Exposure to brominated flame retardant PBDE-99 affects cytoskeletal protein expression in the neonatal mouse cerebral cortex.
Polybrominated diphenyl ethers (PBDEs) are environmental contaminants found in human and animal tissues worldwide. Neonatal exposure to the flame retardant 2,2', 4,4',5-pentabromodiphenyl ether (PBDE-99) disrupts normal brain development in mice, and results in disturbed spontaneous behavior in the adult. The mechanisms underlying the late effects of early exposure are not clear. To gain insight into the initial neurodevelopmental damage inflicted by PBDE-99, we investigated the short-term effects of PBDE-99 on protein expression in the developing cerebral cortex of neonatal mice, and the cytotoxic and apoptotic effects of PBDE-99 in primary cultures of fetal rat cortical cells. We used two-dimensional difference gel electrophoresis (2D-DIGE) to analyze protein samples isolated from the cortex of NMRI mice 24h after exposure to a single oral dose of 12 mg/kg PBDE-99 on post-natal day 10. Protein resolution was enhanced by sample pre-fractionation. In the cell model, we determined cell viability using the trypan blue exclusion assay, and apoptosis using immunocytochemical detection of cleaved caspase-3. We determined the identity of 111 differentially expressed proteins, 32 (29%) of which are known to be cytoskeleton-related. Similar to previous findings in the striatum, we found elevated levels of the neuron growth-associated protein Gap43 in the cortex. In cultured cortical cells, a high concentration of PBDE-99 (30 microM) induced cell death without any apparent increase in caspase-3 activity. These results indicate that the permanent neurological damage induced by PBDE-99 during the brain growth spurt involve detrimental effects on cytoskeletal regulation and neuronal maturation in the developing cerebral cortex.
Alm
Henrik
H
Department of Pharmaceutical Biosciences, Division of Toxicology, Uppsala University, Sweden. Henrik.Alm@farmbio.uu.se
Kultima
Kim
K
Scholz
Birger
B
Nilsson
Anna
A
Andrén
Per E
PE
Fex-Svenningsen
Asa
A
Dencker
Lennart
L
Stigson
Michael
M
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D004622:Embryo, Mammalian; D005260:Female; D005411:Flame Retardants / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects*; D055768:Halogenated Diphenyl Ethers; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000648:ultrastructure; D010647:Phenyl Ethers / Q000633:toxicity*; D011075:Polybrominated Biphenyls / Q000633:toxicity*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
D003598:Cytoskeletal Proteins; D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D010647:Phenyl Ethers; D011075:Polybrominated Biphenyls; C086401:pentabromodiphenyl ether; D053148:Caspase 3