TISSUE-SPECIFIC MODULATION OF RAT GLUCOCORTICOID RECEPTOR-BINDING ACTIVITY BY MELATONIN

The effect of melatonin and 2-Iodomelatonin on nuclear and cytosolic g lucocorticoid receptors in the brain, pituitary, thymus and liver has been examined. The results indicate that both melatonin and 2-Iodomela tonin administration is associated with marked changes in the density and the affinity of cytosolic and nuclear forms of glucocorticoid rece ptors. These observations are discussed in the context of a possible i nvolvement of pineal melatonin in the mechanisms regulating the behavi our and metabolism of steroid receptors.