8888±8.1633U/L） and the solvent group （131.3715±7.4749U/L）, the difference was statistically significant （P <0.05）; Theliver MDA levels in both high dose group （0.1915±0.0674nmol/mg prot） and lowdose group（0.1737±0.0414nmol/mg prot） were higher than that in the saline group（0773±0.0226nmol/mg prot） and the solvent group（0.0790±0.0340nmol/mg prot）, thedifference was statistically significant（P<0.05）. The active of T-SOD in high and lowdose group（0.2867±0.0401,0.3064±0.0219U/mg prot） was lower than which in thesaline group and the sovent group （0.3608±0.0687,0.3596±0.0343U/mg prot） and thedifference was statistically significant （P<0.05）. Liver GSH level in high dosegroup（0.0647±0.0235mg GSH/g prot） was decreased compared with the levels in salinegroup（0.0987±.0189mg GSH/g prot）, solvent group（0.0994±0.0124mgGSH/g prot） andlow dose group（0.0894±0.0314mg GSH/g prot） and the difference was statisticallysignificant （P<0.05）. In Light microscopy, cloudy swelling of liver cells were found inthe liver of mice exposed to BDE-209, small lipid vacuoles were also found in thecytoplasm, hepatic cord arrangement was changed, part of the liver cells were vague,vacuolization was significant. The ultrastructural changes included condensation andmargination of chromatin, swollen mitochondria, and enlargement of endoplasmicreticulum. Western blot results showed that compared with the control groups, theexpression of Bax/Bcl-2, Cyt-C, caspase9, caspase-3, in exposed mice liver was higherand the difference was significant （P<0.05）.Conclusion BDE-209exposure can cause the change of liver’s morphology andultrastructure. Excessive BDE-209may induce oxidative stress in the liver of mice. Thetissue oxidative damage might be one of the primary mechanisms of hepatotoxicity ofBDE-209. While mitochondrial morphological changes and the Bax/Bcl-2expressionchange may lead to Cyt-C releasing, activating the classical pathway of apoptosis,induction of caspase-9and caspase-9expression changes. Objective BDE-209is a persistent organic pollutant and has the potential threats toecological environment and biological. In our previous study we confirmed thatBDE-209can cause oxidative damage to liver tissue and Cyt-C-related apoptotic proteinexpression changes of mitochondrial apoptotic pathway in the liver. So our researchfocus on the effects of N-acetylcysteine antioxidants on mice’s liver tissue oxidativeinjury and Cyt-C-related apoptotic protein expression changes in the liver induced byBDE-209.Methods Twenty one male BALB/c mice were randomizedly divided into three groupswith seven mice in each: saline group, BDE-209(200mg·kg-1·d-1) group and (200mg·kg-1·d-1, BDE-209+100mg·kg-1·d-1, NAC) group. All the groups were exposed withoral gavage and administered6times every week. The mice were sacrificed after6weeks BDE-209treatment. Morphological and ultrastructural changes of liver wereobserved using optical microscope and electron microscope. The levers of alanineaminotransferase（ALT）, glutamic-oxalacetic transaminase（AST） in Serum andmalonyldialdehyde （MDA）, total supemxide dismutase （T-SOD） and glutathione （GSH）in liver were analysised. The protein level was assayed by Western blot in liverincluding Cyt-C, caspase-3, caspase-9, Bax and Bcl-2.Results There was no significant difference among the groups in liver weight/bodyweight. The serum ALT of the mice exposed to BDE-209was （87.7352±7.9656） U/Lhigher than that in saline group （62.0655±8.3967U/L） and BDE-209+NAC group（5.9243±10.8066U/L）, and the difference was significant（P<0.05）. The serum AST ofthe mice exposed to BDE-209was （167.3821±8.4494） U/L higher than that in saline group （130.8888±8.1633U/L） and BDE-209+NAC group （136.7846±8.3145U/L）, andthe difference was significant（P<0.05）. The level of MDA of the mice exposed toBDE-209was （0.1737±0.0414） nmol/mg prot higher than that in saline group （0.0773±0.0226nmol/mg prot） and BDE-209+NAC group （0.0821±0.0171nmol/mg prot）, andthe difference was significant（P<0.05）. The active of T-SOD of the mice exposed toBDE-209was （0.3064±0.0219） U/mg prot lower than that in saline group （0.3608±0.0687U/mg prot） and BDE-209+NAC group （0.3579±0.0421U/mg prot）, and thedifference was significant（P<0.05）.The level of GSH of the mice exposed to BDE-209was （0.0894±0.0314） mg GSH/g prot lower than that in saline group （0.0987±0.0189mg GSH/g prot） and BDE-209+NAC group （0.0979±0.0241mg GSH/g prot）,and the difference was significant（P<0.05）. Western blot results showed that comparedwith the saline group and BDE-209+NAC group: the expression of Bax/Bcl-2, Cyt-C,caspase-9, caspase-3in exposed mice liver were higher and the difference wassignificant（P<0.05）. In Light microscopy, cloudy swelling of liver cells was found inthe liver of mice exposed to BDE-209, small lipid vacuoles were also found in thecytoplasm, hepatic cord arrangement was changed, part of the liver cells were vague,vacuolization was significant. The ultrastructural changes included condensation andmargination of chromatin, swollen mitochondria and enlargement of endoplasmicreticulum. These phenomena is not a significant phenomenon in the saline group andBDE-209+NAC group.Conclusion N-acetylcysteine has a protective effect on liver toxicity BDE-209induced. |
