title: Combined Memantine and Donepezil Treatment Improves Behavioral and Psychological Symptoms of Dementia-Like Behaviors in Olfactory Bulbectomized Mice.
abstract: Memantine, an uncompetitive N-methyl-D-aspartate receptor antagonist, and the cholinesterase inhibitor, donepezil, are approved in most countries for treating moderate-to-severe Alzheimer's disease (AD). These drugs have different molecular targets; thus, it is expected that the effects of combined treatment would be synergistic. Some reports do show memantine/donepezil synergy in ameliorating cognition in AD model animals, but their combined effects on behavioral and psychological symptoms of dementia (BPSD)-like behaviors have not been addressed. Here, we investigate combined memantine/donepezil effects on cognitive impairment and BPSD-like behaviors in olfactory bulbectomized (OBX) mice. Interestingly, combined administration synergistically improved both depressive-like behaviors and impaired social interaction in OBX mice, whereas only weak synergistic effects on cognitive performance were seen. To address mechanisms underlying these effects, we used in vivo microdialysis study and observed impaired nicotine-induced serotonin (5-HT) release in OBX mouse hippocampus. Combined memantine/donepezil administration, but not single administration of either, significantly antagonized the decrease in nicotine-induced 5-HT release seen in OBX mouse hippocampus. Furthermore, decreased autophosphorylation of calcium/calmodulin dependent protein kinase II (CaMKII) was rescued in hippocampal CA1 and dentate gyrus of OBX mice by combined memantine/donepezil administration. These results suggest that improvement of BPSD-like behaviors by the co-administration of both drugs is in part mediated by enhanced 5-HT release and CaMKII activity in OBX mouse hippocampus.
authors.affiliation: Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yabuki
authors.forename: Kazuya
authors.initials: K
authors.lastname: Matsuo
authors.forename: Koga
authors.initials: K
authors.lastname: Hirano
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Shinoda
authors.forename: Shigeki
authors.initials: S
authors.lastname: Moriguchi
authors.forename: Kohji
authors.initials: K
authors.lastname: Fukunaga
mesh_terms: D000818:Animals; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage*; D003704:Dementia / Q000188:drug therapy* / Q000209:etiology / Q000523:psychology; D000077265:Donepezil; D004359:Drug Therapy, Combination; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage*; D007189:Indans / Q000008:administration & dosage*; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008559:Memantine / Q000008:administration & dosage*; D051379:Mice; D009830:Olfactory Bulb / Q000293:injuries* / Q000601:surgery; D010880:Piperidines / Q000008:administration & dosage*; D011897:Random Allocation; D016896:Treatment Outcome
chemical_list: D002800:Cholinesterase Inhibitors; D018691:Excitatory Amino Acid Antagonists; D007189:Indans; D010880:Piperidines; D000077265:Donepezil; D008559:Memantine