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Moriguchi S, Kita S, Iwamoto T, Fukunaga K. [Dysfunction of Na +/Ca 2+ exchangers is associated with cognitive decline in Alzheimer's disease]. Nihon Yakurigaku Zasshi 2018; 152:299-305. [PMID: 30531101 DOI: 10.1254/fpj.152.299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Na+/Ca2+ exchanger (NCX) is mainly expressed in the plasma membrane and mediates electrogenical exchange of one Ca2+ for three Na+, depending on the electrochemical gradients across the plasma membrane. NCX has three different isoforms (NCX1, NCX2, NCX3) encoded by distinct genes in mammals. Here, we report that NCX2 and NCX3 protein levels are relatively reduced in hippocampal CA1 of Alzheimer's disease model mice. Likewise, NCX2+/- or NCX3+/- mice exhibited impaired hippocampal LTP and memory-related behaviors. In immunoblot analyses, calcium/calmodulin-dependent protein kinase II (CaMKII) autophosphorylation significantly decreased in hippocampal CA1 of NCX2+/- mice compared to wild-type mice. By contrast, NCX2+/- mice was correlated with elevated calcineurin (CaN) activity and rescued by treatment with the calcineurin inhibitor FK506. Taken together, the imbalance of CaMKII and CaN activities with concomitant LTP impairment likely accounts for the learning disability observed in NCX2+/- mice.
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Affiliation(s)
- Shigeki Moriguchi
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University
| | - Satomi Kita
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University.,Department of Pharmacology, Faculty of Medicine, Fukuoka University
| | - Takahiro Iwamoto
- Department of Pharmacology, Faculty of Medicine, Fukuoka University
| | - Kohji Fukunaga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University
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Moriguchi S, Kita S, Inagaki R, Yabuki Y, Sasaki Y, Ishikawa S, Sakagami H, Iwamoto T, Fukunaga K. Aberrant Amygdala-Dependent Cued Fear Memory in Na +/Ca 2+ Exchanger 1 Heterozygous Mice. Mol Neurobiol 2018; 56:4381-4394. [PMID: 30324228 DOI: 10.1007/s12035-018-1384-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 10/08/2018] [Indexed: 02/06/2023]
Abstract
Na+/Ca2+ exchangers (NCXs) are mainly expressed in the plasma membrane and exchange one Ca2+ for three Na+, depending on the electrochemical gradients across the plasma membrane. NCXs have three isoforms, NCX1-3, encoded by distinct genes in mammals. Here, we report that heterozygous mice lacking NCX1 (NCX1+/-) exhibit impaired amygdala-dependent cued fear memory. NCX1+/- mice showed significant impairment in fear-related behaviors measured with the elevated-plus maze, light-dark, open-field, and marble-burying tasks. In addition, NCX1+/- mice showed abnormality in cued fear memory but not in contextual fear memory in a fear-conditioning task. In immunohistochemical analyses, NCX1+/- mice had significantly increased number of c-Fos-positive cells in the lateral amygdala (LA) but not in the central amygdala following fear-related tone stimuli. c-Fos expression peaked at 1 h. In concordance with the aberrant fear-related behaviors in NCX1+/- mice, enhanced long-term potentiation was also observed in the LA of these mice. Furthermore, enhancement of CaMKII or CaMKIV activity in the LA was observed in NCX1+/- mice by immunoblot analyses. In contrast, CaMKII+/- but not CaMKIV-/- mice insufficiently exhibited tone-induced cued fear memory and there was no increase in the number of c-Fos-positive cells in the LA. Altogether, the increased CaMKII activity and consequent c-Fos expression likely account for the dysregulation of amygdala-dependent cued fear memory in NCX1+/- mice.
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Affiliation(s)
- Shigeki Moriguchi
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan.
| | - Satomi Kita
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, 7-45-1, Nanakuma, Jonan-ku, Fukuoka, Fukuoka, 814-0180, Japan.,Department of Pharmacology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Ryo Inagaki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Yasushi Yabuki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Yuzuru Sasaki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Shun Ishikawa
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Takahiro Iwamoto
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, 7-45-1, Nanakuma, Jonan-ku, Fukuoka, Fukuoka, 814-0180, Japan.
| | - Kohji Fukunaga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan
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Reduced expression of Na +/Ca 2+ exchangers is associated with cognitive deficits seen in Alzheimer's disease model mice. Neuropharmacology 2017; 131:291-303. [PMID: 29274751 DOI: 10.1016/j.neuropharm.2017.12.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 12/08/2017] [Accepted: 12/20/2017] [Indexed: 11/21/2022]
Abstract
Na+/Ca2+ exchangers (NCXs) are expressed primarily in the plasma membrane of most cell types, where they mediate electrogenic exchange of one Ca2+ for three Na+ ions, depending on Ca2+ and Na+ electrochemical gradients across the membrane. Three mammalian NCX isoforms (NCX1, NCX2, and NCX3) are each encoded by a distinct gene. Here, we report that NCX2 and NCX3 protein and mRNA levels are relatively reduced in hippocampal CA1 of APP23 and APP-KI mice. Likewise, NCX2+/- or NCX3+/- mice exhibited impaired hippocampal LTP and memory-related behaviors. Moreover, relative to controls, calcium/calmodulin-dependent protein kinase II (CaMKII) autophosphorylation significantly decreased in NCX2+/- mouse hippocampus but increased in hippocampus of NCX3+/- mice. NCX2 or NCX3 heterozygotes displayed impaired maintenance of hippocampal LTP, a phenotype that in NCX2+/- mice was correlated with elevated calcineurin activity and rescued by treatment with the calcineurin (CaN) inhibitor FK506. Likewise, FK506 treatment significantly restored impaired hippocampal LTP in APP-KI mice. Moreover, Ca2+ clearance after depolarization following high frequency stimulation was slightly delayed in hippocampal CA1 regions of NCX2+/- mice. Electron microscopy revealed relatively decreased synaptic density in CA1 of NCX2+/- mice, while the number of spines with perforated synapses in CA1 significantly increased in NCX3+/- mice. We conclude that memory impairment seen in NCX2+/- and NCX3+/- mice reflect dysregulated hippocampal CaMKII activity, which alters dendritic spine morphology, findings with implications for memory deficits seen in Alzheimer's disease model mice.
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