The effect of melatonin on eye lens of rats exposed to ultraviolet radiation

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology Vol. 129; no. 1; pp. 57 - 63
• Main Authors: Anwar, Mamdouh M, Moustafa, Mohsen A
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2001
• Subjects: Animals; Antioxidant enzymes; Antioxidants - pharmacology; Biological Assay; Calcium - metabolism; Calcium ions cataract; Cataract - etiology; Cataract - metabolism; Glutathione Peroxidase - metabolism; L-Lactate Dehydrogenase - metabolism; LDH; Lens, Crystalline - drug effects; Lens, Crystalline - metabolism; Lens, Crystalline - radiation effects; Lipid Peroxidation - drug effects; Male; Melatonin; Melatonin - pharmacology; Oxidative Stress; Radiation-Protective Agents - pharmacology; Rat lens; Rats; Rats, Sprague-Dawley; Superoxide Dismutase - metabolism; Ultraviolet radiation; Ultraviolet Rays - adverse effects; LDH; Melatonin; Ultraviolet radiation; Calcium ions cataract; Rat lens; Antioxidant enzymes
• ISSN: 1532-0456; 1878-1659
• DOI: 10.1016/S1532-0456(01)00180-6

We investigated the influence of exogenously administered melatonin on adult rats eye lenses exposed to ultraviolet radiation (UV) A and B ranging from 356–254 nm irradiation at 8 μW/cm 2. Rats exposed to this range of UV for 15 min for one week showed a significant ( P<0.05) reduction in antioxidant enzymes activities; superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and elevated ( P<0.001) lipid peroxidation served as an index of cellular damage by free radicals. UV-radiation significantly ( P<0.001) elevated calcium ions (Ca 2+) and lactate dehydrogenase (LDH) activity in lenses. Depleting animals of their stores of important intracellular antioxidant and elevating lenticular Ca 2+ by UV irradiation, may be the main cause of lens opacification. Melatonin injection with radiation significantly reduced ( P<0.05) lipid peroxidation, Ca 2+ and ( P<0.001) for LDH. When melatonin was injected after radiation, SOD and GSH-Px enzyme activities increased significantly ( P<0.01), and lipid peroxidation, Ca 2+ levels and LDH activities were reduced significantly. Melatonin injection after UV radiation was as effective as melatonin treatment concurrent with UV irradiation. We conclude that melatonin may protect the eye lens from the damaging effects of UV exposure, and its actions protect lens from oxidative stress, elevating Ca 2+ levels, which are considered as an important causes of cataractogenesis.