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Potential Therapeutic Applications of Plant-Derived Alkaloids against Inflammatory and Neurodegenerative Diseases. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2022; 2022:7299778. [PMID: 35310033 PMCID: PMC8926539 DOI: 10.1155/2022/7299778] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/31/2022] [Accepted: 02/11/2022] [Indexed: 12/14/2022]
Abstract
Alkaloids are a type of natural compound possessing different pharmacological activities. Natural products, including alkaloids, which originate from plants, have emerged as potential protective agents against neurodegenerative disorders (NDDs) and chronic inflammations. A wide array of prescription drugs are used against these conditions, however, not free of limitations of potency, side effects, and intolerability. In the context of personalized medicine, further research on alkaloids to unravel novel therapeutic approaches in reducing complications is critical. In this review, a systematic survey was executed to collect the literature on alkaloids and their health complications, from which we found that majority of alkaloids exhibit anti-inflammatory action via nuclear factor-κB and cyclooxygenase-2 (COX-2), and neuroprotective interaction through acetylcholinesterase (AChE), COX, and β-site amyloid precursor protein activity. In silico ADMET and ProTox-II-related descriptors were calculated to predict the pharmacological properties of 280 alkaloids isolated from traditional medicinal plants towards drug development. Out of which, eight alkaloids such as tetrahydropalmatine, berberine, tetrandrine, aloperine, sinomenine, oxymatrine, harmine, and galantamine are found to be optimal within the categorical range when compared to nicotine. These alkaloids could be exploited as starting materials for novel drug synthesis or, to a lesser extent, manage inflammation and neurodegenerative-related complications.
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2
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Chintamaneni PK, Krishnamurthy PT, Pindiprolu SKSS. Polysorbate-80 surface modified nano-stearylamine BQCA conjugate for the management of Alzheimer's disease. RSC Adv 2021; 11:5325-5334. [PMID: 35423107 PMCID: PMC8694636 DOI: 10.1039/d1ra00049g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 01/13/2021] [Indexed: 01/31/2023] Open
Abstract
Acetylcholinesterase (AChE) inhibitors such as donepezil, galantamine and rivastigmine are used for the management of dementia in Alzheimer's Disease (AD). These drugs elevate endogenous acetylcholine (ACh) levels at the M1 muscarinic receptor in the brain to achieve therapeutic benefits. However, their side effects, such as nausea, vomiting, dizziness, insomnia, loss of appetite, altered heart rate, etc., are related to non-specific peripheral activation of M2-M5 muscarinic subtypes. It is logical, therefore, to develop drugs that selectively activate brain M1 receptors. Unfortunately, the orthosteric site homology among the receptor subtypes does not permit this approach. An alternative approach is to use positive allosteric modulator (PAM) of M1 receptors like benzyl quinolone carboxylic acid (BQCA). PAMs although devoid of M1 agonist activity, however, when bound, enhance the binding affinity of orthosteric ligand, Ach. The current challenge with PAMS is their low brain half-life, permeability, and higher elimination rates. This study reports active targeting of brain M1 receptors using surface modified nano lipid-drug conjugates (LDC) of M1 PAM, BQCA, to treat AD. Polysorbate-80 (P-80) surface modified stearylamine (SA)-BQCA conjugated nanoparticles (BQCA-SA-P80-NPs) were prepared by conjugating BQCA to SA, followed by the formation of nanoparticles (NPs) using P-80 by solvent injection method. The BQCA-SA-P80-NPs are near-spherical with a particle size (PS) of 166.62 ± 1.24 nm and zeta potential (ZP) of 23.59 ± 0.37 mV. In the in vitro cytotoxicity (SH-SY5Y cells) and hemolysis assays, BQCA-SA-P80-NPs, show acceptable safety and compatibility. In mice, Alzheimer's model, BQCA-SA-P80-NPs significantly prevent STZ induced changes in memory, neuronal Aβ1-42, p-Tau, APP, NF-κB, and BACE levels and neuronal cell death, when compared to untreated disease control and naïve BQCA treated group. Further, BQCA-SA-P80-NPs significantly improve the therapeutic efficacy of AChE inhibitor, donepezil (DPZ), indicating its potentiating effects. In vivo biodistribution studies in mice show selective accumulation of BQCA-SA-P80-NPs in the brain, suggesting an improved brain bioavailability and reduced peripheral side effects of BQCA. The study results demonstrate that BQCA-SA-P80-NPs can improve brain bioavailability and therapeutic efficacy of BQCA in AD.
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Affiliation(s)
- Pavan Kumar Chintamaneni
- Department of Pharmacology, JSS College of Pharmacy (JSS Academy of Higher Education & Research) Ooty, The Nilgiris Tamil Nadu-643001 India +91-7598223850
- Department of Pharmaceutics, Raghavendra Institute of Pharmaceutical Education and Research (RIPER) Anantapuramu 51572 Andhra Pradesh India
| | - Praveen Thaggikuppe Krishnamurthy
- Department of Pharmacology, JSS College of Pharmacy (JSS Academy of Higher Education & Research) Ooty, The Nilgiris Tamil Nadu-643001 India +91-7598223850
| | - Sai Kiran S S Pindiprolu
- Department of Pharmacology, JSS College of Pharmacy (JSS Academy of Higher Education & Research) Ooty, The Nilgiris Tamil Nadu-643001 India +91-7598223850
- Department of Pharmacology, Aditya Pharmacy College Surampalem East Godavari 533 437 Andhra Pradesh India
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3
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Adjunctive Approaches to Aphasia Rehabilitation: A Review on Efficacy and Safety. Brain Sci 2021; 11:brainsci11010041. [PMID: 33401678 PMCID: PMC7823462 DOI: 10.3390/brainsci11010041] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/24/2020] [Accepted: 12/31/2020] [Indexed: 12/14/2022] Open
Abstract
Aphasia is one of the most socially disabling post-stroke deficits. Although traditional therapies have been shown to induce adequate clinical improvement, aphasic symptoms often persist. Therefore, unconventional rehabilitation techniques which act as a substitute or as an adjunct to traditional approaches are urgently needed. The present review provides an overview of the efficacy and safety of the principal approaches which have been proposed over the last twenty years. First, we examined the effectiveness of the pharmacological approach, principally used as an adjunct to language therapy, reporting the mechanism of action of each single drug for the recovery of aphasia. Results are conflicting but promising. Secondly, we discussed the application of Virtual Reality (VR) which has been proven to be useful since it potentiates the ecological validity of the language therapy by using virtual contexts which simulate real-life everyday contexts. Finally, we focused on the use of Transcranial Direct Current Stimulation (tDCS), both discussing its applications at the cortical level and highlighting a new perspective, which considers the possibility to extend the use of tDCS over the motor regions. Although the review reveals an extraordinary variability among the different studies, substantial agreement has been reached on some general principles, such as the necessity to consider tDCS only as an adjunct to traditional language therapy.
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Koola MM. Alpha7 nicotinic-N-methyl-D-aspartate hypothesis in the treatment of schizophrenia and beyond. Hum Psychopharmacol 2021; 36:1-16. [PMID: 32965756 DOI: 10.1002/hup.2758] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 12/12/2022]
Abstract
Development of novel treatments for positive, cognitive, and negative symptoms continue to be a high-priority area of schizophrenia research and a major unmet clinical need. Given that all randomized controlled trials (RCTs) conducted to date failed with one add-on medication/mechanism of action, future RCTs with the same approach are not warranted. Even if the field develops a medication for cognition, others are still needed to treat negative and positive symptoms. Therefore, fixing one domain does not completely solve the problem. Also, targeting the cholinergic system, glutamatergic system, and cholinergic plus alpha7 nicotinic and N-methyl-D-aspartate (NMDA) receptors failed independently. Hence, targeting other less important pathophysiological mechanisms/targets is unlikely to be successful. Meta-analyses of RCTs targeting major pathophysiological mechanisms have found some efficacy signal in schizophrenia; thus, combination treatments with different mechanisms of action may enhance the efficacy signal. The objective of this article is to highlight the importance of conducting RCTs with novel combination treatments in schizophrenia to develop antischizophrenia treatments. Positive RCTs with novel combination treatments that target the alpha7 nicotinic and NMDA receptors simultaneously may lead to a disease-modifying therapeutic armamentarium in schizophrenia. Novel combination treatments that concurrently improve the three domains of psychopathology and several prognostic and theranostic biomarkers may facilitate therapeutic discovery in schizophrenia.
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Affiliation(s)
- Maju Mathew Koola
- Department of Psychiatry and Behavioral Health, Stony Brook University Renaissance School of Medicine, Stony Brook, New York, USA
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Marotta G, Basagni F, Rosini M, Minarini A. Memantine Derivatives as Multitarget Agents in Alzheimer's Disease. Molecules 2020; 25:molecules25174005. [PMID: 32887400 PMCID: PMC7504780 DOI: 10.3390/molecules25174005] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/31/2020] [Accepted: 09/01/2020] [Indexed: 12/24/2022] Open
Abstract
Memantine (3,5-dimethyladamantan-1-amine) is an orally active, noncompetitive N-methyl-D-aspartate receptor (NMDAR) antagonist approved for treatment of moderate-to-severe Alzheimer’s disease (AD), a neurodegenerative condition characterized by a progressive cognitive decline. Unfortunately, memantine as well as the other class of drugs licensed for AD treatment acting as acetylcholinesterase inhibitors (AChEIs), provide only symptomatic relief. Thus, the urgent need in AD drug development is for disease-modifying therapies that may require approaching targets from more than one path at once or multiple targets simultaneously. Indeed, increasing evidence suggests that the modulation of a single neurotransmitter system represents a reductive approach to face the complexity of AD. Memantine is viewed as a privileged NMDAR-directed structure, and therefore, represents the driving motif in the design of a variety of multi-target directed ligands (MTDLs). In this review, we present selected examples of small molecules recently designed as MTDLs to contrast AD, by combining in a single entity the amantadine core of memantine with the pharmacophoric features of known neuroprotectants, such as antioxidant agents, AChEIs and Aβ-aggregation inhibitors.
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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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Koola MM. Potential Role of Antipsychotic-Galantamine-Memantine Combination in the Treatment of Positive, Cognitive, and Negative Symptoms of Schizophrenia. MOLECULAR NEUROPSYCHIATRY 2018; 4:134-148. [PMID: 30643787 PMCID: PMC6323397 DOI: 10.1159/000494495] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/12/2018] [Indexed: 12/11/2022]
Abstract
Schizophrenia is, in part, a cognitive illness. There are no approved medications for cognitive impairments associated with schizophrenia (CIAS) and primary negative symptoms. Cholinergic and glutamatergic systems, alpha-7 nicotinic acetylcholine (α-7nACh) and N-methyl-D-aspartate (NMDA) receptors, kynurenic acid (KYNA), and mismatch negativity have been implicated in the pathophysiology of CIAS and negative symptoms. Galantamine is an acetylcholinesterase inhibitor that is also a positive allosteric modulator at the α4β2 and α7nACh receptors. Memantine is a noncompetitive NMDA receptor antagonist. Galantamine and memantine alone and in combination were effective for cognition in animals and people with Alzheimer's disease. The objective of this article is to critically dissect the published randomized controlled trials with galantamine and memantine for CIAS to highlight the efficacy signal. These studies may have failed to detect a clinically meaningful efficacy signal due to limitations, methodological issues, and possible medication nonadherence. There is evidence from a small open-label study that the galantamine-memantine combination may be effective for CIAS with kynurenine pathway metabolites as biomarkers to detect the severity of cognitive impairments. Given that there are no available treatments for cognitive impairments and primary negative symptoms in schizophrenia, testing of this "five-pronged strategy" (quintuple hypotheses: dopamine, nicotinic-cholinergic, glutamatergic/NMDA, GABA, and KYNA) is a "low-risk high-gain" approach that could be a major breakthrough in the field. The galantamine-memantine combination has the potential to treat positive, cognitive, and negative symptoms, and targeting the quintuple hypotheses concurrently may lead to a major scientific advancement - from antipsychotic treatment to antischizophrenia treatment.
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Affiliation(s)
- Maju Mathew Koola
- Department of Psychiatry and Behavioral Sciences, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, USA
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Jiang Y, Liu Z, Holenz J, Yang H. Competitive Intelligence–based Lead Generation and Fast Follower Approaches. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/9783527677047.ch08] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Forrest CM, McNair K, Pisar M, Khalil OS, Darlington LG, Stone TW. Altered hippocampal plasticity by prenatal kynurenine administration, kynurenine-3-monoxygenase (KMO) deletion or galantamine. Neuroscience 2015; 310:91-105. [PMID: 26365611 PMCID: PMC4642643 DOI: 10.1016/j.neuroscience.2015.09.022] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/11/2015] [Accepted: 09/07/2015] [Indexed: 11/16/2022]
Abstract
Glutamate receptors sensitive to N-methyl-D-aspartate (NMDA) are involved in embryonic brain development but their activity may be modulated by the kynurenine pathway of tryptophan metabolism which includes an agonist (quinolinic acid) and an antagonist (kynurenic acid) at these receptors. Our previous work has shown that prenatal inhibition of the pathway produces abnormalities of brain development. In the present study kynurenine and probenecid (both 100mg/kg, doses known to increase kynurenic acid levels in the brain) were administered to female Wistar rats on embryonic days E14, E16 and E18 of gestation and the litter was allowed to develop to post-natal day P60. Western blotting revealed no changes in hippocampal expression of several proteins previously found to be altered by inhibition of the kynurenine pathway including the NMDA receptor subunits GluN1, GluN2A and GluN2B, as well as doublecortin, Proliferating Cell Nuclear Antigen (PCNA), sonic hedgehog and unco-ordinated (unc)-5H1 and 5H3. Mice lacking the enzyme kynurenine-3-monoxygenase (KMO) also showed no changes in hippocampal expression of several of these proteins or the 70-kDa and 100-kDa variants of Disrupted in Schizophrenia-1 (DISC1). Electrical excitability of pyramidal neurons in the CA1 region of hippocampal slices was unchanged, as was paired-pulse facilitation and inhibition. Long-term potentiation was decreased in the kynurenine-treated rats and in the KMO(-/-) mice, but galantamine reversed this effect in the presence of nicotinic receptor antagonists, consistent with evidence that it can potentiate glutamate at NMDA receptors. It is concluded that interference with the kynurenine pathway in utero can have lasting effects on brain function of the offspring, implying that the kynurenine pathway is involved in the regulation of early brain development.
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Affiliation(s)
- C M Forrest
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - K McNair
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - M Pisar
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - O S Khalil
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - L G Darlington
- Ashtead Hospital, The Warren, Ashtead, Surrey KT21 2SB, UK
| | - T W Stone
- Institute of Neuroscience and Psychology, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK.
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10
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Effect of dietary iron loading on recognition memory in growing rats. PLoS One 2015; 10:e0120609. [PMID: 25746420 PMCID: PMC4352024 DOI: 10.1371/journal.pone.0120609] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 01/26/2015] [Indexed: 11/22/2022] Open
Abstract
While nutritional and neurobehavioral problems are associated with both iron deficiency during growth and overload in the elderly, the effect of iron loading in growing ages on neurobehavioral performance has not been fully explored. To characterize the role of dietary iron loading in memory function in the young, weanling rats were fed iron-loading diet (10,000 mg iron/kg diet) or iron-adequate control diet (50 mg/kg) for one month, during which a battery of behavioral tests were conducted. Iron-loaded rats displayed elevated non-heme iron levels in serum and liver, indicating a condition of systemic iron overload. In the brain, non-heme iron was elevated in the prefrontal cortex of iron-loaded rats compared with controls, whereas there was no difference in iron content in other brain regions between the two diet groups. While iron loading did not alter motor coordination or anxiety-like behavior, iron-loaded rats exhibited a better recognition memory, as represented by an increased novel object recognition index (22% increase from the reference value) than control rats (12% increase; P=0.047). Western blot analysis showed an up-regulation of dopamine receptor 1 in the prefrontal cortex from iron-loaded rats (142% increase; P=0.002). Furthermore, levels of glutamate receptors (both NMDA and AMPA) and nicotinic acetylcholine receptor (nAChR) were significantly elevated in the prefrontal cortex of iron-loaded rats (62% increase in NR1; 70% increase in Glu1A; 115% increase in nAChR). Dietary iron loading also increased the expression of NMDA receptors and nAChR in the hippocampus. These results support the idea that iron is essential for learning and memory and further reveal that iron supplementation during developmental and rapidly growing periods of life improves memory performance. Our investigation also demonstrates that both cholinergic and glutamatergic neurotransmission pathways are regulated by dietary iron and provides a molecular basis for the role of iron loading in improved memory.
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Abstract
Alzheimer's disease (AD) is the most common form of dementia among older persons. Pathognomonic hallmarks of the disease include the development of amyloid senile plaques and deposits of neurofibrillary tangles. These changes occur in the brain long before the clinical manifestations of AD (cognitive impairment in particular) become apparent. Nicotinic acetylcholine receptors (AChRs), particularly the α7 subtype, are highly expressed in brain regions relevant to cognitive and memory functions and involved in the processing of sensory information. There is strong evidence that implicates the participation of AChRs in AD. This review briefly introduces current strategies addressing the pathophysiologic findings (amyloid-β-peptide plaques, neurofibrillary tangles) and then focuses on more recent efforts of pharmacologic intervention in AD, specifically targeted to the α7 AChR. Whereas cholinesterase inhibitors such as donepezil, galantamine, or rivastigmine, together with the non-competitive N-methyl-D-aspartate receptor antagonist memantine are at the forefront of present-day clinical intervention for AD, new insights into AChR molecular pharmacology are bringing other drugs, directed at AChRs, to center stage. Among these are the positive allosteric modulators that selectively target α7 AChRs and are aimed at unleashing the factors that hinder agonist-mediated, α7 AChR channel activation. This calls for more detailed knowledge of the distribution, functional properties, and involvement of AChRs in various signaling cascades-together with the corresponding abnormalities in all these properties-to be able to engineer strategies in drug design and evaluate the therapeutic possibilities of new compounds targeting this class of neurotransmitter receptors.
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Allison DJ, Ditor DS. The common inflammatory etiology of depression and cognitive impairment: a therapeutic target. J Neuroinflammation 2014; 11:151. [PMID: 25178630 PMCID: PMC4156619 DOI: 10.1186/s12974-014-0151-1] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/13/2014] [Indexed: 12/27/2022] Open
Abstract
Chronic inflammation has been shown to contribute to the development of a wide variety of disorders by means of a number of proposed mechanisms. Depression and cognitive impairment are two such disorders which may share a closely linked inflammatory etiology. The ability of inflammatory mediators to alter the activity of enzymes, from key metabolic pathways, may help explain the connection between these disorders. The chronic up-regulation of the kynurenine pathway results in an imbalance in critical neuroactive compounds involving the reduction of tryptophan and elevation of tryptophan metabolites. Such imbalances have established implications in both depression and cognitive impairment. This may implicate the immune system as a potential therapeutic target in the treatment of these disorders. The most common treatment modalities currently utilized, involve drug interventions which act on downstream targets. Such treatments help to reestablish protein balances, but fail to treat the inflammatory basis of the disorder. The use of anti-inflammatory interventions, such as regular exercise, may therefore, contribute to the effectiveness of current drug interventions in the treatment of both depression and cognitive impairment.
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Affiliation(s)
- David J Allison
- Department of Kinesiology, Faculty of Applied Health Science, Brock University, 500 Glenridge Ave, St, Catharines L2S 3A1, ON, Canada.
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Lopes JP, Tarozzo G, Reggiani A, Piomelli D, Cavalli A. Galantamine potentiates the neuroprotective effect of memantine against NMDA-induced excitotoxicity. Brain Behav 2013; 3:67-74. [PMID: 23532860 PMCID: PMC3607148 DOI: 10.1002/brb3.118] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 12/10/2012] [Accepted: 12/16/2012] [Indexed: 11/15/2022] Open
Abstract
The combination of memantine, an N-methyl-d-aspartate (NMDA) receptor antagonist, with an acetylcholinesterase inhibitor (AChEI) is the current standard of care in Alzheimer's disease (AD). Galantamine, an AChEI currently marketed for the treatment of AD, exerts memory-enhancing and neuroprotective effects via activation of nicotinic acetylcholine receptors (nAChRs). Here, we investigated the neuroprotective properties of galantamine in primary cultures of rat cortical neurons when given alone or in combination with memantine. In agreement with previous findings, we found that memantine was fully effective in reversing NMDA toxicity at concentrations of 2.5 and 5 μmol/L. Galantamine also completely reversed NMDA toxicity at a concentration of 5 μmol/L. The α7 and α4β2 nAChR antagonists, methyllycaconitine, and dihydro-β-erythroidine blocked the neuroprotective effect of galantamine, demonstrating the involvement of nAChRs. The combination of memantine with galantamine produced synergistic actions, such that full neuroprotective efficacy, was obtained at inactive concentrations of memantine (0.1 μmol/L) and galantamine (1 μmol/L). A similar potentiation was also observed when memantine was replaced with ifenprodil, suggesting a possible involvement of the NR2B subunit of the NMDA receptor. In summary, our study reports for the first time at a cellular level that memantine and galantamine interact on the same excitotoxic cascade and that the combination of these two drugs can result in a remarkable neuroprotective effect.
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Affiliation(s)
- João P Lopes
- D3 – Drug Discovery and Development Department, Istituto Italiano di TecnologiaVia Morego, 16163, Genova, Italy
| | - Glauco Tarozzo
- D3 – Drug Discovery and Development Department, Istituto Italiano di TecnologiaVia Morego, 16163, Genova, Italy
| | - Angelo Reggiani
- D3 – Drug Discovery and Development Department, Istituto Italiano di TecnologiaVia Morego, 16163, Genova, Italy
| | - Daniele Piomelli
- D3 – Drug Discovery and Development Department, Istituto Italiano di TecnologiaVia Morego, 16163, Genova, Italy
- Departments of Anatomy and Neurobiology and Biological Chemistry, University of CaliforniaIrvine, CA, 92697-4621
| | - Andrea Cavalli
- D3 – Drug Discovery and Development Department, Istituto Italiano di TecnologiaVia Morego, 16163, Genova, Italy
- Department of Pharmacy and Biotechnologies, Alma Mater Studiorum, Bologna UniversityVia Belmeloro, 40126, Bologna, Italy
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Simoni E, Daniele S, Bottegoni G, Pizzirani D, Trincavelli ML, Goldoni L, Tarozzo G, Reggiani A, Martini C, Piomelli D, Melchiorre C, Rosini M, Cavalli A. Combining Galantamine and Memantine in Multitargeted, New Chemical Entities Potentially Useful in Alzheimer’s Disease. J Med Chem 2012; 55:9708-21. [DOI: 10.1021/jm3009458] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Elena Simoni
- Drug Discovery and Development, Istituto Italiano di Tecnologia, via Morego 30, 16163
Genova, Italy
- Department
of Pharmaceutical
Sciences, Alma Mater Studiorum − Bologna University, via Belmeloro 6, 40126 Bologna, Italy
| | - Simona Daniele
- Drug Discovery and Development, Istituto Italiano di Tecnologia, via Morego 30, 16163
Genova, Italy
- Department of Psychiatry, Neurobiology,
Pharmacology and Biotechnology, University of Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Giovanni Bottegoni
- Drug Discovery and Development, Istituto Italiano di Tecnologia, via Morego 30, 16163
Genova, Italy
| | - Daniela Pizzirani
- Drug Discovery and Development, Istituto Italiano di Tecnologia, via Morego 30, 16163
Genova, Italy
| | - Maria L. Trincavelli
- Department of Psychiatry, Neurobiology,
Pharmacology and Biotechnology, University of Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Luca Goldoni
- Drug Discovery and Development, Istituto Italiano di Tecnologia, via Morego 30, 16163
Genova, Italy
| | - Glauco Tarozzo
- Drug Discovery and Development, Istituto Italiano di Tecnologia, via Morego 30, 16163
Genova, Italy
| | - Angelo Reggiani
- Drug Discovery and Development, Istituto Italiano di Tecnologia, via Morego 30, 16163
Genova, Italy
| | - Claudia Martini
- Department of Psychiatry, Neurobiology,
Pharmacology and Biotechnology, University of Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Daniele Piomelli
- Drug Discovery and Development, Istituto Italiano di Tecnologia, via Morego 30, 16163
Genova, Italy
- Departments of Pharmacology
and Biological Chemistry, University of California, Irvine 92697-4621, United States
| | - Carlo Melchiorre
- Department
of Pharmaceutical
Sciences, Alma Mater Studiorum − Bologna University, via Belmeloro 6, 40126 Bologna, Italy
| | - Michela Rosini
- Department
of Pharmaceutical
Sciences, Alma Mater Studiorum − Bologna University, via Belmeloro 6, 40126 Bologna, Italy
| | - Andrea Cavalli
- Drug Discovery and Development, Istituto Italiano di Tecnologia, via Morego 30, 16163
Genova, Italy
- Department
of Pharmaceutical
Sciences, Alma Mater Studiorum − Bologna University, via Belmeloro 6, 40126 Bologna, Italy
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15
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Egea J, Martín-de-Saavedra MD, Parada E, Romero A, Del Barrio L, Rosa AO, García AG, López MG. Galantamine elicits neuroprotection by inhibiting iNOS, NADPH oxidase and ROS in hippocampal slices stressed with anoxia/reoxygenation. Neuropharmacology 2011; 62:1082-90. [PMID: 22085833 DOI: 10.1016/j.neuropharm.2011.10.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 10/25/2011] [Accepted: 10/31/2011] [Indexed: 01/24/2023]
Abstract
Galantamine is a drug currently used to treat Alzheimer's disease (AD); in this group of patients it has been observed that concomitant ischemic brain injury can accelerate their cognitive deficit. We have previously shown that galantamine can afford neuroprotection on in vitro and in vivo models related to brain ischemia. In this context, this study was planned to investigate the intracellular signaling pathways implicated in the protective effect of galantamine on an in vitro brain ischemia-reperfusion model, namely rat hippocampal slices subjected to oxygen and glucose deprivation (OGD) followed by reoxygenation. Galantamine protected hippocampal slices subjected to OGD in a concentration-dependent manner; at 15 μM, cell death was reduced to almost control levels. The neuroprotective effects of galantamine were reverted by mecamylamine and AG490, but not by atropine, indicating that nicotinic receptors and Jak2 participated in this action. Galantamine also prevented p65 translocation into the nucleus induced by OGD; this effect was also linked to nicotinic receptors and Jak2. Furthermore, galantamine reduced iNOS induction and production of NO caused by OGD via Jak2. ROS production by NADPH oxidase (NOX) activation was also inhibited by galantamine. In conclusion, galantamine afforded neuroprotection under OGD-reoxygenation conditions by activating a signaling pathway that involves nicotinic receptors, Jak2 and the consequent inhibition of NOX and NFκB/iNOS. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.
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Affiliation(s)
- J Egea
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, Spain.
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16
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Moriguchi S. Pharmacological study on Alzheimer's drugs targeting calcium/calmodulin-dependent protein kinase II. J Pharmacol Sci 2011; 117:6-11. [PMID: 21821968 DOI: 10.1254/jphs.11r06cp] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
In the brain of Alzheimer's disease patients, down-regulation of both cholinergic and glutamatergic systems have been found and is thought to play an important role in impairment of cognition, learning, and memory. Nefiracetam is a pyrrolidine-related nootropic drug exhibiting various pharmacological actions such as a cognitive-enhancing effect. The present study was undertaken to elucidate mechanisms underlying the action of nefiracetam on glutamatergic receptors and intracellular protein kinases. N-Methyl-D-aspartate (NMDA)-evoked currents were recorded from rat cortical neurons in long-term cultured primary neurons using the whole-cell patch-clamp technique. NMDA-evoked currents were greatly and reversibly potentiated by bath application of nefiracetam, resulting in a bell-shaped dose-response curve. The maximum potentiation of 170% relative to the control was produced at 10 nM. Treatment with an inhibitor of the glycine binding site of the NMDA receptor, 7-chlorokynurenic acid, at 1 µM prevented augmentation of NMDA-evoked currents by nefiracetam. In rat hippocampal CA1 slices, field excitatory postsynaptic potentials were recorded by stimulation of Schaffer collateral/commissural pathways. Nefiracetam treatment significantly enhanced long-term potentiation (LTP) with the same bell-shaped dose-response curve. Furthermore, nefiracetam-induced LTP enhancement was closely associated with calcium/calmodulin-dependent protein kinase II (CaMKII) activation with concomitant increase in phosphorylation of AMPA-type glutamate receptor subunit 1 (GluA1) (Ser-831) as a postsynaptic CaMKII substrate. In conclusion, nefiracetam enhances NMDA-receptor function through stimulation of its glycine binding site and nefiracetam-induced CaMKII activation likely contributes to improvement of cognition, learning, and memory.
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Affiliation(s)
- Shigeki Moriguchi
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Japan.
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17
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Galantamine rescues lead-impaired synaptic plasticity in rat dentate gyrus. Toxicology 2011; 289:45-51. [PMID: 21803117 DOI: 10.1016/j.tox.2011.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 07/11/2011] [Accepted: 07/13/2011] [Indexed: 11/23/2022]
Abstract
Chronic lead exposure causes a variety of impairments in learning and memory and cognitive function. Synaptic plasticity in hippocampus is an extensively studied cellular model of learning and memory, which includes long-term potentiation (LTP) and long-term depression (LTD) in two forms. Depotentiation (DP) is another form of synaptic plasticity. Previous studies show that chronic lead exposure can damage the induction of LTP/LTD in hippocampal CA1 and dentate gyrus (DG) areas. In the present study, we investigated the repair and protection on lead-caused synaptic plasticity impairment by galantamine, using field potential recording on chronic lead exposure rats. The results showed that chronic lead exposure impaired LTP/DP induction in DG area of the hippocampus, and galantamine caused a significant increase on the amplitudes of LTP/DP of lead-exposed rats, but only a small increase in non-exposed group. These results suggest that galantamine could reverse the lead-induced impairments of synaptic plasticity in rats and might be an effective medicine to cure the cognitive deficits induced by lead.
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18
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Isik AT, Bozoglu E, Naharci MI, Kilic S. Evaluation of the effects of galantamine on cardiac function in elderly patients with Alzheimer's disease. ACTA ACUST UNITED AC 2011; 8:454-9. [PMID: 21335298 DOI: 10.1016/j.amjopharm.2010.09.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2010] [Indexed: 11/28/2022]
Abstract
BACKGROUND Galantamine, a cholinesterase inhibitor, is used as a first-line drug in the treatment of Alzheimer's disease (AD). However, it may have vagotonic effects, which may cause bradycardia and/or heart block in patients with or without a history of cardiac disease. OBJECTIVE The purpose of this study was to evaluate the effects of galantamine on electrophysiology and arterial blood pressure in elderly patients with AD. METHODS From March 2008 through August 2009, consecutive patients ≥65 years of age were approached for enrollment and underwent a comprehensive geriatric assessment. Patients with newly diagnosed AD who were enrolled in the study were treated with galantamine extended-release capsules using a 2- to 4-week titration schedule. The starting dosage was 8 mg once daily. After 2 to 4 weeks on the initial dosage, the dosage was increased to 16 mg once daily. After another 2 to 4 weeks, if galantamine was still well tolerated, the dosage was increased to 24 mg once daily. ECG parameters and blood pressure were recorded at baseline and at each galantamine dose level (8, 16, and 24 mg/d); blood pressure was measured once daily. The study lasted -4 months after baseline assessment. RESULTS Sixty-four patients with newly diagnosed AD were enrolled in the study, 51 of whom completed the study (28 women and 23 men; mean age, 78.5 years). No significant changes relative to baseline occurred in any of the ECG parameters or arterial blood pressure at any of the investigated dosages of galantamine. CONCLUSION None of the dosages of galantamine investigated in this study significantly altered ECG parameters or arterial blood pressure (relative to baseline) in these elderly patients with AD.
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Affiliation(s)
- Ahmet Turan Isik
- Division of Geriatrics, Department of Internal Medicine, Gulhane School of Medicine, Ankara, Turkey
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19
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Wu TY, Chen CP, Jinn TR. Traditional Chinese medicines and Alzheimer’s disease. Taiwan J Obstet Gynecol 2011; 50:131-5. [DOI: 10.1016/j.tjog.2011.04.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/10/2011] [Indexed: 01/09/2023] Open
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20
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Williams DK, Wang J, Papke RL. Positive allosteric modulators as an approach to nicotinic acetylcholine receptor-targeted therapeutics: advantages and limitations. Biochem Pharmacol 2011; 82:915-30. [PMID: 21575610 DOI: 10.1016/j.bcp.2011.05.001] [Citation(s) in RCA: 207] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 04/28/2011] [Accepted: 05/02/2011] [Indexed: 11/16/2022]
Abstract
Neuronal nicotinic acetylcholine receptors (nAChR), recognized targets for drug development in cognitive and neuro-degenerative disorders, are allosteric proteins with dynamic interconversions between multiple functional states. Activation of the nAChR ion channel is primarily controlled by the binding of ligands (agonists, partial agonists, competitive antagonists) at conventional agonist binding sites, but is also regulated in either negative or positive ways by the binding of ligands to other modulatory sites. In this review, we discuss models for the activation and desensitization of nAChR, and the discovery of multiple types of ligands that influence those processes in both heteromeric nAChR, such as the high-affinity nicotine receptors of the brain, and homomeric α7-type receptors. In recent years, α7 nAChRs have been identified as a potential target for therapeutic indications leading to the development of α7-selective agonists and partial agonists. However, unique properties of α7 nAChR, including low probability of channel opening and rapid desensitization, may limit the therapeutic usefulness of ligands binding exclusively to conventional agonist binding sites. New enthusiasm for the therapeutic targeting of α7 has come from the identification of α7-selective positive allosteric modulators (PAMs) that work effectively on the intrinsic factors that limit α7 ion channel activation. While these new drugs appear promising for therapeutic development, we also consider potential caveats and possible limitations for their use, including PAM-insensitive forms of desensitization and cytotoxicity issues.
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Affiliation(s)
- Dustin K Williams
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, FL Neurocypres, United States
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21
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Ludwig J, Höffle-Maas A, Samochocki M, Luttmann E, Albuquerque EX, Fels G, Maelicke A. Localization by site-directed mutagenesis of a galantamine binding site on α7 nicotinic acetylcholine receptor extracellular domain. J Recept Signal Transduct Res 2010; 30:469-83. [PMID: 21062106 DOI: 10.3109/10799893.2010.505239] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Galantamine is an approved drug treatment for Alzheimer's disease. Initially identified as a weak cholinesterase inhibitor, we have established that galantamine mainly acts as an 'allosterically potentiating ligand (APL)' of nicotinic acetylcholine receptors (nAChR). Meanwhile other 'positive allosteric modulators (PAM)' of nAChR channel activity have been discovered, and for one of them a binding site within the transmembrane domain has been proposed. Here we show, by performing site-directed mutagenesis studies of ectopically expressed chimeric chicken α7/mouse 5-hydroxytryptamine 3 receptor-channel complex, in combination with whole-cell current measurements, in the presence and absence of galantamine, that the APL binding site is different from the proposed PAM binding site. We demonstrate that residues T197, I196, and F198 of ß-strand 10 represent major elements of the galantamine binding site. Residue K123, earlier suggested as being 'close to' the APL binding site, is not part of this site but rather appears to play a role in coupling of agonist binding to channel opening and closing. Our data confirm our earlier results that the galantamine binding site is different from the ACh binding site. Both sites are in close proximity and hence may influence each other in a synergistic fashion. Other interesting areas identified in the present study are a 'hinge' region around and containing residues F122, K123, and K143 possibly being involved in relaying the signal of agonist binding to gating of the transmembrane channel, and a 'folding centre', with P119 as the dominating residue, that crucially positions the agonist binding site with respect to the hinge region.
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22
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Liu X, Xu K, Yan M, Wang Y, Zheng X. Protective effects of galantamine against Abeta-induced PC12 cell apoptosis by preventing mitochondrial dysfunction and endoplasmic reticulum stress. Neurochem Int 2010; 57:588-99. [PMID: 20655346 DOI: 10.1016/j.neuint.2010.07.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 06/08/2010] [Accepted: 07/15/2010] [Indexed: 10/19/2022]
Abstract
Amyloid beta (Abeta) is considered to be responsible for the pathogenesis of Alzheimer's disease (AD). Mitochondrial and ER apoptotic pathways are considered to be involved in this process. Galantamine is an acetylcholinesterase (AChE) inhibitor widely used for patients with AD. In this study, we investigated the neuroprotective effects of galantamine on Abeta(25-35)-induced apoptosis in PC12 cells and the underlying mechanisms. Exposure of PC12 cells to 20 microM Abeta(25-35) caused significant cell viability loss and apoptosis, Abeta aggregation, mitochondrial and ER morphological changes, as well as mitochondrial membrane potential dissipation, reactive oxygen species (ROS) production, intracellular calcium elevation, and cytochrome c release from mitochondria. Pretreatment with 10 microM galantamine for 24 h prior to Abeta(25-35) exposure significantly reduced Abeta(25-35)-induced apoptosis not only by preventing Abeta aggregation, mitochondrial and ER morphological changes, mitochondrial membrane potential dissipation, ROS production, intracellular calcium elevation, and cytochrome c release, but also via reversing Bcl-2/Bax ratio and suppressing the activity of GADD153, Grp78/94, caspase-9, caspase-12, and caspase-3. All these data indicate that galantamine protects PC12 cells against Abeta(25-35)-induced apoptosis by preventing mitochondrial dysfunction and endoplasmic reticulum (ER) stress.
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Affiliation(s)
- Xiaoyu Liu
- Department of Biomedical Engineering, Zhejiang University, Key Laboratory of Biomedical Engineering of Ministry of Education, Hangzhou, Zhejiang, China
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23
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Wang Y, Huang LQ, Tang XC, Zhang HY. Retrospect and prospect of active principles from Chinese herbs in the treatment of dementia. Acta Pharmacol Sin 2010; 31:649-64. [PMID: 20523337 PMCID: PMC4002969 DOI: 10.1038/aps.2010.46] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Accepted: 03/23/2010] [Indexed: 12/16/2022] Open
Abstract
With an ageing population, dementia has become one of the world's primary health challenges. However, existing remedies offer limited benefits with certain side effects, which has prompted researchers to seek complementary and alternative therapies. China has long been known for abundant usage of various herbs. Some of these herbal decoctions are effective in stimulating blood circulation, supplementing vital energy and resisting aging, the lack of which are believed to underlie dementia. These herbs are regarded as new and promising sources of potential anti-dementia drugs. With the rapid evolution of life science and technology, numerous active components have been identified that are highly potent and multi-targeted with low toxicity, and therefore meet the requirements for dementia therapy. This review updates the research progress of Chinese herbs in the treatment of dementia, focusing on their effective principles.
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Affiliation(s)
- Ying Wang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Lu-qi Huang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Xi-can Tang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Hai-yan Zhang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
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24
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Park SJ, Kim DH, Lee IK, Jung WY, Park DH, Kim JM, Lee KR, Lee KT, Shin CY, Cheong JH, Ko KH, Ryu JH. The ameliorating effect of the extract of the flower of Prunella vulgaris var. lilacina on drug-induced memory impairments in mice. Food Chem Toxicol 2010; 48:1671-6. [DOI: 10.1016/j.fct.2010.03.042] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 02/20/2010] [Accepted: 03/26/2010] [Indexed: 10/19/2022]
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25
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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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26
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Prvulovic D, Hampel H, Pantel J. Galantamine for Alzheimer's disease. Expert Opin Drug Metab Toxicol 2010; 6:345-54. [DOI: 10.1517/17425251003592137] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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27
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Moriguchi S, Shioda N, Han F, Yeh JZ, Narahashi T, Fukunaga K. Galantamine enhancement of long-term potentiation is mediated by calcium/calmodulin-dependent protein kinase II and protein kinase C activation. Hippocampus 2009; 19:844-54. [DOI: 10.1002/hipo.20572] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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28
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Lorrio S, Negredo P, Roda JM, García AG, López MG. Effects of memantine and galantamine given separately or in association, on memory and hippocampal neuronal loss after transient global cerebral ischemia in gerbils. Brain Res 2009; 1254:128-37. [DOI: 10.1016/j.brainres.2008.11.095] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 11/24/2008] [Accepted: 11/26/2008] [Indexed: 11/29/2022]
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29
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MK801- and scopolamine-induced amnesias are reversed by an Amazonian herbal locally used as a "brain tonic". Psychopharmacology (Berl) 2009; 202:165-72. [PMID: 18695930 DOI: 10.1007/s00213-008-1272-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Accepted: 07/21/2008] [Indexed: 12/27/2022]
Abstract
RATIONALE Traditional remedies prepared from Ptychopetalum olacoides (PO) are used throughout the Amazon to alleviate age-related conditions. These formulas are mainly used by elders, and alleged effects may be related to the anticholinesterase properties identified in a standardized ethanol extract of this species [P. olacoides standardized ethanol extract (POEE)]. OBJECTIVES To further characterize the potential of this extract for developing drugs useful to treat cognitive deficits, the effects of POEE on scopolamine (scop)- and MK801-induced amnesias (acquisition, consolidation, and retrieval) in mice were investigated. RESULTS Scop (3.0 mg/kg, ip) significantly impaired memory (all three phases) in the step-down inhibitory avoidance protocol. As expected, MK801 (0.1 mg/kg, ip) was amnesic regarding acquisition and consolidation, but not retrieval. POEE (100 mg/kg, ip) reversed the scop-induced impairment in all three phases of long-term and short memories, whereas only the memory consolidation deficit was reversed with MK801-induced amnesia. CONCLUSIONS This study complements previously reported promnesic properties of this plant extract and suggests that POEE may be further developed for treating conditions associated with cognitive deficits, especially those linked with cholinergic malfunction.
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30
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Moriguchi S, Shioda N, Han F, Narahashi T, Fukunaga K. CaM kinase II and protein kinase C activations mediate enhancement of long-term potentiation by nefiracetam in the rat hippocampal CA1 region. J Neurochem 2008; 106:1092-103. [PMID: 18445137 DOI: 10.1111/j.1471-4159.2008.05440.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nefiracetam is a pyrrolidine-related nootropic drug exhibiting various pharmacological actions such as cognitive-enhancing effect. We previously showed that nefiracetam potentiates NMDA-induced currents in cultured rat cortical neurons. To address questions whether nefiracetam affects NMDA receptor-dependent synaptic plasticity in the hippocampus, we assessed effects of nefiracetam on NMDA receptor-dependent long-term potentiation (LTP) by electrophysiology and LTP-induced phosphorylation of synaptic proteins by immunoblotting analysis. Nefiracetam treatment at 1-1000 nM increased the slope of fEPSPs in a dose-dependent manner. The enhancement was associated with increased phosphorylation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor through activation of calcium/calmodulin-dependent protein kinase II (CaMKII) without affecting synapsin I phosphorylation. In addition, nefiracetam treatment increased PKCalpha activity in a bell-shaped dose-response curve which peaked at 10 nM, thereby increasing phosphorylation of myristoylated alanine-rich protein kinase C substrate and NMDA receptor. Nefiracetam treatment did not affect protein kinase A activity. Consistent with the bell-shaped PKCalpha activation, nefiracetam treatment enhanced LTP in the rat hippocampal CA1 region with the same bell-shaped dose-response curve. Furthermore, nefiracetam-induced LTP enhancement was closely associated with CaMKII and PKCalpha activation with concomitant increases in phosphorylation of their endogenous substrates except for synapsin I. These results suggest that nefiracetam potentiates AMPA receptor-mediated fEPSPs through CaMKII activation and enhances NMDA receptor-dependent LTP through potentiation of the post-synaptic CaMKII and protein kinase C activities. Together with potentiation of nicotinic acetylcholine receptor function, nefiracetam-enhanced AMPA and NMDA receptor functions likely contribute to improvement of cognitive function.
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Affiliation(s)
- Shigeki Moriguchi
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
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31
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Villarroya M, García AG, Marco-Contelles J, López MG. An update on the pharmacology of galantamine. Expert Opin Investig Drugs 2007; 16:1987-98. [DOI: 10.1517/13543784.16.12.1987] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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32
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Lorrio S, Sobrado M, Arias E, Roda JM, García AG, López MG. Galantamine postischemia provides neuroprotection and memory recovery against transient global cerebral ischemia in gerbils. J Pharmacol Exp Ther 2007; 322:591-9. [PMID: 17526807 DOI: 10.1124/jpet.107.122747] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Galantamine, currently used in Alzheimer's patients, has shown neuroprotection in hippocampal slices subjected to oxygenglucose deprivation. Here, we present an in vivo study to evaluate the potential neuroprotective effects of galantamine in a transient global cerebral ischemia model in gerbils. Three treatment protocols were used. In the pretreatment protocol, gerbils were treated before ischemia and for 3 consecutive days thereafter. Eight groups of animals were included: sham operation plus placebo, 10 mg/kg mecamylamine and 10 mg/kg galantamine, respectively; and ischemia plus placebo, 10 mg/kg mecamylamine, 1 mg/kg galantamine, and 10 mg/kg galantamine and 10 mg/kg mecamylamine plus galantamine, respectively. Postischemia protocols included three groups of animals: sham operation, ischemia plus placebo, and ischemia plus 10 mg/kg galantamine; substances were administered 3 or 6 h after ischemia and for 2 consecutive days thereafter. Pyramidal neurons surviving in the cornus ammonis 1 region of the hippocampus were evaluated 72 h after reperfusion, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) histochemistry, caspase-3 and superoxide dismutase (SOD)-2 immunohistochemistries, and Western blottings were performed, and object placement tests were carried out. Galantamine significantly increased the number of living pyramidal neurons after ischemia-reperfusion injury. Galantamine significantly reduced TUNEL, active caspase-3, and SOD-2 immunoreactivity. The nicotinic antagonist mecamylamine blocked the protective effects of galantamine. The neuroprotective effects of galantamine were preserved even when first administered at 3 h postischemia. These results correlated with the performance in the object placement test. This study shows that galantamine provides in vivo neuroprotection and memory recovery against global cerebral ischemia, even when administration begins 3 h postischemia.
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Affiliation(s)
- Silvia Lorrio
- Instituto Teófilo Hernando, Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, Spain
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Van der Schyf CJ, Geldenhuys WJ, Youdim MBH. Multifunctional drugs with different CNS targets for neuropsychiatric disorders. J Neurochem 2006; 99:1033-48. [PMID: 17054441 DOI: 10.1111/j.1471-4159.2006.04141.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The multiple disease etiologies that lead to neuropsychiatric disorders, such as Parkinson's and Alzheimer's disease, amyotrophic lateral sclerosis, Huntington disease, schizophrenia, depressive illness and stroke, offer significant challenges to drug discovery efforts aimed at preventing or even reversing the progression of these disorders. Transcriptomic tools and proteomic profiling have clearly indicated that such diseases are multifactorial in origin. Further, they are thought to be initiated by a cascade of molecular events that involve several neurotransmitter systems. In response to this complexity, a new paradigm has recently emerged that challenges the widely held assumption that 'silver bullet' agents are superior to 'dirty drugs' in therapeutic approaches aimed at the prevention or treatment of neuropsychiatric diseases. A similar pattern of drug development has occurred in strategies for the treatment of cancer, AIDS and cardiovascular diseases. In this review, we offer an overview of therapeutic strategies and novel investigative drugs discovered or developed in our own and other laboratories, that address multiple CNS etiological targets associated with an array of neuropsychiatric disorders.
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Affiliation(s)
- Cornelis J Van der Schyf
- Department of Pharmaceutical Sciences, Northeastern Ohio Universities College of Pharmacy, Rootstow, Ohio, USA
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34
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Zhao X, Marszalec W, Toth PT, Huang J, Yeh JZ, Narahashi T. In vitro galantamine-memantine co-application: mechanism of beneficial action. Neuropharmacology 2006; 51:1181-91. [PMID: 17011596 DOI: 10.1016/j.neuropharm.2006.08.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 08/16/2006] [Accepted: 08/17/2006] [Indexed: 01/01/2023]
Abstract
Several drugs are in clinical use for symptomatic treatment of Alzheimer's disease patients. Since Alzheimer's disease is known to be associated with down-regulation of the cholinergic and N-methyl-D-aspartate (NMDA) systems, most of these drugs inhibit acetylcholinesterase, potentiate the activity of nicotinic acetylcholine receptors (nAChRs), or modulate NMDA receptors. Galantamine is an anticholinesterase and allosterically potentiates the activity of the nicotinic receptors. We have recently found that galantamine potentiates the activity of NMDA receptors as well. Memantine is unique in that it inhibits the NMDA receptors. We have developed a hypothesis that combining galantamine and memantine will be more effective for improving the patient's conditions than monotherapy with either drug. Patch clamp and intracellular Ca(2+) imaging experiments using rat cortical and hippocampal neurons clearly provided the in vitro bases for our hypothesis. Memantine blocked the extrasynaptic NMDA receptor 100 times more potently than the synaptic NMDA receptor at negative membrane potentials and the block of both types of NMDA receptors was attenuated with depolarization. However, galantamine potentiation of the NMDA receptors was not voltage dependent. Thus, co-application of memantine with galantamine prevented the galantamine potentiation and the activation of extrasynaptic NMDA receptors, but membrane depolarization revealed the galantamine potentiation. Therefore, cell death is expected to be prevented by memantine near the resting potential while the NMDA-mediated synaptic transmission, which is down-regulated in the patients, is maintained and potentiated by galantamine. These results provide in vitro bases for the beneficial actions of galantamine and memantine combinations.
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Affiliation(s)
- Xilong Zhao
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 E. Chicago Avenue, Chicago, IL 60611, USA
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Rispoli V, Marra R, Costa N, Scipione L, Rotiroti D, De Vita D, Liberatore F, Carelli V. Choline pivaloyl ester strengthened the benefit effects of Tacrine and Galantamine on electroencephalographic and cognitive performances in nucleus basalis magnocellularis-lesioned and aged rats. Pharmacol Biochem Behav 2006; 84:453-67. [PMID: 16859739 DOI: 10.1016/j.pbb.2006.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Revised: 06/08/2006] [Accepted: 06/12/2006] [Indexed: 01/02/2023]
Abstract
The aim of the present work was the assessment of the effects produced on the electroencephalographic (EEG) activity and the cognitive and memory performances of nucleus basalis magnocellularis (NBM)-lesioned or aged rats by the combined treatment with [2-(2,2-dimethylpropionyloxy)ethyl]trimethylammonium 2,2-dimethylpropionate (choline pivaloyl ester) (CPE) and the Cholinesterase inhibitors (ChEIs) Tacrine (THA) and Galantamine (GAL). Intraperitoneal administration of CPE combined with THA or GAL to both NBM-lesioned or aged rats, produced EEG desynchronisation, and a significant decrease in the energy of the total EEG spectrum and the lower frequency bands (delta 0.25-3 and theta 4-7 Hz) lasting many minutes. Furthermore, drug associations reversed in aged rats the scopolamine (0.2 mg/kg, i.p.)-induced increase in EEG power, slow waves and high-voltage spindle (HVS). Furthermore, the combined administration of CPE and Cholinesterase inhibitors in both NBM-lesioned or aged animals, improved performances in all behavioural tasks, enhancing object discrimination, increasing locomotory activity and alternation choice in T-maze, ameliorating retention in passive avoidance and decreasing escape latency in Morris water maze. In all test, AChEIs and CPE combinations proved to be more effective than CPE, THA or GAL given alone. In conclusion, the present work shows the ability of choline pivaloyl ester in strengthening the positive cerebral activity of THA and GAL.
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Affiliation(s)
- V Rispoli
- Department of Pharmacobiological Sciences, University Magna Graecia of Catanzaro, Complesso Ninì Barbieri, I-88021 Roccelletta di Borgia (CZ), Italy.
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Broad LM, Zwart R, Pearson KH, Lee M, Wallace L, McPhie GI, Emkey R, Hollinshead SP, Dell CP, Baker SR, Sher E. Identification and pharmacological profile of a new class of selective nicotinic acetylcholine receptor potentiators. J Pharmacol Exp Ther 2006; 318:1108-17. [PMID: 16738207 DOI: 10.1124/jpet.106.104505] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Here we report the discovery, by high-throughput screening, of three novel (2-amino-5-keto)thiazole compounds that act as selective potentiators of nicotinic acetylcholine receptors. Compound selectivity was assessed at seven human nicotinic acetylcholine receptors (alpha1beta1gammadelta, alpha2beta4, alpha3beta2, alpha3beta4, alpha4beta2, alpha4beta4, and alpha7) expressed in mammalian cells or Xenopus oocytes. At alpha2beta4, alpha4beta2, alpha4beta4, and alpha7, but not alpha1beta1gammadelta, alpha3beta2, or alpha3beta4, submaximal responses to nicotinic agonists were potentiated in a concentration-dependent manner by all compounds. At similar concentrations, no potentiation of 5-hydroxytryptamine, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, GABA(A), and N-methyl-d-aspartate receptors or voltage-gated Na(+) and Ca(2+) channels was observed. Furthermore, these compounds did not inhibit acetylcholine esterase. Further profiling revealed that these compounds enhanced the potency and maximal efficacy of a range of nicotinic agonists at alpha4beta2 nicotinic acetylcholine receptors, a profile typical of allosteric potentiators. At concentrations required for potentiation, the compounds did not displace [(3)H]epibatidine from the agonist-binding site, and potentiation was observed at all agonist concentrations, suggesting a noncompetitive mechanism of action. Blockade of common second messenger systems did not affect potentiation. At concentrations higher then required for potentiation the compounds also displayed intrinsic agonist activity, which was blocked by competitive and noncompetitive nicotinic acetylcholine receptor (nAChR) antagonists. These novel selective nicotinic receptor potentiators should help in clarifying the potential therapeutic utility of selective nAChR modulation for the treatment of central nervous system disorders.
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Affiliation(s)
- Lisa M Broad
- Eli Lilly and Company Ltd., Lilly Research Centre, Windlesham, Surrey GU20 6PH, UK
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Unger C, Svedberg MM, Yu WF, Hedberg MM, Nordberg A. Effect of subchronic treatment of memantine, galantamine, and nicotine in the brain of Tg2576 (APPswe) transgenic mice. J Pharmacol Exp Ther 2005; 317:30-6. [PMID: 16354790 DOI: 10.1124/jpet.105.098566] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
An increasing number of studies suggest that the present clinical therapy used in Alzheimer's disease (AD), in addition to having a symptomatic effect, also may interact with the ongoing neuropathological processes in the brain. The aim of this study was to investigate the effect of the cholinesterase inhibitor galantamine and the N-methyl-d-aspartate (NMDA) antagonist memantine in comparison to nicotine on the neuropathology of Tg2576 transgenic mice (APPswe). Nontransgenic and APPswe mice at 10 months of age were treated subcutaneously with saline, memantine, galantamine, or nicotine for 10 days. Nicotine reduced the guanidinium-soluble amyloid-beta peptide (Abeta) levels by 46 to 66%, whereas the intracellular Abeta levels remained unchanged. Treatment with nicotine also resulted in less glial fibrillary acidic protein immunoreactive astrocytes around the plaques, increased levels of synaptophysin, and increased number of alpha7 nicotinic acetylcholine receptors (nAChRs) in the cortex of APPswe transgenic mice. Galantamine treatment caused an increase in the cortical levels of synaptophysin in the APPswe mice. Memantine treatment reduced the total cortical levels of membrane-bound amyloid precursor protein (45-55%) in both transgenic and nontransgenic mice, which eventually may decrease the level of Abeta. In conclusion, galantamine, memantine, and nicotine have different interactions with Abeta processes, alpha7 nAChRs, and NMDA receptors in APPswe mice. These different effects might have therapeutic relevance, and this knowledge might be applicable to the development of new effective therapeutic strategies for AD.
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Affiliation(s)
- Christina Unger
- Karolinska Institutet, Neurotec Department, Division of Molecular Neuropharmacology, Karolinska University Hospital Huddinge, Stockholm, Sweden
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Marco-Contelles J, do Carmo Carreiras M, Rodríguez C, Villarroya M, García AG. Synthesis and Pharmacology of Galantamine. Chem Rev 2005; 106:116-33. [PMID: 16402773 DOI: 10.1021/cr040415t] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- José Marco-Contelles
- Laboratorio de Radicales Libres (CSIC), C/ Juan de la Cierva 3, 28006-Madrid, Spain.
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Moriguchi S, Zhao X, Marszalec W, Yeh JZ, Narahashi T. Modulation of N-Methyl-d-aspartate Receptors by Donepezil in Rat Cortical Neurons. J Pharmacol Exp Ther 2005; 315:125-35. [PMID: 15951396 DOI: 10.1124/jpet.105.087908] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nicotinic acetylcholine receptors and N-methyl-D-aspartate (NMDA) receptors are known to be down-regulated in the brain of patients with Alzheimer's disease. It was previously shown that the nootropic drugs nefiracetam and galantamine potentiate the activity of both nicotinic and NMDA receptors. We hypothesized that donepezil, a nootropic with a potent anticholinesterase activity, might also affect the NMDA system. NMDA-induced currents were recorded from rat cortical neurons in primary culture using the whole-cell patch-clamp technique at a holding potential of -70 mV in Mg2+-free solutions. In multipolar neurons, NMDA currents were decreased by bath and U-tube applications of 1 to 10 microM donepezil but were increased by 30 to 100 microM donepezil. Donepezil suppression occurred in a manner independent of NMDA concentrations ranging from 3 to 1000 microM. The donepezil suppression of NMDA currents was prevented by inhibition of protein kinase C (PKC) but unaffected by protein kinase A (PKA) and G proteins. In bipolar neurons, however, NMDA currents were potently augmented by bath and U-tube applications of 0.01 to 100 microM donepezil. Donepezil potentiation occurred at high NMDA concentrations that evoked the saturating responses and in a manner independent of NMDA concentrations ranging from 3 to 1000 microM. The potentiation of NMDA currents by donepezil was decreased by inhibition of PKC and abolished by modulation of G proteins but not by PKA inhibition. It was concluded that donepezil at low therapeutic concentrations (0.01-1 microM) potentiated the activity of the NMDA system and that this action together with cholinesterase inhibition would contribute to the improvement of learning, memory, and cognition in patients with Alzheimer's disease.
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Affiliation(s)
- Shigeki Moriguchi
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, IL 60611, USA
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Narahashi T, Moriguchi S, Zhao X, Marszalec W, Yeh JZ. Mechanisms of Action of Cognitive Enhancers on Neuroreceptors. Biol Pharm Bull 2004; 27:1701-6. [PMID: 15516710 DOI: 10.1248/bpb.27.1701] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
No strategies for curing Alzheimer's disease have been developed yet as we do not know the exact cause of the disease. The only therapy that is available for patients is symptomatic treatment. Since Alzheimer's disease is associated with downregulation of the cholinergic system in the brain, its stimulation is expected to improve the patients' cognition, learning, and memory. Four anticholinesterases have been approved in the U.S.A. for the treatment of Alzheimer's disease patients. However, because of the inhibition of cholinesterases, these drugs have side effects and their effectiveness does not last long. Thus new approaches are needed. One approach is to stimulate directly nicotinic acetylcholine (nACh) receptors in the brain, and another is to stimulate NMDA receptors which are also known to be downregulated in Alzheimer's patients. Nefiracetam has been shown to potentiate ACh currents in the alpha4beta2 receptor of rat cortical neurons with a bell-shaped dose-response relationship and the maximum effect at 1 nM. This effect was exerted via G(s) proteins. The alpha7 receptor was almost unaffected by nefiracetam. Nefiracetam also potentiated NMDA currents with the maximum effect at 10 nM via interaction with the glycine-binding site of the receptor. Galantamine had a moderate potentiating effect on the alpha4beta2 receptor and potentiated NMDA currents with the maximum effect at 1 microM. However, galantamine did not interact with the glycine-binding site. Donepezil, a potent anticholinesterase, also potentiated NMDA currents at 1-10000 nM. In conclusion, these three drugs potentiate the activity not only of the cholinergic system but also of the NMDA system, thereby stimulating the downregulated nACh receptors and NMDA receptors to improve patients' learning, cognition, and memory.
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Affiliation(s)
- Toshio Narahashi
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, IL 60611, USA.
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