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Comaposada-Baró R, Benito-Martínez A, Escribano-Saiz JJ, Franco ML, Ceccarelli L, Calatayud-Baselga I, Mira H, Vilar M. Cholinergic neurodegeneration and cholesterol metabolism dysregulation by constitutive p75 NTR signaling in the p75 exonIII-KO mice. Front Mol Neurosci 2023; 16:1237458. [PMID: 37900943 PMCID: PMC10611523 DOI: 10.3389/fnmol.2023.1237458] [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: 06/09/2023] [Accepted: 09/28/2023] [Indexed: 10/31/2023] Open
Abstract
Degeneration of basal forebrain cholinergic neurons (BFCNs) is a hallmark of Alzheimer's disease (AD). However, few mouse models of AD recapitulate the neurodegeneration of the cholinergic system. The p75 neurotrophin receptor, p75NTR, has been associated with the degeneration of BFCNs in AD. The senescence-accelerated mouse prone number 8 (SAMP8) is a well-accepted model of accelerated and pathological aging. To gain a better understanding of the role of p75NTR in the basal forebrain during aging, we generated a new mouse line, the SAMP8-p75exonIII-/-. Deletion of p75NTR in the SAMP8 background induces an increase in the number of BFCNs at birth, followed by a rapid decline during aging compared to the C57/BL6 background. This decrease in the number of BFCNs correlates with a worsening in the Y-maze memory test at 6 months in the SAMP8-p75exonIII-/-. We found that SAMP8-p75exonIII-/- and C57/BL6-p75exonIII-/- mice expressed constitutively a short isoform of p75NTR that correlates with an upregulation of the protein levels of SREBP2 and its targets, HMGCR and LDLR, in the BF of both SAMP8-p75exonIII-/- and C57/BL6-p75exonIII-/- mice. As the neurodegeneration of the cholinergic system and the dysregulation of cholesterol metabolism are implicated in AD, we postulate that the generated SAMP8-p75exonIII-/- mouse strain might constitute a good model to study long-term cholinergic neurodegeneration in the CNS. In addition, our results support the role of p75NTR signaling in cholesterol biosynthesis regulation.
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Affiliation(s)
- Raquel Comaposada-Baró
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - Andrea Benito-Martínez
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - Juan Julian Escribano-Saiz
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - María Luisa Franco
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - Lorenzo Ceccarelli
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | | | - Helena Mira
- Stem Cells and Aging Units of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
| | - Marçal Vilar
- Molecular Basis of Neurodegeneration Unit of the Instituto de Biomedicina de Valencia CSIC, Valencia, Spain
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Somera B, Frick M, Fadel JR. Age-related changes in basal forebrain afferent activation in response to food paired stimuli. Neurosci Lett 2023; 802:137155. [PMID: 36842481 PMCID: PMC10155118 DOI: 10.1016/j.neulet.2023.137155] [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: 08/25/2022] [Revised: 02/21/2023] [Accepted: 02/22/2023] [Indexed: 02/28/2023]
Abstract
The basal forebrain contains a phenotypically-diverse assembly of neurons, including those using acetylcholine as their neurotransmitter. This basal forebrain cholinergic system projects to the entire neocortical mantle as well as subcortical limbic structures that include the hippocampus and amygdala. Basal forebrain pathology, including cholinergic dysfunction, is thought to underlie the cognitive impairments associated with several age-related neurodegenerative conditions, including Alzheimer's disease. Basal forebrain dysfunction may stem, in part, from a failure of normal afferent regulation of cholinergic and other neurons in this area. However, little is understood regarding how aging, alone, affects the functional regulation of basal forebrain afferents in the context of motivated behavior. Here, we used neuronal tract-tracing combined with motivationally salient stimuli in an aged rodent model to examine how aging alters activity in basal forebrain inputs arising from several cortical, limbic and brainstem structures. Young rats showed greater stimulus-associated activation of basal forebrain inputs arising from prelimbic cortex, nucleus accumbens and the ventral tegmental area compared with aged rats. Aged rats also showed increased latency to respond to palatable food presentation compared to young animals. Changes in activation of intrinsic basal forebrain cell populations or afferents were also observed as a function of age or experimental condition. These data further demonstrate that age-related changes in basal forebrain activation and related behavioral and cognitive functions reflect a failure of afferent regulation of this important brain region.
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Affiliation(s)
- Brandy Somera
- Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Marla Frick
- Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
| | - Jim R Fadel
- Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States.
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3
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Qian L, Rawashdeh O, Kasas L, Milne MR, Garner N, Sankorrakul K, Marks N, Dean MW, Kim PR, Sharma A, Bellingham MC, Coulson EJ. Cholinergic basal forebrain degeneration due to sleep-disordered breathing exacerbates pathology in a mouse model of Alzheimer's disease. Nat Commun 2022; 13:6543. [PMID: 36323689 PMCID: PMC9630433 DOI: 10.1038/s41467-022-33624-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 09/26/2022] [Indexed: 11/07/2022] Open
Abstract
Although epidemiological studies indicate that sleep-disordered breathing (SDB) such as obstructive sleep apnea is a strong risk factor for the development of Alzheimer's disease (AD), the mechanisms of the risk remain unclear. Here we developed a method of modeling SDB in mice that replicates key features of the human condition: altered breathing during sleep, sleep disruption, moderate hypoxemia, and cognitive impairment. When we induced SDB in a familial AD model, the mice displayed exacerbation of cognitive impairment and the pathological features of AD, including increased levels of amyloid-beta and inflammatory markers, as well as selective degeneration of cholinergic basal forebrain neurons. These pathological features were not induced by chronic hypoxia or sleep disruption alone. Our results also revealed that the cholinergic neurodegeneration was mediated by the accumulation of nuclear hypoxia inducible factor 1 alpha. Furthermore, restoring blood oxygen levels during sleep to prevent hypoxia prevented the pathological changes induced by the SDB. These findings suggest a signaling mechanism whereby SDB induces cholinergic basal forebrain degeneration.
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Affiliation(s)
- Lei Qian
- grid.1003.20000 0000 9320 7537Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia ,grid.1003.20000 0000 9320 7537Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia ,grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Oliver Rawashdeh
- grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Leda Kasas
- grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Michael R. Milne
- grid.1003.20000 0000 9320 7537Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia ,grid.1003.20000 0000 9320 7537Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia ,grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Nicholas Garner
- grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Kornraviya Sankorrakul
- grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia ,grid.10223.320000 0004 1937 0490Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Salaya, Thailand
| | - Nicola Marks
- grid.1003.20000 0000 9320 7537Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Matthew W. Dean
- grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Pu Reum Kim
- grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Aanchal Sharma
- grid.1003.20000 0000 9320 7537Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Mark C. Bellingham
- grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Elizabeth J. Coulson
- grid.1003.20000 0000 9320 7537Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia ,grid.1003.20000 0000 9320 7537Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072 Australia ,grid.1003.20000 0000 9320 7537School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072 Australia
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Illouz T, Madar R, Okun E. A modified Barnes maze for an accurate assessment of spatial learning in mice. J Neurosci Methods 2020; 334:108579. [PMID: 31926999 DOI: 10.1016/j.jneumeth.2020.108579] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 12/17/2019] [Accepted: 01/05/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND The Morris water maze (MWM) and the Barnes maze (BM) are among the most widely-used paradigms for assessing spatial learning in rodents, with specific advantages and disadvantages for each apparatus. Compared with the intense water-related stress exerted during the MWM, the BM exhibits a milder light-induced stress, while suffering from biasing animals towards non-spatial strategies such as serial search, a heuristic non-spatial search strategy. To overcome this problem, we have developed a modified Barnes maze (MBM) apparatus that recapitulates natural environments more accurately without inducing undesirable exploration strategy bias. NEW METHOD Apparatus. A circular 122 cm-wide table with 40 randomly placed holes. One target hole is leading to an escape chamber. Task. Three target locations were examined, varying in their distance from the center. C57BL6/j male mice were given three trials per day to find the target. Following acquisition, a probe test was performed by removing the escape chamber. RESULTS Spatial-encoding-depended reduction in latency to reach the target was observed, along with improvement in path efficiency with test progress. Mice tested with peripheral and distal targets outperformed mice tested with a central target. A robust exploration pattern was identified in the probe test. COMPARISON WITH EXISTING METHOD The MBM mimics natural environment to a higher degree of accuracy than the BM, without eliciting bias towards non-spatial searching strategies. CONCLUSIONS Spatial learning in the MBM is a target-location sensitive process, providing flexibility in task difficulty. Along with overcoming biases towards non-spatial strategies, the MBM represents an improvement over the well-validated BM.
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Affiliation(s)
- Tomer Illouz
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, 5290002, Israel; The Paul Feder Laboratory on Alzheimer's Disease Research, Bar-Ilan University, Ramat Gan, 5290002, Israel.
| | - Ravit Madar
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, 5290002, Israel; The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel; The Paul Feder Laboratory on Alzheimer's Disease Research, Bar-Ilan University, Ramat Gan, 5290002, Israel.
| | - Eitan Okun
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, 5290002, Israel; The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel; The Paul Feder Laboratory on Alzheimer's Disease Research, Bar-Ilan University, Ramat Gan, 5290002, Israel.
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Modulation of the p75 neurotrophin receptor suppresses age-related basal forebrain cholinergic neuron degeneration. Sci Rep 2019; 9:5273. [PMID: 30918278 PMCID: PMC6437186 DOI: 10.1038/s41598-019-41654-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 02/08/2019] [Indexed: 11/19/2022] Open
Abstract
Age-related degeneration of basal forebrain cholinergic neurons (BFCNs) is linked to cognitive impairment. The p75 neurotrophin receptor (p75NTR) has been proposed to mediate neuronal degeneration in aging. Therefore, we tested the hypothesis that modifying p75NTR function would prevent or reverse aging-related neuronal degeneration using LM11A-31, a small molecule p75NTR modulator that downregulates degenerative and upregulates trophic receptor-associated signaling. Morphological analysis in mice showed loss of BFCN area detectable by 18 months of age. Oral administration of LM11A-31 from age 15 to 18 months resulted in a dose-related preservation of BFCN area and one month of treatment from 17 to 18 months also preserved cell area. To evaluate reversal of established neuronal atrophy, animals were treated from 21 to 25 months of age. Treatment was associated with an increase of cell size to a mean area larger than that observed at 18 months, accompanied by increases in mean MS/VDB neurite length, as well as increased cholinergic fiber density and synaptophysin pre-synaptic marker levels in the hippocampus. These findings support the idea that modulation of p75NTR activity can prevent and potentially reverse age-associated BFCN degeneration. Moreover, this may be achieved therapeutically with orally bioavailable agents such as LM11A-31.
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Assessment of spatial learning and memory in the Barnes maze task in rodents-methodological consideration. Naunyn Schmiedebergs Arch Pharmacol 2018; 392:1-18. [PMID: 30470917 PMCID: PMC6311199 DOI: 10.1007/s00210-018-1589-y] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/15/2018] [Indexed: 01/01/2023]
Abstract
Among the methods valuable for assessing spatial learning and memory impairments in rodents, the Barnes maze (BM) task deserves special attention. It is based on the assumption that the animal placed into the aversive environment should learn and remember the location of an escape box located below the surface of the platform. Different phases of the task allow to measure spatial learning, memory retrieval, and cognitive flexibility. Herein, we summarize current knowledge about the BM procedure, its variations and critical parameters measured in the task. We highlight confounding factors which should be taken into account when conducting BM task, discussing briefly its advantages and disadvantages. We then propose an extended version of the BM protocol which allows to measure different aspects of spatial learning and memory in rodents. We believe that this review will help to standardize the BM methodology across the laboratories and eventually make the results comparable.
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7
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Novier A, Diaz-Granados JL, Matthews DB. Alcohol use across the lifespan: An analysis of adolescent and aged rodents and humans. Pharmacol Biochem Behav 2015; 133:65-82. [PMID: 25842258 DOI: 10.1016/j.pbb.2015.03.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 01/26/2015] [Accepted: 03/20/2015] [Indexed: 10/23/2022]
Abstract
Adolescence and old age are unique periods of the lifespan characterized by differential sensitivity to the effects of alcohol. Adolescents and the elderly appear to be more vulnerable to many of alcohol's physiological and behavioral effects compared to adults. The current review explores the differential effects of acute alcohol, predominantly in terms of motor function and cognition, in adolescent and aged humans and rodents. Adolescents are less sensitive to the sedative-hypnotic, anxiolytic, and motor-impairing effects of acute alcohol, but research results are less consistent as it relates to alcohol's effects on cognition. Specifically, previous research has shown adolescents to be more, less, and similarly sensitive to alcohol-induced cognitive deficits compared to adults. These equivocal findings suggest that learning acquisition may be differentially affected by ethanol compared to memory, or that ethanol-induced cognitive deficits are task-dependent. Older rodents appear to be particularly vulnerable to the motor- and cognitive-impairing effects of acute alcohol relative to younger adults. Given that alcohol consumption and abuse is prevalent throughout the lifespan, it is important to recognize age-related differences in response to acute and long-term alcohol. Unfortunately, diagnostic measures and treatment options for alcohol dependence are rarely dedicated to adolescent and aging populations. As discussed, although much scientific advancement has been made regarding the differential effects of alcohol between adolescents and adults, research with the aged is underrepresented. Future researchers should be aware that adolescents and the aged are uniquely affected by alcohol and should continue to investigate alcohol's effects at different stages of maturation.
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Affiliation(s)
- Adelle Novier
- Baylor University, Department of Psychology and Neuroscience, One Bear Place #97334, Waco, TX 76798, United States
| | - Jaime L Diaz-Granados
- Baylor University, Department of Psychology and Neuroscience, One Bear Place #97334, Waco, TX 76798, United States
| | - Douglas B Matthews
- Baylor University, Department of Psychology and Neuroscience, One Bear Place #97334, Waco, TX 76798, United States; University of Wisconsin - Eau Claire, Department of Psychology, HHH 273, Eau Claire, WI 54702, United States.
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8
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N’Go PK, Azzaoui FZ, Soro PR, Samih M, Ahami AOT, Najimi M, Chigr F. Developmental Effects of Malathion Exposure on Recognition Memory and Spatial Learning in Males Wistar Rats. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/jbbs.2013.33033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Mild cognitive impairment (MCI) is an aspect of cognitive aging that is considered to be a transitional state between normal aging and the dementia into which it may convert. Appropriate animal models are necessary in order to understand the pathogenic mechanisms of MCI and develop drugs for its treatment. In this review, we identify the features that should characterize an animal model of MCI, namely old age, subtle memory impairment, mild neuropathological changes, and changes in the cholinergic system, and the age at which these features can be detected in laboratory animals. These features should occur in aging animals with normal motor activity and feeding behavior. The animal models may be middle-aged rats and mice, rats with brain ischemia, transgenic mice overexpressing amyloid precursor protein and presenilin 1 (tested at an early stage), or aging monkeys. Memory deficits can be detected by selecting appropriately difficult behavioral tasks, and the deficits can be associated with neuropathological alterations. The reviewed literature demonstrates that, under certain conditions, these animal species can be considered to be MCI models, and that cognitive impairment in these models responds to drug treatment.
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Affiliation(s)
- Giancarlo Pepeu
- Department of Pharmacology, University of Florence, Florence, Italy
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11
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Twohig JP, Cuff SM, Yong AA, Wang ECY. The role of tumor necrosis factor receptor superfamily members in mammalian brain development, function and homeostasis. Rev Neurosci 2011; 22:509-33. [PMID: 21861782 DOI: 10.1515/rns.2011.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Tumor necrosis factor receptor superfamily (TNFRSF) members were initially identified as immunological mediators, and are still commonly perceived as immunological molecules. However, our understanding of the diversity of TNFRSF members' roles in mammalian physiology has grown significantly since the first discovery of TNFRp55 (TNFRSF1) in 1975. In particular, the last decade has provided evidence for important roles in brain development, function and the emergent field of neuronal homeostasis. Recent evidence suggests that TNFRSF members are expressed in an overlapping regulated pattern during neuronal development, participating in the regulation of neuronal expansion, growth, differentiation and regional pattern development. This review examines evidence for non-immunological roles of TNFRSF members in brain development, function and maintenance under normal physiological conditions. In addition, several aspects of brain function during inflammation will also be described, when illuminating and relevant to the non-immunological role of TNFRSF members. Finally, key questions in the field will be outlined.
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Affiliation(s)
- Jason P Twohig
- Department of Infection, Immunity and Biochemistry, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, Wales, UK
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BMP9 (bone morphogenetic protein 9) induces NGF as an autocrine/paracrine cholinergic trophic factor in developing basal forebrain neurons. J Neurosci 2010; 30:8221-8. [PMID: 20554873 DOI: 10.1523/jneurosci.5611-09.2010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Acetylcholine (ACh) synthesis and release from basal forebrain cholinergic neurons (BFCN) innervating the cerebral cortex and hippocampus are essential processes for normal learning, memory and attention. Bone morphogenetic protein (BMP) 9 is a cholinergic differentiation factor in the developing septum that increases ACh synthesis and choline acetyltransferase (Chat) gene expression both in vivo and in vitro. We investigated the possible induction of cholinergic trophic factors by BMP9 in murine septal cells. Nerve growth factor (NGF) protein expression and secretion into the medium was increased in cultured embryonic septal cells treated with BMP9, and partially mediated BMP9-induced acetylcholine production and Chat gene expression. BMP9-induced Ngf gene expression was detected in postmitotic cells, required new protein synthesis and was blocked by BMP type I receptor inhibition. Cholinergic neurons were isolated by fluorescence-activated cell sorting based on either transgenic expression of green fluorescent protein driven by the Chat promoter or NGF receptor (p75) immunostaining. Although both noncholinergic and cholinergic neurons in untreated cultures expressed similar low levels of Ngf, increased Ngf gene expression was restricted to Chat-positive neurons in BMP9-treated cultures. Likewise, similar levels of Ngf mRNA were detected in p75-negative and p75-positive septal cells, yet only p75-positive BFCN increased their Ngf gene expression when treated with BMP9, and only these cells expressed the Alk1 BMP receptor. The data suggest an autocrine/paracrine role for NGF in the development and/or maintenance of BFCN and imply that the stimulation of NGF production and release contributes to the cholinergic-supportive properties of BMP9.
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McQuail JA, Riddle DR, Nicolle MM. Neuroinflammation not associated with cholinergic degeneration in aged-impaired brain. Neurobiol Aging 2010; 32:2322.e1-4. [PMID: 20561717 DOI: 10.1016/j.neurobiolaging.2010.05.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 05/03/2010] [Accepted: 05/12/2010] [Indexed: 10/19/2022]
Abstract
Degeneration of the cholinergic neurons in the basal forebrain and elevation of inflammatory markers are well-established hallmarks of Alzheimer's disease; however, the interplay of these processes in normal aging is not extensively studied. Consequently, we conducted a neuroanatomical investigation to quantify cholinergic neurons and activated microglia in the medial septum/vertical diagonal band (MS/VDB) of young (6 months) and aged (28 months) Fisher 344 × Brown Norway F(1) rats. Aged rats in this study were impaired relative to the young animals in spatial learning ability as assessed in the Morris water maze. Stereological analysis revealed no difference between aged and young rats in the total numbers of cholinergic neurons, demonstrating that loss of cholinergic neurons is not a necessary condition to observe impaired spatial learning in aged rats. In this same region, the total number of activated microglia was substantially greater in aged rats relative to young rats. Jointly, these data demonstrate that aging is characterized by an increase in the basal inflammatory state within the MS/VDB, but this inflammation is not associated with cholinergic neuron death.
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Affiliation(s)
- Joseph A McQuail
- Program in Neuroscience, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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14
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O'Callaghan RM, Griffin EW, Kelly AM. Long-term treadmill exposure protects against age-related neurodegenerative change in the rat hippocampus. Hippocampus 2009; 19:1019-29. [PMID: 19309034 DOI: 10.1002/hipo.20591] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The potential of exercise or environmental enrichment to prevent or reverse age-related cognitive decline in rats has been widely investigated. The data suggest that the efficacy of these interventions as neuroprotectants may depend upon the duration and nature of the protocols and age of onset. Investigations of the mechanisms underlying these neuroprotective strategies indicate a potential role for the neurotrophin family of proteins, including nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). In this study, we have assessed the effects of 8 months of forced exercise, begun in middle-age, on the expression of long-term potentiation (LTP) and on spatial learning in the Morris water maze in aged Wistar rats. We also assessed these measures in a cage control group and in a group of rats exposed to the stationary treadmill for the same duration as the exercised rats. Our data confirm an age-related decline in expression of LTP and in spatial learning concomitant with decreased expression of NGF and BDNF mRNA in dentate gyrus (DG). The age-related impairments in both plasticity and growth factor expression were prevented in the long-term exercised group and, surprisingly, the treadmill control group. Given the extensive handling that the treadmill control group received and their regular exposure to an environment outside the home cage, this group can be considered to have experienced environmentally enriched conditions when compared with the cage control group. Significant correlations were observed between both learning and LTP and the expression of NGF and BDNF mRNA in the dentate gyrus. We conclude that decreased expression of NGF and BDNF in the dentate gyrus of aged rats is associated with impaired LTP and spatial learning. We suggest that the reversal of these age-related impairments by enrichment and exercise may be linked with prevention of the age-related decline in expression of these growth factors and, furthermore, that enrichment is as efficacious as exercise in preventing this age-related decline.
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Affiliation(s)
- Rachel M O'Callaghan
- Department of Physiology, School of Medicine, and Trinity College Institute of Neuroscience, University of Dublin, Trinity College, Dublin 2, Ireland
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15
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Dwivedi Y, Rizavi HS, Zhang H, Mondal AC, Roberts RC, Conley RR, Pandey GN. Neurotrophin receptor activation and expression in human postmortem brain: effect of suicide. Biol Psychiatry 2009; 65:319-28. [PMID: 18930453 PMCID: PMC2654767 DOI: 10.1016/j.biopsych.2008.08.035] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 07/31/2008] [Accepted: 08/25/2008] [Indexed: 01/19/2023]
Abstract
BACKGROUND The physiological functions of neurotrophins occur through binding to two receptors: pan75 neurotrophin receptor (p75(NTR)) and a family of tropomyosin receptor kinases (Trks A, B, and C). We recently reported that expression of neurotrophins and TrkB were reduced in brains of suicide subjects. This study examines whether expression and activation of Trk receptors and expression of p75(NTR) are altered in brain of these subjects. METHODS Expression levels of TrkA, B, C, and of p75(NTR) were measured by quantitative reverse transcription polymerase chain reaction and Western blot in prefrontal cortex (PFC) and hippocampus of suicide and normal control subjects. The activation of Trks was determined by immunoprecipitation followed by Western blotting using phosphotyrosine antibody. RESULTS In hippocampus, lower mRNA levels of TrkA and TrkC were observed in suicide subjects. In the PFC, the mRNA level of TrkA was decreased, without any change in TrkC. However, the mRNA level of p75(NTR) was increased in both PFC and hippocampus. Immunolabeling studies showed similar results as observed for the mRNAs. In addition, phosphorylation of all Trks was decreased in hippocampus, but in PFC, decreased phosphorylation was noted only for TrkA and B. Increased expression ratios of p75(NTR) to Trks were also observed in PFC and hippocampus of suicide subjects. CONCLUSIONS Our results suggest not only reduced functioning of Trks in brains of suicide subjects but also that increased ratios of p75(NTR) to Trks indicate possible activation of pathways that are apoptotic in nature. These findings may be crucial in the pathophysiology of suicide.
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Affiliation(s)
- Yogesh Dwivedi
- Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Hooriyah S. Rizavi
- Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor St., Chicago IL, 60612, USA
| | - Hui Zhang
- Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor St., Chicago IL, 60612, USA
| | - Amal C. Mondal
- Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor St., Chicago IL, 60612, USA
| | - Rosalinda C. Roberts
- University of Alabama at Birmingham, 865D Sparks Center, 1720 7th Ave South, Birmingham, AL 35294, USA
| | | | - Ghanshyam N. Pandey
- Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor St., Chicago IL, 60612, USA
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Nyffeler M, Yee BK, Feldon J, Knuesel I. Abnormal differentiation of newborn granule cells in age-related working memory impairments. Neurobiol Aging 2008; 31:1956-74. [PMID: 19100662 DOI: 10.1016/j.neurobiolaging.2008.10.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 09/12/2008] [Accepted: 10/15/2008] [Indexed: 10/21/2022]
Abstract
Age-related declines in spatial memory have been linked to abnormal functional properties and connectivity of newborn granule cells. However, the relationship between adult neurogenesis, aging, and cognitive performance seems more complex than previously anticipated, likely due to the difficulty of disentangling alterations related to training as such and those associated with cognitive performance. Here, we investigated how different aspects of adult neurogenesis might be related to training, age and cognitive performance amongst aged subjects by comparing behaviourally naïve and tested rats of 3, 6, 24mo of age. We separated aged rats into learning-impaired and -unimpaired groups based on their performance in the Morris water maze to investigate neurogenesis-related morphological and neurochemical changes. We report an age-related decline in cell proliferation and maturation independent of cognitive performance and testing. We confirm an age-related altered differentiation of newborn neurons which was particularly prominent in learning-impaired rats. This was associated with an abnormally prolonged expression of the early progenitor marker Nestin, potentially also affecting maturation, survival/integration of newborn neurons into existing neuronal networks, which might underlie the individual differences in cognitive performance during aging.
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Affiliation(s)
- Myriel Nyffeler
- Laboratory of Behavioural Neurobiology, ETH Zürich, 8603 Schwerzenbach, Switzerland
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17
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Schnitzler AC, Lopez-Coviella I, Blusztajn JK. Differential modulation of nerve growth factor receptor (p75) and cholinergic gene expression in purified p75-expressing and non-expressing basal forebrain neurons by BMP9. Brain Res 2008; 1246:19-28. [PMID: 18952073 DOI: 10.1016/j.brainres.2008.09.085] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 09/22/2008] [Accepted: 09/24/2008] [Indexed: 11/25/2022]
Abstract
The synthesis of acetylcholine and its release from basal forebrain cholinergic neurons (BFCN) that innervate the cerebral cortex and hippocampus are considered essential processes for normal learning, memory and attention. We have developed a purification and cell culture method of BFCN in order to examine the regulation of their cholinergic phenotype. Cells isolated from the septal region of late embryonic mice were purified by fluorescence-activated cell sorting based on their expression of the nerve growth factor receptor (p75), a surface marker for mature BFCN. Consistent with previous reports, p75-positive (p75+) cells were enriched in choline acetyltransferase (ChAT) and the high-affinity choline transporter (ChT), as measured by reverse transcriptase PCR. In culture, these cells maintained their gene expression of p75, ChAT and ChT, while p75-negative (p75-) cells had a low expression of these genes. Incubation of the cells with BMP9 not only increased p75 and ChAT gene expression in p75- cells, but also augmented the expression of these genes in p75+ cells. Conversely, BMP9 decreased ChT gene expression in p75+ cells and had no such effect in p75- cells. Immunostaining confirmed that p75 protein expression was modulated by BMP9 in a similar way as p75 mRNA, and also revealed that only a subset of p75- cells respond to BMP9 in this manner. These data suggest that mature BFCN in culture may express their cholinergic phenotype in the absence of exogenous trophic input, but that BMP9 can further modulate this phenotype. Moreover, BMP9 induces the cholinergic phenotype in a set of basal forebrain non-cholinergic neurons or precursor cells.
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Affiliation(s)
- Aletta C Schnitzler
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA 02118, USA.
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18
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Al-Shawi R, Hafner A, Olsen J, Olson J, Chun S, Raza S, Thrasivoulou C, Lovestone S, Killick R, Simons P, Cowen T. Neurotoxic and neurotrophic roles of proNGF and the receptor sortilin in the adult and ageing nervous system. Eur J Neurosci 2008; 27:2103-14. [PMID: 18412630 DOI: 10.1111/j.1460-9568.2008.06152.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The precursor form of the nerve growth factor (proNGF), forms a heterotrimeric complex with the receptors p75 and sortilin; this complex has been implicated in neuron cell death. However, it is not known whether proNGF and the receptors p75 and sortilin contribute to age- and disease-related neurodegeneration. Here we show that proNGF induces cell death in subpopulations of basal forebrain and peripheral sympathetic neurons of old, but not of young, adult rodents. In contrast, proNGF appears to induce neurite outgrowth rather than cell death of young adult sympathetic neurons. We have examined the neurotoxic role of proNGF in old age, and find that proNGF protein is elevated during ageing in the projection areas of some populations of vulnerable central and peripheral neurons; caloric restriction, which has known neuroprotective effects, partially prevents these increases. Sortilin was found to play a significant part in the observed patterns of age-related proNGF-mediated neurotoxicity. In particular, survival of aged neurons was rescued by neurotensin, an alternative sortilin ligand that blocks the sortilin-mediated effects of proNGF. Furthermore, sortilin immunoreactivity increases markedly in ageing rodent basal forebrain and sympathetic neurons; in contrast, p75 levels are either unchanged or reduced. From these data we propose that selective age-related neuronal atrophy and neurodegeneration may be mediated by increased sortilin expression in neurons, together with elevated levels of proNGF expression in some targets.
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Affiliation(s)
- Raya Al-Shawi
- Centre for Biomedical Sciences, University College London, Hampstead Campus, Rowland Hill Campus, Rowland Hill Street, London NW3 2PF, UK.
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19
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Therapeutic potential of CERE-110 (AAV2-NGF): targeted, stable, and sustained NGF delivery and trophic activity on rodent basal forebrain cholinergic neurons. Exp Neurol 2008; 211:574-84. [PMID: 18439998 DOI: 10.1016/j.expneurol.2008.03.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Revised: 03/04/2008] [Accepted: 03/06/2008] [Indexed: 10/22/2022]
Abstract
Treatment of degenerating basal forebrain cholinergic neurons with nerve growth factor (NGF) in Alzheimer's disease has long been contemplated, but an effective and safe delivery method has been lacking. Towards achieving this goal, we are currently developing CERE-110, an adeno-associated virus-based gene delivery vector that encodes for human NGF, for stereotactic surgical delivery to the human nucleus basalis of Meynert. Results indicate that NGF transgene delivery to the targeted brain region via CERE-110 is reliable and accurate, that NGF transgene distribution can be controlled by altering CERE-110 dose, and that it is possible to achieve restricted NGF expression limited to but covering the target brain region. Results from animals examined at longer time periods of 3, 6, 9 and 12 months after CERE-110 delivery indicate that NGF transgene expression is stable and sustained at all time points, with no loss or build-up of protein over the long-term. In addition, results from a series of experiments indicate that CERE-110 is neuroprotective and neurorestorative to basal forebrain cholinergic neurons in the rat fimbria-fornix lesion and aged rat models, and has bioactive effects on young rat basal forebrain cholinergic neurons. These findings, as well as those from several additional non-clinical experiments conducted in both rats and monkeys, led to the initiation of a Phase I clinical study to evaluate the safety and efficacy of CERE-110 in Alzheimer's disease subjects, which is currently ongoing.
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20
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Purification and culture of nerve growth factor receptor (p75)-expressing basal forebrain cholinergic neurons. Nat Protoc 2008; 3:34-40. [PMID: 18193019 DOI: 10.1038/nprot.2007.477] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The activity of the basal forebrain cholinergic neurons (BFCNs) that innervate the cerebral cortex and hippocampus is essential for normal learning and memory. Here, we present a method to isolate and culture BFCNs from the embryonic murine septum that takes advantage of their restricted expression of the nerve growth factor receptor (p75) in conjunction with fluorescence-activated cell sorting. The septal region dissection, cell dissociation and staining process, and cell sorting parameters are described in detail. Sufficient cell yield and optimized cell culture conditions make this protocol suitable for multiple assays including immunocytochemistry, reverse transcriptase PCR, microarray profiling, acetylcholine measurements and electrophysiological assessment. The study of these neurons as a purified population will greatly advance our understanding of factors that influence their development and maintenance.
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21
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Ping SE, Trieu J, Wlodek ME, Barrett GL. Effects of estrogen on basal forebrain cholinergic neurons and spatial learning. J Neurosci Res 2008; 86:1588-98. [DOI: 10.1002/jnr.21609] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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22
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23
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Thouvarecq R, Caston J, Protais P. Cholinergic system, rearing environment and trajectory learning during aging in mice. Physiol Behav 2007; 90:155-64. [PMID: 17074375 DOI: 10.1016/j.physbeh.2006.09.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Revised: 09/17/2006] [Accepted: 09/20/2006] [Indexed: 10/24/2022]
Abstract
Three, 12- and 20-month-old C57BL6/J mice, reared in standard conditions or in enriched environments, were administered subcutaneously either scopolamine hydrobromide, 0.6 or 1.2 mg kg(-1), or physiological saline (control mice) 15 min before testing their abilities to find an invisible platform in a modified version of the Morris water maze, the starting point being kept unchanged throughout the experiment to allow the aged animals to solve the task. The results demonstrated that: 1) All control mice, whatever their age, were able to learn the platform location, but the number of trials needed to reach the learning criterion (3 consecutive trials in less than 8 s) increased with age; 2) All the scopolamine-treated mice, whatever their age, were also able to learn the platform location. However, compared to age-matched controls, the number of trials needed to reach the learning criterion was greater; 3) Rearing the animals in an enriched environment antagonized the effect of scopolamine, but only in the youngest (3 month-old) mice. All control and scopolamine-treated mice, whatever their age and their rearing environment, remembered, 7 days later, the platform location.
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Affiliation(s)
- R Thouvarecq
- UPRES PSY.CO EA 1780, Faculté des Sciences, Laboratoire de Neurobiologie de l'Apprentissage, Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France
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24
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Williams B, Granholm AC, Sambamurti K. Age-dependent loss of NGF signaling in the rat basal forebrain is due to disrupted MAPK activation. Neurosci Lett 2006; 413:110-4. [PMID: 17182181 PMCID: PMC1839982 DOI: 10.1016/j.neulet.2006.11.040] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 11/03/2006] [Accepted: 11/17/2006] [Indexed: 10/23/2022]
Abstract
The loss of nerve growth factor (NGF) and its high affinity receptor TrkA has been implicated in the loss of cholinergic tone and function in Alzheimer's disease (AD) and normal aging. We employed an animal model of aging, the aged rat, which also exhibits memory loss and NGF alterations. Basal forebrain TrkA levels increased after injection of NGF in the hippocampus within 1h in young rats, but this response was diminished in aged animals as determined by Western blot analysis. Further, NGF activated MAPK pathways without changing total ERK levels and the activation of these pathways was also diminished in aged animals. The exogenous NGF injection did not appear to activate the PI-3K pathway or alter total levels of Akt significantly. These data shed light on mechanisms of NGF signaling in the CNS, and alterations in this signaling cascade associated with age and memory loss. These findings might lead to development of novel treatment therapies for the memory loss associated with AD and other age-associated neurodegenerative diseases.
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Affiliation(s)
- Brice Williams
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, USA
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25
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Williams BJ, Bimonte-Nelson HA, Granholm-Bentley AC. ERK-mediated NGF signaling in the rat septo-hippocampal pathway diminishes with age. Psychopharmacology (Berl) 2006; 188:605-18. [PMID: 16915384 DOI: 10.1007/s00213-006-0477-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Accepted: 06/10/2006] [Indexed: 01/01/2023]
Abstract
RATIONALE Degeneration of basal forebrain cholinergic neurons (BFCNs) plays an important role in aging and Alzheimer's disease (AD) pathology. This degeneration may be a result of disrupted nerve growth factor (NGF) signaling. Aged rats have memory deficits, BFCN degeneration, and disrupted NGF signaling. OBJECTIVE In this study we identify a rapid NGF signaling pathway in BFCNs and the second messenger system associated with that signaling. We also identify age-dependent alterations in this signaling pathway. MATERIALS AND METHODS After cognitive assessment using the Morris water maze, rats were given an intra-hippocampal NGF injection. Basal forebrain immunohistochemical analysis, confocal microscopy, and inhibitor studies were performed. RESULTS An increase in immunoreactivity for the NGF receptor TrkA was found in cell bodies of BFCNs 15 min and 1 h post-NGF injection. Immunohistochemistry studies with phospho-ERK and phospho-AKT antibodies showed that this rapid signaling occurred through MAP kinase, but not PI-3 kinase pathways. MAPK inhibitor studies attenuated the NGF-induced effects. Both TrkA and phospho-ERK (extracellular signal-regulated kinase) immunoreactivities were diminished in aged rats and phospho-ERK immunoreactivity-correlated with aged rat performance in the Morris water maze. CONCLUSIONS Rapid NGF signaling likely occurs in the rat CNS through the MAPK signaling pathway. This rapid signaling pathway is diminished in aged rats compared to young ones and may contribute to memory deficits observed in aged rats. As cholinergic degeneration coupled with altered levels of NGF and TrkA receptors are also seen in human aging and AD, ERK-related dysfunction may be relevant in human conditions as well.
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Affiliation(s)
- Brice J Williams
- Department of Neurosciences, Center on Aging, Charleston, SC 29425, USA
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26
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Barrett GL, Greferath U, Barker PA, Trieu J, Bennie A. Co-expression of the P75 neurotrophin receptor and neurotrophin receptor-interacting melanoma antigen homolog in the mature rat brain. Neuroscience 2005; 133:381-92. [PMID: 15878242 DOI: 10.1016/j.neuroscience.2005.01.067] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2003] [Revised: 11/02/2004] [Accepted: 01/19/2005] [Indexed: 12/26/2022]
Abstract
The p75 neurotrophin receptor (p75(NTR)) is involved in the regulation of neuronal survival and phenotype, but its signal transduction mechanisms are poorly understood. Recent evidence has implicated the cytoplasmic protein NRAGE (neurotrophin receptor-interacting MAGE (from Melanoma AntiGEn) homolog) in p75(NTR) signaling. To gain further insight into the role of NRAGE, we investigated the co-expression of NRAGE and p75(NTR) in mature rat brain. In all areas examined, NRAGE appeared to be confined to neurons. In the basal forebrain cholinergic complex, NRAGE immunoreactivity was evident in all p75(NTR)-positive neurons. There were many more NRAGE-positive than p75(NTR)-positive neurons in these regions, however. NRAGE was also expressed in areas of the basal forebrain that did not express p75(NTR), including the lateral septal nucleus and the nucleus accumbens. A finding in marked contrast to previous studies was the presence of p75(NTR) immunoreactivity in neuronal cell bodies in the hippocampus. Hippocampal p75(NTR) immunoreactivity was apparent in rats 6 months and older, and was localized to the dentate gyrus and stratum oriens. All p75(NTR)-positive neurons in the dentate gyrus and hippocampal formation were positive for NRAGE. The majority of granular cells of the dentate gyrus and pyramidal cells in the hippocampal formation were positive for NRAGE and negative for p75(NTR). NRAGE was also present in some neuronal populations that express p75(NTR) after injury, including striatal cholinergic interneurons, and motor neurons. A region of marked disparity was the cerebral cortex, in which NRAGE immunoreactivity was widespread whereas p75(NTR) was absent. The results are consistent with an important role for NRAGE in p75(NTR) signaling, as all cells that expressed p75(NTR) also expressed NRAGE. The wider distribution of NRAGE expression suggests that NRAGE may also participate in other signaling processes.
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Affiliation(s)
- G L Barrett
- Department of Physiology, University of Melbourne, Parkville 3010, Australia.
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27
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Wright JW, Alt JA, Turner GD, Krueger JM. Differences in spatial learning comparing transgenic p75 knockout, New Zealand Black, C57BL/6, and Swiss Webster mice. Behav Brain Res 2004; 153:453-8. [PMID: 15265642 DOI: 10.1016/j.bbr.2004.01.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Revised: 12/01/2003] [Accepted: 01/05/2004] [Indexed: 12/26/2022]
Abstract
Four strains of mice were compared regarding their relative abilities to solve the Morris water maze test of spatial memory. Members of the New Zealand Black (NZB) strain revealed steady improvement over the 6 days of training comparable to C57BL/6 mice. The neurotrophin low affinity receptor p75 knockout mouse, in which the binding region is rendered refractory to ligand, displayed profound deficits in the acquisition of this task. Members of the Swiss Webster strain performed intermediate between the poor performance of the p75 mice and the progressively improving learning curves of the NZB and C57 mice. The present results support the notion that interference with functioning of nerve growth factor (NGF) receptors on forebrain cholingergic neurons negatively impacts the animal's ability to utilize the spatial cues necessary for successful spatial navigation. This effect on NGF receptors was more behaviorally disrupting than the influence of neocortical and hippocampal ectopias as present in the NZB mice. These results support the use of the p75 knockout mouse as a model of forebrain cholinergic neuron dysfunction. On the other hand, these results do not support the use of the NZB mouse as an animal model of human learning disability and dementia.
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Affiliation(s)
- John W Wright
- Department of Psychology, Washington State University, Pullman, WA 99164-4820, USA.
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28
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Lee J, Albiston AL, Allen AM, Mendelsohn FAO, Ping SE, Barrett GL, Murphy M, Morris MJ, McDowall SG, Chai SY. Effect of I.C.V. injection of AT4 receptor ligands, NLE1-angiotensin IV and LVV-hemorphin 7, on spatial learning in rats. Neuroscience 2004; 124:341-9. [PMID: 14980384 DOI: 10.1016/j.neuroscience.2003.12.006] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Revised: 11/24/2003] [Accepted: 12/01/2003] [Indexed: 10/26/2022]
Abstract
Central administration of angiotensin IV (Ang IV) or its analogues enhance performance of rats in passive avoidance and spatial memory paradigms. The purpose of this study was to examine the effect of a single bolus injection of two distinct AT4 ligands, Nle1-Ang IV or LVV-haemorphin-7, on spatial learning in the Barnes circular maze. Mean number of days for rats treated with either Nle1-Ang IV or LVV-haemorphin-7 to achieve learner criterion is significantly reduced compared with controls (P < 0.001 and P < 0.05 respectively). This is due to enhanced ability of the peptide-treated rats to adopt a spatial strategy for finding the escape hatch. In all three measures of learning performance, (1) the number of errors made, (2) the distance travelled and (3) the latency in finding the escape hatch, rats treated with either 100 pmol or 1 nmol of Nle1-Ang IV or 100 pmol LVV-haemorphin-7 performed significantly better than the control groups. As early as the first day of testing, the rats treated with the lower dose of Nle1-Ang IV or LVV-haemorphin-7 made fewer errors (P < 0.01 and P < 0.05 respectively) and travelled shorter distances (P < 0.05 for both groups) than the control animals. The enhanced spatial learning induced by Nle1-Ang IV (100 pmol) was attenuated by the co-administration of the AT4 receptor antagonist, divalinal-Ang IV (10 nmol). Thus, administration of AT4 ligands results in an immediate potentiation of learning, which may be associated with facilitation of synaptic transmission and/or enhancement of acetylcholine release.
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Affiliation(s)
- J Lee
- Howard Florey Institute of Experimental Physiology and Medicine, The University of Melbourne, Parkville, Victoria 3010, Australia
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29
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Bizon JL, Han JS, Hudon C, Gallagher M. Effects of hippocampal cholinergic deafferentation on learning strategy selection in a visible platform version of the water maze. Hippocampus 2003; 13:676-84. [PMID: 12962313 DOI: 10.1002/hipo.10113] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Recent evidence has suggested that the relative levels of acetylcholine (ACh) between brain structures may be an important factor in the choice of behavioral strategy in settings in which either hippocampal or dorsal striatal brain systems can be employed both effectively and independently (McIntyre and Gold. 1999. Soc Neurosci Abs 25:1388). The current investigation used the neurotoxin 192 IgG-saporin to deplete the hippocampus of ACh selectively, while leaving ACh in other brain regions, including dorsal striatum, intact. Rats were then trained on a version of the Morris water maze, in which behavioral strategies attributed to the hippocampus and dorsal striatum are placed in direct competition. It was predicted that rats with hippocampal ACh depletion would display a cue bias. Contrary to this prediction, depleting hippocampal ACh did not bias against and, in fact, promoted use of a hippocampal place strategy in this task, as indicated by choice in competition tests and performance on hidden platform training trials. These data add to a growing literature demonstrating that the septohippocampal cholinergic system is not required for accurate spatial learning and suggest a complex role for basal forebrain projections in processing information about the spatial environment.
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Affiliation(s)
- J L Bizon
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland 21218, USA.
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30
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Gibbs RB. Effects of ageing and long-term hormone replacement on cholinergic neurones in the medial septum and nucleus basalis magnocellularis of ovariectomized rats. J Neuroendocrinol 2003; 15:477-85. [PMID: 12694373 DOI: 10.1046/j.1365-2826.2003.01012.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ovariectomized aged rats, some of which received long-term hormone replacement with oestrogen or oestrogen plus progesterone, were evaluated for the number and size of basal forebrain cholinergic neurones, as well as relative levels of choline acetyltransferase (ChAT) and trkA mRNA, in order to determine whether effects on basal forebrain cholinergic cell survival and function correspond with differences in cognitive performance previously described. The results show that ageing combined with long-term loss of ovarian function produced substantial reductions in the levels of ChAT and trkA mRNA in the medial septum and nucleus basalis magnocellularis, relative to much younger ovariectomized controls. In contrast, no significant effects on the number or size of the cholinergic cells were detected, indicating that loss of ovarian function does not cause a loss of cholinergic neurones with age. Long-term hormone replacement had no apparent effect on the number of ChAT-positive neurones detected, and did not prevent the reductions in ChAT and trkA mRNA associated with ovariectomy and ageing. Collectively, the data suggest that ageing combined with long-term loss of ovarian function has a severe negative impact on basal forebrain cholinergic function, but not on cholinergic cell survival per se.
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Affiliation(s)
- R B Gibbs
- Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA, USA. gibbsr+@pitt.edu
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Ping SE, Greferath U, Barrett GL. Estrogen treatment suppresses forebrain p75 neurotrophin receptor expression in aged, noncycling female rats. J Neurosci Res 2002; 69:51-60. [PMID: 12111815 DOI: 10.1002/jnr.10273] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
There is increasing evidence that estrogen has beneficial effects on cognition, both in humans and in rodents, and may delay Alzheimer's disease onset in postmenopausal women. Several rodent studies have utilised the ovariectomy model to show estrogen regulation of the p75 neurotrophin receptor, TrkA, and markers of acetylcholine synthesis in the cholinergic basal forebrain. We studied estrogenic effects in aged (16-17-month-old), noncycling rats. Estrogen treatment for 10 days drastically reduced p75(NTR) immunoreactivity in the rostral parts of the basal forebrain. The number of p75(NTR)-immunoreactive neurons was decreased, and those neurons remaining positive for p75(NTR) showed reduced p75(NTR) staining intensity. In vehicle-treated rats, almost all choline acetyltransferase-immunoreactive neurons were p75(NTR) positive (and vice versa), but, in estrogen treated rats, large numbers of choline acetyltransferase-immunoreactive cells were negative for p75(NTR). Similar levels of p75(NTR) down-regulation in the rostral basal forebrain were found when estrogen treatment was extended to 6 weeks. There was no reduction in the number of p75(NTR)-immunoreactive neurons in the caudal basal forebrain after 10 days of treatment. After 6 weeks of treatment, however, there was evidence of p75(NTR) down-regulation in the caudal basal forebrain. There was no evidence of hypertrophy or atrophy of cholinergic neurons even after 6 weeks of estrogen treatment. Considering the evidence for the role of p75(NTR) in regulating survival, growth and nerve growth factor responsiveness of cholinergic basal forebrain neurons, the results indicate an important aspect of estrogen's effects on the nervous system.
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Affiliation(s)
- Sophie E Ping
- Department of Physiology, University of Melbourne, Parkville, Australia
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