Oxygen-Induced Embryopathy and the Significance of Glutathione-Dependent Antioxidant System in the Rat Embryo During Early Organogenesis

• Published in: Free radical biology & medicine Vol. 22; no. 3; pp. 447 - 454
• Main Authors: Ishibashi, Miwa, Akazawa, Shoichi, Sakamaki, Hiroyuki, Matsumoto, Kazunari, Yamasaki, Hironori, Yamaguchi, Yoshihiko, Goto, Shinji, Urata, Yoshishige, Kondo, Takahito, Nagataki, Shigenobu
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 1997
• Subjects: Animals; Antioxidants; Culture Techniques; Embryo culture; Embryo, Mammalian - metabolism; Embryonic and Fetal Development; Female; Fetal Diseases - chemically induced; Free radicals; Glutamate-Cysteine Ligase - genetics; Glutamate-Cysteine Ligase - metabolism; Glutathione (GSH); Glutathione - pharmacology; Glutathione peroxidase (GPX); Glutathione Peroxidase - genetics; Glutathione Peroxidase - metabolism; Glutathione Transferase - genetics; Glutathione Transferase - metabolism; Glutathione-S transferase (GST); Humans; Hydrogen peroxide (H 2O 2); Male; Neural tube defects; Neural Tube Defects - chemically induced; Oxidative stress; Oxygen - toxicity; Rats; Rats, Wistar; RNA, Messenger - metabolism; γ-Glutamylcysteine synthetase ( γ-GCS); Oxidative stress; Free radicals; Glutathione peroxidase (GPX); Embryo culture; Neural tube defects; γ-Glutamylcysteine synthetase ( γ-GCS); Glutathione-S transferase (GST); Hydrogen peroxide (H 2O 2); Glutathione (GSH)
• DOI: 10.1016/S0891-5849(96)00338-3
• ISSN: 0891-5849

We investigated the effect of glutathione (GSH)-dependent antioxidant system against hydrogen peroxide (H 2O 2) formation in oxygen-induced embryopathy. Exposure of rat embryos to a high concentration of oxygen (20%) during early neurulation (day 9 to 10) significantly increased the incidence of neural tube defects compared with control embryos (10% vs 0%, p < 0.01) exposed to a low O 2 concentration (5%). The concentration of GSH in 20% O 2-exposed embryos was significantly reduced compared with that in control embryos (10.68 ± 0.72 vs 12.34 ± 0.65 nmol/mg protein, p < 0.001). The activity of γ-glutamylcysteine synthetase ( γ-GCS), the rate-limiting GSH synthesizing enzyme increased in 20% O 2-exposed embryos (24.83 ± 0.71 vs 21.00 ± 0.94 microunits/mg protein). Increased activity of γ-GCS was associated with increased expression of γ-GCS mRNA. Substantial increases were also observed in the activities of glutathione peroxidase (GPX) and glutathione S-transferase (GST) in 20% O 2-exposed embryos. The formation of intracellular H 2O 2, measured by flow cytometer using 2′,7′-dichlorofluorescein diacetate (DCFH-DA), increased in isolated embryonic cells of 20% O 2-exposed embryos. The addition of buthionine sulfoxamine (BSO), a specific inhibitor of γ-GCS, to culture media exposed to 20% O 2 produced a marked decrease in the concentration of GSH in association with a further increase in the incidence of embryonic malformations (24.4% vs. 10%, P < 0.01). The addition of 2.0 mM GSH ester to culture media exposed to 20% O 2 prevented the development of embryonic malformations through the restoration of normal GSH contents and reduction of H 2O 2. Our results demonstrated that oxygen-induced embryonic malformations were induced by increased production of H 2O 2 in the presence of an immature free radical scavenger system. We suggest that impaired responsiveness of the GSH dependent antioxidant system against oxidative stress plays a crucial role in oxygen-induced embryopathy. Copyright © 1996 Elsevier Science Inc.