title: Overexpression of alpha2C-adrenoceptors impairs water maze navigation.
abstract: We investigated the role of overexpression of alpha2C-adrenoceptors in water maze navigation in mice transgenically manipulated to have a threefold overexpression of the alpha2C-adrenoreceptors. Alpha2C-adrenoreceptors overexpressing mice swam more in the peripheral annulus of the pool and did not find the hidden escape platform as well as the wild type control mice. A subtype-nonselective alpha2-adrenoreceptor antagonist, atipamezole (ATI, 1000 microg/kg, s.c.), fully reversed the deficit in platform finding and search strategy in overexpressing mice. Noradrenaline depletion (-95%) induced by N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) did not impair platform finding of wild type or overexpressing mice. The DSP-4 lesion slightly increased swimming in the peripheral annulus in wild type mice, but not in overexpressing mice. The DSP-4 lesion produced a dissociable effect on the action of atipamezole to improve platform finding and search strategy in overexpressing mice: atipamezole did not alleviate the platform finding deficit in DSP-4 lesioned overexpressing mice, but normalized their abnormal search strategy. These results suggest that the abnormal search pattern and deficit in the accuracy of platform finding are mediated by constitutive activity of overexpressed alpha2C-adrenoreceptors.
authors.affiliation: Department of Neurology and Neuroscience, University of Kuopio, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Björklund
authors.forename: J
authors.initials: J
authors.lastname: Sirviö
authors.forename: M
authors.initials: M
authors.lastname: Riekkinen
authors.forename: J
authors.initials: J
authors.lastname: Sallinen
authors.forename: M
authors.initials: M
authors.lastname: Scheinin
authors.forename: P
authors.initials: P
authors.lastname: Riekkinen
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006624:Hippocampus / Q000378:metabolism; D006719:Homovanillic Acid / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D014179:Neurotransmitter Uptake Inhibitors / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D018341:Receptors, Adrenergic, alpha-2 / Q000235:genetics*; D012153:Retention, Psychology / Q000187:drug effects / Q000502:physiology; D013037:Spatial Behavior / Q000187:drug effects / Q000502:physiology*; D013550:Swimming
chemical_list: C547775:Adra2c protein, mouse; D000317:Adrenergic alpha-Antagonists; D001596:Benzylamines; D007093:Imidazoles; D014179:Neurotransmitter Uptake Inhibitors; D018341:Receptors, Adrenergic, alpha-2; C050701:atipamezole; C012102:DSP 4; D009638:Norepinephrine; D006719:Homovanillic Acid