1
|
ACh Transfers: Homeostatic Plasticity of Cholinergic Synapses. Cell Mol Neurobiol 2023; 43:697-709. [PMID: 35643882 DOI: 10.1007/s10571-022-01227-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/25/2022] [Indexed: 11/03/2022]
Abstract
The field of homeostatic plasticity continues to advance rapidly, highlighting the importance of stabilizing neuronal activity within functional limits in the context of numerous fundamental processes such as development, learning, and memory. Most homeostatic plasticity studies have been focused on glutamatergic synapses, while the rules that govern homeostatic regulation of other synapse types are less understood. While cholinergic synapses have emerged as a critical component in the etiology of mammalian neurodegenerative disease mechanisms, relatively few studies have been conducted on the homeostatic plasticity of such synapses, particularly in the mammalian nervous system. An exploration of homeostatic mechanisms at the cholinergic synapse may illuminate potential therapeutic targets for disease management and treatment. We will review cholinergic homeostatic plasticity in the mammalian neuromuscular junction, the autonomic nervous system, central synapses, and in relation to pathological conditions including Alzheimer disease and DYT1 dystonia. This work provides a historical context for the field of cholinergic homeostatic regulation by examining common themes, unique features, and outstanding questions associated with these distinct cholinergic synapse types and aims to inform future research in the field.
Collapse
|
2
|
β-Amyloid Peptide: the Cell Compartment Multi-faceted Interaction in Alzheimer's Disease. Neurotox Res 2019; 37:250-263. [PMID: 31811589 DOI: 10.1007/s12640-019-00116-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/29/2019] [Accepted: 09/16/2019] [Indexed: 12/17/2022]
Abstract
Alzheimer's disease (AD) is the most widespread form of dementia, characterized by memory loss and reduction of cognitive functions that strongly interfere with normal daily life. Numerous evidences show that aggregates of the amyloid beta peptide, formed by 39 to 42 amino acid residues (Aβ39-43), from soluble small oligomers to large fibrils are characteristic markers of this pathology. However, AD is a complex disease and its neurodegenerative molecular mechanism is not yet fully understood. Growing evidence suggests a link between Aβ polymorphic nature, oligomers and fibrils, and specific mechanisms of neurodegeneration. The Aβ variable nature and its multiplicity of interactions with different proteins and organelles reflect the complexity of this pathology. In this review, we analyze the effects of the interaction between Aβ peptide and different cellular compartments in relation to the different kinds and sizes of amyloid aggregates. In particular, Aβ interaction with different cell structures such as the plasma membrane, mitochondria, lysosomes, nucleus, and endoplasmic reticulum is discussed. Further, we analyze the Aβ peptide ability to modify the structure and function of the target organelle, inducing alteration of its physiological role thus contributing to the pathological event. Dysfunction of cellular components terminating with the activation of the cellular death mechanism and subsequent neurodegeneration is also taken into consideration.
Collapse
|
3
|
Hahm ET, Nagaraja RY, Waro G, Tsunoda S. Cholinergic Homeostatic Synaptic Plasticity Drives the Progression of Aβ-Induced Changes in Neural Activity. Cell Rep 2019; 24:342-354. [PMID: 29996096 DOI: 10.1016/j.celrep.2018.06.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 04/03/2018] [Accepted: 06/06/2018] [Indexed: 12/23/2022] Open
Abstract
Homeostatic synaptic plasticity (HSP) is the ability of neurons to exert compensatory changes in response to altered neural activity. How pathologically induced activity changes are intertwined with HSP mechanisms is unclear. We show that, in cholinergic neurons from Drosophila, beta-amyloid (Aβ) peptides Aβ40 and Aβ42 both induce an increase in spontaneous activity. In a transgenic line expressing Aβ42, we observe that this early increase in spontaneous activity is followed by a dramatic reduction in spontaneous events, a progression that has been suggested to occur in cholinergic brain regions of mammalian models of Alzheimer's disease. We present evidence that the early enhancement in synaptic activity is mediated by the Drosophila α7 nicotinic acetylcholine receptor (nAChR) and that, later, Aβ42-induced inhibition of synaptic events is a consequence of Dα7-dependent HSP mechanisms induced by earlier hyperactivity. Thus, while HSP may initially be an adaptive response, it may also drive maladaptive changes and downstream pathologies.
Collapse
Affiliation(s)
- Eu-Teum Hahm
- Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523, USA
| | - Raghavendra Y Nagaraja
- Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523, USA
| | - Girma Waro
- Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523, USA
| | - Susan Tsunoda
- Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523, USA.
| |
Collapse
|
4
|
Rodríguez-Soacha DA, Scheiner M, Decker M. Multi-target-directed-ligands acting as enzyme inhibitors and receptor ligands. Eur J Med Chem 2019; 180:690-706. [PMID: 31401465 DOI: 10.1016/j.ejmech.2019.07.040] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/04/2019] [Accepted: 07/11/2019] [Indexed: 12/20/2022]
Abstract
In this review, we present the latest advances in the field of multi-target-directed ligand (MTDL) design for the treatment of various complex pathologies of multifactorial origin. In particular, latest findings in the field of MTDL design targeting both an enzyme and a receptor are presented for different diseases such as Alzheimer's disease (AD), depression, addiction, glaucoma, non-alcoholic steatohepatitis and pain and inflammation. The ethology of the diseases is briefly described, with special emphasis on how the MTDL can evolve into novel therapies that replace the classic pharmacological dogma "one target one disease". Considering the current needs for therapy adherence improvement, it is exposed as from the medicinal chemistry, different molecular scaffolds are studied. With the use of structure activity relationship studies and molecular optimization, new hybrid molecules are generated with improved biological properties acting at two biologically very distinct targets.
Collapse
Affiliation(s)
- Diego Alejandro Rodríguez-Soacha
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, Julius Maximilian University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Matthias Scheiner
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, Julius Maximilian University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Michael Decker
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, Julius Maximilian University of Würzburg, Am Hubland, 97074, Würzburg, Germany.
| |
Collapse
|
5
|
Cecon E, Dam J, Luka M, Gautier C, Chollet AM, Delagrange P, Danober L, Jockers R. Quantitative assessment of oligomeric amyloid β peptide binding to α7 nicotinic receptor. Br J Pharmacol 2019; 176:3475-3488. [PMID: 30981214 DOI: 10.1111/bph.14688] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 03/14/2019] [Accepted: 03/19/2019] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND AND PURPOSE Progressive dysfunction of cholinergic transmission is a well-known characteristic of Alzheimer's disease (AD). Amyloid β (Aβ) peptide oligomers are known to play a central role in AD and are suggested to impair the function of the cholinergic nicotinic ACh receptor α7 (α7nAChR). However, the mechanism underlying the effect of Aβ on α7nAChR function is not fully understood, limiting the therapeutic exploration of this observation in AD. Here, we aimed to detect and characterize Aβ binding to α7nAChR, including the possibility of interfering with this interaction for therapeutic purposes. EXPERIMENTAL APPROACH We developed a specific and quantitative time-resolved FRET (TR-FRET)-based binding assay for Aβ to α7nAChR and pharmacologically characterized this interaction. KEY RESULTS We demonstrated specific and high-affinity (low nanomolar) binding of Aβ to the orthosteric binding site of α7nAChR. Aβ binding was prevented and reversed by the well-characterized orthosteric ligands of α7nAChR (epibatidine, α-bungarotoxin, methylylcaconitine, PNU-282987, S24795, and EVP6124) and by the type II positive allosteric modulator (PAM) PNU-120596 but not by the type I PAM NS1738. CONCLUSIONS AND IMPLICATIONS Our TR-FRET Aβ binding assay demonstrates for the first time the specific binding of Aβ to α7nAChR, which will be a crucial tool for the development, testing, and selection of a novel generation of AD drug candidates targeting Aβ/α7nAChR complexes with high specificity and fewer side effects compared to currently approved α7nAChR drugs. LINKED ARTICLES This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc.
Collapse
Affiliation(s)
- Erika Cecon
- Inserm U1016, Institut Cochin, Dept Endocrinology, Metabolism and Diabetes, Paris, France.,CNRS UMR 8104, Paris, France.,University Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Julie Dam
- Inserm U1016, Institut Cochin, Dept Endocrinology, Metabolism and Diabetes, Paris, France.,CNRS UMR 8104, Paris, France.,University Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Marine Luka
- Inserm U1016, Institut Cochin, Dept Endocrinology, Metabolism and Diabetes, Paris, France.,CNRS UMR 8104, Paris, France.,University Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Clément Gautier
- Institut de Recherches SERVIER, Division Therapeutic Innovation in Neuropsychiatry, Croissy-sur-Seine, France
| | - Anne-Marie Chollet
- Institut de Recherches SERVIER, Division Therapeutic Innovation in Neuropsychiatry, Croissy-sur-Seine, France
| | - Philippe Delagrange
- Institut de Recherches SERVIER, Division Therapeutic Innovation in Neuropsychiatry, Croissy-sur-Seine, France
| | - Laurence Danober
- Institut de Recherches SERVIER, Division Therapeutic Innovation in Neuropsychiatry, Croissy-sur-Seine, France
| | - Ralf Jockers
- Inserm U1016, Institut Cochin, Dept Endocrinology, Metabolism and Diabetes, Paris, France.,CNRS UMR 8104, Paris, France.,University Paris Descartes, Sorbonne Paris Cité, Paris, France
| |
Collapse
|
6
|
Deardorff WJ, Shobassy A, Grossberg GT. Safety and clinical effects of EVP-6124 in subjects with Alzheimer's disease currently or previously receiving an acetylcholinesterase inhibitor medication. Expert Rev Neurother 2014; 15:7-17. [PMID: 25495510 DOI: 10.1586/14737175.2015.995639] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Alzheimer's disease (AD) is a prevalent and currently incurable brain disease whose impact will continue to rise as the population ages. With limited treatment options, a variety of experimental therapies are currently in clinical trials. EVP-6124 (encenicline) is an α7 nicotinic acetylcholine receptor partial agonist under investigation for the symptomatic treatment of AD. EVP-6124 activates the α7 nicotinic acetylcholine receptor at low nanomolar brain concentrations and improves memory performance in rats. Treatment with EVP-6124 in Phase I and II trials involving patients with mild-to-moderate AD was well tolerated and showed statistically significant improvements compared with placebo on cognitive and functional measures. Two Phase III trials under the title COGNITIV AD will assess the efficacy and tolerability of EVP-6124 in patients with mild-to-moderate AD. Based on the completed clinical trials and proposed mechanism of action, EVP-6124 would appear to be a good candidate for therapy in combination with cholinesterase inhibitors.
Collapse
|
7
|
Lombardo S, Maskos U. Role of the nicotinic acetylcholine receptor in Alzheimer's disease pathology and treatment. Neuropharmacology 2014; 96:255-62. [PMID: 25514383 DOI: 10.1016/j.neuropharm.2014.11.018] [Citation(s) in RCA: 174] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/11/2014] [Accepted: 11/24/2014] [Indexed: 11/26/2022]
Abstract
Alzheimer's Disease (AD) is the major form of senile dementia, characterized by neuronal loss, extracellular deposits, and neurofibrillary tangles. It is accompanied by a loss of cholinergic tone, and acetylcholine (ACh) levels in the brain, which were hypothesized to be responsible for the cognitive decline observed in AD. Current medication is restricted to enhancing cholinergic signalling for symptomatic treatment of AD patients. The nicotinic acetylcholine receptor family (nAChR) and the muscarinic acetylcholine receptor family (mAChR) are the target of ACh in the brain. Both families of receptors are affected in AD. It was demonstrated that amyloid beta (Aβ) interacts with nAChRs. Here we discuss how Aβ activates or inhibits nAChRs, and how this interaction contributes to AD pathology. We will discuss the potential role of nAChRs as therapeutic targets. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
Collapse
Affiliation(s)
- Sylvia Lombardo
- Département de Neuroscience, Institut Pasteur, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Paris Cedex 15, France; CNRS, UMR 3571, Paris, France.
| | - Uwe Maskos
- Département de Neuroscience, Institut Pasteur, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Paris Cedex 15, France; CNRS, UMR 3571, Paris, France
| |
Collapse
|
8
|
Ju Y, Asahi T, Sawamura N. Arctic mutant Aβ40 aggregates on α7 nicotinic acetylcholine receptors and inhibits their functions. J Neurochem 2014; 131:667-74. [DOI: 10.1111/jnc.12837] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 07/18/2014] [Accepted: 07/18/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Ye Ju
- Faculty of Science and Engineering; Waseda University; Shinjuku Tokyo Japan
| | - Toru Asahi
- Faculty of Science and Engineering; Waseda University; Shinjuku Tokyo Japan
- Consolidated Research Institute for Advanced Science and Medical Care (ASMeW); Waseda University; Shinjuku Tokyo Japan
| | - Naoya Sawamura
- Faculty of Science and Engineering; Waseda University; Shinjuku Tokyo Japan
- Consolidated Research Institute for Advanced Science and Medical Care (ASMeW); Waseda University; Shinjuku Tokyo Japan
| |
Collapse
|
9
|
Nava-Mesa MO, Jiménez-Díaz L, Yajeya J, Navarro-Lopez JD. GABAergic neurotransmission and new strategies of neuromodulation to compensate synaptic dysfunction in early stages of Alzheimer's disease. Front Cell Neurosci 2014; 8:167. [PMID: 24987334 PMCID: PMC4070063 DOI: 10.3389/fncel.2014.00167] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 06/02/2014] [Indexed: 01/06/2023] Open
Abstract
Alzheimer’s disease (AD) is a progressive neurodegenerative disease characterized by cognitive decline, brain atrophy due to neuronal and synapse loss, and formation of two pathological lesions: extracellular amyloid plaques, composed largely of amyloid-beta peptide (Aβ), and neurofibrillary tangles formed by intracellular aggregates of hyperphosphorylated tau protein. Lesions mainly accumulate in brain regions that modulate cognitive functions such as the hippocampus, septum or amygdala. These brain structures have dense reciprocal glutamatergic, cholinergic, and GABAergic connections and their relationships directly affect learning and memory processes, so they have been proposed as highly susceptible regions to suffer damage by Aβ during AD course. Last findings support the emerging concept that soluble Aβ peptides, inducing an initial stage of synaptic dysfunction which probably starts 20–30 years before the clinical onset of AD, can perturb the excitatory–inhibitory balance of neural circuitries. In turn, neurotransmission imbalance will result in altered network activity that might be responsible of cognitive deficits in AD. Therefore, Aβ interactions on neurotransmission systems in memory-related brain regions such as amygdaloid complex, medial septum or hippocampus are critical in cognitive functions and appear as a pivotal target for drug design to improve learning and dysfunctions that manifest with age. Since treatments based on glutamatergic and cholinergic pharmacology in AD have shown limited success, therapies combining modulators of different neurotransmission systems including recent findings regarding the GABAergic system, emerge as a more useful tool for the treatment, and overall prevention, of this dementia. In this review, focused on inhibitory systems, we will analyze pharmacological strategies to compensate neurotransmission imbalance that might be considered as potential therapeutic interventions in AD.
Collapse
Affiliation(s)
| | - Lydia Jiménez-Díaz
- Neurophysiology and Behavior Lab, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha Ciudad Real, Spain
| | - Javier Yajeya
- Department of Physiology and Pharmacology, University of Salamanca Salamanca, Spain
| | - Juan D Navarro-Lopez
- Neurophysiology and Behavior Lab, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha Ciudad Real, Spain
| |
Collapse
|
10
|
Expression of the small conductance Ca²⁺-activated potassium channel subtype 3 (SK3) in rat uterus after stimulation with 17β-estradiol. PLoS One 2014; 9:e87652. [PMID: 24505302 PMCID: PMC3914860 DOI: 10.1371/journal.pone.0087652] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 12/31/2013] [Indexed: 01/15/2023] Open
Abstract
Preterm births accounts for roughly 9% of all births worldwide and can have detrimental or even lethal consequences for the infant. However to develop new treatment that will lower the rate of preterm births, more knowledge is required on the factors contributing to the contraction and relaxation of the myometrium. The small conductance Ca2+-activated potassium channel subtype 3 (SK3) has been identified in the myometrium of several species including humans, mice and rats, but with great inter species variation of the expression pattern and regulation. The aim of this study was to investigate the expression of SK3 in the uterus of rats stimulated with 17β-estradiol and progesterone in order to get an in depth understanding of the rat uterine SK3. Using immunohistochemistry SK3 was localized to the glandular and luminal endometrial lamina epitheliali. Furthermore, a weak signal was observed in the myometrium. Using Western blot the protein level of SK3 was found to increase in uteri from animals treated with 17β-estradiol, an effect that was not reflected at the mRNA level. The levels of mRNA for SK3 were significantly lower in the uterus of 17β-estradiol-treated animals than in the uterus of ovariectomized animals. We conclude that the SK channels are present in the endometrial epithelium, and possibly also in the myometrium of the rat uterus. Furthermore, the hormonal effect on SK3 caused by 17β-estradiol includes divergent regulation at mRNA and protein levels.
Collapse
|
11
|
Uteshev VV. α7 nicotinic ACh receptors as a ligand-gated source of Ca(2+) ions: the search for a Ca(2+) optimum. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:603-38. [PMID: 22453962 DOI: 10.1007/978-94-007-2888-2_27] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The spatiotemporal distribution of cytosolic Ca(2+) ions is a key determinant of neuronal behavior and survival. Distinct sources of Ca(2+) ions including ligand- and voltage-gated Ca(2+) channels contribute to intracellular Ca(2+) homeostasis. Many normal physiological and therapeutic neuronal functions are Ca(2+)-dependent, however an excess of cytosolic Ca(2+) or a lack of the appropriate balance between Ca(2+) entry and clearance may destroy cellular integrity and cause cellular death. Therefore, the existence of optimal spatiotemporal patterns of cytosolic Ca(2+) elevations and thus, optimal activation of ligand- and voltage-gated Ca(2+) ion channels are postulated to benefit neuronal function and survival. Alpha7 nicotinic -acetylcholine receptors (nAChRs) are highly permeable to Ca(2+) ions and play an important role in modulation of neurotransmitter release, gene expression and neuroprotection in a variety of neuronal and non-neuronal cells. In this review, the focus is placed on α7 nAChR-mediated currents and Ca(2+) influx and how this source of Ca(2+) entry compares to NMDA receptors in supporting cytosolic Ca(2+) homeostasis, neuronal function and survival.
Collapse
Affiliation(s)
- Victor V Uteshev
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, USA.
| |
Collapse
|
12
|
Research update: Alpha7 nicotinic acetylcholine receptor mechanisms in Alzheimer's disease. Biochem Pharmacol 2011; 82:931-42. [DOI: 10.1016/j.bcp.2011.06.039] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/18/2011] [Accepted: 06/27/2011] [Indexed: 11/19/2022]
|
13
|
Activation of nicotinic α(7) acetylcholine receptor enhances long term potentation in wild type mice but not in APP(swe)/PS1ΔE9 mice. Neurosci Lett 2010; 487:325-9. [PMID: 20974225 DOI: 10.1016/j.neulet.2010.10.049] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 10/12/2010] [Accepted: 10/19/2010] [Indexed: 11/23/2022]
Abstract
Amyloid β (Aβ) plays a central role in Alzheimer's disease (AD) and binds to the nicotinic α(7) receptor (α(7) nAChR). Little is known about the degree to which the binding of Aβ to the α(7) nAChR influences the role of this receptor in long-term potentiation (LTP), however. We have studied the effect of the partial α(7) nAChR agonist SSR180711 on hippocampal slice preparations from normal wild type (Wt) and APP(swe)/PS1ΔE9 transgenic (Tg) mice. In the hippocampal slices from the 6 months old Wt mice, the application of both nicotine (5μM) and SSR180711 (300nM) resulted in a significant enhancement of LTP expressed in area CA1. However, in the Tg mice the application of SSR180711 did not result in an increase in LTP beyond control levels. The amount of binding of the α(7) nAChR ligand 125-I-α-bungarotoxin was not different between in Tg and Wt mice. These findings indicate that the α(7) nAChR is functionally blocked in the hippocampal neurons, downstream of the α(7) nAChR, and that this is likely due to an interaction between the receptor and Aβ, which leads to changes in LTP.
Collapse
|
14
|
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.
Collapse
Affiliation(s)
- Jun Toyohara
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| | | |
Collapse
|
15
|
Loss of alpha7 nicotinic receptors enhances beta-amyloid oligomer accumulation, exacerbating early-stage cognitive decline and septohippocampal pathology in a mouse model of Alzheimer's disease. J Neurosci 2010; 30:2442-53. [PMID: 20164328 DOI: 10.1523/jneurosci.5038-09.2010] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Early Alzheimer's disease (AD) is marked by cholinergic hypofunction, neuronal marker loss, and decreased nicotinic acetylcholine receptor (nAChR) density from the cortex and hippocampus. alpha7 nAChRs expressed on cholinergic projection neurons and target regions have been implicated in neuroprotection against beta-amyloid (Abeta) toxicity and maintenance of the septohippocampal phenotype. We tested the role that alpha7 nAChRs perform in the etiology of early AD by genetically deleting the alpha7 nAChR subunit from the Tg2576 mouse model for AD and assessing animals for cognitive function and septohippocampal integrity. Thus, Tg2576 mice transgenic for mutant human amyloid precursor protein (APP) were crossed with alpha7 nAChR knock-out mice (A7KO) to render an animal with elevated Abeta in the absence of alpha7 nAChRs (A7KO-APP). We found that learning and memory deficits seen in 5-month-old APP mice are more severe in the A7KO-APP animals. Analyses of animals in early-stage preplaque cognitive decline revealed signs of neurodegeneration in A7KO-APP hippocampus as well as loss of cholinergic functionality in the basal forebrain and hippocampus. These changes occurred concomitant with the appearance of a dodecameric oligomer of Abeta that was absent from all other genotypic groups, generating the hypothesis that increased soluble oligomeric Abeta may underlie additional impairment of A7KO-APP cognitive function. Thus, alpha7 nAChRs in a mouse model for early-stage AD appear to serve a neuroprotective role through maintenance of the septohippocampal cholinergic phenotype and preservation of hippocampal integrity possibly through influences on Abeta accumulation and oligomerization.
Collapse
|
16
|
Dome P, Lazary J, Kalapos MP, Rihmer Z. Smoking, nicotine and neuropsychiatric disorders. Neurosci Biobehav Rev 2009; 34:295-342. [PMID: 19665479 DOI: 10.1016/j.neubiorev.2009.07.013] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/23/2009] [Accepted: 07/30/2009] [Indexed: 12/20/2022]
Abstract
Tobacco smoking is an extremely addictive and harmful form of nicotine (NIC) consumption, but unfortunately also the most prevalent. Although disproportionately high frequencies of smoking and its health consequences among psychiatric patients are widely known, the neurobiological background of this epidemiological association is still obscure. The diverse neuroactive effects of NIC and some other major tobacco smoke constituents in the central nervous system may underlie this association. This present paper summarizes the pharmacology of NIC and its receptors (nAChR) based on a systematic review of the literature. The role of the brain's reward system(s) in NIC addiction and the results of functional and structural neuroimaging studies on smoking-related states and behaviors (i.e. dependence, craving, withdrawal) are also discussed. In addition, the epidemiological, neurobiological, and genetic aspects of smoking in several specific neuropsychiatric disorders are reviewed and the clinical relevance of smoking in these disease states addressed.
Collapse
Affiliation(s)
- Peter Dome
- Department of Clinical and Theoretical Mental Health, Kutvolgyi Clinical Center, Semmelweis University, Faculty of Medicine, Kutvolgyi ut 4, 1125 Budapest, Hungary.
| | | | | | | |
Collapse
|
17
|
Richner M, Bach G, West MJ. Over expression of amyloid beta-protein reduces the number of neurons in the striatum of APPswe/PS1DeltaE9. Brain Res 2009; 1266:87-92. [PMID: 19245800 DOI: 10.1016/j.brainres.2009.02.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Revised: 02/05/2009] [Accepted: 02/05/2009] [Indexed: 11/16/2022]
Abstract
The effect of increasing amounts of amyloid beta-protein (Abeta) on the number of neurons in the striatum was investigated in APPswe/PS1DeltaE9 transgenic mice. This mouse model of Alzheimer's disease-like amyloidosis displays an increased expression of Abeta in the brain with age. On the basis of reports of disruptions in the anatomy of this part of the brain and the neurotoxic effects of amyloid, it was hypothesized that there would be an age-related decrease in the number of neurons in this part of the brain as a consequence of the age-related increase of Abeta. Estimates of the number of principal neurons of the striatum and the volume of the striatum were made with modern design based stereological techniques in 6- and 12-month-old groups of transgenic and wild type mice. In the 6-month-old groups there was no significant difference in the number of neurons in the striatum. There was a significantly smaller number of neurons in the striatum of the 12-month-old transgenic mice compared to 12-month-old wild type and 6-month-old transgenic mice. There were no significant differences in the volumes of the striatum in any of the four groups of mice studied. The age-related decrease in striatal neuron number is inversely related to an increase in the production of Abeta and suggests a causal relationship between the two.
Collapse
Affiliation(s)
- Mette Richner
- Department of Molecular Biology, The Faculty of Science, University of Aarhus, Denmark
| | | | | |
Collapse
|