title: Effects of monocular enucleation on receptor binding and innervation pattern of the noradrenergic system in the superior colliculus of the pigmented rat.
abstract: To examine visual activity-dependent regulation of the central noradrenergic (NAergic) system, we carried out in vitro autoradiography for alpha2-, beta-adrenergic and NMDA, non-NMDA glutamatergic receptors together with immunohistochemical analysis for dopamine beta-hydroxylase in the major central visual structures, including the lateral geniculate nucleus, superior colliculus (SC), and visual cortex of pigmented rats, that had received monocular enucleation. Beta-adrenergic receptor (beta-AR) binding in the SC contralateral to the enucleated eye was significantly decreased (82%, P < 0.01) following monocular deprivation started at P12 and continued for 2 or 11 weeks. No significant change in beta-AR binding was found in other structures examined. The number of varicosities in NAergic fibers was significantly increased following longer enucleation, i.e. for 11 weeks, in the contralateral SC (197%, P <0.001), whereas that in the ipsilateral SC was reduced (75%, P <0.001). Changes in alpha2-adrenergic, NMDA, and non-NMDA glutamatergic receptor binding were small in these animals. Changes in neither beta-AR binding nor innervation pattern of NAergic fibers were found in one-year-old rats that had received a comparable period of monocular enucleation. Furthermore, neither unilateral ablation of the visual cortex to reduce a different set of major afferents nor neonatal enucleation, which induced anatomical reorganization of the afferents, was found to be effective. These findings suggest that beta-AR binding and innervation pattern of NAergic fibers in the SC are modified only when massive imbalance of retinal afferent activity is imposed during a limited period in early postnatal life (i.e. the sensitive period).
authors.affiliation: Subfemtomole Biorecognition Project, Japan Science and Technology Corporation, and Department of Neuroscience, Osaka Bioscience Institute.
authors.forename: K
authors.initials: K
authors.lastname: Muguruma
authors.forename: K
authors.initials: K
authors.lastname: Matsumura
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Shiomitsu
authors.forename: K
authors.initials: K
authors.lastname: Imamura
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D001345:Autoradiography; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D015353:Eye Enucleation; D007150:Immunohistochemistry; D009473:Neuronal Plasticity / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D012016:Reference Values; D013477:Superior Colliculi / Q000378:metabolism / Q000502:physiology*; D015349:Vision, Monocular / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology
chemical_list: D011941:Receptors, Adrenergic; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D004299:Dopamine beta-Hydroxylase; D009638:Norepinephrine