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Nowadays polybrominated diphenyl ethers (PBDEs) are globle concerned and newly persistent organic pollutants (POPs). Because of its unique advantages, such as low price and application amount, high antiflaming rate, nice thermostabilization et al, PBDEs, as polychlorinated biphenyls (PCBs) alternatives, have been widely used in electronic equipments, buildings, furnitures, and texttiles since 1970s. Followed PBDEs have been detected in various environmental media, such as air, water, soil, sediments, as well as wild animal, fish, domesticated fowl, and human since 1980s. Furthermore, the concentration of PBDEs has the increasing trend of year by year. To date, many in vitro and in vivo experimental studies preliminarily suggested that health hazard caused by PBDEs include neurotoxicity, hepatotoxicity, reproductive toxicity, endocrine disrupting, and carcinogenesis were identified. The massive animal experimental studies indicated that animals exposed to low dose PBDEs in the critical period of cerebrum growth display behavior disorder, the functions of studying and memory decrease and so on. Moreover, it will become more serious with the increasing of age. Furthermore, Female-derived exposure PBDEs bring about the reduction of offspring hippocampal neurons and morphological changes, then lead to the disorder in the nervous system. Therefore, recently the developmental neurotoxic effects of PBDEs get more and more attention from people. However, the neurotoxic effects of PBDEs are still at the starting stage. At present, the studies mainly focus on nerve behavior, cognition function, learning and memory and so on. The further research on the neurotoxic effective mechanism of PBDEs will be advantageous in seeking the target of the neurotoxic effect and also provides the basis theory for the prevention and control of neurotoxicity of PBDEs.Apoptosis is an evolutionarily conserved, usually caspase-dependent form of programmed cell dearth, which enable embryonic development and tissue homeostasis in metazoan. So the necessity of its precise and safe regulation becomes extremely apparent not only in occurrence and development of disease, but also in the toxicity of exogenous compounds. Our primary in vitro experimental results indicated that PBDE-47 (2,2’4,4’-tetrabromodiphenyl ether, PBDE-47) induced apoptosis in the SH-SY5Y cell and hippocampal neuron. Furthermore, Madia et al reported that PBDE-99, a typical predominant congner of PBDEs, may induce the astrocytoma cell to apoptosis. Our further research prompted high mRNA expression of caspase-3, caspase-12, cytochrome C and DAPK were closely related to PBDE-47-induced apoptosis. These findings may suggested that three classic apoptosis pathway (the mitochondrial, endoplasmic reticulum and death receptor pathway) involved in PBDE-47-induced apoptosis. The Fas/FasL system has been known as a prototypic inducer of apoptosis. Fas and FasL are expressed in the normal central nervous system (central nervous system, CNS). Expression of Fas and FasL is significantly elevated in a variety of the neurologic disorder, suggesting the possibility that this system may play great roles in the CNS. So far, the action of Fas/FasL system in the neurotoxicity induced by PBDEs is not yet reported.Therefore, here we used human neuroblastoma SH-SY5Y cells to explore the effects of PBDE-47, with or without blocking the Fas/FasL pathway, on apoptosis and the expression of Fas, FasL, caspase-8 and caspase-3 in order to provide some valuable clues for further study of PBDE-induced neurotoxicity.This paper consists of two partsPartⅠEffects of PBDE-47 on apoptosis, protein expression levels of Fas, FasL, procaspase-8 and procaspase-3, and mRNA expression levels of caspase-3 and Fas in SH-SY5Y cells.Objective To explore the effects of PBDE-47 on apoptosis and the protein expression levels of Fas, FasL, caspase-8 and caspase-3 in SH-SY5Y cells in vitro.Methods SH-SY5Y cells were exposed to different concentrations of PBDE-47 (0,1,5,10μmol/L) for 24 h, then the percentage of apoptosis, protein expression levels of Fas, FasL, procaspase-8 and procaspase-3, and the mRNA expression levels of caspase-3 and Fas were detected in SH-SY5Y cells using flow cytometry, Western blot, and RT-PCR.Results The percentage of apoptosis in 10μmol/L PBDE-47-treated group were markly higher than those of control group, 1μmol/L and 5μmol/L PBDE-47-treated group (P﹤0.05). compared with control group, the protein expression levels of procaspase-3 were clearly decreased (P﹤0.05), but the protein expressions of Fas, FasL and procaspase-8 were not changed in general (P﹥0.05) except 1μmol/L PBDE-47-treated group were higher than the control group (P﹤0.05). Furthermore, the mRNA expression levels of caspase-3 were significantly increased in different PBDE-47-treated groups (P﹤0.05), while the mRNA expressions of Fas were not changed (P﹥0.05).Conclusion PBDE-47 exposure can increase apoptosis rates, the mRNA expression level of caspase-3 and decrease the protein expression level of procaspase-3. However, the expression levels of Fas mRNA and Fas, FasL, procaspase-8 protein were not changed in SH-SY5Y cells.PartⅡEffect of ZB4 on PBDE-47-induced apoptosis and protein expression level of procaspase-3 in SH-SY5Y cellsObjective To explore the effect of ZB4 on PBDE-47-induced apoptosis and protein expression level of procaspase-3 in SH-SY5Y cells.Methods SH-SY5Y cells were treated with 10μmol/L PBDE-47 and/or ZB4 for 24 h, the percentage of apoptosis and protein expression level of procaspase-3 were measured respectively.Results ZB4 has no effects on apoptosis and protein expression level of procaspase-3 in SH-SY5Y cells (P﹥0.05). Moreover, ZB4 with 10μmol/L PBDE-47 did not affect on PBDE-47-induced apoptosis and protein expression level of procaspase-3 in SH-SY5Y cells (P﹥0.05).Conclusion Fas/FasL signal transduction pathway may be not involved in PBDE-47 induced SH-SY5Y cells apoptosis.
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