Diurnal rhythm of melatonin binding in the rat suprachiasmatic nucleus.
We used quantitative in vitro autoradiography to localize and characterize 2-125I-melatonin binding sites in the rat suprachiasmatic nuclei in relation to pineal melatonin production. In a light:dark cycle of 12:12 h, binding density exhibited significant diurnal variation with a peak at the dark-light transition and a trough 12 hours later. Saturation studies suggested that the decreased binding at light-dark transition might be due to a shift of the putative melatonin receptor to a low affinity state.
Laitinen
J T
JT
Unit on Preclinical Neuropharmacology, National Institute of Mental Health, Bethesda, MD 20892.
Castren
E
E
Vakkuri
O
O
Saavedra
J M
JM
D000818:Animals; D002940:Circadian Rhythm; D007457:Iodine Radioisotopes; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D010507:Periodicity; D010870:Pineal Gland / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*
D007457:Iodine Radioisotopes; D008550:Melatonin