title: NMDA receptor binding in rodent suprachiasmatic nucleus.
abstract: NMDA receptors are thought to mediate effects of light on circadian rhythms and on immediate-early gene expression in the suprachiasmatic nucleus (SCN), the primary circadian  pacemaker in mammals. The present study characterized NMDA receptors in autoradiographs of SCN incubated with the NMDA antagonist [3H]MK-801. In both rat and hamster, [3H]MK-801 binding did not delineate the SCN and was fairly uniformly distributed across the SCN region. Binding levels were unaffected by circadian time, light vs. dark conditions, or enucleation. Scatchard analyses revealed species differences in both receptor number and affinity in the SCN. The [3H]MK-801 binding sites characterized in this study could mediate the NMDA antagonist-sensitive effects of light on the SCN and circadian rhythms.
authors.affiliation: Department of Biological Sciences, University of North Texas, Denton 76203-5218.
authors.forename: M D
authors.initials: MD
authors.lastname: Hartgraves
authors.forename: J L
authors.initials: JL
authors.lastname: Fuchs
mesh_terms: D000818:Animals; D001345:Autoradiography; D002940:Circadian Rhythm / Q000502:physiology; D006224:Cricetinae; D003624:Darkness; D016291:Dizocilpine Maleate / Q000493:pharmacokinetics / Q000494:pharmacology; D015353:Eye Enucleation; D007700:Kinetics; D008027:Light; D008297:Male; D008647:Mesocricetus; D016202:N-Methylaspartate / Q000494:pharmacology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012160:Retina / Q000378:metabolism; D013045:Species Specificity; D013493:Suprachiasmatic Nucleus / Q000033:anatomy & histology / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate