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Melatonin Binding Sites
Author(s) -
Vaněček Jiří
Publication year - 1988
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1988.tb01108.x
Subject(s) - melatonin , median eminence , pars tuberalis , choroid plexus , binding site , dissociation constant , medicine , endocrinology , pineal gland , biology , hypothalamus , pinealocyte , melatonin receptor , neurotoxin , pituitary gland , chemistry , central nervous system , biochemistry , receptor , hormone
The distribution and characterization of specific melatonin binding sites were studied using 125 I‐melatonin. Autoradiography revealed only three sites of specific melatonin binding in brain: the suprachiasmatic nuclei, the median eminence, and the small part of choroid plexus at the caudal end of the fourth ventricle. Two other sites were detected outside the CNS: the anterior pituitary and the retina. The specific binding of 125 I‐melatonin was saturable and reversible. The dissociation constant ( K D ) of the binding sites was 60 p M . The concentration of the binding sites ( B max ) in the median eminence was 26 fmol/mg protein, and in the pituitary 3 fmol/mg protein. Specificity of the binding sites was tested by displacement of 125 I‐melatonin. The order of potency—melatonin ≪ N ‐acetyl‐5‐hydroxytryptamine < 5‐methoxytryptamine ≪ 5‐hydroxytryptamine = 3,4‐dihydroxyphenylethylamine = noradrenaline—shows high specificity of the binding sites for melatonin.