Enhanced antioxidative defense in Syrian hamster during arousal from hibernation

Abstract

Mammalian hibernators are often regarded as a unique natural model for resistance to ischemia/reperfusion injuries. However, their protective mechanisms against oxidative stress evoked by repeated torpor-arousal cycles are yet to be elucidated. To study the blood antioxidant status during arousal from hibernation in Syrian hamsters, we determined the levels of uric acid (UA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in the blood. The plasma UA level, an in vivo indicator of reactive oxygen species (ROS) generation, showed a significant increase in mid- to late-arousal phase. Concomitant with the increase of UA, both SOD and CAT activities increased transiently in blood during arousal, whereas GPx activity decreased by 50%, as compared with the cenothermic control. We also found that the increased SOD activity was ascribed to the extracellular SOD (EC-SOD). These results suggest that both EC-SOD and CAT may play some roles in the antioxidative defense of hibernating hamsters by scavenging ROS, which evoked by torpor-arousal cycles. [J Physiol Sci. 2007;57 Suppl:S180]