• Development and Reproduction
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• v.12 no.1
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• pp.9-18
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• 2008

All the organisms on the earth are affected by the repeating signals from the ambient environment caused by the movements of the sun and the earth. Their physiological and behavioral activities such as reproduction, functional pathway of various molecules, and developmental stage, are reflected by the cyclicity whether it is daily(circadian) or annual rhythms. An essential function of circadian rhythms is to provide an internal estimate of the external local time, thereby allowing the organism to program its activities so that they occur at an appropriate time in the daily environment. Of many rhythmic patterns, the circadian rhythms are considered in this review, focusing on the limit cycle, which is a model to investigate the entrainment.

• Journal of Nutrition and Health
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• v.34 no.8
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• pp.872-880
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• 2001

The purpose of this study was to investigate the effects of glucuronic acid on antioxidative defense system and recovery of muscle fatigue in rat artier aerobic exercise. Sprague-Dawley male rats weighing 150 $\pm$ 10g were randomly assigned to one normal(N) group and three exercise training groups. Exercise training groups were classified into glucuronic acid free intubation group(T group), 250mg glucuronic acid/kg bw intubation group(TU group), and 500 mg glucuronic acid/kg bw intubation group(2TU group) according to glucuronic acid supplementation level. The glucuronic acids were administered to rats by oral intubation before exercise training. The experimental rats in exercise training groups(T, TU and 2TU) were exercised on glucuronic acid supplementation or rats in normal group were confined in cage for 4 weeks. And rats were sacrificed with an overdose of pentobarbital injection just after running. Liver xanthine oxidase(XOD) activities were not significantly different among four groups. The activity of superoxide dismutase(SOD) in T group was no significant difference from N group, but those of TU and 2TU groups were increased by 9% and 18%, respectively, compared with that of T group. Liver glutathione peroxidase(GSHpx) activites of T and TU groups showed a similar tendency to that of normal group, but increase 17% in 2TU group compared with normal group. The ratio of GSH/GSSG in liver of T group was lower than that of normal group, but those of TU and 2TU groups were a similar tendency to that of normal group. Contents of thiobarbituric acid reactive substance(TBARS) in T group was increased by 47%, compared with that of normal group but those of TU group and 2TU group were lower 27% and 35%, respectively, compared with that of T group. The contents of glycogen in soleus muscle significantly lower in all three trained exercise groups than that of normal group, but there were no significant differences among the trained exercise groups. Contents of hepatic glycogen in T group were decreased 27% compared with those of normal group while those of TU and 2TU groups were the same as normal group levels. The contents of serum lactic acid in T group were increased 240% of normal group, but hose of TU and 2TU groups were decreased 38%, 39%, respectively, by glucuronic acid supplementations, compared with that of T group. In conclusion, the effects of glucuronic acids in exercise training rats would appear to reduce peroxidation of tissue as an antioxidative defense mechanism and promote recovery of muscle fatigue.

• Journal of Yeungnam Medical Science
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• v.17 no.1
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• pp.21-30
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• 2000

Background: The purpose of the present study was to investigate the effect of exercise on the activities of antioxidant enzymes, super oxide dismutase(SOD), glutathione peroxidase(GPX) and catalase(CAT) of skeletal muscle(gastrocnemius) and liver in streptozotocin(STZ) induced diabetic rats. The malondialdehyde(MDA) concentration was also measured as an index of lipid poroxidation of tho tissues by exercise-induced oxidative stresses in diabetic rats. Material and Methods: Male Sprague-Dawley rats were randomly divided into control and STZ-induced diabetic rats. The STZ in citrate buffer solution was injected twice at S days intervals intraperitoneally(50, 70 mg/kg respectively). On the 28th day after the first STZ injection, the diabetic animals were randomly divided into pre- and post-exercise groups, The exercise was introduced to the rats of post-exercise group by treadmill running until exhaution with moderate intensity ($V_{O2max}$: 50-70%) of exercise. The duration of average running time was 2 hours and 19 minutes. Results: The blood glucose concentration was increased(p<0.001) and plasma insulin concentration was decreased(p<0.001) in the diabetic rats. The glycogen concentration in the muscle and liver was decreased by exhaustive exercise in the diabetic rats(p<0.001), In the skeletal muscle, the activities of GPX was increased(p<0.05) and the activities of SOD and CAT were not changed in the diabetic rats compare to those of the control rats. The activities of GPX was not changed by exercise but the activities of SOD(p<0.01) and CAT(p<0.01) were decreased by exercise in the diabetic rats, The concentration of MDA was not changed by exercise in diabetic rats, and the values of pre-exercise and post-exercise diabetic rats were not different from the value those of control rats, In the liver, the activities of SOD was decreased(p<0.01), and the activities of GPX and CAT were not changed in diabetic rats compared to the values of control rats, The activities of SOD, GPX and CAT were not changed by exercise in diabetic rats but the activity of SOD seemed to decrease slightly, The MDA concentration was increased in the diabetic rats compared to the values of control rats(p<0.001), but there was no change of MDA concentration by exercise in diabetic rats, Conclusions: In summary, exhaustive physical exercise did not seem to impose oxidative stress on the skeletal muscle because of due to oxygen free radicals, regardless of the decrease in SOD and CAT in the diabetic rats, In liver tissue, the tissue damage by oxidative stress was observed in diabetic rats but the additional tissue damage by exhaustive physical exercise was not observed.