Localization and characterization of melatonin receptors in rodent brain by in vitro autoradiography.

摘要: Little is known of the neural sites action for pineal hormone, melatonin. Thus, we developed an in vitro autoradiographic method using 125I-labeled melatonin (I-MEL) to study putative receptors rodent brain. We first determined optimal labeling conditions detection I-MEL binding rat median eminence, most intensely labeled area then assessed pharmacologic and kinetic properties eminence by quantitative autoradiography. These have high affinity (equilibrium dissociation constant = 43 pM). was inhibited nanomolar concentrations or 6-chloromelatonin, but not serotonin, dopamine, norepinephrine (100 microM). results suggest that I- MEL identified autoradiography represent specific, high-affinity receptors. Studies distribution rat, Syrian hamster, Djungarian hamster brain confirm suprachiasmatic nucleus are major brain; other areas one more these species were thalamus (paraventricular, anteroventral, reuniens nuclei, stria medullaris, medial part lateral habenular nucleus), hypothalamus (dorsomedial subiculum, postrema. The presence nuclei suggests regions important loci effects on circadian rhythms reproduction.