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Li XT. Alzheimer's disease therapy based on acetylcholinesterase inhibitor/blocker effects on voltage-gated potassium channels. Metab Brain Dis 2022; 37:581-587. [PMID: 35098414 DOI: 10.1007/s11011-022-00921-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 01/24/2022] [Indexed: 01/11/2023]
Abstract
Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder with progressive loss of memory and other cognitive functions. The pathogenesis of this disease is complex and multifactorial, and remains obscure until now. To enhance the declined level of acetylcholine (ACh) resulting from loss of cholinergic neurons, acetylcholinesterase (AChE) inhibitors are developed and successfully approved for AD treatment in the clinic, with a limited therapeutic effectiveness. At present, it is generally accepted that multi-target strategy is potently useful for designing novel drugs for AD. Accumulated evidence reveals that Kv channels, which are broadly expressed in brain and possess crucial functions in modulating the neuronal activity, are inhibited by several acetylcholinesterase (AChE) inhibitors, such as tacrine, bis(7)-tacrine, donepezil and galantamine. Inhibition of Kv channels by these AChE inhibitors can generate neuroprotective effects by either mitigating Aβ toxicity and neuronal apoptosis, or facilitating cell proliferation. These inhibitory effects provide additional explanations for clinical beneficial effectiveness of AChE inhibitors, meaning that Kv channel is a promising candidate target for novel drugs for AD therapy.
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Affiliation(s)
- Xian-Tao Li
- Department of Neuroscience, South-Central University for Nationalities, 182 Minyuan Road, Wuhan, 430074, China.
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2
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Stone TW. Does kynurenic acid act on nicotinic receptors? An assessment of the evidence. J Neurochem 2020; 152:627-649. [PMID: 31693759 PMCID: PMC7078985 DOI: 10.1111/jnc.14907] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/19/2019] [Accepted: 10/30/2019] [Indexed: 02/06/2023]
Abstract
As a major metabolite of kynurenine in the oxidative metabolism of tryptophan, kynurenic acid is of considerable biological and clinical importance as an endogenous antagonist of glutamate in the central nervous system. It is most active as an antagonist at receptors sensitive to N-methyl-D-aspartate (NMDA) which regulate neuronal excitability and plasticity, brain development and behaviour. It is also thought to play a causative role in hypo-glutamatergic conditions such as schizophrenia, and a protective role in several neurodegenerative disorders, notably Huntington's disease. An additional hypothesis, that kynurenic acid could block nicotinic receptors for acetylcholine in the central nervous system has been proposed as an alternative mechanism of action of kynurenate. However, the evidence for this alternative mechanism is highly controversial, partly because at least eight earlier studies concluded that kynurenic acid blocked NMDA receptors but not nicotinic receptors and five subsequent, independent studies designed to repeat the results have failed to do so. Many studies considered to support the alternative 'nicotinic' hypothesis have been based on the use of analogs of kynurenate such as 7-chloro-kynurenic acid, or putatively nicotinic modulators such as galantamine, but a detailed analysis of the pharmacology of these compounds suggests that the results have often been misinterpreted, especially since the pharmacology of galantamine itself has been disputed. This review examines the evidence in detail, with the conclusion that there is no confirmed, reliable evidence for an antagonist activity of kynurenic acid at nicotinic receptors. Therefore, since there is overwhelming evidence for kynurenate acting at ionotropic glutamate receptors, especially NMDAR glutamate and glycine sites, with some activity at GPR35 sites and Aryl Hydrocarbon Receptors, results with kynurenic acid should be interpreted only in terms of these confirmed sites of action.
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Affiliation(s)
- Trevor W. Stone
- Institute for Neuroscience and PsychologyUniversity of GlasgowGlasgowG12 8QQUK
- Present address:
Kennedy InstituteNDORMSUniversity of OxfordOxfordOX3 7FYUK
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3
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Chen M, Chen Y, Wang X, Zhou Y. Quantitative determination of talatisamine and its pharmacokinetics and bioavailability in mouse plasma by UPLC-MS/MS. J Chromatogr B Analyt Technol Biomed Life Sci 2019; 1124:180-187. [PMID: 31207562 DOI: 10.1016/j.jchromb.2019.06.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 05/17/2019] [Accepted: 06/07/2019] [Indexed: 11/17/2022]
Abstract
Talatisamine, as the efficacy ingredient of Aconitum, was known as a novel specific blocker for the delayed rectifier K+ channels in rat hippocampal neurons. In this study, a rapid, selective and reproducible UPLC-MS/MS separation method was established and fully validated for the quantitative determination of talatisamine levels in ICR (Institute of Cancer Research) mouse blood. A total of 24 healthy male ICR mice were divided into four groups that was administered talatisamine via intravenous at a dose of 1 mg/kg and oral administration of three doses (2, 4, 8 mg/kg). All blood samples were protein precipitate by using acetonitrile with an internal standard (IS) deltaline. The effective chromatographic separation was carried out through an UPLC BEH C18 analytical column (2.1 mm × 50 mm, 1.7 μm) with an initial mobile phase that consisted of acetonitrile and 10 mmol/L ammonium acetate aqueous solution (containing 0.1% formic acid) with a gradient elution pumped at a flow rate of 0.4 mL/min. Also, an electrospray ionization (ESI) was applied to quantify the talatisamine in the positive ions mode. The method validation demonstrated good linearity over the range of 1-1000 ng/mL (r2 ≥ 0.9993) for talatisamine in mouse blood with a lower limit of quantification (LLOQ) at 1 ng/mL. The accuracy values of the method were within 89.4% to 113.3%, and the matrix effects were between 103.2% and 106.3%. The mean extraction recoveries for talatisamine obtained from four concentrations of QC blood samples were exceeded 71.7%, and the relative standard deviation (RSD) both of intra- and inter-day precision values for replicate quality control samples did not exceed 15% respectively for all analytes during the assay validation. This method was successfully applied to the evaluation of the pharmacokinetic of talatisamine, regardless of intragastric or intravenous administration in mice. Based on the pharmacokinetics data, the bioavailability of talatisamine in mice was >65.0% after oral administration, exhibiting an excellent oral absorption.
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Affiliation(s)
- Mengchun Chen
- The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, Zhejiang, China
| | - Yijie Chen
- The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, Zhejiang, China
| | - Xianqin Wang
- Analytical and Testing Centre, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China.
| | - Yunfang Zhou
- The Laboratory of Clinical Pharmacy, The People's Hospital of Lishui, Lishui 323000, China.
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Huang IY, Hsu YL, Chen CC, Chen MF, Wen ZH, Huang HT, Liu IY. Excavatolide-B Enhances Contextual Memory Retrieval via Repressing the Delayed Rectifier Potassium Current in the Hippocampus. Mar Drugs 2018; 16:md16110405. [PMID: 30366389 PMCID: PMC6266063 DOI: 10.3390/md16110405] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 10/21/2018] [Accepted: 10/22/2018] [Indexed: 12/18/2022] Open
Abstract
Memory retrieval dysfunction is a symptom of schizophrenia, autism spectrum disorder (ASD), and absence epilepsy (AE), as well as an early sign of Alzheimer’s disease. To date, few drugs have been reported to enhance memory retrieval. Here, we found that a coral-derived natural product, excavatolide-B (Exc-B), enhances contextual memory retrieval in both wild-type and Cav3.2−/− mice via repressing the delayed rectifier potassium current, thus lowering the threshold for action potential initiation and enhancing induction of long-term potentiation (LTP). The human CACNA1H gene encodes a T-type calcium channel (Cav3.2), and its mutation is associated with schizophrenia, ASD, and AE, which are all characterized by abnormal memory function. Our previous publication demonstrated that Cav3.2−/− mice exhibit impaired contextual-associated memory retrieval, whilst their retrieval of spatial memory and auditory cued memory remain intact. The effect of Exc-B on enhancing the retrieval of context-associated memory provides a hope for novel drug development.
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Affiliation(s)
- Irene Y Huang
- Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien 970, Taiwan.
| | - Yu-Luan Hsu
- Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien 970, Taiwan.
| | - Chien-Chang Chen
- Institute of Biomedical Sciences, Academia Sinica, 128, Academia road, Section 2, Nangang, Taipei 115, Taiwan.
| | - Mei-Fang Chen
- Cardiovascular and Metabolomics Research Center, Department of Medical Research, Buddhist Tzu Chi General Hospital, Hualien 970, Taiwan.
| | - Zhi-Hong Wen
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung 804, Taiwan.
| | - Hsien-Ting Huang
- Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien 970, Taiwan.
- Institute of Medical Sciences, Tzu Chi University, Hualien 970, Taiwan.
| | - Ingrid Y Liu
- Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien 970, Taiwan.
- Institute of Medical Sciences, Tzu Chi University, Hualien 970, Taiwan.
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5
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Paeonol promotes hippocampal synaptic transmission: The role of the Kv2.1 potassium channel. Eur J Pharmacol 2018; 827:227-237. [PMID: 29550337 DOI: 10.1016/j.ejphar.2018.03.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 03/09/2018] [Accepted: 03/14/2018] [Indexed: 12/30/2022]
Abstract
Paeonol is a major constituent of the Chinese herb Moutan cortex radices. Recent studies report that paeonol has neuroprotective effects and improves impaired learning and memory. However, its underlying mechanisms by which paeonol contributes to synaptic transmission remain unclear. In this study, we found that paeonol increased the frequency of miniature excitatory postsynaptic currents (mEPSCs) and spontaneous excitatory postsynaptic currents (sEPSCs), but had no effect on the amplitude in rat hippocampal CA1 neurons. Similarly, the acetylcholinesterase (AChE) inhibitor rivastigmine increased the frequency of mEPSCs, but had no effect upon amplitude in rat hippocampal neurons. Rivastigmine also inhibited the delayed outward K+ currents in rat hippocampal CA1 neurons, but had no effect in nucleus ambiguus (NA) neurons. The Kv2 blocker guangxitoxin-1E increased the frequency of both mEPSCs and sEPSCs of rat hippocampal CA1 neurons, without affecting their amplitude. Our results suggest that paeonol and rivastigmine enhance spontaneous presynaptic transmitter release, which may be associated with the inhibition of the hippocampal Kv2 current and with therapeutic potential in neurotransmitter deficits found in Alzheimer's disease (AD). Moreover, our data also show that paeonol protects against Aβ25-35-induced impairment of long-term potentiation (LTP) in mouse hippocampal neurons. However, guangxitoxin-1E failed to potentiate the evoked field excitatory postsynaptic potentials (fEPSPs), LTP and Aβ25-35-induced impairment of LTP. These results indicate that paeonol may has the potential to improve learning and memory in AD. Interestingly, this effect is not involved in the inhibition of the hippocampal Kv2 current.
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6
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Recent advancements in liposomes targeting strategies to cross blood-brain barrier (BBB) for the treatment of Alzheimer's disease. J Control Release 2017; 260:61-77. [PMID: 28549949 DOI: 10.1016/j.jconrel.2017.05.019] [Citation(s) in RCA: 201] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 05/12/2017] [Accepted: 05/13/2017] [Indexed: 12/20/2022]
Abstract
In this modern era, with the help of various advanced technologies, medical science has overcome most of the health-related issues successfully. Though, some diseases still remain unresolved due to various physiological barriers. One such condition is Alzheimer; a neurodegenerative disorder characterized by progressive memory impairment, behavioral abnormalities, mood swing and disturbed routine activities of the person suffering from. It is well known to all that the brain is entirely covered by a protective layer commonly known as blood brain barrier (BBB) which is responsible to maintain the homeostasis of brain by restricting the entry of toxic substances, drug molecules, various proteins and peptides, small hydrophilic molecules, large lipophilic substances and so many other peripheral components to protect the brain from any harmful stimuli. This functionally essential structure creates a major hurdle for delivery of any drug into the brain. Still, there are some provisions on BBB which facilitate the entry of useful substances in the brain via specific mechanisms like passive diffusion, receptor-mediated transcytosis, carrier-mediated transcytosis etc. Another important factor for drug transport is the selection of a suitable drug delivery systems like, liposome, which is a novel drug carrier system offering a potential approach to resolving this problem. Its unique phospholipid bilayer structure (similar to physiological membrane) had made it more compatible with the lipoidal layer of BBB and helps the drug to enter the brain. The present review work focused on various surface modifications with functional ligand (like lactoferrin, transferrin etc.) and carrier molecules (such as glutathione, glucose etc.) on the liposomal structure to enhance its brain targeting ability towards the successful treatment of Alzheimer disease.
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Wen RJ, Huang D, Zhang Y, Liu YW. Bis(3)-tacrine inhibits the sustained potassium current in cultured rat hippocampal neurons. Physiol Res 2017; 66:539-544. [PMID: 28248535 DOI: 10.33549/physiolres.933354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Bis(3)-tacrine is a dimeric AChE inhibitor derived from tacrine with a potential to treat Alzheimer's disease. It was recently been reported to act as a fast off-rate antagonist of NMDA receptors with moderate affinity. In the present study, we aimed to explore whether bis(3)-tacrine could modulate the function of native sustained potassium current in cultured rat hippocampal neurons using whole-cell patch-clamp technique. We found that bis(3)-tacrine inhibited the amplitude of sustained potassium current in a reversible and concentration-dependent manner, with a potency two orders of magnitude higher than that of tacrine. The inhibition was voltage-independent between 0 to +60 mV. The IC(50) values for bis(3)-tacrine and tacrine inhibition of sustained potassium current were 0.45+/-0.07 and 50.5+/-4.8 microM, respectively. I-V curves showed a more potent inhibition of sustained potassium current by bis(3)-tacrine (1 microM) compared to tacrine at the same concentration. Bis(3)-tacrine hyperpolarized the activation curve of the current by 11.2 mV, albeit leaving the steady-state inactivation of the current unaffected.
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Affiliation(s)
- R-J Wen
- Department of Physiology, School of Medicine, Jianghan University, Wuhan, People's Republic of China; Department of Anatomy, School of Medicine, Jianghan University, Wuhan, People's Republic of China.
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8
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Yang CT, Leung YM, Hsu SF, MacDonald I, Wang ML, Lin JG, Hung SY, Chen YH. A comparison of the delayed outward potassium current between the nucleus ambiguus and hippocampus: sensitivity to paeonol. Eur J Pharmacol 2016; 784:49-60. [PMID: 27164420 DOI: 10.1016/j.ejphar.2016.04.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Revised: 04/26/2016] [Accepted: 04/28/2016] [Indexed: 01/31/2023]
Abstract
Whole-cell patch-clamp recordings investigated the electrophysiological effects of 2'-hydroxy-4'-methoxyacetophenone (paeonol), one of the major components of Moutan Cortex, in hippocampal CA1 neurons and nucleus ambiguus (NA) neurons from neonatal rats as well as in lung epithelial H1355 cells expressing Kv2.1 or Kv1.2. Extracellular application of paeonol at 100μM did not significantly affect the spontaneous action potential frequency, whereas paeonol at 300μM increased the frequency of spontaneous action potentials in hippocampal CA1 neurons. Paeonol (300μM) significantly decreased the tetraethylammonium-sensitive outward current in hippocampal CA1 neurons, but had no effect upon the fast-inactivating potassium current (IA). Extracellular application of paeonol at 300μM did not affect action potentials or the delayed outward currents in NA neurons. Paeonol (100μM) reduced the Kv2.1 current in H1355 cells, but not the Kv1.2 current. The inhibitor of Kv2, guangxitoxin-1E, reduced the delayed outward potassium currents in hippocampal neurons, but had only minimal effects in NA neurons. We demonstrated that paeonol decreased the delayed outward current and increased excitability in hippocampal CA1 neurons, whereas these effects were not observed in NA neurons. These effects may be associated with the inhibitory effects on Kv2.1 currents.
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Affiliation(s)
- Chin-Tsang Yang
- School of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Yuk-Man Leung
- Department of Physiology, China Medical University, Taichung, Taiwan
| | - Sheng-Feng Hsu
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
| | - Iona MacDonald
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
| | - Mei-Ling Wang
- Department of Physiology, China Medical University, Taichung, Taiwan
| | - Jaung-Geng Lin
- School of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Shih-Ya Hung
- Division of Colorectal Surgery, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan.
| | - Yi-Hung Chen
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan; Department of Photonics and Communication Engineering, Asia University, Taiwan.
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Chae YJ, Lee HJ, Jeon JH, Kim IB, Choi JS, Sung KW, Hahn SJ. Effects of donepezil on hERG potassium channels. Brain Res 2014; 1597:77-85. [PMID: 25498859 DOI: 10.1016/j.brainres.2014.11.057] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 11/04/2014] [Accepted: 11/27/2014] [Indexed: 11/26/2022]
Abstract
Donepezil is a potent, selective inhibitor of acetylcholinesterase, which is used for the treatment of Alzheimer's disease. Whole-cell patch-clamp technique and Western blot analyses were used to study the effects of donepezil on the human ether-a-go-go-related gene (hERG) channel. Donepezil inhibited the tail current of the hERG in a concentration-dependent manner with an IC50 of 1.3 μM. The metabolites of donepezil, 6-ODD and 5-ODD, inhibited the hERG currents in a similar concentration-dependent manner; the IC50 values were 1.0 and 1.5 μM, respectively. A fast drug perfusion system demonstrated that donepezil interacted with both the open and inactivated states of the hERG. A fast application of donepezil during the tail currents inhibited the open state of the hERG in a concentration-dependent manner with an IC50 of 2.7 μM. Kinetic analysis of donepezil in an open state of the hERG yielded blocking and unblocking rate constants of 0.54 µM(-1)s(-1) and 1.82 s(-1), respectively. The block of the hERG by donepezil was voltage-dependent with a steep increase across the voltage range of channel activation. Donepezil caused a reduction in the hERG channel protein trafficking to the plasma membrane at low concentration, but decreased the channel protein expression at higher concentrations. These results suggest that donepezil inhibited the hERG at a supratherapeutic concentration, and that it did so by preferentially binding to the activated (open and/or inactivated) states of the channels and by inhibiting the trafficking and expression of the hERG channel protein in the plasma membrane.
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Affiliation(s)
- Yun Ju Chae
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul 137-701, 222 Banpo-daero, Seocho-gu, Korea
| | - Hong Joon Lee
- Department of Pharmacology, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea
| | - Ji Hyun Jeon
- Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea
| | - In-Beom Kim
- Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea
| | - Jin-Sung Choi
- College of Pharmacy, Integrated Research Institute of Pharmaceutical, The Catholic University of Korea, 43-1 Yeokgok 2-dong, Wonmi-gu, Bucheon, Gyeonggi-do, Korea
| | - Ki-Wug Sung
- Department of Pharmacology, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea
| | - Sang June Hahn
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul 137-701, 222 Banpo-daero, Seocho-gu, Korea.
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McCord MC, Aizenman E. The role of intracellular zinc release in aging, oxidative stress, and Alzheimer's disease. Front Aging Neurosci 2014; 6:77. [PMID: 24860495 PMCID: PMC4028997 DOI: 10.3389/fnagi.2014.00077] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 04/02/2014] [Indexed: 01/26/2023] Open
Abstract
Brain aging is marked by structural, chemical, and genetic changes leading to cognitive decline and impaired neural functioning. Further, aging itself is also a risk factor for a number of neurodegenerative disorders, most notably Alzheimer’s disease (AD). Many of the pathological changes associated with aging and aging-related disorders have been attributed in part to increased and unregulated production of reactive oxygen species (ROS) in the brain. ROS are produced as a physiological byproduct of various cellular processes, and are normally detoxified by enzymes and antioxidants to help maintain neuronal homeostasis. However, cellular injury can cause excessive ROS production, triggering a state of oxidative stress that can lead to neuronal cell death. ROS and intracellular zinc are intimately related, as ROS production can lead to oxidation of proteins that normally bind the metal, thereby causing the liberation of zinc in cytoplasmic compartments. Similarly, not only can zinc impair mitochondrial function, leading to excess ROS production, but it can also activate a variety of extra-mitochondrial ROS-generating signaling cascades. As such, numerous accounts of oxidative neuronal injury by ROS-producing sources appear to also require zinc. We suggest that zinc deregulation is a common, perhaps ubiquitous component of injurious oxidative processes in neurons. This review summarizes current findings on zinc dyshomeostasis-driven signaling cascades in oxidative stress and age-related neurodegeneration, with a focus on AD, in order to highlight the critical role of the intracellular liberation of the metal during oxidative neuronal injury.
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Affiliation(s)
- Meghan C McCord
- Department of Neurobiology, University of Pittsburgh School of Medicine Pittsburgh, PA, USA
| | - Elias Aizenman
- Department of Neurobiology, University of Pittsburgh School of Medicine Pittsburgh, PA, USA
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Solntseva EI, Bukanova JV, Skrebitsky VG. Donepezil in low micromolar concentrations modulates voltage-gated potassium currents in pyramidal neurons of rat hippocampus. Biochem Biophys Res Commun 2013; 430:1066-71. [DOI: 10.1016/j.bbrc.2012.12.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 12/08/2012] [Indexed: 02/05/2023]
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12
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Li W, Zhou Y, Zhao N, Hao B, Wang X, Kong P. Pharmacokinetic behavior and efficiency of acetylcholinesterase inhibition in rat brain after intranasal administration of galanthamine hydrobromide loaded flexible liposomes. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2012; 34:272-279. [PMID: 22613079 DOI: 10.1016/j.etap.2012.04.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2011] [Revised: 04/22/2012] [Accepted: 04/25/2012] [Indexed: 06/01/2023]
Abstract
Galanthamine hydrobromide (GH) has been approved for symptomatic treatment of Alzheimer's disease (AD) and vascular dementia. Hence, the effects of intranasal administration of GH loaded flexible liposomes have been investigated for the first time on the efficiency of acetylcholinesterase inhibition, as well as the pharmacokinetic behavior of GH in rat brain. The GH loaded flexible liposomes were characterized for shape, entrapment capacity, size distribution and zeta potential by transmission electron microscopy (TEM), ultracentrifugation and dynamic light scattering (DLS), respectively. The inhibition of acetylcholinesterase was investigated using rat brain homogenates as an enzyme resource and microdialysis was used to determine the pharmacokinetic behavior of GH in rats brain. The rat pheochromocytoma PC-12 cell line was used to evaluate the cytotoxicity of GH loaded flexible liposomes. The results revealed that: (i) the efficiency of acetylcholinesterase inhibition of GH was greatly enhanced by intranasal administration compared with oral administration, especially GH loaded in flexible liposomes; (ii) the C(max) and AUC(0→10) for intranasal administration of GH loaded flexible liposomes were 3.52 and 3.36 times higher than those of orally administered GH, moreover, the T(max) was greatly shortened from 1.5h for oral administration to 0.75h for intranasal administration of GH loaded flexible liposomes; and (iii) PC-12 cells viability tests showed that the flexible liposome carrier is not toxic to the cultured cells and the cytotoxicity of GH to cells was clearly decreased by loading in flexible liposomes. These results indicate that intranasal administration of GH loaded flexible liposomes could readily transport GH into brain tissues, suggesting some promise for this approach in successful brain-drug targeting in AD treatment.
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Affiliation(s)
- Weize Li
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China; Institute of Drug Research and Development, Fengyuan Pharmaceutical Limited Company, Ruicheng 044600, PR China
| | - Yongqiang Zhou
- Center of Nanjing Hailing R&D for Chinese Traditional Medicine Pharmaceutical Technology, Nanjing 210049, PR China.
| | - Ning Zhao
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China
| | - Baohua Hao
- School of Science and Life, Northwest University, Xi'an 710069, PR China
| | - Xiaoning Wang
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China
| | - Peng Kong
- Institute of Drug Research and Development, Fengyuan Pharmaceutical Limited Company, Ruicheng 044600, PR China
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Kumar A, Prakash A, Pahwa D. Galantamine potentiates the protective effect of rofecoxib and caffeic acid against intrahippocampal Kainic acid-induced cognitive dysfunction in rat. Brain Res Bull 2011; 85:158-68. [PMID: 21439356 DOI: 10.1016/j.brainresbull.2011.03.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 03/12/2011] [Accepted: 03/14/2011] [Indexed: 01/12/2023]
Abstract
Role of neuroinflammatory mediators particularly cyclooxygenase (COX), lipoxygenase (LOX), have been well suggested in the pathophysiology of neurodegenerative disorders. Rofecoxib is a selective cyclooxygenase 2 enzymes belongs to non-steroidal anti-inflammatory drug, commonly called as coxibs. Whereas, caffeic acid (3,4-dihydroxycinnamic acid) is one of the natural phenolic compounds and reported to inhibit 5-lipoxygenase (5-LOX) activity as one of mechanisms. Present study has been designed to investigate the effects of rofecoxib, caffeic acid and its potentiation by galantamine against intrahippocampal kainic acid-induced cognitive impairment, oxidative damage and mitochondrial respiratory enzyme alterations in rats. Kainic acid (KA) was administrated in the hippocampus region of rat brain. Various behavioral (locomotor activity and memory performances were assessed by using actophotometer and Morris water maze respectively) followed by oxidative stress, mitochondrial enzyme complex were assessed. Intrahippocampal administration of KA significantly impaired locomotor activity, memory performance, mitochondrial enzyme complexes and caused oxidative stress as compared to sham treatment. Rofecoxib (5 and 10mg/kg), caffeic acid (5 and 10mg/kg), Gal (2.5 and 5mg/kg) treatment for 14 days significantly improved locomotor activity, memory retention and oxidative defense (as evidenced by decrease lipid peroxidation, nitrite, increased superoxide dismutase activity and redox ratio) in hippocampus. Besides, alterations in the levels of mitochondrial enzymes and acetylcholine esterase enzyme were significantly restored by rofecoxib and caffeic acid as compared to control. Further, combination of rofecoxib (5mg/kg) with caffeic acid (5mg/kg) and lower dose of gal (2.5mg/kg) with rofecoxib (5mg/kg) treatments significantly potentiated their protective effect which was significant as compared to their effect per se. The results of the present study suggest that galantamine potentiates the protective effect of rofecoxib and caffeic acid against kainic acid induced cognitive impairment and associated oxidative damage.
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Affiliation(s)
- Anil Kumar
- Pharmacology Division, University Institute of Pharmaceutical Sciences, UGC Center of Advanced Study, Panjab University, Chandigarh 160014, India.
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14
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Vicente MI, Costa PF, Lima PA. Galantamine inhibits slowly inactivating K+ currents with a dual dose–response relationship in differentiated N1E-115 cells and in CA1 neurones. Eur J Pharmacol 2010; 634:16-25. [DOI: 10.1016/j.ejphar.2010.02.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 01/26/2010] [Accepted: 02/13/2010] [Indexed: 11/15/2022]
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15
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Li XY, Zhang J, Dai JP, Liu XM, Li ZW. Actions of bis(7)-tacrine and tacrine on transient potassium current in rat DRG neurons and potassium current mediated by K(V)4.2 expressed in Xenopus oocyte. Brain Res 2010; 1318:23-32. [PMID: 20043893 DOI: 10.1016/j.brainres.2009.12.047] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 12/12/2009] [Accepted: 12/16/2009] [Indexed: 11/18/2022]
Abstract
Bis(7)-tacrine [bis(7)-tetrahydroaminacrine] is a dimeric AChE inhibitor derived from tacrine with a potential to treat Alzheimer's disease. Actions of bis(7)-tacrine on ligand-gated ion channels and voltage-gated cation channels have been identified on neurons of both central and peripheral nervous systems. In the present study, the effect of bis(7)-tacrine was investigated on the K(V)4.2 encoded potassium currents expressed in Xenopus oocytes and the transient A-type potassium current (I(K(A))) on rat DRG neurons. Bis(7)-tacrine suppressed recombinant Kv4.2 potassium channels in a concentration-dependent manner, with IC(50) value of 0.53+/-0.13 muM. Tacrine also inhibited Kv4.2 channels, but with a much lower potency (IC(50) 74+/-15 muM).The possible mechanisms underlying the inhibition on potassium currents by bis(7)-tacrine/tacrine could be that inactivation of the transient potassium currents was accelerated and recovery of the native or Kv4.2 expressed potassium currents was suppressed by bis(7)-tacrine/tacrine.
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Affiliation(s)
- Xiang-Yuan Li
- Institute for Electronics and Informatics, South-Central University for Nationalities, Wuhan 430074, PR China
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16
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Xu LJ, Zhao JX, Zhang T, Ren GG, Yang Z. In vitro study on influence of nano particles of CuO on CA1 pyramidal neurons of rat hippocampus potassium currents. ENVIRONMENTAL TOXICOLOGY 2009; 24:211-217. [PMID: 18623077 DOI: 10.1002/tox.20418] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The effects of nano particles of CuO on voltage-dependent potassium currents were studied in acutely isolated CA1 pyramidal neurons of rat hippocampus using the whole-cell patch-clamp techniques. Nano particles of CuO had small effects on transient outward potassium current (I(A), no statistical significance) and mainly inhibited delayed rectifier potassium current (I(K)) in the concentration of 5 x 10(-5) g/mL. Nano particles of CuO didn't shift the steady-state activation curve of I(K) and I(A) but negatively shifted the inactivation curve of I(K). The effects on inactivation curve of I(A) had no statistical significance. These results suggested that blockades of K+ currents by nano particles of CuO could be preferential for I(k) for the first time. This may interfere with the normal function of nerve cells.
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Affiliation(s)
- Lan-Ju Xu
- College of Medicine, Nankai University, Tianjin 300071, China
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17
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Du H, Li M, Yang P. An acetylcholinesterase inhibitor, 3-benzidino-5-methyl-6-phenylpyridazine, blocking outward potassium currents in acutely isolated rat hippocampal pyramidal neurons. Sci Bull (Beijing) 2009. [DOI: 10.1007/s11434-008-0569-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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18
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González-Cestari TF, Henderson BJ, Pavlovicz RE, McKay SB, El-Hajj RA, Pulipaka AB, Orac CM, Reed DD, Boyd RT, Zhu MX, Li C, Bergmeier SC, McKay DB. Effect of novel negative allosteric modulators of neuronal nicotinic receptors on cells expressing native and recombinant nicotinic receptors: implications for drug discovery. J Pharmacol Exp Ther 2008; 328:504-15. [PMID: 18984653 DOI: 10.1124/jpet.108.144576] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Allosteric modulation of nAChRs is considered to be one of the most promising approaches for drug design targeting nicotinic acetylcholine receptors (nAChRs). We have reported previously on the pharmacological activity of several compounds that seem to act noncompetitively to inhibit the activation of alpha3beta4(*) nAChRs. In this study, the effects of 51 structurally similar molecules on native and recombinant alpha3beta4 nAChRs are characterized. These 51 molecules inhibited adrenal neurosecretion activated via stimulation of native alpha3beta4(*) nAChR, with IC(50) values ranging from 0.4 to 13.0 microM. Using cells expressing recombinant alpha3beta4 nAChRs, these molecules inhibited calcium accumulation (a more direct assay to establish nAChR activity), with IC(50) values ranging from 0.7 to 38.2 microM. Radiolabeled nAChR binding studies to orthosteric sites showed no inhibitory activity on either native or recombinant nAChRs. Correlation analyses of the data from both functional assays suggested additional, non-nAChR activity of the molecules. To test this hypothesis, the effects of the drugs on neurosecretion stimulated through non-nAChR mechanisms were investigated; inhibitory effects ranged from no inhibition to 95% inhibition at concentrations of 10 microM. Correlation analyses of the functional data confirmed this hypothesis. Several of the molecules (24/51) increased agonist binding to native nAChRs, supporting allosteric interactions with nAChRs. Computational modeling and blind docking identified a binding site for our negative allosteric modulators near the orthosteric binding site of the receptor. In summary, this study identified several molecules for potential development as negative allosteric modulators and documented the importance of multiple screening assays for nAChR drug discovery.
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Song MK, Liu H, Jiang HL, Yue JM, Hu GY, Chen HZ. Discovery of talatisamine as a novel specific blocker for the delayed rectifier K+ channels in rat hippocampal neurons. Neuroscience 2008; 155:469-75. [DOI: 10.1016/j.neuroscience.2008.06.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 05/27/2008] [Accepted: 06/04/2008] [Indexed: 01/01/2023]
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20
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Solntseva EI, Bukanova JV, Marchenko E, Skrebitsky VG. Donepezil is a strong antagonist of voltage-gated calcium and potassium channels in molluscan neurons. Comp Biochem Physiol C Toxicol Pharmacol 2007; 144:319-26. [PMID: 17126610 DOI: 10.1016/j.cbpc.2006.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 10/04/2006] [Accepted: 10/15/2006] [Indexed: 11/24/2022]
Abstract
Donepezil is an acetylcholinesterase inhibitor used in Alzheimer's disease therapy. The neuroprotective effect of donepezil has been demonstrated in a number of different models of neurodegeneration including beta-amyloid toxicity. Since the mechanisms of neurodegeneration involve the activation of both Ca(2+)- and K(+)-channels, the study of donepezil action on voltage-gated ionic currents looked advisable. In the present study, the action of donepezil on voltage-gated Ca(2+)- and K(+)-channels was investigated on isolated neurons of the edible snail (Helix pomatia) using the two-microelectrodes voltage-clamp technique. Donepezil rapidly and reversibly inhibited voltage activated Ca(2+)-current (I(Ca)) (IC(50)=7.9 microM) and three types of high threshold K(+)-current: Ca(2+)-dependent K(+)-current (I(C)) (IC(50)=6.4 microM), delayed rectifier K(+)-current (I(DR)) (IC(50)=8.0 microM) and fast transient K(+)-current (I(Adepol)) (IC(50)=9.1 microM). The drug caused a dual effect on low-threshold fast transient K(+)-current (I(A)), potentiating it at low (5 microM) concentration, but inhibiting at higher (7 microM and above) concentration. Donepezil also caused a significant hyperpolarizing shift of the voltage-current relationship of I(Ca) (but not of any type of K(+)-current). Results suggest the possible contribution of the blocking effect of donepezil on the voltage-gated Ca(2+)- and K(+)-channels to the neuroprotective effect of the drug.
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Affiliation(s)
- Elena I Solntseva
- Brain Research Institute, Russian Academy of Medical Sciences, Per. Obukha, 5, 105064, Moscow, Russia
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21
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Nie H, Yu WJ, Li XY, Yuan CH, Pang YP, Li CY, Han YF, Li ZW. Inhibition by bis(7)-tacrine of native delayed rectifier and KV1.2 encoded potassium channels. Neurosci Lett 2006; 412:108-13. [PMID: 17174470 DOI: 10.1016/j.neulet.2006.10.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 10/26/2006] [Accepted: 10/30/2006] [Indexed: 10/23/2022]
Abstract
Bis(7)-tacrine [bis(7)-tetrahydroaminacrine] acts as an AChE inhibitor and also exerts modulatory effects on many ligand-gated ion channels and voltage-gated Ca(2+) and K(+) channels. It has been reported previously that tacrine and some other AChE inhibitors suppressed I(K(A)) in central and peripheral neurons. The present study aimed to explore whether bis(7)-tacrine could modulate the function of native delayed rectifier potassium channels in DRG neurons and K(V)1.2 encoded potassium channels expressed in oocytes. We found that both delayed rectifier potassium currents (I(K(DR))) in rat DRG neurons and the currents recorded from oocytes expressing K(V)1.2 (I(K(K(V)1.2))) were suppressed by bis(7)-tacrine, the potency of which was two orders greater than that of tacrine. The IC(50) values for bis(7)-tacrine and tacrine inhibition of I(K(KD)) in DRG neurons were 0.72+/-0.05 and 58.3+/-3.7 microM, respectively; while the two agents inhibited I(K(K(V)1.2)) in oocytes with an IC(50) of 0.24+/-0.06 and 102.1+/-21.5 microM, respectively. The possible mechanism for bis(7)-tacrine inhibition of I(K(A)) and I(K(K(V)1.2)) was identified as the suppression of their activation, inactivation.
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Affiliation(s)
- Hui Nie
- Department of Neurobiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
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22
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Alés E, Gullo F, Arias E, Olivares R, García AG, Wanke E, López MG. Blockade of Ca2+-activated K+ channels by galantamine can also contribute to the potentiation of catecholamine secretion from chromaffin cells. Eur J Pharmacol 2006; 548:45-52. [PMID: 16949070 DOI: 10.1016/j.ejphar.2006.07.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 07/14/2006] [Accepted: 07/19/2006] [Indexed: 11/30/2022]
Abstract
Galantamine is a drug in clinical use for the treatment of Alzheimer's disease, but its mechanism(s) of action remains controversial. Here we addressed the question whether galantamine could potentiate neurotransmitter release by inhibiting small conductance Ca2+ -activated K+ channels (KCa2). Galantamine potentiated catecholamine secretory responses induced by 10 s pulses of acetylcholine and high [K+]o applied to fast-superfused bovine adrenal chromaffin cell populations. Catecholamine release was significantly enhanced by galantamine although we did not find concentration dependence in the range 0.1-1 microM. The KCa2 channel blocker apamin (0.3 microM) occluded the potentiating effects of galantamine on acetylcholine-evoked secretion. Like apamin, galantamine also modified the firing of action potentials, but to a lesser extent. In addition, 1 microM galantamine reduced by 41% the KCa2 current without modifying the voltage-dependent Ca2+ currents. These results constitute the first direct evidence that galantamine can potentiate neurotransmitter release by blocking KCa2 channels, in addition to its already demonstrated capacity to mildly block acetylcholinesterase or potentiate allosterically nicotinic receptors.
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Affiliation(s)
- Eva Alés
- Instituto Teófilo Hernando. Departamento de Farmacología y Terapéutica, Facultad de Medicina, U.A.M., Universidad Autónoma de Madrid, C/, Arzobispo Morcillo 4, E-28029 Madrid - Spain
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23
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Effects of lithium chloride on outward potassium currents in acutely isolated hippocampal CA1 pyramidal neurons. CHINESE SCIENCE BULLETIN-CHINESE 2006. [DOI: 10.1007/s11434-006-2076-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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24
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Du HZ, Zhang CF, Li MY, Yang P. 3-Benzidino-6(4-chlorophenyl) pyridazine blocks delayed rectifier and transient outward potassium current in acutely isolated rat hippocampal pyramidal neurons. Neurosci Lett 2006; 402:159-63. [PMID: 16647816 DOI: 10.1016/j.neulet.2006.03.067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 03/08/2006] [Accepted: 03/29/2006] [Indexed: 10/24/2022]
Abstract
3-[(beta-morpholinoethyl)amino]-4-methyl-6-phenylpyridazine (minaprine) is an acetylcholinesterase (AChE) inhibitor. 3-Benzidino-6(4-chlorophenyl) pyridazine (BCP) and minaprine have a central pyridazine ring in common. In this study, we investigated the effects of BCP on delayed rectifier potassium current (IK(DR)) and transient outward potassium current (IK(A)) in acutely isolated rat hippocampal pyramidal neurons by using whole-cell patch-clamp technique. IK(DR) and IK(A) were inhibited by BCP (0.01-500 microM) in a concentration-dependent and voltage-dependent manner. The IC50 value for the blocking action of BCP on IK(DR) and IK(A) was calculated as 7.13+/-0.18 microM and 0.55+/-0.11 microM, respectively. At the concentration of 10 microM, BCP shifted the activation curve of IK(DR) to positive potential by 29.09 mV. Meanwhile, at the concentration of 10 microM, BCP also shifted the activation and inactivation curve of IK(A) to positive potential by 34.18 and 22.47 mV, respectively. In conclusion, BCP potently inhibits IK(DR) and IK(A) in rat hippocampal pyramidal neurons.
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Affiliation(s)
- Hui-Zhi Du
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Molecular Science, Shanxi University, Taiyuan 030006, PR China
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25
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Zhang CF, Yang P. Zinc-induced aggregation of Abeta (10-21) potentiates its action on voltage-gated potassium channel. Biochem Biophys Res Commun 2006; 345:43-9. [PMID: 16674922 DOI: 10.1016/j.bbrc.2006.04.044] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Accepted: 04/15/2006] [Indexed: 11/18/2022]
Abstract
Zinc may play an important role in the pathogenesis of Alzheimer's disease (AD) through influencing the conformation and neurotoxicity of amyloid beta-proteins (Abeta). Zn(2+) induces rapid aggregation of synthetic or endogenous Abeta in a pH-dependent fashion. Here we show for the first time that Zn(2+)-induced aggregation of Abeta (10-21) potentiates its action on outward potassium currents in hippocampal CA1 pyramidal neurons. Using the whole-cell voltage-clamp technique, we showed that Abeta (10-21) blocked the fast-inactivating outward potassium current (I(A)) in a concentration- and aggregation-dependent manner, but with no effect on the delayed rectifier potassium current (I(K)). Both the unaggregated and aggregated forms of Abeta (10-21) significantly shifted the activation curve and the inactivation curve of I(A) to more negative potentials. But the aggregated form has more effects than the unaggregated form. These data indicated that aggregation of amyloid fragments by zinc ions is required in order to obtain full modulatory effects on potassium channel currents.
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Affiliation(s)
- Chao-Feng Zhang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Molecular Science, Shanxi University, Taiyuan 030006, China
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26
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Oh MM, Wu WW, Power JM, Disterhoft JF. Galantamine increases excitability of CA1 hippocampal pyramidal neurons. Neuroscience 2005; 137:113-23. [PMID: 16242849 DOI: 10.1016/j.neuroscience.2005.08.063] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 08/03/2005] [Accepted: 08/30/2005] [Indexed: 11/25/2022]
Abstract
Galantamine is a third generation cholinesterase inhibitor and an allosteric potentiating ligand of nicotinic acetylcholine receptors. It enhances learning in aging rabbits and alleviates cognitive deficits observed in patients with Alzheimer's disease. We examined galantamine's effect on CA1 neurons from hippocampal slices of young and aging rabbits using current-clamp, intracellular recording techniques. Galantamine (10-200 microM) dose-dependently reduced the postburst afterhyperpolarization and the spike-frequency accommodation of CA1 neurons from both young and aging animals. These reductions were partially, but significantly, reversed by the addition of the muscarinic receptor antagonist, atropine (1 microM), to the perfusate. In contrast, the nicotinic acetylcholine receptor antagonist, alpha-bungarotoxin (10 nM), had no effect; i.e. alpha-bungarotoxin did not reverse the afterhyperpolarization and accommodation reductions. The allosteric potentiating ligand effect was examined by stimulating the Schaffer collateral and measuring the excitatory postsynaptic potentials for 30 min during bath application of galantamine. Galantamine (200 microM) significantly enhanced the excitatory postsynaptic potential amplitude and area over time. These effects were blocked by 10 nM alpha-bungarotoxin, supporting a role for galantamine as an allosteric potentiating ligand. We did not observe a facilitation of the excitatory postsynaptic potentials with 1 microM galantamine. However, when the excitatory postsynaptic potential was pharmacologically isolated by adding 10 microM gabazine (GABA(A) receptor antagonist) to the perfusate, 1 microM galantamine potentiated the subthreshold excitatory postsynaptic potentials into action potentials. We propose that the learning enhancement observed in aging animals and the alleviation of cognitive deficits associated with Alzheimer's disease after galantamine treatment may in part be due to the enhanced function of both nicotinic and muscarinic excitatory transmission on hippocampal pyramidal neurons.
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Affiliation(s)
- M M Oh
- Department of Physiology and Institute for Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611-3008, USA.
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27
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Abstract
The prevalence of dementia is growing in developed countries where elderly patients are increasing in numbers. Neurotransmission modulation is one approach to the treatment of dementia. Cholinergic precursors, anticholinesterases, nicotine receptor agonists and muscarinic M(2) receptor antagonists are agents that enhance cholinergic neurotransmission and that depend on having some intact cholinergic innervation to be effective in the treatment of dementia. The cholinergic precursor choline alfoscerate may be emerging as a potential useful drug in the treatment of dementia, with few adverse effects. Of the anticholinesterases, donepezil, in addition to having a similar efficacy to tacrine in mild-to-moderate Alzheimer's disease (AD), appears to have major advantages; its use is associated with lower drop-out rates in clinical trials, a lower incidence of cholinergic-like side effects and no liver toxicity. Rivastigmine is efficacious in the treatment in dementia with Lewy bodies, a condition in which the other anticholinesterases have not been tested extensively to date. Galantamine is an anticholinesterase and also acts as an allosteric potentiating modulator at nicotinic receptors to increase the release of acetylcholine. Pooled data from clinical trials of patients with mild-to-moderate AD suggest that the benefits and safety profile of galantamine are similar to those of the anticholinesterases. Selective nicotine receptor agonists are being developed that enhance cognitive performance without influencing autonomic and skeletal muscle function, but these have not yet entered clinical trial for dementia. Unlike the cholinergic enhancers, the M(1) receptor agonists do not depend upon intact cholinergic nerves but on intact M(1) receptors for their action, which are mainly preserved in AD and dementia with Lewy bodies. The M(1) receptor-selective agonists developed to date have shown limited efficacy in clinical trials and have a high incidence of side effects. A major recent advancement in the treatment of dementia is memantine, a non-competitive antagonist at NMDA receptors. Memantine is beneficial in the treatment of severe and moderate-to-severe AD and may also be of some benefit in the treatment of mild-to-moderate vascular dementia. Drugs that modulate 5-HT, somatostatin and noradrenergic neurotransmission are also being considered for the treatment of dementia.
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Affiliation(s)
- Sheila A Doggrell
- School of Biomedical Sciences, the University of Queensland, QLD 4072, Australia
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28
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Zhang HX, Zhang W, Jin HW, Wang XL. Galantamine blocks cloned Kv2.1, but not Kv1.5 potassium channels. ACTA ACUST UNITED AC 2005; 131:136-40. [PMID: 15530663 DOI: 10.1016/j.molbrainres.2004.08.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2004] [Indexed: 10/26/2022]
Abstract
Galantamine is a cholinesterase inhibitor (AChEI) currently used in treatment of Alzheimer's disease (AD). In the present study, the effects of galantamine on currents of cloned Kv2.1 and Kv1.5 potassium channels were investigated by using patch-clamp whole cell recording techniques. Kv2.1 and Kv1.5 were stably expressed in HEK293 cells. Galantamine blocked Kv2.1 current in a concentration-dependent manner. When depolarizing from -50 to +40 mV, the IC50 of galantamine for inhibition of Kv2.1 was 5.6 microM. Galantamine 10 microM shifted the activation curve of Kv2.1 to negative potential by 4.0 mV. At the same concentration, galantamine shifted the inactivation curve to negative potential by 25.2 mV. While Kv1.5 was not sensitive to galantamine, Kv1.5 current was not changed by galantamine at concentration of 10 microM. Our data suggest that galantamine potently blocks Kv2.1, but not Kv1.5 channels.
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Affiliation(s)
- Hai-Xia Zhang
- Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, 1 Xian Nong Tan Street, Beijing 100050, PR China
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29
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Yu B, Hu GY. Donepezil blocks voltage-gated ion channels in rat dissociated hippocampal neurons. Eur J Pharmacol 2005; 508:15-21. [PMID: 15680250 DOI: 10.1016/j.ejphar.2004.12.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2004] [Revised: 11/29/2004] [Accepted: 12/06/2004] [Indexed: 10/26/2022]
Abstract
Donepezil (E2020) is a novel cholinesterase inhibitor for the treatment of Alzheimer's disease. Recent studies show that it may act on targets other than acetylcholinesterase in the brain. In the present study, the actions of donepezil on voltage-gated Na+ and K+ channels were investigated in rat dissociated hippocampal neurons. Donepezil reversibly inhibited voltage-activated Na+ current (I(Na)), delayed rectifier K+ current (I(K)) and fast transient K+ current (I(A)). The inhibition of donepezil on I(Na) was dependent on the holding potential. When neurons were held at -100, -80 and -60 mV, the IC50 value was 436+/-19, 291+/-26 and 3.8+/-0.3 microM, respectively. The drug did not affect the activation, fast inactivation of I(Na) and its recovery from fast inactivation. The inhibition of donepezil on I(K) (IC50=78+/-5 microM) was voltage-dependent, whereas that on I(A) (IC50=249+/-25 microM) was voltage-independent. Donepezil caused a significant hyperpolarizing shift of the voltage-dependence of the activation and steady-state inactivation of I(K), without affecting the kinetic properties of I(A). Due to the high concentrations used, the blocking effects of donepezil on the voltage-gated ion channels are unlikely to contribute to the clinical benefits in patients with Alzheimer's disease.
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Affiliation(s)
- Bo Yu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, PR China
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30
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Wang F, Zhao G, Cheng L, Zhou HY, Fu LY, Yao WX. Effects of berberine on potassium currents in acutely isolated CA1 pyramidal neurons of rat hippocampus. Brain Res 2004; 999:91-7. [PMID: 14746925 DOI: 10.1016/j.brainres.2003.11.036] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The effects of berberine, an isoquinoline alkaloid with antiarrhythmic action, on voltage-dependent potassium currents were studied in acutely isolated CA1 pyramidal neurons of rat hippocampus by using the whole-cell patch-clamp techniques. Berberine blocked transient outward potassium current (IA) and delayed rectifier potassium current (IK) in a concentration-dependent manner with EC50 of 22.94+/-4.96 microM and 10.86+/-1.06 microM, Emax of 67.47+/-4.00% and 67.14+/-1.79%, n of 0.77+/-0.08 and 0.96+/-0.07, respectively. Berberine 30 microM shifted the steady-state activation curve and inactivation curve of IA to more negative potentials, but mainly affected the inactivation kinetics. Berberine 30 microM positively shifted the steady-state activation curve of IK. These results suggested that blockades on K+ currents by berberine are preferential for IK, and contribute to its protective action against ischemic brain damage.
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Affiliation(s)
- Fang Wang
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Hong Kong Road 13, Wuhan, Hubei 430030, PR China.
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31
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Pan Y, Xu X, Wang X. Rivastigmine blocks voltage-activated K+ currents in dissociated rat hippocampal neurons. Br J Pharmacol 2003; 140:907-12. [PMID: 14504131 PMCID: PMC1574096 DOI: 10.1038/sj.bjp.0705503] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Rivastigmine is an acetylcholinesterase inhibitor used in Alzheimer's disease therapy. In the present study, we investigated the effects of rivastigmine on the transient outward K+ current (IK(A)) and the delayed rectifier K+ current (IK(DR)) in acutely dissociated rat hippocampal pyramidal neurons using the whole-cell patch-clamp technique. Rivastigmine inhibited the amplitudes of IK(A) and IK(DR) in a reversible and concentration-dependent manner. At a concentration of 100 mum, rivastigmine inhibited IK(A) and IK(DR), recorded when the cells were depolarized from -50 to +40 mV, by 65.9 (P<0.01) and 67.3% (P<0.01), respectively. The IC50 values for IK(A) and IK(DR) were 3.8 and 1.7 microM, respectively. The decay time constant of IK(A), recorded following a test pulse to +40 mV, was prolonged reversibly by rivastigmine at concentrations of 10 and 100 microM (both P<0.05). Rivastigmine affected the voltage dependence of IK(A) and IK(DR). At a concentration of 10 mum, it shifted the steady-state inactivation curve of IK(A) towards more negative potentials by -11 mV (P<0.05), but had no effect on the steady-state activation curve or the recovery from inactivation. Regarding the kinetic properties of IK(DR), 10 microM rivastigmine shifted the steady-state activation and inactivation curves towards more negative potentials by -10 (P<0.05) and -27 mV (P<0.01), respectively. Our findings that rivastigmine inhibits IK(A) and IK(DR) in rat hippocampal pyramidal neurons suggest that this agent has other pharmacological actions besides its antiacetylcholinesterase activity.
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Affiliation(s)
- Yaping Pan
- Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Xian Nong Tan Street, Beijing 100050, China
| | - Xianghua Xu
- Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Xian Nong Tan Street, Beijing 100050, China
| | - Xiaoliang Wang
- Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 1 Xian Nong Tan Street, Beijing 100050, China
- Author for correspondence:
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