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Chen F, Zhang Z, Zhang H, Guo P, Feng J, Shen H, Liu X. Activation of α7 Nicotinic Acetylcholine Receptor Improves Muscle Endurance by Upregulating Orosomucoid Expression and Glycogen Content in Mice. J Cell Biochem 2024:e30630. [PMID: 39014907 DOI: 10.1002/jcb.30630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 06/13/2024] [Accepted: 07/01/2024] [Indexed: 07/18/2024]
Abstract
There are presently no acknowledged therapeutic targets or official drugs for the treatment of muscle fatigue. The alpha7 nicotinic acetylcholine receptor (α7nAChR) is expressed in skeletal muscle, with an unknown role in muscle endurance. Here, we try to explore whether α7nAChR could act as a potential therapeutic target for the treatment of muscle fatigue. Results showed that nicotine and PNU-282987 (PNU), as nonspecific and specific agonists of α7nAChR, respectively, could both significantly increase C57BL6/J mice treadmill-running time in a time- and dose-dependent manner. The improvement effect of PNU on running time and ex vivo muscle fatigue index disappeared when α7nAChR deletion. RNA sequencing revealed that the differential mRNAs affected by PNU were enriched in glycolysis/gluconeogenesis signaling pathways. Further studies found that PNU treatment significantly elevates glycogen content and ATP level in the muscle tissues of α7nAChR+/+ mice but not α7nAChR-/- mice. α7nAChR activation specifically increased endogenous glycogen-targeting protein orosomucoid (ORM) expression both in vivo skeletal muscle tissues and in vitro C2C12 skeletal muscle cells. In ORM1 deficient mice, the positive effects of PNU on running time, glycogen and ATP content, as well as muscle fatigue index, were abolished. Therefore, the activation of α7nAChR could enhance muscle endurance via elevating endogenous anti-fatigue protein ORM and might act as a promising therapeutic strategy for the treatment of muscle fatigue.
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Affiliation(s)
- Fei Chen
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Zhen Zhang
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
- Department of Nutrition and Food Hygiene, Second Military Medical University, Shanghai, China
| | - Huimin Zhang
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Pengyue Guo
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Jiayi Feng
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Hui Shen
- Department of Nutrition and Food Hygiene, Second Military Medical University, Shanghai, China
| | - Xia Liu
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
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Zhao J, Wei M, Guo M, Wang M, Niu H, Xu T, Zhou Y. GSK3: A potential target and pending issues for treatment of Alzheimer's disease. CNS Neurosci Ther 2024; 30:e14818. [PMID: 38946682 PMCID: PMC11215492 DOI: 10.1111/cns.14818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 05/21/2024] [Accepted: 05/27/2024] [Indexed: 07/02/2024] Open
Abstract
Glycogen synthase kinase-3 (GSK3), consisting of GSK3α and GSK3β subtypes, is a complex protein kinase that regulates numerous substrates. Research has observed increased GSK3 expression in the brains of Alzheimer's disease (AD) patients and models. AD is a neurodegenerative disorder with diverse pathogenesis and notable cognitive impairments, characterized by Aβ aggregation and excessive tau phosphorylation. This article provides an overview of GSK3's structure and regulation, extensively analyzing its relationship with AD factors. GSK3 overactivation disrupts neural growth, development, and function. It directly promotes tau phosphorylation, regulates amyloid precursor protein (APP) cleavage, leading to Aβ formation, and directly or indirectly triggers neuroinflammation and oxidative damage. We also summarize preclinical research highlighting the inhibition of GSK3 activity as a primary therapeutic approach for AD. Finally, pending issues like the lack of highly specific and affinity-driven GSK3 inhibitors, are raised and expected to be addressed in future research. In conclusion, GSK3 represents a target in AD treatment, filled with hope, challenges, opportunities, and obstacles.
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Affiliation(s)
- Jiahui Zhao
- School of Basic Medical SciencesZhejiang Chinese Medical UniversityHangzhouChina
| | - Mengying Wei
- College of Pharmaceutical SciencesZhejiang UniversityHangzhouChina
- Future Health Laboratory, Innovation Center of Yangtze River DeltaZhejiang UniversityJiaxingChina
| | - Minsong Guo
- College of Pharmaceutical SciencesZhejiang UniversityHangzhouChina
- Cangnan County Qiushi Innovation Research Institute of Traditional Chinese MedicineWenzhouChina
| | - Mengyao Wang
- School of Basic Medical SciencesZhejiang Chinese Medical UniversityHangzhouChina
| | - Hongxia Niu
- School of Basic Medical SciencesZhejiang Chinese Medical UniversityHangzhouChina
- Key Laboratory of Blood‐stasis‐toxin Syndrome of Zhejiang ProvinceHangzhouChina
| | - Tengfei Xu
- College of Pharmaceutical SciencesZhejiang UniversityHangzhouChina
- Cangnan County Qiushi Innovation Research Institute of Traditional Chinese MedicineWenzhouChina
| | - Yuan Zhou
- School of Basic Medical SciencesZhejiang Chinese Medical UniversityHangzhouChina
- Key Laboratory of Blood‐stasis‐toxin Syndrome of Zhejiang ProvinceHangzhouChina
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Inhibition of Microglial GSK3β Activity Is Common to Different Kinds of Antidepressants: A Proposal for an In Vitro Screen to Detect Novel Antidepressant Principles. Biomedicines 2023; 11:biomedicines11030806. [PMID: 36979785 PMCID: PMC10045655 DOI: 10.3390/biomedicines11030806] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/17/2023] [Accepted: 03/04/2023] [Indexed: 03/09/2023] Open
Abstract
Depression is a major public health concern. Unfortunately, the present antidepressants often are insufficiently effective, whilst the discovery of more effective antidepressants has been extremely sluggish. The objective of this review was to combine the literature on depression with the pharmacology of antidepressant compounds, in order to formulate a conceivable pathophysiological process, allowing proposals how to accelerate the discovery process. Risk factors for depression initiate an infection-like inflammation in the brain that involves activation microglial Toll-like receptors and glycogen synthase kinase-3β (GSK3β). GSK3β activity alters the balance between two competing transcription factors, the pro-inflammatory/pro-oxidative transcription factor NFκB and the neuroprotective, anti-inflammatory and anti-oxidative transcription factor NRF2. The antidepressant activity of tricyclic antidepressants is assumed to involve activation of GS-coupled microglial receptors, raising intracellular cAMP levels and activation of protein kinase A (PKA). PKA and similar kinases inhibit the enzyme activity of GSK3β. Experimental antidepressant principles, including cannabinoid receptor-2 activation, opioid μ receptor agonists, 5HT2 agonists, valproate, ketamine and electrical stimulation of the Vagus nerve, all activate microglial pathways that result in GSK3β-inhibition. An in vitro screen for NRF2-activation in microglial cells with TLR-activated GSK3β activity, might therefore lead to the detection of totally novel antidepressant principles with, hopefully, an improved therapeutic efficacy.
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Alpha7 nicotinic acetylcholine receptor agonist PHA-543613 improves memory deficits in presenilin 1 and presenilin 2 conditional double knockout mice. Exp Neurol 2023; 359:114271. [PMID: 36370840 DOI: 10.1016/j.expneurol.2022.114271] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 10/18/2022] [Accepted: 11/06/2022] [Indexed: 11/11/2022]
Abstract
Cholinergic system dysfunction has been considered as a critical feature of neurodegenerative progression in Alzheimer's disease (AD). The α7 nicotinic acetylcholine receptors (α7-nAChRs) are widely expressed in the hippocampus cortex and play an important role in memory formation, considered as potential therapeutic agents targets. However, underlying mechanisms have not been fully elucidated. Here, we combine behavioral, molecular biological methods with in vitro slice and in vivo multichannel electrophysiological recording techniques to investigate the molecular, cellular synaptic and neuronal mechanisms of activating α7-nAChR by PHA-543613 (a selective α7-nAChR agonist), which influences the impaired cognitive function using presenilin 1 (PS1) and presenilin 2 (PS2) conditional double knockout (cDKO) mice. Our results demonstrated that PHA-543613 treatment significantly improved the impaired hippocampus-related memory via recovering the reduced the hippocampal synaptic protein levels of α7-nAChR, NMADAR and AMPAR, thereby restoring the impaired post-tetanic potentiation (PTP), long-term potentiation (LTP), activation of molecular signaling pathway for neuronal protection, theta power and strength of theta-gamma phase-amplitude coupling (PAC) at hippocampus in 6-month-old cDKO mice. For the first time, we systematically reveal the mechanisms by which PHA-543613 improves memory deficits at different levels. Therefore, our findings may be significant for the development of therapeutic strategies for AD.
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Mathew A, Balaji E V, Pai SRK, Kishore A, Pai V, Pemmireddy R, K S C. Current Drug Targets in Alzheimer's Associated Memory Impairment: A Comprehensive Review. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2023; 22:255-275. [PMID: 35366787 DOI: 10.2174/1871527321666220401124719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 12/17/2021] [Accepted: 01/19/2022] [Indexed: 12/16/2022]
Abstract
Alzheimer's disease (AD) is the most prevalent form of dementia among geriatrics. It is a progressive, degenerative neurologic disorder that causes memory and cognition loss. The accumulation of amyloid fibrils and neurofibrillary tangles in the brain of AD patients is a distinguishing feature of the disease. Therefore, most of the current therapeutic goals are targeting inhibition of beta-amyloid synthesis and aggregation as well as tau phosphorylation and aggregation. There is also a loss of the cholinergic neurons in the basal forebrain, and first-generation therapeutic agents were primarily focused on compensating for this loss of neurons. However, cholinesterase inhibitors can only alleviate cognitive symptoms of AD and cannot reduce the progression of the disease. Understanding the molecular and cellular changes associated with AD pathology has advanced significantly in recent decades. The etiology of AD is complex, with a substantial portion of sporadic AD emerging from unknown reasons and a lesser proportion of early-onset familial AD (FAD) caused by a mutation in several genes, such as the amyloid precursor protein (APP), presenilin 1 (PS1), and presenilin 2 (PS2) genes. Hence, efforts are being made to discover novel strategies for these targets for AD therapy. A new generation of AChE and BChE inhibitors is currently being explored and evaluated in human clinical trials for AD symptomatic treatment. Other approaches for slowing the progression of AD include serotonergic modulation, H3 receptor antagonism, phosphodiesterase, COX-2, and MAO-B inhibition. The present review provides an insight into the possible therapeutic strategies and their molecular mechanisms, enlightening the perception of classical and future treatment approaches.
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Affiliation(s)
- Anna Mathew
- Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Vignesh Balaji E
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Sreedhara Ranganath K Pai
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Anoop Kishore
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Vasudev Pai
- Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Ramadevi Pemmireddy
- Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
| | - Chandrashekar K S
- Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Karnataka-576104, India
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α7nAChR activation protects against oxidative stress, neuroinflammation and central insulin resistance in ICV-STZ induced sporadic Alzheimer's disease. Pharmacol Biochem Behav 2022; 217:173402. [DOI: 10.1016/j.pbb.2022.173402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/28/2022] [Accepted: 05/04/2022] [Indexed: 12/29/2022]
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The α7 nAChR allosteric modulator PNU-120596 amends neuroinflammatory and motor consequences of parkinsonism in rats: Role of JAK2/NF-κB/GSk3β/ TNF-α pathway. Biomed Pharmacother 2022; 148:112776. [PMID: 35272136 DOI: 10.1016/j.biopha.2022.112776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 02/01/2022] [Accepted: 02/27/2022] [Indexed: 11/20/2022] Open
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disorder and a leading cause of disability. The current gold standard for PD treatment, L-Dopa, has limited clinical efficacy and multiple side effects. Evidence suggests that activation of α7 nicotinic acetylcholine receptors (α7nAChRs) abrogates neuronal and inflammatory insults. Here we tested whether PNU-120596 (PNU), a type II positive allosteric modulator of α7 nAChR, has a critical role in regulating motor dysfunction and neuroinflammation correlated with the associated PD dysfunction. Neuroprotective mechanisms were investigated through neurobehavioral, molecular, histopathological, and immunohistochemical studies. PNU reversed motor incoordination and hypokinesia induced via the intrastriatal injection of 6-hydroxydopamine and manifested by lower falling latency in the rotarod test, short ambulation time and low rearing incidence in open field test. Tyrosine hydroxylase immunostaining showed a significant restoration of dopaminergic neurons following PNU treatment, in addition to histopathological restoration in nigrostriatal tissues. PNU halted striatal neuroinflammation manifested as a suppressed expression of JAK2/NF-κB/GSk3β accompanied by a parallel decline in the protein expression of TNF-α in nigrostriatal tissue denoting the modulator anti-inflammatory capacity. Moreover, the protective effects of PNU were partially reversed by the α7 nAChR antagonist, methyllycaconitine, indicating the role of α7 nAChR modulation in the mechanism of action of PNU. This is the first study to reveal the positive effects of PNU-120596 on motor derangements of PD via JAK2/NF-κB/GSk3β/ TNF-α neuroinflammatory pathways, which could offer a potential therapeutic strategy for PD.
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1-(7-Chloroquinolin-4-yl)-N-(4-Methoxybenzyl)-5-Methyl-1H-1,2, 3-Triazole-4- carboxamide Reduces Aβ Formation and Tau Phosphorylation in Cellular Models of Alzheimer's Disease. Neurochem Res 2022; 47:1110-1122. [PMID: 35165799 DOI: 10.1007/s11064-021-03514-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/17/2021] [Accepted: 12/18/2021] [Indexed: 10/19/2022]
Abstract
1-(7-Chloroquinolin-4-yl)-N-(4-methoxybenzyl)-5-methyl-1H-1,2,3-triazole-4- carboxamide (QTC-4-MeOBnE) is a new multi-target directed ligand (MTDL) rationally designed to have affinity with β-secretase (BACE), Glycogen Synthase Kinase 3β (GSK3β) and acetylcholinesterase, which are considered promising targets on the development of disease-modifying therapies against Alzheimer's Disease (AD). Previously, QTC-4-MeOBnE treatment showed beneficial effects in preclinical AD-like models by influencing in vivo neurogenesis, oxidative and inflammatory pathways. However, the biological effect and mechanism of action exerted by QTC-4-MeOBnE in AD cellular models have not been elucidated yet. Hereby we investigate the acute effect of QTC-4-MeOBnE on neuronal cells overexpressing Amyloid Protein Precursor (APP) or human tau protein, the two main features of the AD pathophysiology. When compared to the control group, QTC-4-MeOBnE treatment prevented amyloid beta (Aβ) formation through the downregulation of APP and BACE levels in APPswe-expressing cells. Furthermore, in N2a cells overexpressing human tau, QTC-4-MeOBnE reduced the levels of phosphorylated forms of tau via the modulation of the GSK3β pathway. Taken together, our findings provide new insights into the mechanism of action exerted by QTC-4-MeOBnE in AD cellular models, and further support its potential as an interesting therapeutic strategy against AD.
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McCallum RT, Perreault ML. Glycogen Synthase Kinase-3: A Focal Point for Advancing Pathogenic Inflammation in Depression. Cells 2021; 10:cells10092270. [PMID: 34571919 PMCID: PMC8470361 DOI: 10.3390/cells10092270] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/26/2021] [Accepted: 08/28/2021] [Indexed: 01/03/2023] Open
Abstract
Increasing evidence indicates that the host immune response has a monumental role in the etiology of major depressive disorder (MDD), motivating the development of the inflammatory hypothesis of depression. Central to the involvement of chronic inflammation in MDD is a wide range of signaling deficits induced by the excessive secretion of pro-inflammatory cytokines and imbalanced T cell differentiation. Such signaling deficits include the glutamatergic, cholinergic, insulin, and neurotrophin systems, which work in concert to initiate and advance the neuropathology. Fundamental to the communication between such systems is the protein kinase glycogen synthase kinase-3 (GSK-3), a multifaceted protein critically linked to the etiology of MDD and an emerging target to treat pathogenic inflammation. Here, a consolidated overview of the widespread multi-system involvement of GSK-3 in contributing to the neuropathology of MDD will be discussed, with the feed-forward mechanistic links between all major neuronal signaling pathways highlighted.
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Affiliation(s)
- Ryan T. McCallum
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada;
| | - Melissa L. Perreault
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada;
- Collaborative Program in Neuroscience, University of Guelph, Guelph, ON N1G 2W1, Canada
- Correspondence: ; Tel.: +1-(519)-824-4120 (ext. 52013)
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Genetic deletion of α7 nicotinic acetylcholine receptors induces an age-dependent Alzheimer's disease-like pathology. Prog Neurobiol 2021; 206:102154. [PMID: 34453977 DOI: 10.1016/j.pneurobio.2021.102154] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 05/29/2021] [Accepted: 08/18/2021] [Indexed: 11/22/2022]
Abstract
The accumulation of amyloid-beta peptide (Aβ) and the failure of cholinergic transmission are key players in Alzheimer's disease (AD). However, in the healthy brain, Aβ contributes to synaptic plasticity and memory acting through α7 subtype nicotinic acetylcholine receptors (α7nAChRs). Here, we hypothesized that the α7nAChR deletion blocks Aβ physiological function and promotes a compensatory increase in Aβ levels that, in turn, triggers an AD-like pathology. To validate this hypothesis, we studied the age-dependent phenotype of α7 knock out mice. We found that α7nAChR deletion caused an impairment of hippocampal synaptic plasticity and memory at 12 months of age, paralleled by an increase of Amyloid Precursor Protein expression and Aβ levels. This was accompanied by other classical AD features such as a hyperphosphorylation of tau at residues Ser 199, Ser 396, Thr 205, a decrease of GSK-3β at Ser 9, the presence of paired helical filaments and neurofibrillary tangles, neuronal loss and an increase of GFAP-positive astrocytes. Our findings suggest that α7nAChR malfunction might precede Aβ and tau pathology, offering a different perspective to interpret the failure of anti-Aβ therapies against AD and to find novel therapeutical approaches aimed at restoring α7nAChRs-mediated Aβ function at the synapse.
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Jaworski T. Control of neuronal excitability by GSK-3beta: Epilepsy and beyond. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118745. [PMID: 32450268 DOI: 10.1016/j.bbamcr.2020.118745] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/07/2020] [Accepted: 05/09/2020] [Indexed: 12/22/2022]
Abstract
Glycogen synthase kinase 3beta (GSK-3β) is an enzyme with a variety of cellular functions in addition to the regulation of glycogen metabolism. In the central nervous system, different intracellular signaling pathways converge on GSK-3β through a cascade of phosphorylation events that ultimately control a broad range of neuronal functions in the development and adulthood. In mice, genetically removing or increasing GSK-3β cause distinct functional and structural neuronal phenotypes and consequently affect cognition. Precise control of GSK-3β activity is important for such processes as neuronal migration, development of neuronal morphology, synaptic plasticity, excitability, and gene expression. Altered GSK-3β activity contributes to aberrant plasticity within neuronal circuits leading to neurological, psychiatric disorders, and neurodegenerative diseases. Therapeutically targeting GSK-3β can restore the aberrant plasticity of neuronal networks at least in animal models of these diseases. Although the complete repertoire of GSK-3β neuronal substrates has not been defined, emerging evidence shows that different ion channels and their accessory proteins controlling excitability, neurotransmitter release, and synaptic transmission are regulated by GSK-3β, thereby supporting mechanisms of synaptic plasticity in cognition. Dysregulation of ion channel function by defective GSK-3β activity sustains abnormal excitability in the development of epilepsy and other GSK-3β-linked human diseases.
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Affiliation(s)
- Tomasz Jaworski
- Laboratory of Animal Models, Nencki Institute of Experimental Biology, Warsaw, Poland.
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12
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Unal G, Bekci H, Cumaoglu A, Yerer MB, Aricioglu F. Alpha 7 nicotinic receptor agonist and positive allosteric modulators improved social and molecular deficits of MK-801 model of schizophrenia in rats. Pharmacol Biochem Behav 2020; 193:172916. [PMID: 32220620 DOI: 10.1016/j.pbb.2020.172916] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 03/20/2020] [Accepted: 03/23/2020] [Indexed: 01/28/2023]
Abstract
Schizophrenia is a common psychiatric disease that cannot be fully treated with current antipsychotic drugs. It has shown that glutamatergic NMDA receptor antagonists such as MK-801 cause schizophrenia-like phenotype in rodents. Recent studies indicated that α7 nicotinic acetylcholine receptor (nAChR) deficits contribute to schizophrenia. Enhancing its activity with agonist or positive allosteric modulators (PAMs) may be a valuable approach for treatment. The certain intracellular pathways such as Akt/Glycogen synthase kinase 3 beta (GSK-3β) and phosphodiesterase-4 (PDE-4)/cAMP are associated with the pathogenesis of schizophrenia. In this study, we examined the effect of α7 nAChR agonists and PAMs on the behavioral and molecular phenotype of schizophrenia in the subchronic MK-801 administered rats. Social interaction, the levels of α7 nAChR, and related intracellular pathways (cAMP, PDE4A, PDE4D, p-Akt/Akt, p-GSK-3β/GSK-3β) were measured by behavioral or ELISA and western blot tests. Subchronic MK-801 administration decreased the following behaviors and increased the avoiding behaviors. However, only α7 nAChR agonist (A-582941) increased the following behavior while α7 nAChR agonist, PAMs (CCMI and PNU-120596), and clozapine decreased the avoiding behavior compared to MK-801. For molecular parameters, MK-801 administration decreased the α7 nAChR, p-Akt/Akt, p-GSK-3β/GSK-3β expressions, and cAMP levels while it increased PDE4A, PDE4D expressions in the prefrontal cortex. Besides, MK-801 decreased the α7 nAChR, p-GSK-3β/GSK-3β expressions in the hippocampus. We found clozapine, α7 nAChR agonists, and PAMs reversed the molecular deficits induced by MK-801. Herein, we showed that prefrontal cortex is more sensitive to the devastating effects of subchronic MK-801 administration, especially for PDE4, in rats. In addition to clozapine, α7 nAChR agonists and PAMs found to be beneficial on both social and molecular deficits induced by MK-801 in rats. We suggested that α7 nAChR agonists and PAMs might be valuable approaches to treat negative symptoms of schizophrenia when unmet needs and current limitations considered in this pathology.
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Affiliation(s)
- G Unal
- Erciyes University, Faculty of Pharmacy, Department of Pharmacology, Kayseri, Turkey
| | - H Bekci
- Kayseri University, Yahyalı Vocational School, Kayseri, Turkey
| | - A Cumaoglu
- Erciyes University, Faculty of Pharmacy, Department of Biochemistry, Kayseri, Turkey
| | - M B Yerer
- Erciyes University, Faculty of Pharmacy, Department of Pharmacology, Kayseri, Turkey
| | - F Aricioglu
- Marmara University, Faculty of Pharmacy, Department of Pharmacology and Psychopharmacology Research Unit, Istanbul, Turkey.
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13
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Ma KG, Qian YH. Alpha 7 nicotinic acetylcholine receptor and its effects on Alzheimer's disease. Neuropeptides 2019; 73:96-106. [PMID: 30579679 DOI: 10.1016/j.npep.2018.12.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/26/2018] [Accepted: 12/16/2018] [Indexed: 01/16/2023]
Abstract
Alzheimer's disease (AD) is one of the major disabling and lethal diseases for aged individuals worldwide. To date, there are more than 10 hypotheses proposed for AD pathology. The beta-amyloid (Aβ) cascade hypothesis is the most widely accepted and proposes that the accumulation of Aβ in the brain is one potential mechanism for AD pathogenesis. Because some Aβ-overloaded patients do not have AD syndrome, this hypothesis is challenged from time to time. More recently, it has been shown that intracellular Aβ plays a key role in AD pathology. Aβ is internalized by receptors distributed on the cell membrane. Among these receptors, the alpha7 nicotinic acetylcholine receptor (α7 nAChR) has been shown to play an important role in AD. The α7 nAChR is a ligand-gated ion channel and is expressed in pivotal brain regions (e.g., the cerebral cortex and hippocampus) responsible for cognitive functions. The α7 nAChR is localized both presynaptically and postsynaptically, where it activates intracellular signaling cascades. Its agonist has been investigated in clinical studies to improve cognitive functions in AD. Although many studies have shown the importance of the α7 nAChR in AD, little is known regarding its role in AD pathology. Therefore, in the current review, we summarized the basic information regarding the structures and functions of the α7 nAChR, the distribution and expression of the α7 nAChR, and the role of the α7 nAChR in mediating Aβ internalization. We subsequently focused on introducing the comprehensive α7 nAChR related signaling pathways and how these signaling pathways are integrated with the α7 nAChR to play a role in AD. Finally, we stressed the AD therapy that targets the α7 nAChR.
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Affiliation(s)
- Kai-Ge Ma
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an 710061, China; Institute of Neurobiology, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China
| | - Yi-Hua Qian
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an 710061, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an 710061, China.
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ArunSundar M, Shanmugarajan TS, Ravichandiran V. 3,4-Dihydroxyphenylethanol Assuages Cognitive Impulsivity in Alzheimer's Disease by Attuning HPA-Axis via Differential Crosstalk of α7 nAChR with MicroRNA-124 and HDAC6. ACS Chem Neurosci 2018; 9:2904-2916. [PMID: 29901389 DOI: 10.1021/acschemneuro.7b00532] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cognitive impulsivity, a form of suboptimal cost-benefit decision making, is an illustrious attribute of an array of neurodegenerative diseases including Alzheimer's disease (AD). In this study, a delay discounting paradigm was used to assess the effect of 3,4-dihydroxyphenylethanol (DOPET) on cognitive impulsivity, in an oA42i (oligomeric amyloid β1-42 plus ibotenic acid) induced AD mouse model, using a nonspatial T-maze task. The results depicted that oA42i administration elevated cognitive impulsivity, whereas DOPET treatment attenuated the impulsive behavior and matched the choice of the sham-operated controls. In addition, DOPET treatment has ameliorated the anxiety-like behavior in the oA42i-challenged mice. Probing the molecular signaling cascades underpinning these functional ramifications in the oA42i-challenged mice revealed reduced cholinergic (α7 nAChR; alpha 7 nicotinic acetylcholine receptor) function, dysregulated hypothalamic-pituitary-adrenal (HPA) axis (manifested by amplified glucocorticoid receptor expression and plasma corticosterone levels), and also aberrations in the neuroepigenetic (microRNA-124, HDAC6 (histone deacetylase 6), and HSP90 (heat-shock protein 90) expressions) as well as nucleocytoplasmic (importin-α1 expression and nuclear ultra-architecture) continuum. Nonetheless, DOPET administration ameliorated these perturbations and the observations were in line with that of the sham-operated mice. Further validation of the results with organotypic hippocampal slice cultures (OHSCs) confirmed the in vivo findings. We opine that HPA-axis attunement by DOPET might be orchestrated through the α7 nAChR-mediated pathway. Based on these outcomes, we posit that 3,4-dihydroxyphenylethanol might be a potential multimodal agent for the management of cognitive impulsivity and neuromolecular quagmire in AD.
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Affiliation(s)
- Mohanasundaram ArunSundar
- Department of Pharmacology, School of Pharmaceutical Sciences, Vels University (VISTAS), Pallavaram, Chennai-600117, India
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Ruan Q, Yu Z, Zhang W, Ruan J, Liu C, Zhang R. Cholinergic Hypofunction in Presbycusis-Related Tinnitus With Cognitive Function Impairment: Emerging Hypotheses. Front Aging Neurosci 2018; 10:98. [PMID: 29681847 PMCID: PMC5897739 DOI: 10.3389/fnagi.2018.00098] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 03/22/2018] [Indexed: 01/21/2023] Open
Abstract
Presbycusis (age-related hearing loss) is a potential risk factor for tinnitus and cognitive deterioration, which result in poor life quality. Presbycusis-related tinnitus with cognitive impairment is a common phenotype in the elderly population. In these individuals, the central auditory system shows similar pathophysiological alterations as those observed in Alzheimer's disease (AD), including cholinergic hypofunction, epileptiform-like network synchronization, chronic inflammation, and reduced GABAergic inhibition and neural plasticity. Observations from experimental rodent models indicate that recovery of cholinergic function can improve memory and other cognitive functions via acetylcholine-mediated GABAergic inhibition enhancement, nicotinic acetylcholine receptor (nAChR)-mediated anti-inflammation, glial activation inhibition and neurovascular protection. The loss of cholinergic innervation of various brain structures may provide a common link between tinnitus seen in presbycusis-related tinnitus and age-related cognitive impairment. We hypothesize a key component of the condition is the withdrawal of cholinergic input to a subtype of GABAergic inhibitory interneuron, neuropeptide Y (NPY) neurogliaform cells. Cholinergic denervation might not only cause the degeneration of NPY neurogliaform cells, but may also result in decreased AChR activation in GABAergic inhibitory interneurons. This, in turn, would lead to reduced GABA release and inhibitory regulation of neural networks. Reduced nAChR-mediated anti-inflammation due to the loss of nicotinic innervation might lead to the transformation of glial cells and release of inflammatory mediators, lowering the buffering of extracellular potassium and glutamate metabolism. Further research will provide evidence for the recovery of cholinergic function with the use of cholinergic input enhancement alone or in combination with other rehabilitative interventions to reestablish inhibitory regulation mechanisms of involved neural networks for presbycusis-related tinnitus with cognitive impairment.
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Affiliation(s)
- Qingwei Ruan
- Shanghai Institute of Geriatrics and Gerontology, Shanghai Key Laboratory of Clinical Geriatrics, Huadong Hospital, and Research Center of Aging and Medicine, Shanghai Medical College, Fudan University, Shanghai, China
| | - Zhuowei Yu
- Shanghai Institute of Geriatrics and Gerontology, Shanghai Key Laboratory of Clinical Geriatrics, Huadong Hospital, and Research Center of Aging and Medicine, Shanghai Medical College, Fudan University, Shanghai, China
| | - Weibin Zhang
- Shanghai Institute of Geriatrics and Gerontology, Shanghai Key Laboratory of Clinical Geriatrics, Huadong Hospital, and Research Center of Aging and Medicine, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jian Ruan
- Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chunhui Liu
- Department of Otolaryngology, Huadong Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Ruxin Zhang
- Department of Otolaryngology, Huadong Hospital, Shanghai Medical College, Fudan University, Shanghai, China
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Callahan PM, Bertrand D, Bertrand S, Plagenhoef MR, Terry AV. Tropisetron sensitizes α7 containing nicotinic receptors to low levels of acetylcholine in vitro and improves memory-related task performance in young and aged animals. Neuropharmacology 2017; 117:422-433. [PMID: 28259598 DOI: 10.1016/j.neuropharm.2017.02.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/06/2017] [Accepted: 02/25/2017] [Indexed: 01/02/2023]
Abstract
Tropisetron, a 5-HT3 receptor antagonist commonly prescribed for chemotherapy-induced nausea and vomiting also exhibits high affinity, partial agonist activity at α7 nicotinic acetylcholine receptors (α7 nAChRs). α7 nAChRs are considered viable therapeutic targets for neuropsychiatric disorders such as Alzheimer's disease (AD). Here we further explored the nAChR pharmacology of tropisetron to include the homomeric α7 nAChR and recently characterized heteromeric α7β2 nAChR (1:10 ratio) and we evaluated its cognitive effects in young and aged animals. Electrophysiological studies on human nAChRs expressed in Xenopus oocytes confirmed the partial agonist activity of tropisetron at α7 nAChRs (EC50 ∼2.4 μM) with a similar effect at α7β2 nAChRs (EC50 ∼1.5 μM). Moreover, currents evoked by irregular pulses of acetylcholine (40 μM) at α7 and α7β2 nAChRs were enhanced during sustained exposure to low concentrations of tropisetron (10 and 30 nM) indicative of a "priming" or co-agonist effect. Tropisetron (0.1-10 mg/kg) improved novel object recognition performance in young Sprague-Dawley rats and in aged Fischer rats. In aged male and female rhesus monkeys, tropisetron (0.03-1 mg/kg) produced a 17% increase from baseline levels in delayed match to sample long delay accuracy while combination of non-effective doses of donepezil (0.1 mg/kg) and tropisetron (0.03 and 0.1 mg/kg) produced a 24% change in accuracy. Collectively, these animal experiments indicate that tropisetron enhances cognition and has the ability to improve the effective dose range of currently prescribed AD therapy (donepezil). Moreover, these effects may be explained by tropisetron's ability to sensitize α7 containing nAChRs to low levels of acetylcholine.
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Affiliation(s)
- Patrick M Callahan
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States.
| | - Daniel Bertrand
- HiQScreen Sàrl, 6, rte de Compois, 1222 Vésenaz, Geneva, Switzerland
| | - Sonia Bertrand
- HiQScreen Sàrl, 6, rte de Compois, 1222 Vésenaz, Geneva, Switzerland
| | - Marc R Plagenhoef
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States
| | - Alvin V Terry
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States
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Damar U, Gersner R, Johnstone JT, Schachter S, Rotenberg A. Huperzine A: A promising anticonvulsant, disease modifying, and memory enhancing treatment option in Alzheimer's disease. Med Hypotheses 2016; 99:57-62. [PMID: 28110700 DOI: 10.1016/j.mehy.2016.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 12/17/2016] [Indexed: 12/22/2022]
Abstract
Alzheimer's disease (AD) is the most frequent cause of dementia. Besides cognitive deterioration, patients with AD are prone to seizures - more than 20% of patients diagnosed with AD experience at least one unprovoked seizure and up to 7% have recurrent seizures. Although available antiepileptic drugs (AEDs) may suppress seizures in patients with AD, they may also worsen cognitive dysfunction and increase the risk of falls. On the basis of preclinical studies, we hypothesize that Huperzine A (HupA), a safe and potent acetylcholinesterase (AChE) inhibitor with potentially disease-modifying qualities in AD, may have a realistic role as an anticonvulsant in AD.
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Affiliation(s)
- Ugur Damar
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Roman Gersner
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Steven Schachter
- Department of Neurology, Beth Israel Deaconess Medical Center, and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Alexander Rotenberg
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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Kalkman HO, Feuerbach D. Modulatory effects of α7 nAChRs on the immune system and its relevance for CNS disorders. Cell Mol Life Sci 2016; 73:2511-30. [PMID: 26979166 PMCID: PMC4894934 DOI: 10.1007/s00018-016-2175-4] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/25/2016] [Accepted: 03/01/2016] [Indexed: 02/08/2023]
Abstract
The clinical development of selective alpha-7 nicotinic acetylcholine receptor (α7 nAChR) agonists has hitherto been focused on disorders characterized by cognitive deficits (e.g., Alzheimer's disease, schizophrenia). However, α7 nAChRs are also widely expressed by cells of the immune system and by cells with a secondary role in pathogen defense. Activation of α7 nAChRs leads to an anti-inflammatory effect. Since sterile inflammation is a frequently observed phenomenon in both psychiatric disorders (e.g., schizophrenia, melancholic and bipolar depression) and neurological disorders (e.g., Alzheimer's disease, Parkinson's disease, and multiple sclerosis), α7 nAChR agonists might show beneficial effects in these central nervous system disorders. In the current review, we summarize information on receptor expression, the intracellular signaling pathways they modulate and reasons for receptor dysfunction. Information from tobacco smoking, vagus nerve stimulation, and cholinesterase inhibition is used to evaluate the therapeutic potential of selective α7 nAChR agonists in these inflammation-related disorders.
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Affiliation(s)
- Hans O Kalkman
- Neuroscience Research, NIBR, Fabrikstrasse 22-3.001.02, 4002, Basel, Switzerland.
- , Gänsbühlgartenweg 7, 4132, Muttenz, Switzerland.
| | - Dominik Feuerbach
- Neuroscience Research, NIBR, Fabrikstrasse 22-3.001.02, 4002, Basel, Switzerland
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Provensi G, Costa A, Passani MB, Blandina P. Donepezil, an acetylcholine esterase inhibitor, and ABT-239, a histamine H3 receptor antagonist/inverse agonist, require the integrity of brain histamine system to exert biochemical and procognitive effects in the mouse. Neuropharmacology 2016; 109:139-147. [PMID: 27291828 DOI: 10.1016/j.neuropharm.2016.06.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 06/06/2016] [Accepted: 06/08/2016] [Indexed: 01/07/2023]
Abstract
Histaminergic H3 receptors (H3R) antagonists enhance cognition in preclinical models and modulate neurotransmission, in particular acetylcholine (ACh) release in the cortex and hippocampus, two brain areas involved in memory processing. The cognitive deficits seen in aging and Alzheimer's disease have been associated with brain cholinergic deficits. Donepezil is one of the acetylcholinesterase (AChE) inhibitor approved for use across the full spectrum of these cognitive disorders. We addressed the question if H3R antagonists and donepezil require an intact histamine neuronal system to exert their procognitive effects. The effect of the H3R antagonist ABT-239 and donepezil were evaluated in the object recognition test (ORT), and on the level of glycogen synthase kinase 3 beta (GSK-3β) phosphorylation in normal and histamine-depleted mice. Systemic administration of ABT-239 or donepezil ameliorated the cognitive performance in the ORT. However, these compounds were ineffective in either genetically (histidine decarboxylase knock-out, HDC-KO) or pharmacologically, by means of intracerebroventricular (i.c.v.) injections of the HDC irreversible inhibitor a-fluoromethylhistidine (a-FMHis), histamine-deficient mice. Western blot analysis revealed that ABT-239 or donepezil systemic treatments increased GSK-3β phosphorylation in cortical and hippocampal homogenates of normal, but not of histamine-depleted mice. Furthermore, administration of the PI3K inhibitor LY294002 that blocks GSK-3β phosphorylation, prevented the procognitive effects of both drugs in normal mice. Our results indicate that both donepezil and ABT-239 require the integrity of the brain histaminergic system to exert their procognitive effects and strongly suggest that impairments of PI3K/AKT/GSK-3β intracellular pathway activation is responsible for the inefficacy of both drugs in histamine-deficient animals.
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Affiliation(s)
- Gustavo Provensi
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmacologia and Tossicologia, Universitá di Firenze, Viale G. Pieraccini 6, 50139, Firenze, Italy
| | - Alessia Costa
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmacologia and Tossicologia, Universitá di Firenze, Viale G. Pieraccini 6, 50139, Firenze, Italy
| | - M Beatrice Passani
- Dipartimento di Scienze della Salute, Sezione di Farmacologia e Oncologia, Universitá di Firenze, Viale G. Pieraccini 6, 50139, Firenze, Italy
| | - Patrizio Blandina
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmacologia and Tossicologia, Universitá di Firenze, Viale G. Pieraccini 6, 50139, Firenze, Italy.
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Accumulation of human full-length tau induces degradation of nicotinic acetylcholine receptor α4 via activating calpain-2. Sci Rep 2016; 6:27283. [PMID: 27277673 PMCID: PMC4899694 DOI: 10.1038/srep27283] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 05/13/2016] [Indexed: 01/07/2023] Open
Abstract
Cholinergic impairments and tau accumulation are hallmark pathologies in sporadic Alzheimer’s disease (AD), however, the intrinsic link between tau accumulation and cholinergic deficits is missing. Here, we found that overexpression of human wild-type full-length tau (termed hTau) induced a significant reduction of α4 subunit of nicotinic acetylcholine receptors (nAChRs) with an increased cleavage of the receptor producing a ~55kDa fragment in primary hippocampal neurons and in the rat brains, meanwhile, the α4 nAChR currents decreased. Further studies demonstrated that calpains, including calpain-1 and calpain-2, were remarkably activated with no change of caspase-3, while simultaneous suppression of calpain-2 by selective calpain-2 inhibitor but not calpain-1 attenuated the hTau-induced degradation of α4 nAChR. Finally, we demonstrated that hTau accumulation increased the basal intracellular calcium level in primary hippocampal neurons. We conclude that the hTau accumulation inhibits nAChRs α4 by activating calpain-2. To our best knowledge, this is the first evidence showing that the intracellular accumulation of tau causes cholinergic impairments.
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Zhao L, Xiao Y, Wang XL, Pei J, Guan ZZ. Original Research: Influence of okadaic acid on hyperphosphorylation of tau and nicotinic acetylcholine receptors in primary neurons. Exp Biol Med (Maywood) 2016; 241:1825-33. [PMID: 27190248 DOI: 10.1177/1535370216650759] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 04/25/2016] [Indexed: 11/15/2022] Open
Abstract
The aim of the study was to investigate the influence of hyperphosphorylation of tau induced by okadaic acid on the expression of nicotinic acetylcholine receptors and the neurotoxicity of β-amyloid peptide. Primary cultures of neurons isolated from the hippocampus of the brains of neonatal rats were exposed to okadaic acid or/and Aβ1-42 Tau phosphorylated at Ser404 and Ser202, and the protein expressions of α7, α4 and α3 nAChR subunits were quantified by Western blotting, and their corresponding mRNAs by real-time PCR. Superoxide dismutase activity was assayed biochemically and malondialdehyde by thiobarbituric acid-reactive substance. As compared to controls, phosphorylations of tau at Ser404 and Ser202 in the neurons were elevated by exposure to 20 nM okadaic acid for 48 h but not by 1 or 2 µM Aβ1-42 Treatment with 20 nM okadaic acid or 1 µM Aβ1-42 for 48 h resulted in the reduced α7, α4 and α3 proteins, and α4 and α3 mRNAs, as well as the decreased activity of superoxide dismutase and the increased malondialdehyde. Okadaic acid and Aβ1-42 together caused more pronounced changes in the expressions of α7 and α4, superoxide dismutase activity and lipid peroxidation than either alone. When pre-treatment with vitamin E or lovastatin, the neurotoxicity induced by okadaic acid was significantly attenuated. These findings indicate that hyperphosphorylation of tau induced by okadaic acid inhibits the expression of nicotinic acetylcholine receptors at both the protein and mRNA levels, as well as enhances the neurotoxicity of β-amyloid peptide.
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Affiliation(s)
- Liang Zhao
- Department of Pathology at the Affiliated Hospital, Guizhou Medical University, Guiyang 550004, Guizhou, PR China
| | - Yan Xiao
- The Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang 550004, Guizhou, PR China
| | - Xiao-Liang Wang
- The Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang 550004, Guizhou, PR China
| | - Jinjing Pei
- KI-Alzheimer Disease Research Center, Karolinska Institutet, Novum, SE14186 Huddinge, Sweden
| | - Zhi-Zhong Guan
- Department of Pathology at the Affiliated Hospital, Guizhou Medical University, Guiyang 550004, Guizhou, PR China The Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang 550004, Guizhou, PR China
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22
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Cuadrado A. Structural and functional characterization of Nrf2 degradation by glycogen synthase kinase 3/β-TrCP. Free Radic Biol Med 2015; 88:147-157. [PMID: 25937177 DOI: 10.1016/j.freeradbiomed.2015.04.029] [Citation(s) in RCA: 183] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 04/21/2015] [Accepted: 04/22/2015] [Indexed: 12/30/2022]
Abstract
Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a master regulator of cellular homeostasis that controls the expression of more than 1% of human genes related to biotransformation reactions, redox homeostasis, energetic metabolism, DNA repair, and proteostasis. Its activity has a tremendous impact on physiology and pathology and therefore it is very tightly regulated, mainly at the level of protein stability. In addition to the very well established regulation by the ubiquitin E3 ligase adapter Keap1, recent advances have identified a novel mechanism based on signaling pathways that regulate glycogen synthase kinse-3 (GSK-3). This kinase phosphorylates specific serine residues in the Neh6 domain of Nrf2 to create a degradation domain that is then recognized by the ubiquitin ligase adapter β-TrCP and tagged for proteasome degradation by a Cullin1/Rbx1 complex. Here we review the mechanistic elements and the signaling pathways that participate in this regulation by GSK-3/β-TrCP. These pathways include those activated by ligands of tyrosine kinase, G protein-coupled, metabotropic, and ionotropic receptors that activate phosphatidyl inositol 3-kinase (PI3K)/ATK and by the canonical WNT signaling pathway, where a fraction of Nrf2 interacts with Axin1/GSK-3. Considering that free Nrf2 protein is localized in the nucleus, we propose a model termed "double flux controller" to explain how Keap1 and β-TrCP coordinate the stability of Nrf2 in several scenarios. The GSK-3/β-TrCP axis provides a novel therapeutic strategy to modulate Nrf2 activity.
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Affiliation(s)
- Antonio Cuadrado
- Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Investigaciones Biomedicas "Alberto Sols" UAM-CSIC, Instituto de Investigación Sanitaria La Paz (IdiPaz), and Department of Biochemistry, Faculty of Medicine, Autonomous University of Madrid, 28029 Madrid, Spain.
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23
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BAG2 expression dictates a functional intracellular switch between the p38-dependent effects of nicotine on tau phosphorylation levels via the α7 nicotinic receptor. Exp Neurol 2015; 275 Pt 1:69-77. [PMID: 26496817 DOI: 10.1016/j.expneurol.2015.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/25/2015] [Accepted: 10/19/2015] [Indexed: 01/03/2023]
Abstract
The histopathological hallmarks present in Alzheimer's disease (AD) brain are plaques of Aβ peptide, neurofibrillary tangles of hyperphosphorylated tau protein, and a reduction in nicotinic acetylcholine receptor (nAChR) levels. The role of nAChRs in AD is particularly controversial. Tau protein function is regulated by phosphorylation, and its hyperphosphorylated forms are significantly more abundant in AD brain. Little is known about the relationship between nAChR and phospho-tau degradation machinery. Activation of nAChRs has been reported to increase and decrease tau phosphorylation levels, and the mechanisms responsible for this discrepancy are not presently understood. The co-chaperone BAG2 is capable of regulating phospho-tau levels via protein degradation. In SH-SY5Y cell line and rat primary hippocampal cell culture low endogenous BAG2 levels constitute an intracellular environment conducive to nicotine-induced accumulation of phosphorylated tau protein. Further, nicotine treatment inhibited endogenous expression of BAG2, resulting in increased levels of phosphorylated tau indistinguishable from those induced by BAG2 knockdown. Conversely, overexpression of BAG2 is conducive to a nicotine-induced reduction in cellular levels of phosphorylated tau protein. In both cases the effect of nicotine was p38MAPK-dependent, while the α7 antagonist MLA was synthetic to nicotine treatment, either increasing levels of phospho-Tau in the absence of BAG2, or further decreasing the levels of phospho-Tau in the presence of BAG2. Taken together, these findings reconcile the apparently contradictory effects of nicotine on tau phosphorylation by suggesting a role for BAG2 as an important regulator of p38-dependent tau kinase activity and phospho-tau degradation in response to nicotinic receptor stimulation. Thus, we report that BAG2 expression dictates a functional intracellular switch between the p38-dependent functions of nicotine on tau phosphorylation levels via the α7 nicotinic receptor.
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24
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The α7 nicotinic acetylcholine receptor: A mediator of pathogenesis and therapeutic target in autism spectrum disorders and Down syndrome. Biochem Pharmacol 2015; 97:363-377. [DOI: 10.1016/j.bcp.2015.06.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/04/2015] [Indexed: 01/06/2023]
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25
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Bertrand D, Lee CHL, Flood D, Marger F, Donnelly-Roberts D. Therapeutic Potential of α7 Nicotinic Acetylcholine Receptors. Pharmacol Rev 2015; 67:1025-73. [DOI: 10.1124/pr.113.008581] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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26
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Deutsch SI, Burket JA, Benson AD. Targeting the α7 nicotinic acetylcholine receptor to prevent progressive dementia and improve cognition in adults with Down's syndrome. Prog Neuropsychopharmacol Biol Psychiatry 2014; 54:131-9. [PMID: 24865150 DOI: 10.1016/j.pnpbp.2014.05.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 05/19/2014] [Accepted: 05/19/2014] [Indexed: 12/11/2022]
Abstract
As persons with Down's syndrome (DS) age into the third decade and beyond, they develop Alzheimer's disease (AD)-like histopathological changes in brain and may manifest progressive worsening of adaptive functions. Increasingly, persons with DS have near-normal to normal life spans; thus, it has become a therapeutic imperative to preserve adaptive functions and ability to live as independently as possible in the least restrictive environment throughout adulthood. Data suggest that these histopathological changes and worsening adaptive functions result, at least in part, from the binding of the amyloidogenic Aβ1-42 peptide to α7 nicotinic acetylcholine receptors (α7nAChRs) on the surface of neurons, which can lead to the internalization of the tightly-bound complex and cell lysis. Pharmacotherapeutic targeting of the α7nAChR may inhibit the creation of the Aβ1-42-α7nAChR complex, which has been observed both intraneuronally and as a component of the amyloid plaque seen in AD. Additionally, selective α7nAChR agonists may improve memory and cognition independently of their potential ability to attenuate the cytotoxicity of Aβ1-42 and retard the deposition of amyloid plaques in adults with DS. However, there are conflicting data supporting an antagonist strategy to improve cognition in the presence of elevated levels of Aβ amyloidogenic peptides, as well as to prevent emergence of pyramidal neuron hyperexcitability. A major challenge to the implementation of clinical trials of targeted α7nAChR interventions in adults with DS will be the ability to detect medication-induced changes in cognition in the context of intellectual disability. The Review will consider some of the current evidence supporting both the role of the Aβ1-42-α7nAChR complex in the pathogenesis of the AD-like histopathology in adult persons with DS, and pharmacotherapeutic interventions with α7nAChR agonists.
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Affiliation(s)
- Stephen I Deutsch
- Department of Psychiatry and Behavioral Sciences1, Eastern Virginia Medical School, Norfolk, VA, United States.
| | - Jessica A Burket
- Department of Psychiatry and Behavioral Sciences1, Eastern Virginia Medical School, Norfolk, VA, United States
| | - Andrew D Benson
- Department of Psychiatry and Behavioral Sciences1, Eastern Virginia Medical School, Norfolk, VA, United States
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27
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Cochran JN, Hall AM, Roberson ED. The dendritic hypothesis for Alzheimer's disease pathophysiology. Brain Res Bull 2014; 103:18-28. [PMID: 24333192 PMCID: PMC3989444 DOI: 10.1016/j.brainresbull.2013.12.004] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 11/28/2013] [Accepted: 12/02/2013] [Indexed: 01/02/2023]
Abstract
Converging evidence indicates that processes occurring in and around neuronal dendrites are central to the pathogenesis of Alzheimer's disease. These data support the concept of a "dendritic hypothesis" of AD, closely related to the existing synaptic hypothesis. Here we detail dendritic neuropathology in the disease and examine how Aβ, tau, and AD genetic risk factors affect dendritic structure and function. Finally, we consider potential mechanisms by which these key drivers could affect dendritic integrity and disease progression. These dendritic mechanisms serve as a framework for therapeutic target identification and for efforts to develop disease-modifying therapeutics for Alzheimer's disease.
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Affiliation(s)
- J Nicholas Cochran
- Center for Neurodegeneration and Experimental Therapeutics, Departments of Neurology and Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Alicia M Hall
- Center for Neurodegeneration and Experimental Therapeutics, Departments of Neurology and Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Erik D Roberson
- Center for Neurodegeneration and Experimental Therapeutics, Departments of Neurology and Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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Medeiros R, Castello NA, Cheng D, Kitazawa M, Baglietto-Vargas D, Green KN, Esbenshade TA, Bitner RS, Decker MW, LaFerla FM. α7 Nicotinic receptor agonist enhances cognition in aged 3xTg-AD mice with robust plaques and tangles. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 184:520-9. [PMID: 24269557 DOI: 10.1016/j.ajpath.2013.10.010] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 10/20/2013] [Accepted: 10/23/2013] [Indexed: 12/31/2022]
Abstract
Alzheimer disease (AD) is a progressive neurodegenerative disorder with associated memory loss, spatial disorientation, and other psychiatric problems. Cholinergic system dysfunction is an early and salient feature of AD, and enhancing cholinergic signaling with acetylcholinesterase inhibitors is currently the primary strategy for improving cognition. The beneficial effects of acetylcholinesterase inhibitors, however, are typically short-lived and accompanied by adverse effects. Recent evidence suggests that activating α7 nicotinic acetylcholine receptors (α7 nAChR) may facilitate the specific modulation of brain cholinergic signaling, leading to cognitive enhancement and possibly to amelioration of AD pathologic findings. In the present study, we determined the effect of long-term treatment with the selective α7 nAChR agonist A-582941 in aged 3xTg-AD mice with robust AD-like pathology, which is particularly significant not only because this is the only mouse model that co-develops amyloid plaques and neurofibrillary tangles but also because it enabled us to explore whether A-582941 is able to restore brain function after the severe damage associated with AD. Analysis of β-amyloid deposits, tau phosphorylation, and inflammatory cells revealed that, overall, pathologic findings were unchanged. Rather, α7 nAChR activation induced expression of c-Fos and brain-derived neurotrophic factor and phosphorylation of cyclic adenosine monophosphate response element binding and neurotrophic tyrosine receptor kinase type 2. More important, A-582941 completely restored cognition in aged 3xTg-AD mice to the level of that in age-matched nontransgenic mice. These novel findings indicate that activating α7 nAChR is a promising treatment for cognitive impairment in AD.
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Affiliation(s)
- Rodrigo Medeiros
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California; Department of Neurobiology and Behavior, University of California, Irvine, California
| | - Nicholas A Castello
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California; Department of Neurobiology and Behavior, University of California, Irvine, California
| | - David Cheng
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California; Department of Neurobiology and Behavior, University of California, Irvine, California
| | - Masashi Kitazawa
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California; Department of Neurobiology and Behavior, University of California, Irvine, California
| | - David Baglietto-Vargas
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California; Department of Neurobiology and Behavior, University of California, Irvine, California
| | - Kim N Green
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California; Department of Neurobiology and Behavior, University of California, Irvine, California
| | | | | | | | - Frank M LaFerla
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, California; Department of Neurobiology and Behavior, University of California, Irvine, California.
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Effects of sub-chronic donepezil on brain Abeta and cognition in a mouse model of Alzheimer's disease. Psychopharmacology (Berl) 2013; 230:279-89. [PMID: 23783773 DOI: 10.1007/s00213-013-3152-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 05/15/2013] [Indexed: 02/06/2023]
Abstract
RATIONALE Acetylcholinesterase inhibitors (AChEIs) are approved to treat the symptoms of mild to moderate Alzheimer's disease by restoring acetylcholine levels at synapses where the neurotransmitter has been depleted due to neurodegeneration. This assumption is challenged by more recent clinical studies suggesting the potential for disease-modifying effects of AChEIs as well as in vitro studies showing neuroprotective effects. However, few preclinical studies have assessed whether the improvement of cognitive symptoms may be mediated by reductions in Abeta or Tau pathology. OBJECTIVES The objective of the present study was to determine whether short-duration treatment with donepezil could improve spatial learning and memory in transgenic mice overexpressing mutant human amyloid precursor protein (hAPP) and presenilin 1 (PS1) (Dewachter et al., J Neurosci 20(17):6452-6458, 2000) after amyloid pathology has fully developed, consistent with early stages of Alzheimer'sdisease in humans. In parallel, the effect of donepezil treatment on brain amyloid, Tau, and glial endpoints was measured. RESULTS This study showed a significant improvement in reference memory in hAPP/PS1 mice along with dose-dependent reductions in brain amyloid-β (Aβ). CONCLUSION These results suggest that the observed cognitive improvement produced by donepezil in Alzheimer's disease may be due, at least in part, to reduction of brain Aβ.
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Posadas I, López-Hernández B, Ceña V. Nicotinic receptors in neurodegeneration. Curr Neuropharmacol 2013; 11:298-314. [PMID: 24179465 PMCID: PMC3648781 DOI: 10.2174/1570159x11311030005] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 01/04/2013] [Accepted: 03/04/2013] [Indexed: 02/07/2023] Open
Abstract
Many studies have focused on expanding our knowledge of the structure and diversity of peripheral and central nicotinic receptors. Nicotinic acetylcholine receptors (nAChRs) are members of the Cys-loop superfamily of pentameric ligand-gated ion channels, which include GABA (A and C), serotonin, and glycine receptors. Currently, 9 alpha (α2-α10) and 3 beta (β2-β4) subunits have been identified in the central nervous system (CNS), and these subunits assemble to form a variety of functional nAChRs. The pentameric combination of several alpha and beta subunits leads to a great number of nicotinic receptors that vary in their properties, including their sensitivity to nicotine, permeability to calcium and propensity to desensitize. In the CNS, nAChRs play crucial roles in modulating presynaptic, postsynaptic, and extrasynaptic signaling, and have been found to be involved in a complex range of CNS disorders including Alzheimer’s disease (AD), Parkinson’s disease (PD), schizophrenia, Tourette´s syndrome, anxiety, depression and epilepsy. Therefore, there is growing interest in the development of drugs that modulate nAChR functions with optimal benefits and minimal adverse effects. The present review describes the main characteristics of nAChRs in the CNS and focuses on the various compounds that have been tested and are currently in phase I and phase II trials for the treatment of neurodegenerative diseases including PD, AD and age-associated memory and mild cognitive impairment.
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Affiliation(s)
- Inmaculada Posadas
- Unidad Asociada Neurodeath. CSIC-Universidad de Castilla-La Mancha, Departamento de Ciencias Médicas. Albacete, Spain and CIBERNED, Instituto de Salud Carlos III, Spain
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Dinamarca MC, Ríos JA, Inestrosa NC. Postsynaptic Receptors for Amyloid-β Oligomers as Mediators of Neuronal Damage in Alzheimer's Disease. Front Physiol 2012; 3:464. [PMID: 23267328 PMCID: PMC3526732 DOI: 10.3389/fphys.2012.00464] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 11/22/2012] [Indexed: 11/13/2022] Open
Abstract
The neurotoxic effect of amyloid-β peptide (Aβ) over the central synapses has been described and is reflected in the decrease of some postsynaptic excitatory proteins, the alteration in the number and morphology of the dendritic spines, and a decrease in long-term potentiation. Many studies has been carried out to identify the putative Aβ receptors in neurons, and is still no clear why the Aβ oligomers only affect the excitatory synapses. Aβ oligomers bind to neurite and preferentially to the postsynaptic region, where the postsynaptic protein-95 (PSD-95) is present in the glutamatergic synapse, and interacts directly with the N-methyl-D-aspartate receptor (NMDAR) and neuroligin (NL). NL is a postsynaptic protein which binds to the presynaptic protein, neurexin to form a heterophilic adhesion complex, the disruption of this interaction affects the integrity of the synaptic contact. Structurally, NL has an extracellular domain homolog to acetylcholinesterase, the first synaptic protein that was found to interact with Aβ. In the present review we will document the interaction between Aβ and the extracellular domain of NL-1 at the excitatory synapse, as well as the interaction with other postsynaptic components, including the glutamatergic receptors (NMDA and mGluR5), the prion protein, the neurotrophin receptor, and the α7-nicotinic acetylcholine receptor. We conclude that several Aβ oligomers receptors exist at the excitatory synapse, which could be the responsible for the neurotoxic effect described for the Aβ oligomers. The characterization of the interaction between Aβ receptors and Aβ oligomers could help to understand the source of the neurologic damage observed in the brain of the Alzheimer's disease patients.
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Affiliation(s)
- Margarita C Dinamarca
- Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
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Vohora D, Bhowmik M. Histamine H3 receptor antagonists/inverse agonists on cognitive and motor processes: relevance to Alzheimer's disease, ADHD, schizophrenia, and drug abuse. Front Syst Neurosci 2012; 6:72. [PMID: 23109919 PMCID: PMC3478588 DOI: 10.3389/fnsys.2012.00072] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 10/04/2012] [Indexed: 12/18/2022] Open
Abstract
Histamine H3 receptor (H3R) antagonists/inverse agonists possess potential to treat diverse disease states of the central nervous system (CNS). Cognitive dysfunction and motor impairments are the hallmark of multifarious neurodegenerative and/or psychiatric disorders. This review presents the various neurobiological/neurochemical evidences available so far following H3R antagonists in the pathophysiology of Alzheimer's disease (AD), attention-deficit hyperactivity disorder (ADHD), schizophrenia, and drug abuse each of which is accompanied by deficits of some aspects of cognitive and/or motor functions. Whether the H3R inverse agonism modulates the neurochemical basis underlying the disease condition or affects only the cognitive/motor component of the disease process is discussed with the aim to provide a rationale for their use in diverse disease states that are interlinked and are accompanied by some common motor, cognitive and attentional deficits.
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Affiliation(s)
- Divya Vohora
- Faculty of Pharmacy, Department of Pharmacology, Jamia Hamdard (Hamdard University) New Delhi, India
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The novel calpain inhibitor A-705253 prevents stress-induced tau hyperphosphorylation in vitro and in vivo. Neuropharmacology 2012; 63:606-12. [PMID: 22613839 DOI: 10.1016/j.neuropharm.2012.05.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 05/03/2012] [Accepted: 05/10/2012] [Indexed: 11/23/2022]
Abstract
Calcium-mediated pathologic activation of the cysteine protease calpain has been linked to neurodegenerative disorders such as Alzheimer's disease (AD) through the cleavage of proteolytic substrates that negatively affect neuronal function. Hyperphosphorylation of the microtubule-associated protein tau and the subsequent aggregation of tau filaments resulting in the intracellular formation of neurofibrillary tangles are recognized as key etiological factors in AD pathology. Cyclin-dependent kinase 5 (Cdk5), a major kinase responsible for tau hyperphosphorylation in the AD brain, becomes hyperactivated through calpain-mediated cleavage-conversion of the Cdk5 regulatory protein p35 to p25. In the present study, we examined the effects of the novel small-molecule calpain inhibitor A-705253 in acute models of tau hyperphosphorylation in vitro and in vivo. In hippocampal slices in vitro, lowering medium temperature to 33 °C increased tau phosphorylation in which incubation with A-705253 blocked low temperature-induced tau phosphorylation as measured by Western blot analysis. Pentobarbital-induced hypothermia or acute systemic LPS treatment in normal mice increased tau phosphorylation in hippocampal CA3 mossy fibers, as measured by immunohistochemistry, whereas acute A-705253 pretreatment prevented the stress-induced tau hyperphosphorylation in both models. In support of a Cdk5-mediated mechanism, A-705253 administered for two weeks in the drinking water of six month-old prepathogenic 3x Tg-AD mice resulted in decreased expression of the calpain proteolytic p25 fragment. Taken together, results of these studies suggest that calpain inhibition has potential utility in reducing tau hyperphosphorylation and may represent a novel disease-modifying approach in the treatment of AD.
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Nicotine stimulated bone marrow-derived dendritic cells could augment HBV specific CTL priming by activating PI3K-Akt pathway. Immunol Lett 2012; 146:40-9. [PMID: 22546501 DOI: 10.1016/j.imlet.2012.02.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 01/16/2012] [Accepted: 02/19/2012] [Indexed: 01/08/2023]
Abstract
Our previous studies have revealed that nicotine-treated immature dendritic cells (imDCs) have anti-tumor effects in murine lymphoma models. The present study is to explore HBV-specific CTL priming and its cytolytic activities of nicotine-treated murine DCs, the mechanism of α7 nicotinic acetylcholine receptor (nAChR) up-regulation by nicotine and the efficiency of nicotine with other cytokines. To address these hypotheses, bone marrow-derived imDCs were stimulated by nicotine and expression of α7 nAChR was firstly determined by flow cytometry and Western blot. Then, DCs-dependent HBV-specific T cell proliferation and IL-12 secretion were secondly determined by BrdU cell proliferation assay and ELISA, respectively. The HBV-specific CTL priming and its activities were further explored by intraperitoneal transfer of nicotine treated imDCs. The mechanism of nicotine up-regulating α7 nAChR was finally explored by Western blot. The results showed that: first, the maximal activation of PI3K and Akt was reached at 30 and 60-120 min respectively after nicotine stimulation. Nicotine up-regulated the expression of α7 nAChR by activating PI3K-Akt pathway in murine DCs; secondly, nicotine stimulation could enhance DCs' ability of HBV-specific T cell proliferation and IL-12 secretion; thirdly, adoptive transfer of nicotine stimulated DCs could induce HBV specific CTL priming in vivo and those CTL had cytolytic activities; fourthly, nicotine had equal efficiencies to 2 ng/ml IFN-γ in DCs-mediated T cell proliferation. All these data presented here indicated that nicotine treated imDCs might be considered as a potential candidate for HBV immunotherapy.
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Abdrakhmanova GR, Kang M, Imad Damaj M, Akbarali HI. Nicotine suppresses hyperexcitability of colonic sensory neurons and visceral hypersensivity in mouse model of colonic inflammation. Am J Physiol Gastrointest Liver Physiol 2012; 302:G740-7. [PMID: 22241859 PMCID: PMC3330777 DOI: 10.1152/ajpgi.00411.2011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Recently, we reported that nicotine in vitro at a low 1-μM concentration suppresses hyperexcitability of colonic dorsal root ganglia (DRG; L(1)-L(2)) neurons in the dextran sodium sulfate (DSS)-induced mouse model of acute colonic inflammation (1). Here we show that multiple action potential firing in colonic DRG neurons persisted at least for 3 wk post-DSS administration while the inflammatory signs were diminished. Similar to that in DSS-induced acute colitis, bath-applied nicotine (1 μM) gradually reduced regenerative multiple-spike action potentials in colonic DRG neurons to a single action potential in 3 wk post-DSS neurons. Nicotine (1 μM) shifted the activation curve for tetrodotoxin (TTX)-resistant sodium currents in inflamed colonic DRG neurons (voltage of half-activation changed from -37 to -32 mV) but did not affect TTX-sensitive currents in control colonic DRG neurons. Further, subcutaneous nicotine administration (2 mg/kg b.i.d.) in DSS-treated C57Bl/J6 male mice resulted in suppression of hyperexcitability of colonic DRG (L(1)-L(2)) neurons and the number of abdominal constrictions in response to intraperitoneal injection of 0.6% acetic acid. Collectively, the data suggest that neuronal nicotinic acetylcholine receptor-mediated suppression of hyperexcitability of colonic DRG neurons attenuates reduction of visceral hypersensitivity in DSS mouse model of colonic inflammation.
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Affiliation(s)
- Galya R. Abdrakhmanova
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Minho Kang
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - M. Imad Damaj
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Hamid I. Akbarali
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
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Cardinale A, Nastrucci C, Cesario A, Russo P. Nicotine: specific role in angiogenesis, proliferation and apoptosis. Crit Rev Toxicol 2011; 42:68-89. [PMID: 22050423 DOI: 10.3109/10408444.2011.623150] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Nowadays, tobacco smoking is the cause of ~5-6 million deaths per year, counting 31% and 6% of all cancer deaths (affecting 18 different organs) in middle-aged men and women, respectively. Nicotine is the addictive component of tobacco acting on neuronal nicotinic receptors (nAChR). Functional nAChR, are also present on endothelial, haematological and epithelial cells. Although nicotine itself is regularly not referred to as a carcinogen, there is an ongoing debate whether nicotine functions as a 'tumour promoter'. Nicotine, with its specific binding to nAChR, deregulates essential biological processes like regulation of cell proliferation, apoptosis, migration, invasion, angiogenesis, inflammation and cell-mediated immunity in a wide variety of cells including foetal (regulation of development), embryonic and adult stem cells, adult tissues as well as cancer cells. Nicotine seems involved in fundamental aspects of the biology of malignant diseases, as well as of neurodegeneration. Investigating the biological effects of nicotine may provide new tools for therapeutic interventions and for the understanding of neurodegenerative diseases and tumour biology.
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Wallace TL, Porter RHP. Targeting the nicotinic alpha7 acetylcholine receptor to enhance cognition in disease. Biochem Pharmacol 2011; 82:891-903. [PMID: 21741954 DOI: 10.1016/j.bcp.2011.06.034] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 06/18/2011] [Accepted: 06/24/2011] [Indexed: 01/05/2023]
Abstract
A promising drug target currently under investigation to improve cognitive deficits in neuropsychiatric and neurological disorders is the neuronal nicotinic alpha7 acetylcholine receptor (α7nAChR). Improving cognitive impairments in diseases such as Alzheimer's (AD) and schizophrenia remains a large unmet medical need, and the α7nAChR has many properties that make it an attractive therapeutic target. The α7nAChR is a ligand gated ion channel that has particularly high permeability to Ca(2+) and is expressed in key brain regions involved in cognitive processes (e.g., hippocampus). The α7nAChRs are localized both pre-synaptically, where they can regulate neurotransmitter release, and post-synaptically where they can activate intracellular signaling cascades and influence downstream processes involved in learning and memory. In particular, activation of the α7nAChR with small molecule agonists enhances long-term potentiation, an in vitro model of synaptic plasticity, and improves performance across multiple cognitive domains in rodents, monkeys, and humans. Positive allosteric modulation of the α7nAChR offers an alternate approach to direct agonism that could prove to be particularly beneficial in certain disease populations where smoking nicotine is prevalent (e.g., schizophrenia) and could interfere with an orthosteric agonist approach. The current review focuses on the neurobiology of the α7nAChR, its role in cognition and the development status of some of the most promising molecules advancing for the treatment of cognitive dysfunction in disease.
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Affiliation(s)
- Tanya L Wallace
- Center for Neuroscience, SRI International, 333 Ravenswood Avenue, M/S 100-69, Menlo Park, CA 94025, USA.
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Del Barrio L, Martín-de-Saavedra MD, Romero A, Parada E, Egea J, Avila J, McIntosh JM, Wonnacott S, López MG. Neurotoxicity induced by okadaic acid in the human neuroblastoma SH-SY5Y line can be differentially prevented by α7 and β2* nicotinic stimulation. Toxicol Sci 2011; 123:193-205. [PMID: 21715663 DOI: 10.1093/toxsci/kfr163] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A good model of neuronal death that reproduces the characteristic tau (τ) hyperphosphorylation of Alzheimeŕs disease is the use of okadaic acid (OA). The aim of this study was to determine the contribution of α7 and β2* nicotinic acetylcholine receptor (nAChR) subtypes to neuroprotection against OA in the SH-SY5Y cell line by using the selective α7 and β2* nAChR agonists PNU 282987 and 5-Iodo-A85380, respectively. The results of this study show that both α7 and β2* nAChR can afford neuroprotection against OA-induced neurotoxicity. Protection mediated by α7 nAChRs was independent of Ca(2+) and involved the intracellular signaling pathway Janus Kinase-2/Phosphatidylinositol-3-kinase/Akt. When Ca(2+) entry was promoted through the α7 nAChR by using the α7-selective positive allosteric modulator PNU 120596, protection was lost. By contrast, protection mediated by β2* nAChRs was Ca(2+) dependent and implicated the signaling pathways PI3K/Akt and extracellular regulated kinase 1/2. Both α7 and β2* nAChR activation converged on downregulation of GSK-3β and reduction of τ phosphorylation in cells undergoing cell death induced by OA. Therefore, targeting nAChR could offer a strategy for reducing neurodegeneration secondary to hyperphosphorylation of protein τ.
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Affiliation(s)
- Laura Del Barrio
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Auto´noma de Madrid, 28029 Madrid, Spain
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Bitner RS, Markosyan S, Nikkel AL, Brioni JD. In-vivo histamine H3 receptor antagonism activates cellular signaling suggestive of symptomatic and disease modifying efficacy in Alzheimer’s disease. Neuropharmacology 2011; 60:460-6. [DOI: 10.1016/j.neuropharm.2010.10.026] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 10/21/2010] [Accepted: 10/25/2010] [Indexed: 11/30/2022]
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Maiese K, Chong ZZ, Shang YC, Hou J. Novel avenues of drug discovery and biomarkers for diabetes mellitus. J Clin Pharmacol 2011; 51:128-52. [PMID: 20220043 PMCID: PMC3033756 DOI: 10.1177/0091270010362904] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Globally, developed nations spend a significant amount of their resources on health care initiatives that poorly translate into increased population life expectancy. As an example, the United States devotes 16% of its gross domestic product to health care, the highest level in the world, but falls behind other nations that enjoy greater individual life expectancy. These observations point to the need for pioneering avenues of drug discovery to increase life span with controlled costs. In particular, innovative drug development for metabolic disorders such as diabetes mellitus becomes increasingly critical given that the number of diabetic people will increase exponentially over the next 20 years. This article discusses the elucidation and targeting of novel cellular pathways that are intimately tied to oxidative stress in diabetes mellitus for new treatment strategies. Pathways that involve wingless, β-nicotinamide adenine dinucleotide (NAD(+)) precursors, and cytokines govern complex biological pathways that determine both cell survival and longevity during diabetes mellitus and its complications. Furthermore, the role of these entities as biomarkers for disease can further enhance their utility irrespective of their treatment potential. Greater understanding of the intricacies of these unique cellular mechanisms will shape future drug discovery for diabetes mellitus to provide focused clinical care with limited or absent long-term complications.
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Affiliation(s)
- Kenneth Maiese
- Department of Neurology, 8C-1 UHC, Wayne State University School of Medicine, 4201 St. Antoine, Detroit, MI 48201, USA.
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Wu J, Ishikawa M, Zhang J, Hashimoto K. Brain imaging of nicotinic receptors in Alzheimer's disease. Int J Alzheimers Dis 2010; 2010:548913. [PMID: 21253523 PMCID: PMC3022172 DOI: 10.4061/2010/548913] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 12/08/2010] [Indexed: 11/30/2022] Open
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) are a family of ligand-gated ion channels which are widely distributed in the human brain. Several lines of evidence suggest that two major subtypes (α4β2 and α7) of nAChRs play an important role in the pathophysiology of Alzheimer's disease (AD). Postmortem studies demonstrated alterations in the density of these subtypes of nAChRs in the brain of patients with AD. Currently, nAChRs are one of the most attractive therapeutic targets for AD. Therefore, several researchers have made an effort to develop novel radioligands that can be used to study quantitatively the distribution of these two subtypes in the human brain with positron emission tomography (PET) and single-photon emission computed tomography (SPECT). In this paper, we discuss the current topics on in vivo imaging of two subtypes of nAChRs in the brain of patients with AD.
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Affiliation(s)
- Jin Wu
- Division of Clinical Neuroscience, Center for Forensic Mental Health, Chiba University, 1-8-1 Inohana Chiba 260-8670, Japan
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The γ-Secretase Modulator CHF5074 Reduces the Accumulation of Native Hyperphosphorylated Tau in a Transgenic Mouse Model of Alzheimer’s Disease. J Mol Neurosci 2010; 45:22-31. [DOI: 10.1007/s12031-010-9482-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 12/02/2010] [Indexed: 01/29/2023]
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Dinklo T, Shaban H, Thuring JW, Lavreysen H, Stevens KE, Zheng L, Mackie C, Grantham C, Vandenberk I, Meulders G, Peeters L, Verachtert H, De Prins E, Lesage ASJ. Characterization of 2-[[4-fluoro-3-(trifluoromethyl)phenyl]amino]-4-(4-pyridinyl)-5-thiazolemethanol (JNJ-1930942), a novel positive allosteric modulator of the {alpha}7 nicotinic acetylcholine receptor. J Pharmacol Exp Ther 2010; 336:560-74. [PMID: 21084390 DOI: 10.1124/jpet.110.173245] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The α(7) nicotinic acetylcholine receptor (nAChR) is a potential therapeutic target for the treatment of cognitive deficits associated with schizophrenia, Alzheimer's disease, Parkinson's disease, and attention-deficit/hyperactivity disorder. Activation of α(7) nAChRs improved sensory gating and cognitive function in animal models and in early clinical trials. Here we describe the novel highly selective α(7) nAChR positive allosteric modulator, 2-[[4-fluoro-3-(trifluoromethyl)phenyl]amino]-4-(4-pyridinyl)-5-thiazolemethanol (JNJ-1930942). This compound enhances the choline-evoked rise in intracellular Ca(2+) levels in the GH4C1 cell line expressing the cloned human α(7) nAChR. JNJ-1930942 does not act on α4β2, α3β4 nAChRs or on the related 5-HT3A channel. Electrophysiological assessment in the GH4C1 cell line shows that JNJ-1930942 increases the peak and net charge response to choline, acetylcholine, and N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-4-chlorobenzamide (PNU-282987). The potentiation is obtained mainly by affecting the receptor desensitization characteristics, leaving activation and deactivation kinetics as well as recovery from desensitization relatively unchanged. Choline efficacy is increased over its full concentration response range, and choline potency is increased more than 10-fold. The potentiating effect is α(7) channel-dependent, because it is blocked by the α(7) antagonist methyllycaconitine. Moreover, in hippocampal slices, JNJ-1930942 enhances neurotransmission at hippocampal dentate gyrus synapses and facilitates the induction of long-term potentiation of electrically evoked synaptic responses in the dentate gyrus. In vivo, JNJ-1930942 reverses a genetically based auditory gating deficit in DBA/2 mice. JNJ-1930942 will be a useful tool to study the therapeutic potential of α(7) nAChR potentiation in central nervous system disorders in which a deficit in α(7) nAChR neurotransmission is hypothesized to be involved.
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Affiliation(s)
- Theo Dinklo
- Johnson & Johnson Pharmaceutical Research and Development, Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340 Beerse, Belgium
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44
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Brioni JD, Esbenshade TA, Garrison TR, Bitner SR, Cowart MD. Discovery of Histamine H3 Antagonists for the Treatment of Cognitive Disorders and Alzheimer's Disease. J Pharmacol Exp Ther 2010; 336:38-46. [DOI: 10.1124/jpet.110.166876] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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Maiese K, Shang YC, Chong ZZ, Hou J. Diabetes mellitus: channeling care through cellular discovery. Curr Neurovasc Res 2010; 7:59-64. [PMID: 20158461 DOI: 10.2174/156720210790820217] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 12/29/2009] [Indexed: 12/13/2022]
Abstract
Diabetes mellitus (DM) impacts a significant portion of the world's population and care for this disorder places an economic burden on the gross domestic product for any particular country. Furthermore, both Type 1 and Type 2 DM are becoming increasingly prevalent and there is increased incidence of impaired glucose tolerance in the young. The complications of DM are protean and can involve multiple systems throughout the body that are susceptible to the detrimental effects of oxidative stress and apoptotic cell injury. For these reasons, innovative strategies are necessary for the implementation of new treatments for DM that are generated through the further understanding of cellular pathways that govern the pathological consequences of DM. In particular, both the precursor for the coenzyme beta-nicotinamide adenine dinucleotide (NAD(+)), nicotinamide, and the growth factor erythropoietin offer novel platforms for drug discovery that involve cellular metabolic homeostasis and inflammatory cell control. Interestingly, these agents and their tightly associated pathways that consist of cell cycle regulation, protein kinase B, forkhead transcription factors, and Wnt signaling also function in a broader sense as biomarkers for disease onset and progression.
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Affiliation(s)
- Kenneth Maiese
- Division of Cellular and Molecular Cerebral Ischemia, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
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Medeiros R, Baglietto-Vargas D, LaFerla FM. The role of tau in Alzheimer's disease and related disorders. CNS Neurosci Ther 2010; 17:514-24. [PMID: 20553310 DOI: 10.1111/j.1755-5949.2010.00177.x] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Tau, the microtubule-associated protein, forms insoluble filaments that accumulate as neurofibrillary tangles in Alzheimer's disease (AD) and related tauopathies. Under physiological conditions, tau regulates the assembly and maintenance of the structural stability of microtubules. In the diseased brain, however, tau becomes abnormally hyperphosphorylated, which ultimately causes the microtubules to disassemble, and the free tau molecules aggregate into paired helical filaments. A large body of evidence suggests that tau hyperphosphorylation results from perturbation of cellular signaling, mainly through imbalance in the activities of different protein kinases and phosphatases. In AD, it appears that ß-amyloid peptide (Aß) plays a pivotal role in triggering this imbalance. In this review, we summarize our current understanding of the role of tau in AD and other tauopathies, and highlight key issues that need to be addressed to improve the success of developing novel therapies.
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Affiliation(s)
- Rodrigo Medeiros
- Department of Neurobiology and Behavior and Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
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47
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Toyohara J, Hashimoto K. α7 Nicotinic Receptor Agonists: Potential Therapeutic Drugs for Treatment of Cognitive Impairments in Schizophrenia and Alzheimer's Disease. THE OPEN MEDICINAL CHEMISTRY JOURNAL 2010; 4:37-56. [PMID: 21249164 PMCID: PMC3023065 DOI: 10.2174/1874104501004010037] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 10/23/2009] [Accepted: 10/30/2009] [Indexed: 01/19/2023]
Abstract
Accumulating evidence suggests that α7 nicotinic receptors (α7 nAChRs), a subtype of nAChRs, play a role in the pathophysiology of neuropsychiatric diseases, including schizophrenia and Alzheimer's disease (AD). A number of psychopharmacological and genetic studies shown that α7 nAChRs play an important role in the deficits of P50 auditory evoked potential in patients with schizophrenia, and that (α nAChR agonists would be potential therapeutic drugs for cognitive impairments associated with P50 deficits in schizophrenia. Furthermore, some studies have demonstrated that α7 nAChRs might play a key role in the amyloid-β (Aβ)-mediated pathology of AD, and that α7 nAChR agonists would be potential therapeutic drugs for Aβ deposition in the brains of patients with AD. Interestingly, the altered expression of α7 nAChRs in the postmortem brain tissues from patients with schizophrenia and AD has been reported. Based on all these findings, selective α7 nAChR agonists can be considered potential therapeutic drugs for cognitive impairments in both schizophrenia and AD. In this article, we review the recent research into the role of α7 nAChRs in the pathophysiology of these diseases and into the potential use of novel α7 nAChR agonists as therapeutic drugs.
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Affiliation(s)
- Jun Toyohara
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
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Bitner RS, Bunnelle WH, Decker MW, Drescher KU, Kohlhaas KL, Markosyan S, Marsh KC, Nikkel AL, Browman K, Radek R, Anderson DJ, Buccafusco J, Gopalakrishnan M. In Vivo Pharmacological Characterization of a Novel Selective α7 Neuronal Nicotinic Acetylcholine Receptor Agonist ABT-107: Preclinical Considerations in Alzheimer's Disease. J Pharmacol Exp Ther 2010; 334:875-86. [DOI: 10.1124/jpet.110.167213] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Affiliation(s)
- Henry W Querfurth
- Department of Neurology, Caritas St. Elizabeth's Medical Center, Brighton, MA, USA.
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50
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Hanger DP, Seereeram A, Noble W. Mediators of tau phosphorylation in the pathogenesis of Alzheimer's disease. Expert Rev Neurother 2010; 9:1647-66. [PMID: 19903024 DOI: 10.1586/ern.09.104] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The need for disease-modifying drugs for Alzheimer's disease has become increasingly important owing to escalating disease prevalence and the associated socio-economic burden. Until recently, reducing brain amyloid accumulation has been the main therapeutic focus; however, increasing evidence suggests that targeting abnormal tau phosphorylation could be beneficial. Tau is phosphorylated by several protein kinases and this is balanced by dephosphorylation by protein phosphatases. Phosphorylation at specific sites can influence the physiological functions of tau, including its role in binding to and stabilizing the neuronal cytoskeleton. aberrant phosphorylation of tau could render it susceptible to potentially pathogenic alterations, including conformational changes, proteolytic cleavage and aggregation. While strategies that reduce tau phosphorylation in transgenic models of disease have been promising, our understanding of the mechanisms through which tau becomes abnormally phosphorylated in disease is lacking.
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Affiliation(s)
- Diane P Hanger
- MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry, Department of Neuroscience (P037), De Crespigny Park, London SE5 8AF, UK.
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