Effect of melatonin on enzyme activities of glutathione reductase from human erythrocytes in vitro and from rat erythrocytes in vivo

For in vitro experiments, the enzyme activity increased at 0.02 mM and decreased at 0.08 mM melatonin concentration and reached a plateau above 0.08 mM. Melatonin was administered 10 mg/kg intraperitoneally (ip) and had a stimulatory effect on the enzyme. In vivo studies were performed for melatonin in Sprague-Dawley rats and time-dependent effects were demonstrated. Glutathione reductase activity in erythrocytes was increased more by melatonin at 1 and 3 h. These results indicate that pharmacological levels of melatonin increased enzyme activity in erythrocytes. They also indicate that melatonin may be pharmacologically useful in patients with a deficiency of the enzyme in red blood cells causing hemolytic anemia.