1
|
Scolz A, Vezzoli E, Villa M, Talpo F, Cazzola J, Raffin F, Cordiglieri C, Falqui A, Pepe G, Maglione V, Besusso D, Biella G, Zuccato C. Neuroprotection by ADAM10 inhibition requires TrkB signaling in the Huntington's disease hippocampus. Cell Mol Life Sci 2024; 81:333. [PMID: 39112663 PMCID: PMC11335257 DOI: 10.1007/s00018-024-05382-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 07/24/2024] [Accepted: 07/25/2024] [Indexed: 08/22/2024]
Abstract
Synaptic dysfunction is an early pathogenic event leading to cognitive decline in Huntington's disease (HD). We previously reported that the active ADAM10 level is increased in the HD cortex and striatum, causing excessive proteolysis of the synaptic cell adhesion protein N-Cadherin. Conversely, ADAM10 inhibition is neuroprotective and prevents cognitive decline in HD mice. Although the breakdown of cortico-striatal connection has been historically linked to cognitive deterioration in HD, dendritic spine loss and long-term potentiation (LTP) defects identified in the HD hippocampus are also thought to contribute to the cognitive symptoms of the disease. The aim of this study is to investigate the contribution of ADAM10 to spine pathology and LTP defects of the HD hippocampus. We provide evidence that active ADAM10 is increased in the hippocampus of two mouse models of HD, leading to extensive proteolysis of N-Cadherin, which has a widely recognized role in spine morphology and synaptic plasticity. Importantly, the conditional heterozygous deletion of ADAM10 in the forebrain of HD mice resulted in the recovery of spine loss and ultrastructural synaptic defects in CA1 pyramidal neurons. Meanwhile, normalization of the active ADAM10 level increased the pool of synaptic BDNF protein and activated ERK neuroprotective signaling in the HD hippocampus. We also show that the ADAM10 inhibitor GI254023X restored LTP defects and increased the density of mushroom spines enriched with GluA1-AMPA receptors in HD hippocampal neurons. Notably, we report that administration of the TrkB antagonist ANA12 to HD hippocampal neurons reduced the beneficial effect of GI254023X, indicating that the BDNF receptor TrkB contributes to mediate the neuroprotective activity exerted by ADAM10 inhibition in HD. Collectively, these findings indicate that ADAM10 inhibition coupled with TrkB signaling represents an efficacious strategy to prevent hippocampal synaptic plasticity defects and cognitive dysfunction in HD.
Collapse
Affiliation(s)
- Andrea Scolz
- Department of Biosciences, University of Milan, Milan, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan, Italy
| | - Elena Vezzoli
- Department of Biosciences, University of Milan, Milan, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan, Italy
- Advanced Light and Electron Microscopy BioImaging Centre (ALEMBIC), IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Michela Villa
- Department of Biosciences, University of Milan, Milan, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan, Italy
| | - Francesca Talpo
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Jessica Cazzola
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Francesca Raffin
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Chiara Cordiglieri
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan, Italy
| | - Andrea Falqui
- Interdisciplinary Centre for Nanostructured Materials and Interfaces (CIMaINa), Department of Physics, University of Milan, Milan, Italy
| | | | | | - Dario Besusso
- Department of Biosciences, University of Milan, Milan, Italy
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan, Italy
| | - Gerardo Biella
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Chiara Zuccato
- Department of Biosciences, University of Milan, Milan, Italy.
- Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", Milan, Italy.
| |
Collapse
|
2
|
Cuestas Torres DM, Cardenas FP. Synaptic plasticity in Alzheimer's disease and healthy aging. Rev Neurosci 2021; 31:245-268. [PMID: 32250284 DOI: 10.1515/revneuro-2019-0058] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 11/01/2019] [Indexed: 12/17/2022]
Abstract
The strength and efficiency of synaptic connections are affected by the environment or the experience of the individual. This property, called synaptic plasticity, is directly related to memory and learning processes and has been modeled at the cellular level. These types of cellular memory and learning models include specific stimulation protocols that generate a long-term strengthening of the synapses, called long-term potentiation, or a weakening of the said long-term synapses, called long-term depression. Although, for decades, researchers have believed that the main cause of the cognitive deficit that characterizes Alzheimer's disease (AD) and aging was the loss of neurons, the hypothesis of an imbalance in the cellular and molecular mechanisms of synaptic plasticity underlying this deficit is currently widely accepted. An understanding of the molecular and cellular changes underlying the process of synaptic plasticity during the development of AD and aging will direct future studies to specific targets, resulting in the development of much more efficient and specific therapeutic strategies. In this review, we classify, discuss, and describe the main findings related to changes in the neurophysiological mechanisms of synaptic plasticity in excitatory synapses underlying AD and aging. In addition, we suggest possible mechanisms in which aging can become a high-risk factor for the development of AD and how its development could be prevented or slowed.
Collapse
Affiliation(s)
- Diana Marcela Cuestas Torres
- Departamento de Psicología and Departamento de Biología, Laboratorio de Neurociencia y Comportamiento, Universidad de los Andes, Cra 1 N° 18A-12, CP 111711, Bogotá, Colombia
| | - Fernando P Cardenas
- Departamento de Psicología, Laboratorio de Neurociencia y Comportamiento, Universidad de los Andes, Cra 1 N° 18A-12, CP 111711, Bogotá, Colombia
| |
Collapse
|
3
|
Bączyńska E, Pels KK, Basu S, Włodarczyk J, Ruszczycki B. Quantification of Dendritic Spines Remodeling under Physiological Stimuli and in Pathological Conditions. Int J Mol Sci 2021; 22:4053. [PMID: 33919977 PMCID: PMC8070910 DOI: 10.3390/ijms22084053] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 12/14/2022] Open
Abstract
Numerous brain diseases are associated with abnormalities in morphology and density of dendritic spines, small membranous protrusions whose structural geometry correlates with the strength of synaptic connections. Thus, the quantitative analysis of dendritic spines remodeling in microscopic images is one of the key elements towards understanding mechanisms of structural neuronal plasticity and bases of brain pathology. In the following article, we review experimental approaches designed to assess quantitative features of dendritic spines under physiological stimuli and in pathological conditions. We compare various methodological pipelines of biological models, sample preparation, data analysis, image acquisition, sample size, and statistical analysis. The methodology and results of relevant experiments are systematically summarized in a tabular form. In particular, we focus on quantitative data regarding the number of animals, cells, dendritic spines, types of studied parameters, size of observed changes, and their statistical significance.
Collapse
Affiliation(s)
- Ewa Bączyńska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (E.B.); (K.K.P.); (J.W.)
| | - Katarzyna Karolina Pels
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (E.B.); (K.K.P.); (J.W.)
| | - Subhadip Basu
- Department of Computer Science and Engineering, Jadvapur University, Kolkata 700032, India;
| | - Jakub Włodarczyk
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (E.B.); (K.K.P.); (J.W.)
| | - Błażej Ruszczycki
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (E.B.); (K.K.P.); (J.W.)
| |
Collapse
|
4
|
Sanchez V, Bakhti-Suroosh A, Chen A, Brunzell DH, Erisir A, Lynch WJ. Exercise during abstinence normalizes ultrastructural synaptic plasticity associated with nicotine-seeking following extended access self-administration. Eur J Neurosci 2019; 50:2707-2721. [PMID: 30888721 PMCID: PMC6742551 DOI: 10.1111/ejn.14408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/28/2019] [Accepted: 03/08/2019] [Indexed: 12/16/2022]
Abstract
Nicotine-craving progressively increases, or incubates, over abstinence following extended access self-administration. While not yet examined for nicotine, the incubation of cocaine-seeking is accompanied by changes in synaptic plasticity in the nucleus accumbens. Here, we determined whether such changes also accompany enhanced nicotine-seeking following extended access self-administration and abstinence, and whether exercise, a potential intervention for nicotine addiction, may exert its efficacy by normalizing these changes. Given that in humans, tobacco/nicotine use begins during adolescence, we used an adolescent-onset model. Nicotine-seeking was assessed in male rats following extended access nicotine or saline self-administration (23-hr/day, 10 days) and 10 days of abstinence, conditions known to induce the incubation of nicotine-seeking, using a within-session extinction/cue-induced reinstatement procedure. A subset of rats had 2-hr/day access to a running wheel during abstinence. Ultrastructural alterations of synapses in the nucleus accumbens core and shell were examined using electron microscopy. Nicotine-seeking was elevated following extended access self-administration and abstinence (in sedentary group), and levels of seeking were associated with an increase in the density of asymmetric (excitatory) and symmetric (inhibitory) synapses onto dendrites in the core, as well as longer asymmetric synapses onto spines, a marker of synaptic potentiation, in both the core and shell. Exercise normalized each of these changes; however, in the shell, exercise and nicotine similarly increased the synapse length. Together, these findings indicate an association between nicotine-seeking and synaptic plasticity in the nucleus accumbens, particularly the core, and indicate that the efficacy of exercise to reduce nicotine-seeking may be mediated by reversing these adaptations.
Collapse
Affiliation(s)
- Victoria Sanchez
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
| | - Anousheh Bakhti-Suroosh
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
| | - Andrew Chen
- Department of Psychology, University of Virginia, Charlottesville, Virginia
| | - Darlene H Brunzell
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Alev Erisir
- Department of Psychology, University of Virginia, Charlottesville, Virginia
| | - Wendy J Lynch
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
| |
Collapse
|
5
|
Gerosa L, Grillo B, Forastieri C, Longaretti A, Toffolo E, Mallei A, Bassani S, Popoli M, Battaglioli E, Rusconi F. SRF and SRFΔ5 Splicing Isoform Recruit Corepressor LSD1/KDM1A Modifying Structural Neuroplasticity and Environmental Stress Response. Mol Neurobiol 2019; 57:393-407. [DOI: 10.1007/s12035-019-01720-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
6
|
Segal M. Dendritic spines: Morphological building blocks of memory. Neurobiol Learn Mem 2016; 138:3-9. [PMID: 27311757 DOI: 10.1016/j.nlm.2016.06.007] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 05/22/2016] [Accepted: 06/12/2016] [Indexed: 12/22/2022]
Abstract
The introduction of novel technologies, including high resolution time lapse imaging in behaving animals, molecular modification of the genome and optogenetic control of neuronal excitability have revolutionized the ability to detect subcellular changes in the brain, associated with learning and memory. The sequence of molecular cascades leading to formation, longevity and erasure of memories are being addressed in growing number of studies. Still, major issues concerning the relationship between the morphology and physiology of dendritic spines and memory mechanisms and the functional, neuronal network relevance of such parameters remain unsettled. The present review will summarize recent studies related to the immediate and long lasting changes in density, morphology and function of dendritic spines and their parent neurons following exposure to plasticity-producing stimulation in vivo and in vitro. Standing issues such as the relations between volume/shape and longevity, with respect to different classes of memories in different brain regions will be addressed. These studies indicate that the rules governing the structure/function relations of dendritic spines and memory in the brain are still not conclusive.
Collapse
Affiliation(s)
- Menahem Segal
- Department of Neurobiology, The Weizmann Institute, Rehovot 76100, Israel.
| |
Collapse
|
7
|
Nakadate K, Tanaka-Nakadate S. Three-Dimensional Electron Microscopy Reconstruction of Degenerative Dopaminergic Neurons Surrounded by Activated Microglia in Substantia Nigra. Ultrastruct Pathol 2015; 39:369-77. [PMID: 26111207 DOI: 10.3109/01913123.2015.1042609] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
There is an urgent need to investigate the reason for the pathogenic mechanism of intractable central neurological diseases such as Parkinson's disease. It has been reported that the activation of microglial cells is involved in the pathology of these diseases. However, due to technical difficulties, the relationship between degenerative neurons and activated microglial cells remains unclear. Therefore, we tried the improved analysis technique to clarify the spatial relationship between these cell types. We were able to establish an analysis technique that consists of a three-dimensional reconstruction method using serial immunoelectron micrographs after having identified both degenerative neurons and activated microglial cells under optical microscope. Using this technique, we have relatively easily been able to clarify the spatial relationship between degenerative neurons and activated microglial cells. Furthermore, using this technique it is possible to determine the neuronal degeneration process in detail, because it is able to identify structures implicated in degeneration, such as accumulation of lipofuscin in degenerated neuronal somata and phagocytotic structures of microglial cells. In future, this technical approach may be applied to elucidate the relationship between degenerative neurons and activated glial cells in human diseases.
Collapse
Affiliation(s)
- Kazuhiko Nakadate
- a Department of Basic Science , Educational and Research Center for Pharmacy, Meiji Pharmaceutical University , Tokyo , Japan and
| | - Sawako Tanaka-Nakadate
- b Department of Pharmacology and Toxicology , Dokkyo Medical University School of Medicine , Tochigi , Japan
| |
Collapse
|
8
|
Roscoe RF, Mactutus CF, Booze RM. HIV-1 transgenic female rat: synaptodendritic alterations of medium spiny neurons in the nucleus accumbens. J Neuroimmune Pharmacol 2014; 9:642-53. [PMID: 25037595 DOI: 10.1007/s11481-014-9555-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 07/08/2014] [Indexed: 12/31/2022]
Abstract
HIV-1 associated neurocognitive deficits are increasing in prevalence, although the neuronal basis for these deficits is unclear. HIV-1 Tg rats constitutively express 7 of 9 HIV-associated proteins, and may be useful for studying the neuropathological substrates of HIV-1 associated neurocognitive disorders (HAND). In this study, adult female HIV-1 Tg rats and F344 control rats had similar growth rates, estrous cyclicity and startle reflex inhibition to a visual prepulse stimulus. Medium spiny neurons (MSNs) in the nucleus accumbens (NAcc) were ballistically-labeled utilizing the indocarbocyanine dye DiI. The branching complexity of MSNs in the NAcc was significantly decreased in HIV-1 Tg rats, relative to controls; moreover, the shorter length and decreased volume of dendritic spines, but unchanged head diameter, in HIV-1 Tg rats suggested a reduction of longer spines and an increase in shorter, less projected spines, indicating a population shift to a more immature spine phenotype. Collectively, these results from HIV-1 Tg female rats indicated significant synaptodendritic alterations of MSNs in the NAcc occur as a consequence of chronic, low-level, exposure to HIV-1 associated proteins.
Collapse
Affiliation(s)
- Robert F Roscoe
- Laboratory of Behavioral Neuroscience, Department of Psychology, University of South Carolina, 29208, Columbia, SC, USA
| | | | | |
Collapse
|
9
|
Sala C, Segal M. Dendritic spines: the locus of structural and functional plasticity. Physiol Rev 2014; 94:141-88. [PMID: 24382885 DOI: 10.1152/physrev.00012.2013] [Citation(s) in RCA: 338] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The introduction of high-resolution time lapse imaging and molecular biological tools has changed dramatically the rate of progress towards the understanding of the complex structure-function relations in synapses of central spiny neurons. Standing issues, including the sequence of molecular and structural processes leading to formation, morphological change, and longevity of dendritic spines, as well as the functions of dendritic spines in neurological/psychiatric diseases are being addressed in a growing number of recent studies. There are still unsettled issues with respect to spine formation and plasticity: Are spines formed first, followed by synapse formation, or are synapses formed first, followed by emergence of a spine? What are the immediate and long-lasting changes in spine properties following exposure to plasticity-producing stimulation? Is spine volume/shape indicative of its function? These and other issues are addressed in this review, which highlights the complexity of molecular pathways involved in regulation of spine structure and function, and which contributes to the understanding of central synaptic interactions in health and disease.
Collapse
|
10
|
Effect of Chronic Morphine Consumption on Synaptic Plasticity of Rat's Hippocampus: A Transmission Electron Microscopy Study. Neurol Res Int 2013; 2013:290414. [PMID: 24379975 PMCID: PMC3863539 DOI: 10.1155/2013/290414] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Revised: 09/27/2013] [Accepted: 09/29/2013] [Indexed: 01/20/2023] Open
Abstract
It is well known that the synapses undergo some changes in the brain during the course of normal life and under certain pathological or experimental circumstances. One of the main goals of numerous researchers has been to find the reasons for these structural changes. In the present study, we investigated the effects of chronic morphine consumption on synaptic plasticity, postsynaptic density thickness, and synaptic curvatures of hippocampus CA1 area of rats. So for reaching these goals, 24 N-Mary male rats were randomly divided into three groups, morphine (n = 8), placebo (n = 8), and control (n = 8) groups. In the morphine group, complex of morphine (0.1, 0.2, 0.3, and 0.4) mg/mL and in the placebo (sucrose) group complex of sucrose (% 0.3) were used for 21 days. After the end of drug treatment the animals were scarified and perfused intracardinally and finally the CA1 hippocampal samples were taken for ultrastructural studies, and then the obtained data were analyzed by SPSS and one-way analysis of variance. Our data indicated that synaptic numbers per nm(3) change significantly in morphine group compared to the other two groups (placebo and control) (P < 0.001) and also statistical analysis revealed a significant difference between groups in terms of thickness of postsynaptic density (P < 0.001) and synaptic curvature (P < 0.007). It seems that morphine dependence in rats plays a main role in the ultrastructural changes of hippocampus.
Collapse
|
11
|
Dulcis D, Spitzer NC. Reserve pool neuron transmitter respecification: Novel neuroplasticity. Dev Neurobiol 2012; 72:465-74. [PMID: 21595049 DOI: 10.1002/dneu.20920] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The identity of the neurotransmitters expressed by neurons has been thought to be fixed and immutable, but recent studies demonstrate that changes in electrical activity can rapidly and reversibly reconfigure the transmitters and corresponding transmitter receptors that neurons express. Induction of transmitter expression can be achieved by selective activation of afferents recruited by a physiological range of sensory input. Strikingly, neurons acquiring an additional transmitter project to appropriate targets prior to transmitter respecification in some cases, indicating the presence of reserve pools of neurons that can boost circuit function. We discuss the evidence for such reserve pools, their likely locations and ways to test for their existence, and the potential clinical value of such circuit-specific neurotransmitter respecification for treatments of neurological disorders.
Collapse
Affiliation(s)
- Davide Dulcis
- Neurobiology Section, Division of Biological Sciences and Center for Neural Circuits and Behavior, Kavli Institute for Brain and Mind, University of California-San Diego, La Jolla, CA 92093, USA.
| | | |
Collapse
|
12
|
Molnár E. Long-term potentiation in cultured hippocampal neurons. Semin Cell Dev Biol 2011; 22:506-13. [PMID: 21807105 DOI: 10.1016/j.semcdb.2011.07.017] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 06/23/2011] [Accepted: 07/01/2011] [Indexed: 10/18/2022]
Abstract
Studies performed on low-density primary neuronal cultures have enabled dissection of molecular and cellular changes during N-methyl-D-aspartate (NMDA) receptor-dependent long-term potentiation (LTP). Various electrophysiological and chemical induction protocols were developed for the persistent enhancement of excitatory synaptic transmission in hippocampal neuronal cultures. The characterisation of these plasticity models confirmed that they share many key properties with the LTP of CA1 neurons, extensively studied in hippocampal slices using electrophysiological techniques. For example, LTP in dissociated hippocampal neuronal cultures is also dependent on Ca(2+) influx through post-synaptic NMDA receptors, subsequent activation and autophosphorylation of the Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and an increase in alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor insertion at the post-synaptic membrane. The availability of models of LTP in cultured hippocampal neurons significantly facilitated the monitoring of changes in endogenous postsynaptic receptor proteins and the investigation of the associated signalling mechanisms that underlie LTP. A central feature of LTP of excitatory synapses is the recruitment of AMPA receptors at the postsynaptic site. Results from the use of cell culture-based models started to establish the mechanism by which synaptic input controls a neuron's ability to modify its synapses in LTP. This review focuses on key features of various LTP induction protocols in dissociated hippocampal neuronal cultures and the applications of these plasticity models for the investigation of activity-induced changes in native AMPA receptors.
Collapse
Affiliation(s)
- Elek Molnár
- MRC Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, UK.
| |
Collapse
|
13
|
Alcantara AA, Lim HY, Floyd CE, Garces J, Mendenhall JM, Lyons CL, Berlanga ML. Cocaine- and morphine-induced synaptic plasticity in the nucleus accumbens. Synapse 2010; 65:309-20. [PMID: 20730804 DOI: 10.1002/syn.20849] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2008] [Accepted: 07/24/2010] [Indexed: 01/05/2023]
Abstract
The critical brain areas and molecular mechanisms involved in drug abuse and dependence have been extensively studied. Drug-induced persistent behaviors such as sensitization, tolerance, or relapse, however, far outlast any previously reported mechanisms. A challenge in the field of addiction, therefore, has been to identify drug-induced changes in brain circuitry that may subserve long-lasting changes in behavior. This study examined behavioral changes and electron microscopic evidence of altered synaptic connectivity within the nucleus accumbens (NAc) following repeated administration of cocaine or morphine. The unbiased quantitative stereological physical disector method was used to estimate the number of synapses per neuron. Increases in the synapse-to-neuron ratio were found in the NAc shell of cocaine-treated (49.1%) and morphine-treated (55.1%) rats and in the NAc core of cocaine-treated animals (49.1%). This study provides direct ultrastructural evidence of drug-induced synaptic plasticity and identifies synaptic remodeling as a potential neural substrate underlying drug-induced behavioral sensitization.
Collapse
Affiliation(s)
- Adriana A Alcantara
- Institute for Neuroscience, The University of Texas at Austin, Austin, Texas 78712, USA.
| | | | | | | | | | | | | |
Collapse
|
14
|
Long-term potentiation-dependent spine enlargement requires synaptic Ca2+-permeable AMPA receptors recruited by CaM-kinase I. J Neurosci 2010; 30:11565-75. [PMID: 20810878 DOI: 10.1523/jneurosci.1746-10.2010] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
It is well established that long-term potentiation (LTP), a paradigm for learning and memory, results in a stable enlargement of potentiated spines associated with recruitment of additional GluA1-containing AMPA receptors (AMPARs). Although regulation of the actin cytoskeleton is involved, the detailed signaling mechanisms responsible for this spine expansion are unclear. Here, we used cultured mature hippocampal neurons stimulated with a glycine-induced, synapse-specific form of chemical LTP (GI-LTP). We report that the stable structural plasticity (i.e., spine head enlargement and spine length shortening) that accompanies GI-LTP was blocked by inhibitors of NMDA receptors (NMDARs; APV) or CaM-kinase kinase (STO-609), the upstream activator of CaM-kinase I (CaMKI), as well as by transfection with dominant-negative (dn) CaMKI but not dnCaMKIV. Recruitment of GluA1 to the spine surface occurred after GI-LTP and was mimicked by transfection with constitutively active CaMKI. Spine enlargement induced by transfection of GluA1 was associated with synaptic recruitment of Ca(2+)-permeable AMPARs (CP-AMPARs) as assessed by an increase in the rectification index of miniature EPSCs (mEPSCs) and their sensitivity to IEM-1460, a selective antagonist of CP-AMPARs. Furthermore, the increase in spine size and mEPSC amplitude resulting from GI-LTP itself was blocked by IEM-1460, demonstrating involvement of CP-AMPARs. Downstream signaling effectors of CP-AMPARs, identified by suppression of their activation by IEM-1460, included the Rac/PAK/LIM-kinase pathway that regulates spine actin dynamics. Together, our results suggest that synaptic recruitment of CP-AMPARs via CaMKI may provide a mechanistic link between NMDAR activation in LTP and regulation of a signaling pathway that drives spine enlargement via actin polymerization.
Collapse
|