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Alexandris AS, Walker L, Liu AKL, McAleese KE, Johnson M, Pearce RKB, Gentleman SM, Attems J. Cholinergic deficits and galaninergic hyperinnervation of the nucleus basalis of Meynert in Alzheimer's disease and Lewy body disorders. Neuropathol Appl Neurobiol 2019; 46:264-278. [PMID: 31454423 DOI: 10.1111/nan.12577] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 08/17/2019] [Indexed: 12/27/2022]
Abstract
AIMS Galanin is a highly inducible neuroprotective neuropeptide and in Alzheimer's disease (AD), a network of galaninergic fibres has been reported to hypertrophy and hyperinnervate the surviving cholinergic neurons in the basal forebrain. We aimed to determine (i) the extent of galanin hyperinnervation in patients with AD and Lewy body disease and (ii) whether galanin expression relates to the neuropathological burden and cholinergic losses. METHODS Galanin immunohistochemistry was carried out in the anterior nucleus basalis of Meynert of 27 Parkinson's disease (PD) cases without cognitive impairment (mild cognitive impairment [MCI]), 15 with PD with MCI, 42 with Parkinson's disease dementia (PDD), 12 with Dementia with Lewy bodies (DLB), 19 with AD, 12 mixed AD/DLB and 16 controls. Galaninergic innervation of cholinergic neurons was scored semiquantitatively. For a subgroup of cases (n = 60), cholinergic losses were determined from maximum densities of choline acetyltransferase positive (ChAT+ve) neurons and their projection fibres. Quantitative data for α-synuclein, amyloid beta and tau pathology were obtained from tissue microarrays covering cortical/subcortical regions. RESULTS Significant losses of cholinergic neurons and their projection fibres were observed across all diseases. Galaninergic hyperinnervation was infrequent and particularly uncommon in established AD and DLB. We found that hyperinnervation frequencies are significantly higher in the transition between PD without MCI to PDD and that higher burdens of co-existent AD pathology impair this galaninergic response. CONCLUSIONS Our results suggest that galanin upregulation represents an intrinsic response early in Lewy body diseases but which fails with increasing burdens of AD related pathology.
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Affiliation(s)
- A S Alexandris
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.,Neuropathology Unit, Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK.,Division of Neuropathology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - L Walker
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - A K L Liu
- Neuropathology Unit, Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - K E McAleese
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - M Johnson
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - R K B Pearce
- Neuropathology Unit, Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - S M Gentleman
- Neuropathology Unit, Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - J Attems
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
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Alexandris A, Liu AKL, Chang RCC, Pearce RKB, Gentleman SM. Differential expression of galanin in the cholinergic basal forebrain of patients with Lewy body disorders. Acta Neuropathol Commun 2015; 3:77. [PMID: 26621352 PMCID: PMC4666186 DOI: 10.1186/s40478-015-0249-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 10/30/2015] [Indexed: 01/04/2023] Open
Abstract
INTRODUCTION Depletion of cholinergic neurons within the nucleus basalis of Meynert (nbM) is thought to contribute to the development of cognitive impairments in both Alzheimer's disease (AD) and Lewy body disorders (LBD). It has been reported that, in late stage AD, a network of fibres that contain the neuropeptide galanin displays significant hypertrophy and 'hyperinnervates' the surviving cholinergic neurons. Galanin is considered as a highly inducible neuroprotective factor and in AD this is assumed to be part of a protective tissue response. The aim of this study was to determine if a similar galanin upregulation is present in the nbM in post-mortem tissue from patients with LBD. Gallatin immunohistochemistry was carried out on anterior nbM sections from 76 LBD cases (27 PD, 15 PD with mild cognitive impairment (MCI), 34 PD with dementia (PDD) and 4 aged-matched controls. Galaninergic innervation of cholinergic neurons was assessed on a semi-quantitative scale. RESULTS The LBD group had significantly higher galaninergic innervation scores (p = 0.016) compared to controls. However, this difference was due to increased innervation density only in a subgroup of LBD cases and this correlated positively with choline acetyltransferase-immunopositive neuron density. CONCLUSION Galanin upregulation within the basal forebrain cholinergic system in LBD, similar to that seen in AD, may represent an intrinsic adaptive response to neurodegeneration that is consistent with its proposed roles in neurogenesis and neuroprotection.
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Mufson EJ, Mahady L, Waters D, Counts SE, Perez SE, DeKosky ST, Ginsberg SD, Ikonomovic MD, Scheff SW, Binder LI. Hippocampal plasticity during the progression of Alzheimer's disease. Neuroscience 2015; 309:51-67. [PMID: 25772787 PMCID: PMC4567973 DOI: 10.1016/j.neuroscience.2015.03.006] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 02/05/2015] [Accepted: 03/04/2015] [Indexed: 11/27/2022]
Abstract
Neuroplasticity involves molecular and structural changes in central nervous system (CNS) throughout life. The concept of neural organization allows for remodeling as a compensatory mechanism to the early pathobiology of Alzheimer's disease (AD) in an attempt to maintain brain function and cognition during the onset of dementia. The hippocampus, a crucial component of the medial temporal lobe memory circuit, is affected early in AD and displays synaptic and intraneuronal molecular remodeling against a pathological background of extracellular amyloid-beta (Aβ) deposition and intracellular neurofibrillary tangle (NFT) formation in the early stages of AD. Here we discuss human clinical pathological findings supporting the concept that the hippocampus is capable of neural plasticity during mild cognitive impairment (MCI), a prodromal stage of AD and early stage AD.
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Affiliation(s)
- E J Mufson
- Barrow Neurological Institute, St. Joseph's Medical Center, Department of Neurobiology, Phoenix, AZ 85013, United States.
| | - L Mahady
- Barrow Neurological Institute, St. Joseph's Medical Center, Department of Neurobiology, Phoenix, AZ 85013, United States
| | - D Waters
- Barrow Neurological Institute, St. Joseph's Medical Center, Department of Neurobiology, Phoenix, AZ 85013, United States
| | - S E Counts
- Department of Translational Science & Molecular Medicine, Michigan State University College of Human Medicine, Grand Rapids, MI, United States
| | - S E Perez
- Division of Neurological Sciences, Rush University Medical Center, Chicago, IL, United States
| | - S T DeKosky
- Department of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - S D Ginsberg
- Center for Dementia Research, Nathan Kline Institute, Departments of Psychiatry and Physiology & Neuroscience, New York University Langone Medical Center, Orangeburg, NY, United States
| | - M D Ikonomovic
- Departments of Neurology and Psychiatry, University of Pittsburgh, Geriatric Research Education and Clinical Center, VA Pittsburgh Healthcare System, Pittsburgh, PA, United States
| | - S W Scheff
- Sanders Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - L I Binder
- Department of Translational Science & Molecular Medicine, Michigan State University College of Human Medicine, Grand Rapids, MI, United States
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Mitsukawa K, Lu X, Bartfai T. Galanin, galanin receptors, and drug targets. EXPERIENTIA SUPPLEMENTUM (2012) 2010; 102:7-23. [PMID: 21299058 DOI: 10.1007/978-3-0346-0228-0_2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Galanin, a neuropeptide widely expressed in the central and peripheral nervous systems and in the endocrine system, has been shown to regulate numerous physiological and pathological processes through interactions with three G-protein-coupled receptors, GalR1 through GalR3. Over the past decade, some of the receptor subtype-specific effects have been elucidated through pharmacological studies using subtype selective ligands, as well as through molecular approaches involving knockout animals. In this chapter, we summarize the current data which constitute the basis of targeting GalR1, GalR2, and GalR3 for the treatment of various human diseases and pathological conditions, including seizure, Alzheimer's disease, mood disorders, anxiety, alcohol intake in addiction, metabolic diseases, pain and solid tumors.
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Affiliation(s)
- K Mitsukawa
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Counts SE, Perez SE, Ginsberg SD, Mufson EJ. Neuroprotective role for galanin in Alzheimer's disease. EXPERIENTIA SUPPLEMENTUM (2012) 2010; 102:143-62. [PMID: 21299067 DOI: 10.1007/978-3-0346-0228-0_11] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Galanin (GAL) and GAL receptors (GALR) are overexpressed in degenerating brain regions associated with cognitive decline in Alzheimer's disease (AD). The functional consequences of GAL plasticity in AD are unclear. GAL inhibits cholinergic transmission in the hippocampus and impairs spatial memory in rodent models, suggesting that GAL overexpression exacerbates cognitive impairment in AD. By contrast, gene expression profiling of individual cholinergic basal forebrain (CBF) neurons aspirated from AD tissue revealed that GAL hyperinnervation positively regulates mRNAs that promote CBF neuronal function and survival. GAL also exerts neuroprotective effects in rodent models of neurotoxicity. These data support the growing concept that GAL overexpression preserves CBF neuron function, which may in turn delay the onset of symptoms of AD. Further elucidation of GAL activity in selectively vulnerable brain regions will help gauge the therapeutic potential of GALR ligands in the treatment of AD.
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Affiliation(s)
- Scott E Counts
- Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison Street, Suite 300, Chicago, IL 60612, USA
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Abstract
Galanin (GAL) and GAL receptors (GALRs) are overexpressed in degenerating brain regions associated with cognitive decline in Alzheimer's disease (AD). The functional consequences of GAL plasticity in AD are unclear. GAL inhibits cholinergic transmission in the hippocampus and impairs spatial memory in rodent models, suggesting GAL overexpression exacerbates cognitive impairment in AD. By contrast, gene expression profiling of individual cholinergic basal forebrain (CBF) neurons aspirated from AD tissue revealed that GAL hyperinnervation positively regulates mRNAs that promote CBF neuronal function and survival. GAL also exerts neuroprotective effects in rodent models of neurotoxicity. These data support the growing concept that GAL overexpression preserves CBF neuron function which in turn may slow the onset of AD symptoms. Further elucidation of GAL activity in selectively vulnerable brain regions will help gauge the therapeutic potential of GALR ligands for the treatment of AD.
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Affiliation(s)
- S. E. Counts
- Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison Street Suite 300, Chicago, Ilinois 60612 USA
| | - S. E. Perez
- Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison Street Suite 300, Chicago, Ilinois 60612 USA
| | - E. J. Mufson
- Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison Street Suite 300, Chicago, Ilinois 60612 USA
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Counts SE, Chen EY, Che S, Ikonomovic MD, Wuu J, Ginsberg SD, Dekosky ST, Mufson EJ. Galanin fiber hypertrophy within the cholinergic nucleus basalis during the progression of Alzheimer's disease. Dement Geriatr Cogn Disord 2006; 21:205-14. [PMID: 16410678 DOI: 10.1159/000090906] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/07/2005] [Indexed: 01/19/2023] Open
Abstract
Galanin (GAL)-containing fibers enlarge and hyperinnervate remaining cholinergic basal forebrain (CBF) neurons within the anterior nucleus basalis (NB) in late-stage Alzheimer's disease (AD). Whether GAL hypertrophy occurs in the CBF in the prodromal or early stages of AD remains unknown. The present study used GAL immunohistochemistry and an unbiased semiquantitative scoring method to evaluate GAL innervation in the anterior NB of subjects clinically diagnosed as having no cognitive impairment, mild cognitive impairment or early-stage (mild/moderate) AD. There was no difference in GAL fiber staining within the anterior NB across the three clinical groups examined. Furthermore, GAL fiber innervation was not correlated with the number of NB neurons expressing the nerve growth factor receptors p75(NTR) or TrkA or with cortical choline acetyltransferase activity in the same cases. Single-cell gene expression analysis demonstrated that cholinergic NB neurons express mRNA for the GAL receptors GALR1, GALR2 and GALR3, yet the levels of these mRNAs were unchanged across the three diagnostic groups. These observations indicate that GAL hypertrophy within the anterior NB subfield is a late-stage AD response, which may play a role in regulating the cholinergic tone of remaining basocortical projection neurons.
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Affiliation(s)
- Scott E Counts
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612, USA
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He B, Counts SE, Perez SE, Hohmann JG, Koprich JB, Lipton JW, Steiner RA, Crawley JN, Mufson EJ. Ectopic galanin expression and normal galanin receptor 2 and galanin receptor 3 mRNA levels in the forebrain of galanin transgenic mice. Neuroscience 2005; 133:371-80. [PMID: 15885921 DOI: 10.1016/j.neuroscience.2005.01.068] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Revised: 01/21/2005] [Accepted: 01/25/2005] [Indexed: 10/25/2022]
Abstract
The functional interactions of the neuropeptide galanin (GAL) occur through its binding to three G protein-coupled receptor subtypes: galanin receptor (GALR) 1, GALR2 and GALR3. Previously, we demonstrated that GALR1 mRNA expression was increased in the CA1 region of the hippocampus and discrete hypothalamic nuclei in galanin transgenic (GAL-tg) mice. This observation suggested a compensatory adjustment in cognate receptors in the face of chronic GAL exposure. To evaluate the molecular alterations to GALR2 and GALR3 in the forebrain of GAL overexpressing mice, we performed complementary quantitative, real-time PCR (qPCR), in situ hybridization, and immunohistochemistry in select forebrain regions of GAL-tg mice to characterize the neuronal distribution and magnitude of GAL mRNA and peptide expression and the consequences of genetically manipulating the neuropeptide GAL on the expression of GALR2 and GALR3 receptors. We found that GAL-tg mice displayed dramatic increases in GAL mRNA and peptide in the frontal cortex, posterior cortex, hippocampus, septal diagonal band complex, amygdala, piriform cortex, and olfactory bulb. Moreover, there was evidence for ectopic neuronal GAL expression in forebrain limbic regions that mediate cognitive and affective behaviors, including the piriform and entorhinal cortex and amygdala. Interestingly, regional qPCR analysis failed to reveal any changes in GALR2 or GALR3 expression in the GAL-tg mice, suggesting that, contrary to GALR1, these receptor genes are not under ligand-mediated regulatory control. The GAL-tg mouse model may provide a useful tool for the investigation of GAL ligand-receptor relationships and their role in normal cognitive and affective functions as well as in the onset of neurological disease.
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MESH Headings
- Animals
- Galanin/genetics
- Galanin/metabolism
- Gene Expression Regulation/genetics
- Immunohistochemistry/methods
- In Situ Hybridization/methods
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Prosencephalon/anatomy & histology
- Prosencephalon/metabolism
- RNA, Messenger/metabolism
- Receptor, Galanin, Type 2/genetics
- Receptor, Galanin, Type 2/metabolism
- Receptor, Galanin, Type 3/genetics
- Receptor, Galanin, Type 3/metabolism
- Reverse Transcriptase Polymerase Chain Reaction/methods
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Affiliation(s)
- B He
- Department of Neurological Sciences, Rush University Medical Center, 1735 West Harrison Street, Chicago, IL 60612, USA
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Barbelivien A, Vaussy C, Marchalant Y, Maubert E, Bertrand N, Beley A, Roussel S, Mackenzie ET, Dauphin F. Degeneration of the basalocortical pathway from the cortex induces a functional increase in galaninergic markers in the nucleus basalis magnocellularis of the rat. J Cereb Blood Flow Metab 2004; 24:1255-66. [PMID: 15545921 DOI: 10.1097/01.wcb.0000139447.69413.05] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The present work aimed 1) to evaluate whether an increase in galanin or galanin receptors could be induced in the nucleus basalis magnocellularis (nbm) by degeneration of the basalocortical neurons from the cortex and 2) to analyze the consequences of such an increase on cortical activity. First, a mild ischemic insult to the frontoparietal cortex was performed to induce the degeneration of the basalocortical system; galanin immunoreactivity, galanin binding sites, and cholinergic muscarinic receptors were quantified through immunocytochemistry and autoradiography. Second, galanin infusions in the nbm were undertaken to mimic a local increase of the galaninergic innervation; cortical acetylcholine release, cerebral glucose use, and cerebral blood flow were then measured as indices of cortical activity. As a result of the cortical ischemic lesion, the postsynaptic M1 and presynaptic M2 muscarinic receptors were found to be reduced in the altered cortex. In contrast, galaninergic binding capacity and fiber density were found to be increased in the ipsilateral nbm in parallel with a local decrease in the cholinergic markers such as the muscarinic M1 receptor density. Galanin infusion into the nbm inhibited the cortical acetylcholine release and cerebral blood flow increases elicited by the activation of the cholinergic basalocortical system but failed to affect acetylcholine release, cerebral blood flow, and cerebral glucose use when injected alone in the nbm. These results demonstrate that degeneration of the basalocortical system from the cortex induces an increase in galaninergic markers in the nbm, a result that might suggest that the galaninergic overexpression described in the basal forebrain of patients with Alzheimer's disease can result from a degeneration of the cholinergic basalocortical system from the cortex. Because galanin was found to reduce the activity of the basalocortical cholinergic system only when this one is activated, galanin might exert its role rather during activation deficits than under resting conditions such as the resting cortical hypometabolism, which is characteristic of Alzheimer's disease.
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