IRON DECREASES THE NUCLEAR BUT NOT THE CYTOSOLIC CONTENT OF THE NEUROHORMONE MELATONIN IN SEVERAL TISSUES IN CHICKS

This paper describes the influence of iron on both nuclear and cytosol ic melatonin contents in several tissues of chicks. The neurohormone m elatonin was estimated by means of radioimmunoassay. Iron, administere d as FeCl3, decreased the nuclear melatonin level in a variety of tiss ues, including brain, heart, lung, kidney, and erythrocytes (nucleated cells in chicks) but was not seen in either the liver or gut. All var iations related with iron were seen in the nuclear fraction, while onl y in the pineal gland did the melatonin content of the cytosol change as a result of iron treatment. We also observed a day-night rhythm in the nuclear melatonin: high nuclear levels of melatonin at night and l ow levels during the light period. This is the first report of nuclear localization of melatonin in any avian cell. (C) 1996 Wiley-Liss, Inc .