Activity of the glutathione system and NADPH-generating enzymes under the action of melatonin during cerebral ischemia/reperfusion in rats

Abstract

Due to the involvement of oxidative stress in brain ischemic damage and to antioxidant properties of the hormone melatonin, it was relevant to study the effect of melatonin on antioxidant enzymes and some enzymes of oxidative metabolism that limit free radical processes in pathology. The aim was to study the effect of melaxen, a melatonin analogue, on activities of glutathione peroxidase, glutathione reductase, and glutathione transferase, content of reduced glutathione, and activities of glucose-6-phosphate dehydrogenase and NADP-isocitrate dehydrogenase, which can supply NADPH to the glutathione antioxidant system, in the brain and blood serum of rats with cerebral ischemia/reperfusion. Methods. White male rats were used in the study. Cerebral ischemia was induced by 30-min occlusion of common carotid arteries; reperfusion was induced by removing the occlusion. Activities of enzymes and concentration of reduced glutathione were measured spectrophotometrically. Results. Melaxen reversed the increased enzyme activities and the reduced glutathione level induced by the pathological conditions returning them to the control values. This can be explained by inhibition of free radical processes under the action of the antioxidant melatonin and its neuroprotective effect in oxidative stress associated with disorders of cerebral circulation. The result is decreased mobilization of the antioxidant system and some enzymes of oxidative metabolism, which act as a single system in the adaptive response. Conclusion. The study justified further investigation of the possibility for using melatonin-correcting agents for pharmacological correction of metabolic changes in such pathologies.