Autoradiographic localization of putative melatonin receptors in the brains of two Old World primates: Cercopithecus aethiops and Papio ursinus

摘要: The distribution of putative melatonin receptors in the brains two Old World primates superfamily Catarrhina, Cercopithecus aethiops and Papio ursinus, was characterized using 2-[125I]iodomelatonin autoradiography. specific binding demonstrated a discrete pattern. median eminence intensely labelled, examination at light microscopic level that confined to small layer cells comprising pars tuberalis pituitary gland. collar distalis, present baboon (Papio ursinus), diffusely labelled. No detected distalis proper or neural lobe suprachiasmatic nuclei weaker, but well discernible. Diffuse faint found frontal cortex dentate gyrus hippocampus. Two non-neural sites expressed strong, well-delineated binding: walls some brain blood vessels (the vertebral spinal arteries, inferior cerebellar acoustic basilar, pericallosal, internal carotid arteries forming circle Willis) choroid plexuses. Binding Willis, readily displaceable. Addition 1 microM unlabelled 2-iodomelatonin following 45 min preincubation with radioactive ligand completely abrogated binding. Co-incubation guanosine 5'-O-(3-thiotriphosphate) led significant decrease apparent density abolished nuclei, without effect on adjacent This qualitative pattern demonstrates primate species studied, high-affinity, G-protein-linked are hypothalamic may be acting as synchronizer endogenous pacemakers' circadian activity, apart from its possible reproductive effects tuberalis, where highest receptor observed. strongly labelled arterial walls, flimsy hippocampus, different characteristics: though reversible, it apparently not regulated by guanine nucleotide-binding protein.