title: Antibodies against extracellular domains of α4 and α7 subunits alter the levels of nicotinic receptors in the mouse brain and affect memory: possible relevance to Alzheimer's pathology.
abstract: Nicotinic acetylcholine receptors (nAChRs) of α4β2 and α7 subtypes expressed in the brain neurons are involved in regulating memory and cognition. Their level is decreased upon several neurodegenerative disorders including Alzheimer's disease (AD), although the reasons for such a decrease are not completely understood. To test whether the nAChR-specific antibodies can affect the brain nAChRs and influence the behavior, we either immunized mice with recombinant extracellular domains of α4 and α7, subunits α4(1-209) and α7(1-208), or injected them with α7(1-208)-specific antibodies. A decrease of α4β2- and α7-nAChRs accompanied with an increase of α4β4-nAChRs in brain membranes of immunized mice was observed. Both α4(1-209)- and α7(1-208)-specific antibodies were detected in the brain membrane lysates of immunized mice. Antibody injection resulted in brain nAChR decrease only if mice were co-injected intraperitoneally with bacterial lipopolysaccharide. Brain sections of immunized mice were analyzed for the binding of [125I]-α-bungarotoxin and [125I]-epibatidine. A decrease in α-bungarotoxin binding in striatum (nucleus accumbens and caudate putamen) accompanied with an increase of epibatidine binding in the forebrain and caudate putamen was observed in mice immunized with either α4 or α7 nAChR domains compared to those immunized with BSA. Mice immunized with α7(1-208) demonstrated significantly worse episodic memory measured in a novel object recognition task compared to non-immunized animals but did not differ from the controls in locomotor or anxiety-related tests. These results suggest that nAChR-specific antibodies are able to penetrate the brain upon inflammation with resulting decreases of brain nAChRs and worsening episodic memory.
authors.affiliation: Palladin Institute of Biochemistry, Kyiv, Ukraine.
authors.forename: Olena
authors.initials: O
authors.lastname: Lykhmus
authors.forename: Lyudmyla
authors.initials: L
authors.lastname: Koval
authors.forename: Maryna
authors.initials: M
authors.lastname: Skok
authors.forename: Marios
authors.initials: M
authors.lastname: Zouridakis
authors.forename: Paraskevi
authors.initials: P
authors.lastname: Zisimopoulou
authors.forename: Socrates
authors.initials: S
authors.lastname: Tzartos
authors.forename: Victor
authors.initials: V
authors.lastname: Tsetlin
authors.forename: Sylvie
authors.initials: S
authors.lastname: Granon
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Changeux
authors.forename: Sergiy
authors.initials: S
authors.lastname: Komisarenko
authors.forename: Isabelle
authors.initials: I
authors.lastname: Cloëz-Tayarani
mesh_terms: D000544:Alzheimer Disease / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D000906:Antibodies / Q000009:adverse effects*; D001921:Brain / Q000276:immunology / Q000378:metabolism*; D045604:Extracellular Fluid / Q000276:immunology; D006801:Humans; D008297:Male; D008568:Memory; D061212:Memory, Episodic; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D021122:Protein Subunits / Q000037:antagonists & inhibitors / Q000276:immunology*; D011817:Rabbits; D011978:Receptors, Nicotinic / Q000276:immunology* / Q000502:physiology*; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: D000906:Antibodies; D021122:Protein Subunits; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; C579167:Chrna7 protein, human; C579166:Chrna7 protein, mouse