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Whiteaker P, George AA. Discoveries and future significance of research into amyloid-beta/α7-containing nicotinic acetylcholine receptor (nAChR) interactions. Pharmacol Res 2023; 191:106743. [PMID: 37084859 DOI: 10.1016/j.phrs.2023.106743] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/13/2023] [Accepted: 03/21/2023] [Indexed: 04/23/2023]
Abstract
Initiated by findings that Alzheimer's disease is associated with a profound loss of cholinergic markers in human brain, decades of studies have examined the interactions between specific subtypes of nicotinic acetylcholine receptors and amyloid-β [derive from the amyloid precursor protein (APP), which is cleaved to yield variable isoforms of amyloid-β]. We review the evolving understanding of amyloid-β's roles in Alzheimer's disease and pioneering studies that highlighted a role of nicotinic acetylcholine receptors in mediating important aspects of amyloid-β's effects. This review also surveys the current state of research into amyloid-β / nicotinic acetylcholine receptor interactions. The field has reached an exciting point in which common themes are emerging from the wide range of prior research and a range of accessible, relevant model systems are available to drive further progress. We highlight exciting new areas of inquiry and persistent challenges that need to be considered while conducting this research. Studies of amyloid-β and nicotinic acetylcholine receptor populations that it interacts with provide opportunities for innovative basic and translational scientific breakthroughs related to nicotinic receptors biology, Alzheimer's disease, and cholinergic contributions to cognition more broadly.
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Affiliation(s)
- Paul Whiteaker
- Virginia Commonwealth University School of Medicine, Department of Pharmacology and Toxicology, VCU Health Sciences Research Building, Box 980613, Richmond, VA 23298-0613, USA
| | - Andrew A George
- Virginia Commonwealth University School of Medicine, Department of Pharmacology and Toxicology, VCU Health Sciences Research Building, Box 980613, Richmond, VA 23298-0613, USA.
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2
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A Review on Phyto-Therapeutic Approaches in Alzheimer's Disease. J Funct Biomater 2023; 14:jfb14010050. [PMID: 36662097 PMCID: PMC9861153 DOI: 10.3390/jfb14010050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 12/29/2022] [Accepted: 01/14/2023] [Indexed: 01/19/2023] Open
Abstract
Neurodegenerative diseases occur due to progressive and sometimes irreversible loss of function and death of nerve cells. A great deal of effort is being made to understand the pathogenesis of neurodegenerative diseases. In particular, the prevalence of Alzheimer's disease (AD) is quite high, and only symptomatic therapy is available due to the absence of radical treatment. The aim of this review is to try to elucidate the general pathogenesis of AD, to provide information about the limit points of symptomatic treatment approaches, and to emphasize the potential neurologic effects of phytocompounds as new tools as therapeutic agents for disease prevention, retardation, and therapy. This survey also covers the notable properties of herbal compounds such as their effects on the inhibition of an enzyme called acetylcholinesterase, which has significant value in the treatment of AD. It has been proven that phytopharmaceuticals have long-term effects that could protect nervous system health, eliminate inflammatory responses, improve cognitive damage, provide anti-aging effects in the natural aging process, and alleviate dementia sequelae. Herbal-based therapeutic agents can afford many advantages and can be used as potentially as new-generation therapeutics or complementary agents with high compliance, fewer adverse effects, and lower cost in comparison to the traditional pharmaceutical agents in the fight against AD.
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Paulo JA, Jedrychowski MP, Chouchani ET, Kazak L, Gygi SP. Multiplexed Isobaric Tag-Based Profiling of Seven Murine Tissues Following In Vivo Nicotine Treatment Using a Minimalistic Proteomics Strategy. Proteomics 2018; 18:e1700326. [PMID: 29660237 PMCID: PMC5992107 DOI: 10.1002/pmic.201700326] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 11/24/2017] [Indexed: 12/18/2022]
Abstract
Nicotine is a major addictive compound in tobacco and a component of smoking-related products, such as e-cigarettes. Once internalized, nicotine can perturb many cellular pathways and can induce alterations in proteins across different cell types; however, the mechanisms thereof remain undetermined. The authors hypothesize that both tissue-specific and global protein abundance alterations result from nicotine exposure. Presented here is the first proteomic profiling of multiple tissues from mice treated orally with nicotine. Proteins extracted from seven tissues (brain, heart, kidney, liver, lung, pancreas, and spleen) from treated (n = 5) and untreated control (n = 5) mice are assembled into a TMT10-plex experiment. A minimalistic proteomics strategy is employed using TMT reagents efficiently and centrifugation-based reversed-phase columns to streamline sample preparation. Combined, over 11 000 non-redundant proteins from over 138 000 different peptides are quantified in seven TMT10-plex experiments. Between 7 and 126 proteins are significantly altered in tissues from nicotine-exposed mice, 11 which are altered in two or more tissues. Our data showcase the vast extent of nicotine exposure across murine tissue.
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Affiliation(s)
- Joao A. Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, United States
| | - Mark P. Jedrychowski
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, United States
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, United States
| | - Edward T. Chouchani
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, United States
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, United States
| | - Lawrence Kazak
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, United States
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, United States
| | - Steven P. Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, United States
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Daulatzai MA. Dysfunctional Sensory Modalities, Locus Coeruleus, and Basal Forebrain: Early Determinants that Promote Neuropathogenesis of Cognitive and Memory Decline and Alzheimer’s Disease. Neurotox Res 2016; 30:295-337. [DOI: 10.1007/s12640-016-9643-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/08/2016] [Accepted: 06/10/2016] [Indexed: 12/22/2022]
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Gonçalves R, Vasques J, Trindade P, Serfaty C, Campello-Costa P, Faria-Melibeu A. Nicotine-induced plasticity in the retinocollicular pathway: Evidence for involvement of amyloid precursor protein. Neuroscience 2016; 313:1-9. [DOI: 10.1016/j.neuroscience.2015.11.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/12/2015] [Accepted: 11/13/2015] [Indexed: 10/22/2022]
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Brown D, Ramlochansingh C, Manaye KF, Tizabi Y. Nicotine promotes survival of cells expressing amyloid precursor protein and presenilin: implication for Alzheimer's disease. Neurosci Lett 2013; 535:57-61. [PMID: 23313596 DOI: 10.1016/j.neulet.2012.12.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 12/09/2012] [Accepted: 12/21/2012] [Indexed: 11/16/2022]
Abstract
Amyloid-β protein (Aβ) accumulation is one of the major hallmarks of Alzheimer's disease (AD) and plays a crucial role in its pathogenesis. Cellular models whereby amyloid precursor protein (APP) is highly expressed are commonly used to test the efficacy of novel neuroprotective compounds. In addition to Aβ, it is known that mutation in the protein presenilin contributes to early onset AD. Recently, a cellular neuroblastoma model where both APP and presenilin are expressed has become available. Since protective effects of nicotine against various neurotoxins have been observed, this study was designed to determine whether nicotine would also protect against cellular damage induced by APP or APP and presenilin. Wild type neuroblastoma (N2a) cell line, and those transfected with amyloid precursor protein (APP), and the combination of APP and presenilin were pretreated with various concentrations of nicotine and the survivability of the cells were determined by MTT assay. Nicotine dose dependently provided protection against cellular loss in all cell lines, with highest protection in the double transfected (44%) followed by single transfected (30%), and wild type (21%). The effects of nicotine in turn were blocked by mecamylamine, a non-selective nicotinic antagonist. These results suggest differential sensitivity of cell lines representing AD pathology to the protective effects of nicotine and provide further support of therapeutic potential of nicotinic agonists in at least a subtype of AD patients.
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Affiliation(s)
- Dwayne Brown
- Department of Pharmacology, College of Medicine, Howard University, Washington, DC, United States
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Gil-Bea FJ, Gerenu G, Aisa B, Kirazov LP, Schliebs R, Ramírez MJ. Cholinergic denervation exacerbates amyloid pathology and induces hippocampal atrophy in Tg2576 mice. Neurobiol Dis 2012; 48:439-46. [DOI: 10.1016/j.nbd.2012.06.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 06/22/2012] [Indexed: 01/21/2023] Open
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Scerri C, Stewart CA, Balfour DJK, Breen KC. Nicotine modifies in vivo and in vitro rat hippocampal amyloid precursor protein processing in young but not old rats. Neurosci Lett 2012; 514:22-6. [PMID: 22381398 DOI: 10.1016/j.neulet.2012.02.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 02/08/2012] [Accepted: 02/13/2012] [Indexed: 11/30/2022]
Abstract
Previous studies have shown that administration of nicotine modifies the expression and secretion of amyloid precursor protein (APP) in various cell lines. The present study investigated the extent to which chronic subcutaneous nicotine administration influences APP levels and processing in cerebral cortex, striatum and hippocampus of young and old rat brains. The results showed that constant nicotine infusion (0.25 or 4.00mg/kg/day) increased the levels of particulate APP (APPp) but not secreted APP (APPs) in the hippocampus of young rats in vivo. This response to nicotine was not observed in the striatum or cerebral cortex of young rats or in any of the brain regions examined in old animals. Subsequent in vitro analysis demonstrated that nicotine enhanced the release of APPs from hippocampal slice preparations and that this increase was attenuated by mecamylamine, a non-selective nicotinic acetylcholine receptor (nAChR) antagonist. The in vitro effect of nicotine on APPs was age-related, being only detected from hippocampal slices derived from the young but not the older animals. These results suggest that nicotine modulates APP expression and secretion in the hippocampus and that the responses observed to the drug are age-dependent being only detected in younger rats.
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Affiliation(s)
- Charles Scerri
- Division of Neuroscience, Medical Research Institute, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK.
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Xu Q, Li MD. Nicotine modulates expression of dynamin 1 in rat brain and SH-SY5Y cells. Neurosci Lett 2011; 489:168-71. [PMID: 21159320 PMCID: PMC3025076 DOI: 10.1016/j.neulet.2010.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 12/01/2010] [Accepted: 12/07/2010] [Indexed: 01/08/2023]
Abstract
Our previous genetic and proteomic studies demonstrated that dynamin 1 is significantly associated with nicotine dependence (ND) in human smokers and its expression is highly modulated by nicotine in the brains of animals. To provide further molecular evidence for the involvement of dynamin 1 in the etiology of ND, we investigated the regulatory effect of nicotine on the expression of dynamin 1 using both in vivo and in vitro approaches. With quantitative real-time RT-PCR, we found that dynamin 1 mRNA was significantly downregulated, by 30%, 31%, and 38%, in the striatum, hippocampus, and medial basal hypothalamus (MBH), respectively, of nicotine-treated rats (P<0.01 for all three regions). Further, dynamin 1 protein was downregulated by nicotine in the ventral tegmental area (VTA: 39.5%; P<0.01), hippocampus (13.4%, P<0.05), MBH (24.6%, P<0.01), and amygdala (15.7%, P<0.05). We also determined the effect of nicotine on human SH-SY5Y cells and found that dynamin 1 mRNA was significantly down-regulated by nicotine after treatment (51.4%; P<0.01), and a consistent decrease in the amount of the protein was also observed (36.6%; P<0.05). Taken together, our findings provide further molecular evidence for the involvement of dynamin 1 in the etiology of ND.
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Affiliation(s)
- Qing Xu
- Institute of Biological Science and Bioengineering, Beijing Jiaotong University, Beijing 100044, China
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA 22911, USA
| | - Ming D. Li
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA 22911, USA
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Bencherif M. Neuronal nicotinic receptors as novel targets for inflammation and neuroprotection: mechanistic considerations and clinical relevance. Acta Pharmacol Sin 2009; 30:702-14. [PMID: 19498416 PMCID: PMC4002381 DOI: 10.1038/aps.2009.37] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Accepted: 03/09/2009] [Indexed: 01/18/2023] Open
Abstract
A number of studies have confirmed the potential for neuronal nicotinic acetylcholine receptor (NNR)-mediated neuroprotection and, more recently, its anti-inflammatory effects. The mechanistic overlap between these pathways and the ubiquitous effects observed following diverse insults suggest that NNRs modulate fundamental pathways involved in cell survival. These results have wide-reaching implications for the design of experimental therapeutics that regulate inflammatory and anti-apoptotic responses through NNRs and represent an initial step toward understanding the benefits of novel therapeutic strategies for the management of central nervous system disorders that target neuronal survival and associated inflammatory processes.
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Jinno S, Araki K, Matsumoto Y, Suh YH, Yamamoto T. Selective apoptosis induction in the hippocampal mossy fiber pathway by exposure to CT105, the C-terminal fragment of Alzheimer's amyloid precursor protein. Brain Res 2008; 1249:68-78. [PMID: 19007761 DOI: 10.1016/j.brainres.2008.10.052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 09/29/2008] [Accepted: 10/17/2008] [Indexed: 10/21/2022]
Abstract
Beta-amyloid protein (Abeta), a proteolytic byproduct of Alzheimer's amyloid precursor protein (APP), has been shown to play a central role in the development of Alzheimer's disease (AD). In addition, recent studies strongly suggest that other byproducts of proteolysis, such as C-terminal fragments of APP (APP-CTF), are also critically involved in the AD pathology. To explore this possibility, we investigated the histopathological changes induced by repeated low-dose intrahippocampal injection of a recombinant 105 amino acid C-terminal fragment of APP (CT105). First, we carried out a behavioral analysis by using the three-panel runway task, and found that the working memory was significantly impaired by CT105 exposure. Then, via propidium iodide staining, we encountered a number of cells exhibiting fragmented or shrank nuclei in the mossy fiber pathway (stratum lucidum and dentate hilus) in CT105-treated rats. These cells were positive for single-stranded DNA (ssDNA), an apoptosis-specific marker, and thus were considered to be apoptotic. Some of the ssDNA-positive cells were also positive for somatostatin. But neither ionized calcium-binding adapter molecule 1 (Iba1) nor S100beta occurred in ssDNA-positive cells. These findings suggest that CT105 induces apoptotic changes in cells of neuronal origin. Quantitative analysis showed that the densities of ssDNA-positive cells in the mossy fiber pathway were significantly higher in CT105-treated rats than in control animals. The present results suggest that CT105 causes dysfunction in the hippocampal mossy fiber system, and also provide some key to understand the relationship between APP-CTF and glutamatergic synaptic dysregulation in AD.
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Affiliation(s)
- Shozo Jinno
- Department of Anatomy and Neurobiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
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Sabri O, Kendziorra K, Wolf H, Gertz HJ, Brust P. Acetylcholine receptors in dementia and mild cognitive impairment. Eur J Nucl Med Mol Imaging 2008; 35 Suppl 1:S30-45. [PMID: 18228017 DOI: 10.1007/s00259-007-0701-1] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE To clarify whether changes in the cholinergic transmission occur early in the course of Alzheimer's disease (AD), we carried out positron emission tomography (PET) with the radioligand 2-[(18)F]F-A-85380, which is supposed to be specific for alpha4beta2 nicotinic acetylcholine receptors (nAChRs). METHOD We included patients with moderate to severe AD and patients with amnestic mild cognitive impairment (MCI), presumed to present preclinical AD. RESULTS Both patients with AD and MCI showed significant reductions in alpha4beta2 nAChRs in brain regions typically affected by AD pathology. These findings indicate that a reduction in alpha4beta2 nAChRs occurs during early symptomatic stages of AD. The alpha4beta2 nAChR availability in these regions correlated with the severity of cognitive impairment, indicating a stage sensitivity of the alpha4beta2 nAChR status. CONCLUSION Together, our results provide evidence for the potential of 2-[(18)]F-A-85380 nAChR PET in the diagnosis of patients at risk for AD. Because of the extraordinary long acquisition time with 2-[(18)F]F-A-85380, we developed the new alpha4beta2 nAChR-specific radioligands (+)- and (-)-[(18)F]norchloro-fluoro-homoepibatidine (NCFHEB) and evaluated them preclinically. (-)-[(18)F]NCFHEB shows twofold higher brain uptake and significantly shorter acquisition times. Therefore, (-)-[(18)F]NCFHEB should be a suitable radioligand for larger clinical investigations.
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Affiliation(s)
- Osama Sabri
- Department of Nuclear Medicine, University of Leipzig, Stephanstrasse 11, Leipzig, Germany.
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Shim SB, Lee SH, Chae KR, Kim CK, Hwang DY, Kim BG, Jee SW, Lee SH, Sin JS, Bae CJ, Lee BC, Lee HH, Kim YK. Nicotine leads to improvements in behavioral impairment and an increase in the nicotine acetylcholine receptor in transgenic mice. Neurochem Res 2008; 33:1783-8. [PMID: 18307030 DOI: 10.1007/s11064-008-9629-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Accepted: 02/11/2008] [Indexed: 10/22/2022]
Abstract
Nicotine is the principal psychoactive ingredient in cigarette smoke, and has been associated with health problems in humans. However, the pure form of nicotine may prove to be a valuable pharmaceutical agent for the treatment of AD. However, the beneficial effects of nicotine remain a matter of much controversy. In order to clarify this issue, 12-month-old transgenic mice, expressing neuron-specific enolase (NSE)-controlled APPsw, were treated with low, middle, and high doses of nicotine for 6 months. Herein, we have concluded that the nicotine-treated groups evidenced improvements in behavior and increases in the nicotine acetylcholine receptor, nAchRalpha7. These findings provide experimental evidence that nicotine effects an improvement in impaired memory, and that this improvement is associated with an increase in nAchRalpha7. Thus, nicotine may prove a good preventative or therapeutic modality for AD patients.
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Affiliation(s)
- Sun B Shim
- Team of Laboratory Animal Resources, National Institute of Toxicological Research, Korea Food and Drug Administration, 194 Tongilro Eunpyung-ku, Seoul, 122-704, Republic of Korea
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Aztiria E, Cataudella T, Spampinato S, Leanza G. Septal grafts restore cognitive abilities and amyloid precursor protein metabolism. Neurobiol Aging 2008; 30:1614-25. [PMID: 18258336 DOI: 10.1016/j.neurobiolaging.2007.12.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 12/12/2007] [Accepted: 12/19/2007] [Indexed: 12/25/2022]
Abstract
Cortical cholinergic loss and amyloidogenic processing of the beta-amyloid precursor protein (APP), may functionally interact in Alzheimer's disease. However, it is still unknown whether biological restoration of regulatory cholinergic inputs affects APP metabolism in vivo. Rats immunolesioned with 192 IgG-saporin exhibited severe acquisition deficits in place navigation that were paralleled by a dramatic loss of terminal cholinergic innervation and by marked changes in the regional expression of APP-like immunoreactivity. Moreover, in these animals, we observed a drastic reduction of soluble APP (sAPP) and a concomitant increase of the unsoluble, membrane-bound fraction (mAPP). Notably, at about 6 months post-surgery, lesioned animals implanted with reinnervating cholinergic-rich septal tissue grafts exhibited fairly normal spatial navigation abilities, as well as cortical and hippocampal APP levels that were restored up to normal or near-normal values. APP levels correlated significantly with lesion- or graft-induced changes in cholinergic innervation density, and both these measures correlated with performance in the spatial navigation task. Thus, integrity of ascending cholinergic inputs may be required to prevent amyloidogenic processing of APP in vivo and to modulate cognitive performance.
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Affiliation(s)
- Eugenio Aztiria
- B.R.A.I.N. Centre for Neuroscience, Department of Physiology and Pathology, University of Trieste, Via Fleming 22, 34127 Trieste, Italy
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Fischer C, Fredriksson A, Eriksson P. Coexposure of neonatal mice to a flame retardant PBDE 99 (2,2',4,4',5-pentabromodiphenyl ether) and methyl mercury enhances developmental neurotoxic defects. Toxicol Sci 2007; 101:275-85. [PMID: 17982161 DOI: 10.1093/toxsci/kfm271] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Epidemiological studies indicate that exposure to environmental pollutants during early human development can have deleterious effects on cognitive development. The interaction between environmental pollutants is suggested as one reason for the observed defective neurological development in children from the Faeroe Islands as compared to children from the Seychelles. We have previously seen in mice that polychlorinated biphenyls (PCBs) can interact together with methyl mercury (MeHg), as well as PCB together with polybrominated diphenyl ether (PBDE 99) to exacerbate developmental neurotoxic effects when present during a critical period of neonatal brain development. PBDEs are a new class of global environmental contaminants. The present study shows that neonatal coexposure to PBDE 99 (0.8 mg/kg body weight) and MeHg (0.4 or 4.0 mg/kg body weight) can exacerbate developmental neurotoxic effects. These effects are manifested as disrupted spontaneous behavior, reduced habituation, and impaired learning/memory abilities. This is seen in the low dose range, where the sole compounds do no give rise to developmental neurotoxic effects. The effects seen are more than just additive. Furthermore, a significant effect of interaction was seen on the cholinergic nicotinic receptors in the cerebral cortex and hippocampus. This suggests that a mechanism for the observed cognitive defects is via the cholinergic system. Furthermore, PBDE can interact with MeHg causing developmental neurotoxic effects similar to those we previously have observed between PCB 153 + MeHg and PCB 52 + PBDE 99. This is of vital importance, as the levels of PBDEs are increasing in mother's milk and in the environment generally.
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Affiliation(s)
- Celia Fischer
- Department of Environmental Toxicology, Uppsala University, Norbyvägen 18A, S-752 36 Uppsala, Sweden
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Schliebs R, Arendt T. The significance of the cholinergic system in the brain during aging and in Alzheimer's disease. J Neural Transm (Vienna) 2006; 113:1625-44. [PMID: 17039298 DOI: 10.1007/s00702-006-0579-2] [Citation(s) in RCA: 370] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Accepted: 09/27/2006] [Indexed: 12/11/2022]
Abstract
Acetylcholine is widely distributed in the nervous system and has been implicated to play a critical role in cerebral cortical development, cortical activity, controlling cerebral blood flow and sleep-wake cycle as well as in modulating cognitive performances and learning and memory processes. Cholinergic neurons of the basal forebrain complex have been described to undergo moderate degenerative changes during aging, resulting in cholinergic hypofunction that has been related to the progressing memory deficits with aging. Basal forebrain cholinergic cell loss is also a consistent feature of Alzheimer's disease, which has been suggested to cause, at least partly, the cognitive deficits observed, and has led to the formulation of the cholinergic hypotheses of geriatric memory dysfunction. Impaired cortical cholinergic neurotransmission may also contribute to beta-amyloid plaque pathology and increase phosphorylation of tau protein the main component of neurofibrillar tangles in Alzheimer's disease. Understanding the molecular mechanisms underlying the interrelationship between cortical cholinergic dysfunction, beta-amyloid formation and deposition, and tau pathology in Alzheimer's disease, would allow to derive potential treatment strategies to pharmacologically intervene in the disease-causing signaling cascade.
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Affiliation(s)
- R Schliebs
- Department of Neurochemistry, Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany.
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Liu Q, Wu J. Neuronal nicotinic acetylcholine receptors serve as sensitive targets that mediate beta-amyloid neurotoxicity. Acta Pharmacol Sin 2006; 27:1277-86. [PMID: 17007734 DOI: 10.1111/j.1745-7254.2006.00430.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Alzheimer's disease (AD) is the most common form of brain dementia characterized by the accumulation of beta-amyloid peptides (Abeta) and loss of forebrain cholinergic neurons. Abeta accumulation and aggregation are thought to contribute to cholinergic neuronal degeneration, in turn causing learning and memory deficits, but the specific targets that mediate Abeta neurotoxicity remain elusive. Recently, accumulating lines of evidence have demonstrated that Abeta directly modulates the function of neuronal nicotinic acetylcholine receptors (nAChRs), which leads to the new hypothesis that neuronal nAChRs may serve as important targets that mediate Abeta neurotoxicity. In this review, we summarize current studies performed in our laboratory and in others to address the question of how Abeta modulates neuronal nAChRs, especially nAChR subunit function.
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Affiliation(s)
- Qiang Liu
- Division of Neurology, Barrow Neurological Institute, St Joseph's Hospital and Medical Center, Phoenix, Arizona 85013, USA
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Schliebs R. Basal forebrain cholinergic dysfunction in Alzheimer's disease--interrelationship with beta-amyloid, inflammation and neurotrophin signaling. Neurochem Res 2006; 30:895-908. [PMID: 16187224 DOI: 10.1007/s11064-005-6962-9] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2005] [Indexed: 12/21/2022]
Abstract
Alzheimer's disease, the most common neurodegenerative disorder of senile dementia, is characterized by two major morpho-pathological hallmarks. Deposition of extracellular neuritic, beta-amyloid peptide-containing plaques (senile plaques) in cerebral cortical regions of Alzheimer patients is accompanied by the presence of intracellular neurofibrillary tangles in cerebral pyramidal neurons. Basal forebrain cholinergic dysfunction is also a consistent feature of Alzheimer's disease, which has been suggested to cause, at least partly, the cognitive deficits observed in patients with Alzheimer's disease. Impaired cortical cholinergic neurotransmission may also contribute to beta-amyloid plaque pathology in Alzheimer's disease by affecting expression and processing of the beta-amyloid precursor protein (APP). Vice versa, low level of soluble beta-amyloid has been observed to inhibit cholinergic synaptic function. Deposition of beta-amyloid plaques in Alzheimer's disease is also accompanied by a significant plaque-associated glial up-regulation of interleukin-1, which has been attributed to affect expression and metabolism of APP and to interfere with cholinergic transmission. Understanding the molecular mechanisms underlying the interrelationship between cortical cholinergic dysfunction, beta-amyloid formation and deposition, as well as local inflammatory upregulation, would allow to derive potential treatment strategies to pharmacologically intervene in the disease-causing signaling cascade.
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Affiliation(s)
- Reinhard Schliebs
- Paul Flechsig Institute for Brain Research, Department of Neurochemistry, University of Leipzig, Jahnallee 59, D-04109 Leipzig, Germany.
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Oh MM, Wu WW, Power JM, Disterhoft JF. Galantamine increases excitability of CA1 hippocampal pyramidal neurons. Neuroscience 2005; 137:113-23. [PMID: 16242849 DOI: 10.1016/j.neuroscience.2005.08.063] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 08/03/2005] [Accepted: 08/30/2005] [Indexed: 11/25/2022]
Abstract
Galantamine is a third generation cholinesterase inhibitor and an allosteric potentiating ligand of nicotinic acetylcholine receptors. It enhances learning in aging rabbits and alleviates cognitive deficits observed in patients with Alzheimer's disease. We examined galantamine's effect on CA1 neurons from hippocampal slices of young and aging rabbits using current-clamp, intracellular recording techniques. Galantamine (10-200 microM) dose-dependently reduced the postburst afterhyperpolarization and the spike-frequency accommodation of CA1 neurons from both young and aging animals. These reductions were partially, but significantly, reversed by the addition of the muscarinic receptor antagonist, atropine (1 microM), to the perfusate. In contrast, the nicotinic acetylcholine receptor antagonist, alpha-bungarotoxin (10 nM), had no effect; i.e. alpha-bungarotoxin did not reverse the afterhyperpolarization and accommodation reductions. The allosteric potentiating ligand effect was examined by stimulating the Schaffer collateral and measuring the excitatory postsynaptic potentials for 30 min during bath application of galantamine. Galantamine (200 microM) significantly enhanced the excitatory postsynaptic potential amplitude and area over time. These effects were blocked by 10 nM alpha-bungarotoxin, supporting a role for galantamine as an allosteric potentiating ligand. We did not observe a facilitation of the excitatory postsynaptic potentials with 1 microM galantamine. However, when the excitatory postsynaptic potential was pharmacologically isolated by adding 10 microM gabazine (GABA(A) receptor antagonist) to the perfusate, 1 microM galantamine potentiated the subthreshold excitatory postsynaptic potentials into action potentials. We propose that the learning enhancement observed in aging animals and the alleviation of cognitive deficits associated with Alzheimer's disease after galantamine treatment may in part be due to the enhanced function of both nicotinic and muscarinic excitatory transmission on hippocampal pyramidal neurons.
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Affiliation(s)
- M M Oh
- Department of Physiology and Institute for Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611-3008, USA.
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Court JA, Johnson M, Religa D, Keverne J, Kalaria R, Jaros E, McKeith IG, Perry R, Naslund J, Perry EK. Attenuation of Abeta deposition in the entorhinal cortex of normal elderly individuals associated with tobacco smoking. Neuropathol Appl Neurobiol 2005; 31:522-35. [PMID: 16150123 DOI: 10.1111/j.1365-2990.2005.00674.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Investigating correlates of tobacco smoking provides the only currently available opportunity of examining effects of long-term exposure of nicotinic receptors on a specific nicotinic agonist in human. Alzheimer-type pathology (Abeta and abnormally phosphorylated tau assessed on the basis of AT8 immunoreactivity) together with vascular markers has been compared in age-matched groups of normal elderly smokers and non-smokers in the entorhinal cortex, an area of noted age-related pathology. The density of total Abeta and diffuse Abeta immunoreactivity, together with formic acid-extractable Abeta42 but not Abeta40, was reduced in smokers (n = 10-18) compared with non-smokers (n = 10-20) (P < 0.05). There was also a reduced percentage of cortical and leptomeningeal vessels with associated Abeta immunoreactivity in smokers (n = 13) compared with non-smokers (n = 14) (P < 0.005 and 0.05, respectively). There was a significant inverse correlation between formic acid-extractable Abeta42 and pack years (n = 34, r = -0.389, P = 0.025), with a similar trend for total Abeta immunoreactivity which did not reach statistical significance (n = 30, r = -0.323, P = 0.082). In contrast, there were no significant group differences for vascular markers (collagen IV, alpha-actin or glucose transporter 1), AT8 immunoreactivity or phosphate-buffered saline-soluble Abeta peptides, and no significant associations with gender for any of the measured parameters. These findings are consistent with previously reported reductions in histologically assessed amyloid plaques in aged human brain associated with tobacco use and dramatic lessening of Abeta deposits in APPsw mice after nicotine treatment. Development of nicotinic drugs to protect against beta-amyloidosis as one of the principal pathological hallmarks of brain ageing and Alzheimer's disease is indicated.
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Affiliation(s)
- J A Court
- MRC Building, Newcastle General Hospital, Westgate Road, Newcastle upon Tyne, NE4 6BE, UK.
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Van Den Heuvel C, Donkin JJ, Finnie JW, Blumbergs PC, Kuchel T, Koszyca B, Manavis J, Jones NR, Reilly PL, Vink R. Downregulation of amyloid precursor protein (APP) expression following post-traumatic cyclosporin-A administration. J Neurotrauma 2005; 21:1562-72. [PMID: 15684649 DOI: 10.1089/neu.2004.21.1562] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The aim of these studies was to assess and quantitate the effects of cyclosporin-A (CyA) on brain APP messenger RNA and neuronal perikaryal APP antigen expression following controlled focal head impact in sheep. Impact results in a significant increase in both APP mRNA and neuronal perikaryal APP antigen expression. Post-traumatic administration of CyA (intrathecal 10 mg/kg) resulted in a reduction in APP mRNA and neuronal perikaryal antigen expression. At 2 h postinjury, CyA treatment caused a statistically significant (p < 0.05) 1.3 +/- 0.1-fold decrease in APP mRNA in the central gray matter of impacted sheep compared to untreated impacted sheep. A more profound reduction in APP mRNA synthesis (1.6 +/- 0.2 fold) was evident at 6 h (p < 0.05). The mean percentage brain area with APP immunoreactive neuronal perikarya at 6 h post-injury was 94.5% in untreated impacted animals, 10.0% in CyA-treated impacted animals, 5.5% in untreated nonimpacted animals, and 6% in CyA-treated non-impacted controls. These results demonstrate that CyA has a downregulatory effect on increased APP expression caused by TBI.
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Angiotensin II blocks nicotine-mediated neuroprotection against beta-amyloid (1-42) via activation of the tyrosine phosphatase SHP-1. J Neurosci 2003. [PMID: 14657181 DOI: 10.1523/jneurosci.23-35-11224.2003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We showed recently that nicotine activates the growth-promoting enzyme Janus kinase 2 (JAK2) in PC12 cells and that preincubation of these cells with the JAK2-specific inhibitor AG-490 blocked the nicotine-induced neuroprotection against beta-amyloid (1-42) [Abeta (1-42)]. These results provided direct evidence for linkage between JAK2 and the alpha7 nicotinic acetylcholine receptor-induced neuroprotection in PC12 cells. We also showed that preincubation with angiotensin II (Ang II), functioning via the angiotensin II type 2 (AT2) receptor, blocked both the nicotine-induced activation of JAK2 and its neuroprotection against Abeta (1-42). Recently growth-inhibitory effects of the AT2 receptor have been reported to be mediated by the activation of protein tyrosine phosphatases (PTPases) and that AT2 receptor stimulation is associated with a rapid activation of the PTPase SHP-1 (the cytoplasmic tyrosine phosphatase that contains Src homology 2 domains), a negative regulator of JAK2 signaling. Therefore, the potential biological significance of AT2 receptor-induced effects on both the nicotine-induced activation of JAK2 and its neuroprotection against Abeta (1-42) led us to investigate whether SHP-1 activation could be involved in this process. We found that Ang II induced the activation of SHP-1 and that an antisense against SHP-1 not only augmented the nicotine-induced tyrosine phosphorylation of JAK2 but also blocked the Ang II neutralization of the nicotine-induced neuroprotection. These results demonstrate that nicotine-induced tyrosine phosphorylation of JAK2 and neuroprotection against Abeta (1-42) in PC12 cells are blocked by Ang II via AT2 receptor-induced activation of SHP-1.
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Shaw S, Bencherif M, Marrero MB. Janus Kinase 2, an Early Target of α7 Nicotinic Acetylcholine Receptor-mediated Neuroprotection against Aβ-(1–42) Amyloid. J Biol Chem 2002; 277:44920-4. [PMID: 12244045 DOI: 10.1074/jbc.m204610200] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molecular mechanisms of alpha7 nicotinic acetylcholine receptor (nAChR)-mediated neuroprotection remain unclear. In this study we provide evidence that nicotine stimulation of alpha7 nAChR transduces signals to phosphatidylinositol 3-kinase and Akt via Janus kinase 2 (JAK2) in a cascade, which results in neuroprotection. Exposure to beta-amyloid results in the activation of the apoptotic enzyme caspase-3 and cleavage of the DNA-repairing enzyme poly-(ADP-ribose) polymerase. This cascade is inhibited by nicotine through JAK2 activation, and these effects are blocked by preincubation with the JAK2-specific inhibitor AG-490. We also found that pretreatment of cells with angiotensin II blocks the nicotine-induced activation of JAK2 via the AT(2) receptor and completely prevents alpha7 nAChR-mediated neuroprotective effects further suggesting a pivotal role for JAK2. These findings identify novel mechanisms of receptor interactions relevant to neuronal viability and suggest novel therapeutic strategies to optimize neuroprotection.
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Affiliation(s)
- Seán Shaw
- Vascular Biology Center, Medical College of Georgia, Augusta, Georgia 30912-2500, USA
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Lahiri DK, Utsuki T, Chen D, Farlow MR, Shoaib M, Ingram DK, Greig NH. Nicotine reduces the secretion of Alzheimer's beta-amyloid precursor protein containing beta-amyloid peptide in the rat without altering synaptic proteins. Ann N Y Acad Sci 2002; 965:364-72. [PMID: 12105112 DOI: 10.1111/j.1749-6632.2002.tb04178.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alzheimer's disease (AD) is characterized by cerebrovascular deposition of the amyloid beta-peptide (A beta), which is derived from a larger beta-amyloid precursor protein (beta APP). Altered metabolism of beta APP, resulting in increased A beta production, appears central in the neuropathology of AD. The processing of the holoprotein beta APP by different "secretase" enzymes results in three major carboxyl-truncated species. One species, which results from the cleavage of beta APP by gamma-secretase, is secreted into the cerebrospinal fluid (CSF) and is called sAPP gamma as it contains an intact A beta domain. Moreover, AD is characterized by cholinergic dysfunction and the loss of synaptic proteins. Reports of an inverse relation between nicotine intake, due to cigarette smoking, and the incidence of AD prompted us to investigate the effects of nicotine on beta APP processing and synaptic proteins in rats and in cell culture. Nicotine, 1 and 8 mg/kg/day, doses commensurate with cigarette smoking, and a higher but well tolerated dose, respectively, was administered over 14 days to rats. Levels of sAPP in the CSF sample were evaluated by Western blot analysis. The higher dose significantly increased levels of total sAPP; however, both doses significantly reduced sAPP gamma, which contains the amyloidogenic portion of A beta. These actions were blocked by nicotinic receptor antagonism. Nicotinic antagonists alone had no effect on either total sAPP or sAPP gamma levels in CSF. Nicotine did not significantly change the intracellular levels of total beta APP in rat brain extracts, which is consistent with neuronal cell culture data. Similarly, levels of vesicular protein, such as synaptophysin, and presynaptic terminal protein SNAP-25 were unaffected by nicotine treatment both in vivo and in cell culture experiments. Taken together, these results suggest that nicotine modifies beta APP processing away from the formation of potentially amyloidogenic products, without altering the levels of synaptic proteins, and that this can potentially offer therapeutic potential for Alzheimer's disease.
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Affiliation(s)
- D K Lahiri
- Laboratory of Molecular Neurogenetics, Department of Psychiatry and Neurology, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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