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Kishore A, James P, Rajeswari P, Sarma G, Krishnan S, Meunier S, Popa T. Depotentiation of associative plasticity is intact in Parkinson's disease with mild dyskinesia. Parkinsonism Relat Disord 2022; 99:16-22. [PMID: 35569298 DOI: 10.1016/j.parkreldis.2022.04.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Depotentiation of homosynaptic plasticity of the primary motor cortex (M1) is impaired in patients with Parkinson's disease (PD) who have developed dyskinesias. In this exploratory study, we tested whether this holds true for heterosynaptic plasticity induced by paired associative stimulation (PAS). METHODS Dyskinetic (n=11) and Non-dyskinetic (n=11), levodopa-treated PD patients were tested in M1 with PAS25ms alone, PAS25ms preceded by continuous theta-burst stimulation of the cerebellum (cTBSCB-PAS) as a method to evoke a larger plastic response in M1, and each of these two interventions followed by a depotentiation protocol (cTBS150pulses) to M1. RESULTS PAS25ms and cTBSCB-PAS25ms induced long-term potentiation (LTP)-like responses in both groups of PD patients, with cTBSCB significantly boosting the plastic response. Both these LTP-like responses could be depotentiated by cTBS150, in both groups of patients. CONCLUSIONS Cerebellar stimulation enhances heterosynaptic plasticity in PD irrespective of dyskinesias. Depotentiation mechanisms of heterosynaptic plasticity are preserved in PD patients, including those with dyskinesias. The lack of depotentiation of LTP-like plasticity as a hallmark of dyskinesia in PD patients is not absolute. The ability to depotentiate LTP-like plasticity may potentially depend on the type of plasticity induced (homosynaptic or heterosynaptic), the circuits involved in these responses and the adequacy of dopaminergic stimulation.
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Faldini E, Ahmed T, Bueé L, Blum D, Balschun D. Tau- but not Aß -pathology enhances NMDAR-dependent depotentiation in AD-mouse models. Acta Neuropathol Commun 2019; 7:202. [PMID: 31815648 PMCID: PMC6902514 DOI: 10.1186/s40478-019-0813-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 09/22/2019] [Indexed: 11/10/2022] Open
Abstract
Many mouse models of Alzheimer's disease (AD) exhibit impairments in hippocampal long-term-potentiation (LTP), seemingly corroborating the strong correlation between synaptic loss and cognitive decline reported in human studies. In other AD mouse models LTP is unaffected, but other defects in synaptic plasticity may still be present. We recently reported that THY-Tau22 transgenic mice, that overexpress human Tau protein carrying P301S and G272 V mutations and show normal LTP upon high-frequency-stimulation (HFS), develop severe changes in NMDAR mediated long-term-depression (LTD), the physiological counterpart of LTP. In the present study, we focused on putative effects of AD-related pathologies on depotentiation (DP), another form of synaptic plasticity. Using a novel protocol to induce DP in the CA1-region, we found in 11-15 months old male THY-Tau22 and APPPS1-21 transgenic mice that DP was not deteriorated by Aß pathology while significantly compromised by Tau pathology. Our findings advocate DP as a complementary form of synaptic plasticity that may help in elucidating synaptic pathomechanisms associated with different types of dementia.
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3
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Park P, Sanderson TM, Bortolotto ZA, Georgiou J, Zhuo M, Kaang BK, Collingridge GL. Differential sensitivity of three forms of hippocampal synaptic potentiation to depotentiation. Mol Brain 2019; 12:30. [PMID: 30943994 PMCID: PMC6446328 DOI: 10.1186/s13041-019-0451-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/18/2019] [Indexed: 12/02/2022] Open
Abstract
Theta-burst stimulation (TBS) induces short-term potentiation (STP) plus two types of transcriptionally-independent forms of long-term potentiation (LTP), termed LTP1 and LTP2. We have compared the susceptibility of these three types of synaptic plasticity to depotentiation, induced by low frequency stimulation (LFS; 2 Hz for 10 min) at the Schaffer collateral-commissural pathway in area CA1 of adult rat hippocampal slices. In interleaved experiments, STP and LTP were induced by three episodes of either compressed or spaced TBS (cTBS or sTBS). LFS had a more pronounced effect on the LTP induced by the cTBS. One traditional interpretation of these results is a difference in the time-dependent immunity against depotentiation. We suggest an alternative explanation: LFS rapidly reverses STP to reveal a slowly developing LTP. The cTBS protocol induces LTP1 that is moderately sensitive to depotentiation. The sTBS induces an additional component of LTP (LTP2) that is resistant to depotentiation.
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Affiliation(s)
- Pojeong Park
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, 151-746, Korea.,Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada.,Centre for Synaptic Plasticity, School of Physiology and Pharmacology and Neuroscience, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
| | - Thomas M Sanderson
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, 151-746, Korea.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada.,Centre for Synaptic Plasticity, School of Physiology and Pharmacology and Neuroscience, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
| | - Zuner A Bortolotto
- Centre for Synaptic Plasticity, School of Physiology and Pharmacology and Neuroscience, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
| | - John Georgiou
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada
| | - Min Zhuo
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, 151-746, Korea.,Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Bong-Kiun Kaang
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, 151-746, Korea
| | - Graham L Collingridge
- Department of Biological Sciences and Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, 151-746, Korea. .,Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada. .,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada. .,Centre for Synaptic Plasticity, School of Physiology and Pharmacology and Neuroscience, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK.
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Babür E, Tan B, Delibaş S, Yousef M, Dursun N, Süer C. Depotentiation of Long-Term Potentiation Is Associated with Epitope-Specific Tau Hyper-/Hypophosphorylation in the Hippocampus of Adult Rats. J Mol Neurosci 2019; 67:193-203. [PMID: 30498986 DOI: 10.1007/s12031-018-1224-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 11/18/2018] [Indexed: 01/19/2023]
Abstract
It is well-known that some kinases which are involved in the induction of synaptic plasticity probably modulate tau phosphorylation. However, how depression of potentiated synaptic strength contributes to tau phosphorylation is unclear because of the lack of experiments in which depotentiation of LTP was induced. Field excitatory postsynaptic potential (fEPSP) and population spike (PS) were recorded from the dentate gyrus in response to the perforant pathway stimulation. To induce LTP, high-frequency stimulation (HFS) was used, while, for depotentiation of LTP, low-frequency stimulation (LFS) consisting of 900 pulses at 1 Hz was applied 5 min after tetanization. In some experiments, a neutral protocol at 0.033 Hz was applied throughout the experiment without any induction of synaptic plasticity. One-hertz depotentiation protocol was able to decrease fEPSP slope which was previously increased by HFS, whereas no significant change in fEPSP slope and PS amplitude was observed in neutral protocol experiments. Relative to saline infusion, LTP was lower in magnitude and was more reversed by subsequent LFS in the presence of ERK1/2 inhibitor. Western blot experiments indicated that tau protein was hyperphosphorylated at ser416 epitope but rather hypophosphorylated at thr231 epitope in the whole hippocampus upon depotentiation of LTP. These changes concomitantly occurred with a notable increase in the levels of total tau and in the levels of phosphorylated form of the extracellular signal-regulated protein kinases 1 and 2 (ERK1/2). ERK1/2 inhibition resulted in a decrease in phosphorylation of tau at p416Tau when ERK1/2 was inhibited. These findings indicate that some forms of long-term plastic changes might be related with epitope-specific tau phosphorylation and ERK1/2 activation in the hippocampus. Therefore, we emphasize that tau may be crucial for physiological learning as well as Alzheimer's disease pathology.
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Picconi B, De Leonibus E, Calabresi P. Synaptic plasticity and levodopa-induced dyskinesia: electrophysiological and structural abnormalities. J Neural Transm (Vienna) 2018; 125:1263-1271. [PMID: 29492662 DOI: 10.1007/s00702-018-1864-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 02/19/2018] [Indexed: 12/15/2022]
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive degeneration of dopaminergic neurons located in the midbrain. The gold-standard therapy for PD is the restoration of dopamine (DA) levels through the chronic administration of the DA precursor levodopa (L-DOPA). Although levodopa therapy is the main therapeutic approach for PD, its use is limited by the development of very disabling dyskinetic movements, mainly due to the fluctuation of DA cerebral content. Experimental animal models of PD identified in DA D1/ERK-signaling pathway aberrant activation, occurring in striatal projection neurons, coupled with structural spines abnormalities, the molecular and neuronal basis of L-DOPA-induced dyskinesia (LIDs) occurrence. Different electrophysiological approaches allowed the identification of the alteration of homeostatic structural and synaptic changes, the neuronal bases of LIDs either in vivo in parkinsonian patients or in vitro in experimental animals. Here, we report the most recent studies showing electrophysiological and morphological evidence of aberrant synaptic plasticity in parkinsonian patients during LIDs in different basal ganglia nuclei and also in cortical transmission, accounting for the complexity of the synaptic changes during dyskinesias. All together, these studies suggest that LIDs are associated with a loss of homeostatic synaptic mechanisms.
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Affiliation(s)
- Barbara Picconi
- Laboratory of Neurophysiology, IRCCS Fondazione Santa Lucia c/o CERC, via del Fosso di Fiorano 64, 00143, Rome, Italy.
| | - Elvira De Leonibus
- Institute of Genetics and Biophysics (IGB), National Research Council, Naples, Italy
- Telethon Institute of Genetics and Medicine, Telethon Foundation, Pozzuoli, Italy
| | - Paolo Calabresi
- Laboratory of Neurophysiology, IRCCS Fondazione Santa Lucia c/o CERC, via del Fosso di Fiorano 64, 00143, Rome, Italy
- Clinica Neurologica, Università degli studi di Perugia, Ospedale Santa Maria della Misericordia, S. Andrea delle Fratte, 06156, Perugia, Italy
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Lu GL, Yau HJ, Chiou LC. Conditioned place preference training prevents hippocampal depotentiation in an orexin-dependent manner. J Biomed Sci 2017; 24:69. [PMID: 28877723 PMCID: PMC5585888 DOI: 10.1186/s12929-017-0378-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 08/31/2017] [Indexed: 12/17/2022] Open
Abstract
Background Long-term potentiation (LTP) is well recognized as a cellular-correlated synaptic plasticity of learning and memory. However, its reversal forms of synaptic plasticity, depotentiation, is less studied and its association with behaviors is also far from clear. Previously, we have shown that nanomolar orexin A can prevent the depotentiation induced by low frequency stimulation (LFS) following theta burst stimulation-induced LTP, namely inducing re-potentiation, at hippocampal CA1 synapses in vitro. Here, we explored the functional correlate of this orexin-mediated hippocampal re-potentiation. Methods and results We found that intraperitoneal (i.p.) injection process-paired contextual exposures during the conditioned place preference (CPP) task in mice resulted in re-potentiation at CA1 synapses of hippocampal slices, regardless of whether the CPP behavior is expressed or not. Simply exposing the mouse in the CPP apparatus, or giving the mouse consecutive i.p. injections of saline in its home cage or a novel cage did not lead to hippocampal re-potentiation. Besides, this CPP training process-induced hippocampal re-potentiation was prevented when mice were pretreated with TCS1102, a dual orexin receptor antagonist. These results suggest that the expression of hippocampal re-potentiation is orexin-dependent and requires the association of differential spatial contexts and i.p. injections in the CPP apparatus. Conclusions Together, we reveal an unprecedentedly orexin-mediated modulation on hippocampal depotentiation by the training process in the CPP paradigm. Electronic supplementary material The online version of this article (10.1186/s12929-017-0378-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Guan-Ling Lu
- Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Hau-Jie Yau
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Lih-Chu Chiou
- Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan. .,Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan. .,Reserach Center for Chinese Medicine & Acupuncture, China Medical University, Taichung, Taiwan. .,Department of Pharmacology, College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 100, Taiwan.
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Lago-Rodriguez A, Ponzo V, Jenkinson N, Benitez-Rivero S, Del-Olmo MF, Hu M, Koch G, Cheeran B. Paradoxical facilitation after depotentiation protocol can precede dyskinesia onset in early Parkinson's disease. Exp Brain Res 2016; 234:3659-3667. [PMID: 27566172 DOI: 10.1007/s00221-016-4759-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 08/17/2016] [Indexed: 12/30/2022]
Abstract
Loss of dopamine, a key modulator of synaptic signalling, and subsequent pulsatile non-physiological levodopa replacement is believed to underlie altered neuroplasticity in Parkinson's disease (PD). Animal models suggest that maladaptive plasticity (e.g. deficient depotentiation at corticostriatal synapses) is key in the development of levodopa-induced dyskinesia (LID), a common complication following levodopa replacement in PD. Human studies using transcranial magnetic stimulation protocols have shown similar depotentiation deficit in patients with LID. We hypothesized that subtle depotentiation deficits should precede LID if these deficits are mechanistically linked to LID onset. Moreover, patients on pulsatile levodopa-based therapy may show these changes earlier than those treated with levodopa-sparing strategies. We recruited 22 early non-dyskinetic PD patients (<5 years since diagnosis) and 12 age-matched healthy controls. We grouped patients into those on Levodopa-Based (n = 11) and Levodopa-Sparing therapies (n = 11). Patients were selected to obtain groups matched for age and disease severity. We used a theta-burst stimulation protocol to investigate potentiation and depotentiation in a single session. We report significant depotentiation deficits in the Levodopa-Based group, compared to both Levodopa-Sparing and Healthy Control groups. Potentiation and Depotentiation responses were similar between Levodopa-Sparing and Healthy Control groups. Although differences persist after accounting for potential confounds (e.g. levodopa-equivalent dose), these results may yet be caused by differences in disease severity and cumulative levodopa-equivalent dose as discussed in the text. In conclusion, we show for the first time that paradoxical facilitation in response to depotentiation protocols can occur in PD even prior to LID onset.
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Affiliation(s)
- Angel Lago-Rodriguez
- Nuffield Department of Clinical Neurosciences, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Oxford, UK
- School of Psychology, University of Birmingham, Birmingham, UK
| | - Viviana Ponzo
- Laboratorio di Neurologia Clinica e Comportamentale, Fondazione Santa Lucia IRCCS, Rome, Italy
| | - Ned Jenkinson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Oxford, UK
| | - Sonia Benitez-Rivero
- Nuffield Department of Clinical Neurosciences, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Oxford, UK
| | - Miguel Fernandez Del-Olmo
- Department of Physical Education, Faculty of Sciences of Sport and Physical Education, University of A Coruña, A Coruña, Spain
| | - Michele Hu
- Nuffield Department of Clinical Neurosciences, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Oxford, UK
| | - Giacomo Koch
- Laboratorio di Neurologia Clinica e Comportamentale, Fondazione Santa Lucia IRCCS, Rome, Italy
- Stroke Unit, Dipartimento di Neuroscienze, Università di Roma Tor Vergata, Rome, Italy
| | - Binith Cheeran
- Nuffield Department of Clinical Neurosciences, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Oxford, UK.
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Song WS, Cha JH, Yoon SH, Cho YS, Park KY, Kim MH. The atypical antipsychotic olanzapine disturbs depotentiation by modulating mAChRs and impairs reversal learning. Neuropharmacology 2017; 114:1-11. [PMID: 27866902 DOI: 10.1016/j.neuropharm.2016.11.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 10/13/2016] [Accepted: 11/16/2016] [Indexed: 11/22/2022]
Abstract
Antipsychotic medication is an essential component for treating schizophrenia, which is a serious mental disorder that affects approximately 1% of the global population. Olanzapine (Olz), one of the most frequently prescribed atypical antipsychotics, is generally considered a first-line drug for treating schizophrenia. In contrast to psychotic symptoms, the effects of Olz on cognitive symptoms of schizophrenia are still unclear. In addition, the mechanisms by which Olz affects the neural circuits associated with cognitive function are unknown. Here we show that Olz interrupts depotentiation (reversal of long-term potentiation) without disturbing de novo LTP (long-term potentiation) and LTD (long-term depression). At hippocampal SC-CA1 synapses, inhibition of NMDARs (N-methyl-d-aspartate receptors), mGluRs (metabotropic glutamate receptors), or mAChRs (muscarinic acetylcholine receptors) disrupted depotentiation. In addition, co-activation of NMDARs, mGluRs, and mAChRs reversed stably expressed LTP. Olz inhibits the activation of mAChRs, which amplifies glutamate signaling through enhanced NMDAR opening and Gq (Gq class of G protein)-mediated signal transduction. Behaviorally, Olz impairs spatial reversal learning of mice in the Morris water maze test. Our results uncover a novel mechanism underpinning the cognitive modulation of Olz and show that the anticholinergic property of Olz affects glutamate signaling and synaptic plasticity.
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Abstract
Synapses undergo significant structural and functional reorganization in response to varying patterns of stimulation. These forms of plasticity are considered fundamental to cognition and neuronal homeostasis. An increasing number of reports highlight the importance of activity-dependent synaptic strengthening (long term potentiation: LTP) for learning. However, the functional significance of activity-dependent weakening of synapses (long term depression: LTD) remains relatively poorly understood. One form of synaptic weakening, induced by group I metabotropic glutamate receptors (mGluRs), has received significant attention from a mechanistic point of view and because of its augmentation in a murine model of Fragile X Syndrome. Yet, studies of this form of plasticity often yield confusing, contradictory results. These conflicting findings are likely attributable to the bulk stimulation and recording techniques often used to study synaptic plasticity (typically involving evoked extracellular recordings, which represent the summed activity of many synapses). Such studies inherently blur the identity of the synapses undergoing change, thus giving the illusion that synapses per se are being modified when in fact this may only be true of a specific subset of synapses. Indeed, studies employing minimal synaptic activation paint a fundamentally different picture of what is commonly called "mGluR-LTD". Here, I review the evidence in favour of group I mGluRs as mediators of various forms of synaptic downregulation and attempt to explain discrepancies in the literature. I argue that, while multiple forms of synaptic weakening may be triggered by these receptors, the canonical form of group I mGluR-mediated depression, mGluR-LTD, is in fact not a depression of basal synaptic responses. Rather, it is a reversal of established LTP and thus a form of depotentiation. Far from being arbitrary, this distinction has significant implications for the role of group I mGluRs in cognition, both in the healthy brain and in pathological conditions. Further, the differential actions of group I mGluRs at naïve and potentiated synapses suggest these receptors signal in a state-dependent manner to regulate various stages of the learning process.
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Affiliation(s)
- Owen D Jones
- Department of Psychology, Brain Health Research Centre & Brain Research New Zealand, University of Otago, Dunedin, New Zealand.
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Sachser RM, Haubrich J, Lunardi PS, de Oliveira Alvares L. Forgetting of what was once learned: Exploring the role of postsynaptic ionotropic glutamate receptors on memory formation, maintenance, and decay. Neuropharmacology 2016; 112:94-103. [PMID: 27425202 DOI: 10.1016/j.neuropharm.2016.07.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 07/12/2016] [Accepted: 07/13/2016] [Indexed: 12/26/2022]
Abstract
Over the past years, extensive research in experimental cognitive neuroscience has provided a comprehensive understanding about the role of ionotropic glutamate receptor (IGluR)-dependent signaling underpinning postsynaptic plasticity induced by long-term potentiation (LTP), the leading cellular basis of long-term memory (LTM). However, despite the fact that iGluR-mediated postsynaptic plasticity regulates the formation and persistence of LTP and LTM, here we discuss the state-of-the-art regarding the mechanisms underpinning both LTP and LTM decay. First, we review the crucial roles that iGluRs play on memory encoding and stabilization. Second, we discuss the latest findings in forgetting considering hippocampal GluA2-AMPAR trafficking at postsynaptic sites as well as dendritic spine remodeling possibly involved in LTP decay. Third, on the role of retrieving consolidated LTMs, we discuss the mechanisms involved in memory destabilization that occurs followed reactivation that share striking similarities with the neurobiological basis of forgetting. Fourth, since different AMPAR subunits as well as postsynaptic scaffolding proteins undergo ubiquitination, the ubiquitin-proteasome system (UPS) is discussed in light of memory decay. In conclusion, we provide an integrated overview revealing some of the mechanisms determining memory forgetting that are mediated by iGluRs. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'.
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Affiliation(s)
- Ricardo Marcelo Sachser
- Neurobiology of Memory Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Graduate Program in Neuroscience, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Josué Haubrich
- Psychobiology and Neurocomputation Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Graduate Program in Neuroscience, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Paula Santana Lunardi
- Neurobiology of Memory Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Graduate Program in Neuroscience, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Lucas de Oliveira Alvares
- Neurobiology of Memory Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Graduate Program in Neuroscience, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
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11
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Lu GL, Lee CH, Chiou LC. Orexin A induces bidirectional modulation of synaptic plasticity: Inhibiting long-term potentiation and preventing depotentiation. Neuropharmacology 2016; 107:168-180. [PMID: 26965217 DOI: 10.1016/j.neuropharm.2016.03.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 02/19/2016] [Accepted: 03/01/2016] [Indexed: 01/30/2023]
Abstract
The orexin system consists of two peptides, orexin A and B and two receptors, OX1R and OX2R. It is implicated in learning and memory regulation while controversy remains on its role in modulating hippocampal synaptic plasticity in vivo and in vitro. Here, we investigated effects of orexin A on two forms of synaptic plasticity, long-term potentiation (LTP) and depotentiation of field excitatory postsynaptic potentials (fEPSPs), at the Schaffer Collateral-CA1 synapse of mouse hippocampal slices. Orexin A (≧30 nM) attenuated LTP induced by theta burst stimulation (TBS) in a manner antagonized by an OX1R (SB-334867), but not OX2R (EMPA), antagonist. Conversely, at 1 pM, co-application of orexin A prevented the induction of depotentiation induced by low frequency stimulation (LFS), i.e. restoring LTP. This re-potentiation effect of sub-nanomolar orexin A occurred at LFS of 1 Hz, but not 2 Hz, and with LTP induced by either TBS or tetanic stimulation. It was significantly antagonized by SB-334867, EMPA and TCS-1102, selective OX1R, OX2R and dual OXR antagonists, respectively, and prevented by D609, SQ22536 and H89, inhibitors of phospholipase C (PLC), adenylyl cyclase (AC) and protein kinase A (PKA), respectively. LFS-induced depotentiation was antagonized by blockers of NMDA, A1-adenosine and type 1/5 metabotropic glutamate (mGlu1/5) receptors, respectively. However, orexin A (1 pM) did not affect chemical-induced depotentiation by agonists of these receptors. These results suggest that orexin A bidirectionally modulates hippocampal CA1 synaptic plasticity, inhibiting LTP via OX1Rs at moderate concentrations while inducing re-potentiation via OX1Rs and OX2Rs, possibly through PLC and AC-PKA signaling at sub-nanomolar concentrations.
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Affiliation(s)
- Guan-Ling Lu
- Graduate Institute and College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chia-Hsu Lee
- Graduate Institute and College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Lih-Chu Chiou
- Graduate Institute and College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan; Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan; Reserach Center for Chinese Medicine & Acupuncture, China Medical University, Taichung, Taiwan.
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Galvez B, Gross N, Sumikawa K. Activation of α7 nicotinic acetylcholine receptors protects potentiated synapses from depotentiation during theta pattern stimulation in the hippocampal CA1 region of rats. Neuropharmacology 2016; 105:378-87. [PMID: 26867505 DOI: 10.1016/j.neuropharm.2016.02.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 01/24/2016] [Accepted: 02/05/2016] [Indexed: 11/21/2022]
Abstract
Long-term potentiation (LTP) shows memory-like consolidation and thus becomes increasingly resistant to disruption by low-frequency stimulation (LFS). However, it is known that nicotine application during LFS uniquely depotentiates consolidated LTP. Here, we investigated how nicotine contributes to the disruption of stabilized LTP in the hippocampal CA1 region. We found that nicotine-induced depotentiation is not due to masking LTP by inducing long-term depression and requires the activation of GluN2A-containing NMDARs. We further examined whether nicotine-induced depotentiation involves the reversal of LTP mechanisms. LTP causes phosphorylation of Ser-831 on GluA1 subunits of AMPARs that increases the single-channel conductance of AMPARs. This phosphorylation remained unchanged after depotentiation. LTP involves the insertion of new AMPARs into the synapse and the internalization of AMPARs is associated with dephosphorylation of Ser-845 on GluA1 and caspase-3 activity. Nicotine-induced depotentiation occurred without dephosphorylation of the Ser-845 and in the presence of a caspase-3 inhibitor. LTP is also accompanied by increased filamentous actin (F-actin), which controls spine size. Nicotine-induced depotentiation was prevented by jasplakinolide, which stabilizes F-actin, suggesting that nicotine depotentiates consolidated LTP by destabilizing F-actin. α7 nicotinic acetylcholine receptor (nAChR) antagonists mimicked the effect of nicotine and selective removal of hippocampal cholinergic input caused depotentiation in the absence of nicotine, suggesting that nicotine depotentiates consolidated LTP by inducing α7 nAChR desensitization. Our results demonstrate a new role for nicotinic cholinergic systems in protecting potentiated synapses from depotentiation by preventing GluN2A-NMDAR-mediated signaling for actin destabilization.
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Kadowaki S, Enomoto H, Murakami T, Nakatani-Enomoto S, Kobayashi S, Ugawa Y. Influence of phasic muscle contraction upon the quadripulse stimulation (QPS) aftereffects. Clin Neurophysiol 2015; 127:1568-1573. [PMID: 26702773 DOI: 10.1016/j.clinph.2015.10.063] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 10/06/2015] [Accepted: 10/23/2015] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Contractions of the target muscle influence the aftereffects of repetitive transcranial magnetic stimulation (rTMS). The aim of this paper is to investigate whether or not voluntary hand movement influences the aftereffects of quadripulse stimulation (QPS) on the hand motor area. METHODS Thirteen healthy volunteers participated in this study. After QPS-5 or QPS-50 intervention over the motor hot spot for the right first dorsal interosseous muscle (FDI), the subjects performed voluntary motor tasks (opening-closing right hand movements at 1 Hz for 1 min). We compared the time courses of MEP size between the conditions with and without voluntary movement. RESULTS When the subjects moved their hands immediately after QPS, both QPS-5 and QPS-50 aftereffects were abolished. However, if they moved their hands at 20 min after QPS, the long-term aftereffects were preserved. CONCLUSIONS Voluntary hand movement applied after intervention influences QPS aftereffects, but the magnitude of the influence depends on the delay between QPS and the voluntary movement. SIGNIFICANCE In the plasticity induction experiments, we should always be mindful of the fact that voluntary movement, including the target muscle, seriously influences the induced long-term effects of QPS.
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Affiliation(s)
- Suguru Kadowaki
- Department of Neurology, School of Medicine, Fukushima Medical University, Fukushima, Japan.
| | - Hiroyuki Enomoto
- Department of Neurology, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Takenobu Murakami
- Department of Neurology, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Setsu Nakatani-Enomoto
- Department of Neurology, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Shunsuke Kobayashi
- Department of Neurology, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Yoshikazu Ugawa
- Department of Neurology, School of Medicine, Fukushima Medical University, Fukushima, Japan
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Abstract
Considerable research indicates that long-term synaptic plasticity in the amygdala underlies the acquisition of emotional memories, including those learned during Pavlovian fear conditioning. Much less is known about the synaptic mechanisms involved in other forms of associative learning, including extinction, that update fear memories. Extinction learning might reverse conditioning-related changes (e.g., depotentiation) or induce plasticity at inhibitory synapses (e.g., long-term potentiation) to suppress conditioned fear responses. Either mechanism must account for fear recovery phenomena after extinction, as well as savings of extinction after fear recovery. This article is part of a Special Issue entitled SI: Brain and Memory.
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Affiliation(s)
- Stephen Maren
- Department of Psychology and Institute for Neuroscience, Texas A&M University, USA
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An L, Zhang T. Prenatal ethanol exposure impairs spatial cognition and synaptic plasticity in female rats. Alcohol 2015; 49:581-8. [PMID: 26251263 DOI: 10.1016/j.alcohol.2015.05.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 05/20/2015] [Accepted: 05/27/2015] [Indexed: 01/12/2023]
Abstract
Chronic prenatal ethanol exposure (CPEE) can impair long-term potentiation (LTP) in the male hippocampus. Sexually specific alterations were frequently reported in female animals that had been prenatally exposed to ethanol. This study aimed to examine the effects of CPEE on spatial learning and memory, as well as on hippocampal synaptic plasticity in female adolescent rats. Female offspring were selected from dams that had been exposed to 4 g/kg/day of ethanol throughout the gestational period. Subsequently, performance in the Morris water maze (MWM) was determined, while LTP and depotentiation were measured in the hippocampal CA3-CA1 pathway. In the behavioral test, the escape latencies in both initial and reversal training stages were significantly prolonged. Interestingly, LTP was considerably enhanced while depotentiation was significantly depressed. Our results suggest a critical role of synaptic plasticity balance, which may prominently contribute to the cognitive deficits present in CPEE offspring.
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Bologna M, Rocchi L, Paparella G, Nardella A, Li Voti P, Conte A, Kojovic M, Rothwell JC, Berardelli A. Reversal of Practice-related Effects on Corticospinal Excitability has no Immediate Effect on Behavioral Outcome. Brain Stimul 2015; 8:603-12. [PMID: 25697591 DOI: 10.1016/j.brs.2015.01.405] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 01/12/2015] [Accepted: 01/14/2015] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Motor training usually increases the excitability of corticospinal outputs to the trained muscles. However, it is uncertain to what extent the change in excitability is a critical component of behavioral learning or whether it is a non-specific side effect. OBJECTIVE/HYPOTHESIS We used a depotentiation protocol to abolish the training-induced increase of corticospinal excitability and tested whether this had any immediate effect on the improved motor performance. METHODS We used an index finger abduction task in which behavioral improvement is known to be associated with M1 excitability changes as monitored by the amplitude of motor-evoked potentials produced by single-pulse transcranial magnetic stimulation (TMS). These effects could be reversed by a depotentiation protocol using a short form of continuous theta-burst stimulation (cTBS150). Participants underwent three experimental interventions: 'motor training', 'motor training plus cTBS150' and 'cTBS150'. M1 excitability and TMS-evoked finger movements were assessed before the experimental interventions and 5 min, 15 min, and 30 min thereafter. Motor retention was tested 45 min after the experimental interventions. RESULTS During training, acceleration of the practiced movement improved. At the end of training, M1 excitability and the acceleration of TMS-evoked index finger movements in the direction of training had increased and the enhanced performance was retained when tested 45 min later. The depotentiation protocol, delivered immediately after the end of training, reversed the excitability changes in M1 but did not affect the acceleration of the TMS-evoked finger movement nor the retention of performance. The depotentiation protocol alone did not modify M1 excitability. CONCLUSIONS The present study indicates that in the short term, increases in corticospinal excitability are not related to immediate changes in behavioral motor outcome.
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Affiliation(s)
| | - Lorenzo Rocchi
- Department of Neurology and Psychiatry, Sapienza University of Rome, Italy
| | - Giulia Paparella
- Department of Neurology and Psychiatry, Sapienza University of Rome, Italy
| | | | | | | | - Maja Kojovic
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK; Department of Neurology, University of Ljubljana, Slovenia
| | - John C Rothwell
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK
| | - Alfredo Berardelli
- Neuromed Institute (IRCCS), Pozzilli, Isernia, Italy; Department of Neurology and Psychiatry, Sapienza University of Rome, Italy.
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Cerovic M, Bagetta V, Pendolino V, Ghiglieri V, Fasano S, Morella I, Hardingham N, Heuer A, Papale A, Marchisella F, Giampà C, Calabresi P, Picconi B, Brambilla R. Derangement of Ras-guanine nucleotide-releasing factor 1 (Ras-GRF1) and extracellular signal-regulated kinase (ERK) dependent striatal plasticity in L-DOPA-induced dyskinesia. Biol Psychiatry 2015; 77:106-15. [PMID: 24844602 DOI: 10.1016/j.biopsych.2014.04.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 03/17/2014] [Accepted: 04/01/2014] [Indexed: 02/02/2023]
Abstract
BACKGROUND Bidirectional long-term plasticity at the corticostriatal synapse has been proposed as a central cellular mechanism governing dopamine-mediated behavioral adaptations in the basal ganglia system. Balanced activity of medium spiny neurons (MSNs) in the direct and the indirect pathways is essential for normal striatal function. This balance is disrupted in Parkinson's disease and in l-3,4-dihydroxyphenylalanine (l-DOPA)-induced dyskinesia (LID), a common motor complication of current pharmacotherapy of Parkinson's disease. METHODS Electrophysiological recordings were performed in mouse cortico-striatal slice preparation. Synaptic plasticity, such as long-term potentiation (LTP) and depotentiation, was investigated. Specific pharmacological inhibitors or genetic manipulations were used to modulate the Ras-extracellular signal-regulated kinase (Ras-ERK) pathway, a signal transduction cascade implicated in behavioral plasticity, and synaptic activity in different subpopulations of striatal neurons was measured. RESULTS We found that the Ras-ERK pathway, is not only essential for long-term potentiation induced with a high frequency stimulation protocol (HFS-LTP) in the dorsal striatum, but also for its reversal, synaptic depotentiation. Ablation of Ras-guanine nucleotide-releasing factor 1 (Ras-GRF1), a neuronal activator of Ras proteins, causes a specific loss of HFS-LTP in the medium spiny neurons in the direct pathway without affecting LTP in the indirect pathway. Analysis of LTP in animals with unilateral 6-hydroxydopamine lesions (6-OHDA) rendered dyskinetic with chronic L-DOPA treatment reveals a complex, Ras-GRF1 and pathway-independent, apparently stochastic involvement of ERK. CONCLUSIONS These data not only demonstrate a central role for Ras-ERK signaling in striatal LTP, depotentiation, and LTP restored after L-DOPA treatment but also disclose multifaceted synaptic adaptations occurring in response to dopaminergic denervation and pulsatile administration of L-DOPA.
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Affiliation(s)
- Milica Cerovic
- School of Biosciences, Cardiff University, Cardiff, United Kingdom; Institute of Experimental Neurology, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milano
| | | | | | | | - Stefania Fasano
- Institute of Experimental Neurology, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milano
| | - Ilaria Morella
- Institute of Experimental Neurology, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milano
| | - Neil Hardingham
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Andreas Heuer
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Alessandro Papale
- Institute of Experimental Neurology, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milano
| | - Francesca Marchisella
- Institute of Experimental Neurology, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milano
| | | | - Paolo Calabresi
- Fondazione Santa Lucia, IRCCS, Rome; Clinica Neurologica, University of Perugia, Ospedale S. Maria della Misericordia, Perugia, Italy
| | | | - Riccardo Brambilla
- Institute of Experimental Neurology, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milano.
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Abstract
The ability of drug-associated cues to reinitiate drug craving and seeking, even after long periods of abstinence, has led to the hypothesis that addiction represents a form of pathological learning, in which drugs of abuse hijack normal learning and memory processes to support long-term addictive behaviors. In this chapter, we review evidence suggesting that G protein-gated inwardly rectifying potassium (GIRK/Kir3) channels are one mechanism through which numerous drugs of abuse can modulate learning and memory processes. We will examine the role of GIRK channels in two forms of experience-dependent long-term changes in neuronal function: homeostatic plasticity and synaptic plasticity. We will also discuss how drug-induced changes in GIRK-mediated signaling can lead to changes that support the development and maintenance of addiction.
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19
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Sebastião AM, Ribeiro JA. Neuromodulation and metamodulation by adenosine: Impact and subtleties upon synaptic plasticity regulation. Brain Res 2014; 1621:102-13. [PMID: 25446444 DOI: 10.1016/j.brainres.2014.11.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 10/30/2014] [Accepted: 11/05/2014] [Indexed: 01/06/2023]
Abstract
Synaptic plasticity mechanisms, i.e. the sequence of events that underlies persistent changes in synaptic strength as a consequence of transient alteration in neuronal firing, are greatly influenced by the 'chemical atmosphere' of the synapses, that is to say by the presence of molecules at the synaptic cleft able to fine-tune the activity of other molecules more directly related to plasticity. One of those fine tuners is adenosine, known for a long time as an ubiquitous neuromodulator and metamodulator and recognized early as influencing synaptic plasticity. In this review we will refer to the mechanisms that adenosine can use to affect plasticity, emphasizing aspects of the neurobiology of adenosine relevant to its ability to control synaptic functioning. This article is part of a Special Issue entitled Brain and Memory.
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Affiliation(s)
- Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Unidade de Neurociências, Instituto de Medicina Molecular, Universidade de Lisboa, Lisboa, Portugal.
| | - Joaquim A Ribeiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Unidade de Neurociências, Instituto de Medicina Molecular, Universidade de Lisboa, Lisboa, Portugal.
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20
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Prescott IA, Liu LD, Dostrovsky JO, Hodaie M, Lozano AM, Hutchison WD. Lack of depotentiation at basal ganglia output neurons in PD patients with levodopa-induced dyskinesia. Neurobiol Dis 2014; 71:24-33. [PMID: 25116960 DOI: 10.1016/j.nbd.2014.08.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 07/29/2014] [Accepted: 08/01/2014] [Indexed: 11/26/2022] Open
Abstract
Parkinson's disease (PD), characterized by the loss of dopaminergic nigrostriatal projections, is a debilitating neurodegenerative disease which produces bradykinesia, rigidity, tremor and postural instability. The dopamine precursor levodopa (L-Dopa) is the most effective treatment for the amelioration of PD signs and symptoms, but long-term administration can lead to disabling motor fluctuations and L-Dopa-induced dyskinesias. In animal models of PD, a form of plasticity called depotentiation, or the reversal of previous potentiation, is selectively lost after the development of dyskinetic movements following L-Dopa treatment. We investigated whether low frequency stimulation (LFS) in the globus pallidus internus (GPi) and substantia nigra pars reticulata (SNr) could induce depotentiation at synapses that had already undergone high frequency stimulation (HFS)-induced potentiation. To do so, we measured the field potentials (fEPs) evoked by stimulation from a nearby microelectrode in 28 patients undergoing implantation of deep brain stimulating (DBS) electrodes in the subthalamic nucleus (STN) or GPi. We found that GPi and SNr synapses in patients with less severe dyskinesia underwent greater depotentiation following LFS than in patients with more severe dyskinesia. This demonstration of impaired depotentiation in basal ganglia output nuclei in PD patients with dyskinesia is an important validation of animal models of levodopa-induced dyskinesia. The ability of a synapse to reverse previous potentiation may be crucial to the normal function of the BG, perhaps by preventing saturation of the storage capacity required in motor learning and optimal motor function. Loss of this ability at the output nuclei may underlie, or contribute to the cellular basis of dyskinetic movements.
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Affiliation(s)
- I A Prescott
- Department of Physiology, University of Toronto, Canada.
| | - L D Liu
- Department of Physiology, University of Toronto, Canada
| | | | - M Hodaie
- Dept. of Surgery, Division of Neurosurgery, Toronto Western Research Institute, Canada; Krembil Neuroscience Centre, Canada
| | - A M Lozano
- Dept. of Surgery, Division of Neurosurgery, Toronto Western Research Institute, Canada; Krembil Neuroscience Centre, Canada
| | - W D Hutchison
- Department of Physiology, University of Toronto, Canada; Dept. of Surgery, Division of Neurosurgery, Toronto Western Research Institute, Canada; Krembil Neuroscience Centre, Canada
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Sanderson TM, Sher E. The role of phosphodiesterases in hippocampal synaptic plasticity. Neuropharmacology 2013; 74:86-95. [PMID: 23357335 DOI: 10.1016/j.neuropharm.2013.01.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/08/2013] [Accepted: 01/12/2013] [Indexed: 01/19/2023]
Abstract
Phosphodiesterases (PDEs) degrade cyclic nucleotides, signalling molecules that play important roles in synaptic plasticity and memory. Inhibition of PDEs may therefore enhance synaptic plasticity and memory as a result of elevated levels of these signalling molecules, and this has led to interest in PDE inhibitors as cognitive enhancers. The development of new mouse models in which PDE subtypes have been selectively knocked out and increasing selectivity of PDE antagonists means that this field is currently expanding. Roles for PDE2, 4, 5 and 9 in synaptic plasticity have so far been demonstrated and we review these studies here in the context of cyclic nucleotide signalling more generally. The role of other PDE families in synaptic plasticity has not yet been investigated, and this area promises to advance our understanding of cyclic nucleotide signalling in synaptic plasticity in the future. This article is part of the Special Issue entitled 'Glutamate Receptor-Dependent Synaptic Plasticity'.
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