Induction of oxidative stress in Rana ridibunda during recovery from winter hibernation

The effect of transfer from winter hibernation at 5degreesC to a warm temperature (20degreesC for 1 or 24 h) on oxidative stress and-antioxidant defenses was assessed-in the frog, Rana ridibunda. The temperature increase had little effect on the levels of thiobarbituric acid reactive substances but carbonylprotein levels (581, 740, 1270 and 614 pmol/mg protein in brain, liver, kidney and muscle, respectively, at 5degreesC) mse 3.2-fold in brain and 2.6-fold in liver after transfer to 20degreesC. The switch to 20degreesC also affected the activities of antioxidant enzymes: catalase in liver, kidney and muscle rose 33%, 55% and 126%, respectively, whereas superoxide dismutase increased 2.4-fold in liver and 2.5-fold- in muscle. Glutathione reductase and glucose-6-phosphate dehydrogenase activities were also-affected in some organs. The data show that recovery from winter hibernation in frogs causes increased oxidative stress and stimulates an elevation of organ antioxidant defenses. (C) 2002 Elsevier Science Ltd. All rights reserved.