ABSTRACT
Recently, melatonin is a broad-spectrum antioxidant for both animals and plants. It prevents oxidative damage at the level of cells, tissues, organs and organisms. In the present study, the effect of different doses of melatonin [10, 100, 500 and 1000 mu g] on the retinal rhodopsin was studied after different periods of 24 hr, one, three and five months. The rabbits were injected with melatonin daily early in the morning. After the studied periods, rhodopsin was extracted then the following measurements were carried out on it; purification of rhodopsin using a column of calcium triphosphate and celite; electrophoretic separation using SDS-polyacrylamide gel and dielectric measurements in the frequency range of 105 - 107 Hz. The obtained results indicated that there was no change in the molecular weight of rhodopsin at different doses and periods. The dipole moment was decreased at low doses and increased at high doses of melatonin. From the obtained results, it was concluded that melatonin at physiological doses could be useful for the eye