The study was carried out on 61 healthy donors of both sexes (aged 20-30). Blood samples were collected at two different timings viz., 10:00 a.m. and 10:00 p.m. PMRS and AFR reductase were determined by methods already reported. The concentration-dependent effect of the melatonin was evaluated by incubating the RBCs with the hormone at different doses.
We present results to show that erythrocyte PMRS and AFR reductase activity are modulated by melatonin, a higher activity (p < 0.05) of PMRS and AFR reductase is observed during night when the level of melatonin is high. The effect of in vitro treatment of erythrocytes with melatonin (10鈭? M to 10鈭?1 M final concentration) shows significant changes during day at a melatonin concentration of 10鈭? M.
To the best of our knowledge this study shows for the first time the circadian rhythmicity of erythrocyte PMRS and AFR reductase activities. The modulatory effect of melatonin on PMRS and AFR reductase opens the possibility of melatonin being used in treatment of such physiological and metabolic dysfunctions that involve photic cues in association with oxidative stress.