Circadian variations in melatonin-binding sites in discrete areas of the male rat brain

Nava Zisapel*, Isaac Nir, Moshe Laudon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


The binding of 125I-melatonin to synaptosomes prepared from whole brains of male rats of the CD strain and from the brain, hypothalamus and striatum of male rats of the Sabra-Wistar strain was assessed throughout a 24 h period. The animals were maintained under a daily schedule of 14 h light (05:00-19:00 h) and 10 h darkness. In whole brain preparations the density of binding sites at 18:00 h was higher by about 70% than at 02:00 h with no variations in apparent affinity of the binding sites throughout the daily period. Specific binding of 125I-melatonin was found in both hypothalamus and striatum of the male rat with a distinct diurnal variation in binding site density in the hypothalamus only. The density of 125I-melatonin-binding sites in the hypothalamus was maximal between 10:00 and 18:00 h and dropped sharply after the lights went off. The apparent 125I-melatonin-binding affinities in these regions were constant and very similar to those in whole brain preparations. The daily variations in densities of 125I-melatonin-binding sites in discrete brain areas may represent a diurnal rhythmicity in the responsiveness of the neuroendocrine axis to melatonin.

Original languageEnglish
Pages (from-to)172-176
Number of pages5
JournalFEBS Letters
Issue number1
StatePublished - 9 May 1988


FundersFunder number
Israel Academy of Sciencesa nd Humanities,B asic Research Foundation


    • (Rat brain)
    • Binding site
    • Circadian rhythm
    • Iodomelatonin
    • Melatonin


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