Valproic acid-induced DNA damage increases embryonic p27KIP1 and caspase-3 expression: A mechanism for valproic-acid induced neural tube defects

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 (400 mg/kg) on gestational day 9 (plug = day 1) and embryos extracted 0.5, 1, 3, 6, and 24 h after injection. Western blotting and immunohistochemistry were performed for γH2A.X, p21WAF1/CIP1, p27KIP1, and cleaved caspase-3. A rapid increase in γH2A.X expression was observed a half hour following VPA exposure, followed by a subsequent decrease. p27KIP1and cleaved caspase-3 expression was significantly increased 3 and 6 h following VPA exposure. Immunohistochemistry revealed increased staining for γH2A.X, p27KIP1, and cleaved caspase 3in the head, confirming our hypothesis that DNA damage, cell cycle inhibition, and apoptosis are induced by VPA.

► Valproic acid (VPA) is a known teratogenic agent that causes neural tube defects.
► We examine the effect of VPA on DNA damage, cell cycle arrest, and apoptosis.
► VPA increases the expression of γH2A.X, p27KIP1, and cleaved caspase-3.
► VPA may induce neural tube defects by increasing cell death in the neuroepithelium.