Depletion of glutathione induces 4hydroxynonenal protein adducts and hydroxyurea teratogenicity in the organogenesis stage mouse embryo. J Pharmacol Exp Ther 2006; 319(2

Glutathione (GSH) homeostasis is important during organogen-esis. To elucidate the impact of GSH depletion in organogen-esis stage embryos on oxidative stress and drug teratogenicity, L-buthionine-S,R-sulfoximine (BSO) was given to timed preg-nant CD-1 mice 4 h before exposure to a model teratogen, hydroxyurea (HU) [400 mg/kg (HU-400) or 600 mg/kg (HU-600)]. Treatment with BSO or HU alone or with BSO plus HU-400 did not alter the ratios of glutathione disulfide/GSH in the embryo; in contrast, the combination of BSO plus HU-600 did increase this ratio at both 0.5 and 3 h post-HU, indicating the induction of oxidative stress in the embryos. Immunoreac-tivity to a product of lipid peroxidation, 4-hydroxynonenal (4-HNE) protein adducts, was detected in saline-treated embryos; the intensity and nuclear localization of 4-HNE protein adduct immunoreactivity in specific regions in the embryo was signif-icantly increased by exposure to BSO alone or BSO and either dose of HU. BSO pretreatment increased the spectrum and incidence of external and skeletal malformations (curly tail, hind limb malformations, hydrocephaly, exencephaly, open eye, spina bifida, and gastroschisis) induced by HU-400 and HU-600; BSO exposure did not alter the effects of HU on fetal mortality or fetal weights or HU induction of c-Fos heterodimer-dependent activator protein 1 DNA binding activity. The forma-tion of 4-HNE protein adducts in teratogen-exposed embryos was localized to regions of the embryo that were highly sus-ceptible to insult, namely the somites and caudal neural tube, correlating the presence of 4-HNE adducts with the disruption of pattern formation during organogenesis. Glutathione (-glutamylcysteinylglycine, GSH), synthe-sized de novo by the sequential actions of -glutamylcysteine synthetase (-GCS) and glutathione synthetase, is the prin-cipal nonprotein sulfhydryl in mammalian cells. GSH serves mainly as a thiol substrate for enzymes to reduce free radi-cals and hydroperoxides and regulate protein functions. Dis-turbances in GSH homeostasis may cause oxidative stress, inducing damage to cellular macromolecules (lipids, proteins