title: Enhanced antioxidant defense due to extracellular catalase activity in Syrian hamster during arousal from hibernation.
abstract: Mammalian hibernators are considered a natural model for resistance to ischemia-reperfusion injuries, and protective mechanisms against oxidative stress evoked by repeated hibernation-arousal cycles in these animals are increasingly the focus of experimental investigation. Here we show that extracellular catalase activity provides protection against oxidative stress during arousal from hibernation in Syrian hamster. To examine the serum antioxidant defense system, we first assessed the hibernation-arousal state-dependent change in serum attenuation of cytotoxicity induced by hydrogen peroxide. Serum obtained from hamsters during arousal from hibernation at a rectal temperature of 32 degrees C, concomitant with the period of increased oxidative stress, attenuated the cytotoxicity four-fold more effectively than serum from cenothermic control hamsters. Serum catalase activity significantly increased during arousal, whereas glutathione peroxidase activity decreased by 50%, compared with cenothermic controls. The cytoprotective effect of purified catalase at the concentration found in serum was also confirmed in a hydrogen peroxide-induced cytotoxicity model. Moreover, inhibition of catalase by aminotriazole led to an 80% loss of serum hydrogen peroxide scavenging activity. These results suggest that extracellular catalase is effective for protecting hibernators from oxidative stress evoked by arousal from hibernation.
authors.affiliation: Fujisaki Institute, Hayashibara Biochemical Laboratories, Inc. 675-1 Fujisaki, Okayama 702-8006, Japan. fujisaki@hayashibara.co.jp
authors.forename: Hitomi
authors.initials: H
authors.lastname: Ohta
authors.forename: Iwao
authors.initials: I
authors.lastname: Okamoto
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Hanaya
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Arai
authors.forename: Tsunetaka
authors.initials: T
authors.lastname: Ohta
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001143:Arousal / Q000502:physiology*; D002374:Catalase / Q000378:metabolism*; D006224:Cricetinae; D005260:Female; D005978:Glutathione / Q000097:blood; D005979:Glutathione Peroxidase / Q000097:blood; D005980:Glutathione Reductase / Q000097:blood; D006605:Hibernation / Q000502:physiology; D006861:Hydrogen Peroxide / Q000633:toxicity; D008647:Mesocricetus; D016716:PC12 Cells; D051381:Rats
chemical_list: D000975:Antioxidants; D006861:Hydrogen Peroxide; D002374:Catalase; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D005978:Glutathione