title: Valproic acid-induced DNA damage increases embryonic p27(KIP1) and caspase-3 expression: a mechanism for valproic-acid induced neural tube defects.
abstract: Valproic acid is a commonly prescribed antiepileptic agent that causes birth defects including neural tube defects. The purpose of this study was to measure DNA damage and downstream changes in cell cycle inhibitors and apoptosis to further elucidate the molecular changes that occur following VPA exposure. Pregnant CD-1 mice were administered a teratogenic dose of VPA (400mg/kg) on gestational day 9 (plug=day 1) and embryos extracted 0.5, 1, 3, 6, and 24h after injection. Western blotting and immunohistochemistry were performed for γH2A.X, p21(WAF1/CIP1), p27(KIP1), and cleaved caspase-3. A rapid increase in γH2A.X expression was observed a half hour following VPA exposure, followed by a subsequent decrease. p27(KIP1)and cleaved caspase-3 expression was significantly increased 3 and 6h following VPA exposure. Immunohistochemistry revealed increased staining for γH2A.X, p27(KIP1), and cleaved caspase 3 in the head, confirming our hypothesis that DNA damage, cell cycle inhibition, and apoptosis are induced by VPA.
authors.affiliation: Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario, Canada.
authors.forename: Emily W Y
authors.initials: EW
authors.lastname: Tung
authors.forename: Louise M
authors.initials: LM
authors.lastname: Winn
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000633:toxicity*; D017209:Apoptosis; D053148:Caspase 3 / Q000096:biosynthesis*; D059447:Cell Cycle Checkpoints; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000096:biosynthesis*; D004249:DNA Damage; D005260:Female; D006657:Histones / Q000096:biosynthesis; D051379:Mice; D009436:Neural Tube Defects / Q000139:chemically induced* / Q000378:metabolism; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced* / Q000378:metabolism; D014635:Valproic Acid / Q000633:toxicity*
chemical_list: D000927:Anticonvulsants; C493957:Cdkn1a protein, mouse; C493961:Cdkn1b protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D006657:Histones; C475961:gamma-H2AX protein, mouse; D050760:Cyclin-Dependent Kinase Inhibitor p27; D014635:Valproic Acid; D053148:Caspase 3