ALTERATION OF GLUTATHIONE AND ANTIOXIDANT STATUS WITH EXERCISE IN UNFED AND REFED RATS

The influences of food deprivation and refeeding on glutathione (GSH) status, antioxidant enzyme activity and lipid peroxidation in response to an acute bout of exercise were investigated in the liver and skele tal muscles of male Sprague-Dawley rats randomly divided into three gr oups: starved for 48 h without refeeding; starved for 48 h and refed f or 24 or 48 h. Half of each group of rats was exercised on a treadmill until exhaustion and killed immediately, whereas the other half group was killed at rest. Food-deprived rats had significantly lower liver GSH concentration and GSH:glutathione disulfide (GSSG) ratio. Malondia ldehyde concentrations in the liver and skeletal muscle were both high er in the starved than in the refed rats (P < 0.05). Refed rats had si gnificantly greater liver GSH level, gamma-glutamylcysteine synthetase and glucose 6-phosphate dehydrogenase activities and plasma insulin c oncentration than unfed rats. Exercised 24- and 48-h refed rats had 27 % and 31% lower liver GSH (P < 0.05), respectively, and a 21% lower GS H:GSSG ratio (P < 0.05) than their rested counterparts. Plasma insulin concentrations were significantly lower, whereas glucagon concentrati ons were greater in the exercised than in the rested rats. Muscle GSH concentration was significantly lower in the food-deprived than in the refed rats (P < 0.05) but was unaffected by exercise. Exercised 24-h refed rats had significantly elevated muscle GSSG concentration compar ed with rested rats, along with a higher GSH peroxidase and a lower ga mma-glutamyltranspeptidase activity (P < 0.05). These data indicate th at both food deprivation-refeeding and exhaustive exercise influence l iver and skeletal muscle glutathione status and that these changes may be controlled by hepatic glutathione synthesis and release due to hor monal stimulation.