title: Calcium signaling, excitability, and synaptic plasticity defects in a mouse model of Alzheimer's disease.
abstract: Alzheimer's disease (AD) and aging result in impaired ability to store memories, but the cellular mechanisms responsible for these defects are poorly understood. Presenilin 1 (PS1) mutations are responsible for many early-onset familial AD (FAD) cases. The phenomenon of hippocampal long-term potentiation (LTP) is widely used in studies of memory formation and storage. Recent data revealed long-term LTP maintenance (L-LTP) is impaired in PS1-M146V knock-in (KI) FAD mice. To understand the basis for this phenomenon, in the present study we analyzed structural synaptic plasticity in hippocampal cultures from wild type (WT) and KI mice. We discovered that exposure to picrotoxin induces formation of mushroom spines in both WT and KI cultures, but the maintenance of mushroom spines is impaired in KI neurons. This maintenance defect can be explained by an abnormal firing pattern during the consolidation phase of structural plasticity in KI neurons. Reduced frequency of neuronal firing in KI neurons is caused by enhanced calcium-induced calcium release (CICR), enhanced activity of calcium-activated potassium channels, and increased afterhyperpolarization. As a result, "consolidation" pattern of neuronal activity converted to "depotentiation" pattern of neuronal activity in KI neurons. Consistent with this model, we demonstrated that pharmacological inhibitors of CICR (dantrolene), of calcium-activated potassium channels (apamin), and of calcium-dependent phosphatase calcineurin (FK506) are able to rescue structural plasticity defects in KI neurons. Furthermore, we demonstrate that incubation with dantrolene or apamin also rescued L-LTP defects in KI hippocampal slices, suggesting a role for a similar mechanism. This proposed mechanism may be responsible for memory defects in AD but also for age-related memory decline.
authors.affiliation: Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA Department of Neurology and Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Suya
authors.initials: S
authors.lastname: Sun
authors.affiliation: Laboratory of Molecular Neurodegeneration, St Petersburg State Polytechnical University, St Petersburg, Russia.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Pchitskaya
authors.affiliation: Laboratory of Molecular Neurodegeneration, St Petersburg State Polytechnical University, St Petersburg, Russia.
authors.forename: Elena
authors.initials: E
authors.lastname: Popugaeva
authors.affiliation: Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA Laboratory of Molecular Neurodegeneration, St Petersburg State Polytechnical University, St Petersburg, Russia.
authors.forename: Ilya
authors.initials: I
authors.lastname: Bezprozvanny
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D049229:Dendritic Spines / Q000235:genetics; D004195:Disease Models, Animal; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000473:pathology; D010852:Picrotoxin / Q000494:pharmacology; D053764:Presenilin-1 / Q000235:genetics; D055366:Synaptic Potentials / Q000187:drug effects / Q000235:genetics; D013997:Time Factors
chemical_list: D002121:Calcium Channel Blockers; D000697:Central Nervous System Stimulants; D010852:Picrotoxin; D053764:Presenilin-1
keywords: Alzheimer's disease; calcium signaling; excitability; synaptic plasticity