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The pineal hormone melatonin has been shown to directly scavenge free radicals and to stimulate, in the mammalian brain, at least one enzyme, glutathione peroxidase, which reduces free radical generation. In the present studies, we examined the effect of melatonin on glutathione peroxidase activity in several tissues of an avian species. Melatonin (500(More)
Melatonin was detected by an improved immunocytochemical technique in the cell nuclei of most tissues studied including several brain areas, pineal gland, Harderian gland, gut, liver, kidney, and spleen from rodents and primates. Cryostat sections from tissues fixed in Bouin's fluid, formalin, or acetone/ethanol were used. The nuclear staining appeared(More)
High-affinity 2-125I-iodomelatonin binding sites in homogenates of purified cell nuclei from rat liver were localized and characterized using biochemical binding techniques. Binding at these sites was found to be rapid, reversible, saturable, and to demonstrate pharmacological selectivity. At 0 degrees C, binding reached equilibrium in about 10 min.(More)
Specific binding of [125I]iodomelatonin to homogenates from purified rat liver nuclei was characterized. The binding is rapid, reversible, saturable and of high affinity. Specific binding seems to be found in the nuclear protein fraction, since after precipitation of the proteins with trichloroacetic acid, the specific binding disappeared. The Kd (180 +/-(More)
Hyperbaric oxygen exposure rapidly induces lipid peroxidation and cellular damage in a variety of organs. In this study, we demonstrate that the exposure of rats to 4 atmospheres of 100% oxygen for 90 min is associated with increased levels of lipid peroxidation products [malonaldehyde (MDA) and 4-hydroxyalkenals (4-HDA)] and with changes in the activities(More)
Exogenously administered melatonin causes a 2-fold rise in glutathione peroxidase activity within 30 min in the brain of the rat. Furthermore, brain glutathione peroxidase activity is higher at night than during the day and is correlated with high night-time tissue melatonin levels. Glutathione peroxidase is thought to be the principal enzyme eliminating(More)
Melatonin was recently shown to be a component of the antioxidative defense system of organisms due to its free radical scavenging and antioxidant activities. Pharmacologically, melatonin stimulates the activity of the peroxide detoxifying enzyme glutathione peroxidase in rat brain and in several tissues of chicks. In this report, we studied the endogenous(More)
Carbon tetrachloride (CCl4) exerts its toxic effects by the generation of free radicals. In this study we investigated whether melatonin, a potent free radical scavenger, could prevent the deleterious effects of CCl4. Liver homogenates and liver microsomes were incubated with CCl4 in the presence of melatonin and lipid peroxidation and glucose-6 phosphatase(More)
Melatonin was recently shown to be a component of the antioxidative defense system of organisms due to its free radical scavenging ability and to its capacity to stimulate several antioxidant enzymes. In this report, we studied the endogenous rhythm of the antioxidant enzyme superoxide dismutase (SOD) in three different tissues (cerebral cortex, liver and(More)