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Yadav Y, Dey CS. Ser/Thr phosphatases: One of the key regulators of insulin signaling. Rev Endocr Metab Disord 2022; 23:905-917. [PMID: 35697962 DOI: 10.1007/s11154-022-09727-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/18/2022] [Indexed: 10/18/2022]
Abstract
Protein phosphorylation is an important post-translational modification that regulates several cellular processes including insulin signaling. The evidences so far have already portrayed the importance of balanced actions of kinases and phosphatases in regulating the insulin signaling cascade. Therefore, elucidating the role of both kinases and phosphatases are equally important. Unfortunately, the role of phosphatases is less studied as compared to kinases. Since brain responds to insulin and insulin signaling is reported to be crucial for many neuronal processes, it is important to understand the role of neuronal insulin signaling regulators. Ser/Thr phosphatases seem to play significant roles in regulating neuronal insulin signaling. Therefore, in this review, we discussed the involvement of Ser/Thr phosphatases in regulating insulin signaling and insulin resistance in neuronal system at the backdrop of the same phosphatases in peripheral insulin sensitive tissues.
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Affiliation(s)
- Yamini Yadav
- Kusuma School of Biological Sciences, Indian Institute of Technology, Delhi, New Delhi, 110016, India
| | - Chinmoy Sankar Dey
- Kusuma School of Biological Sciences, Indian Institute of Technology, Delhi, New Delhi, 110016, India.
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Proteomic profiling reveals neuronal ion channel dysregulation and cellular responses to DNA damage-induced cell cycle arrest and senescence in human neuroblastoma SH-SY5Y cells exposed to cypermethrin. Neurotoxicology 2022; 93:71-83. [PMID: 36063984 DOI: 10.1016/j.neuro.2022.08.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/27/2022] [Accepted: 08/28/2022] [Indexed: 11/20/2022]
Abstract
Cypermethrin (CYP), a synthetic pyrethroid of class II, is widely used as a pesticide worldwide. The primary target of cypermethrin is a voltage-gated sodium channel. The neurotoxicity of CYP has been extensively studied in terms of affecting neuronal development, increasing cellular oxidative stress, and apoptosis. However, little is known about how it affects the expression of channel proteins involved in synaptic transmission, as well as the effects of cypermethrin on DNA damage and cell cycle processes. We found that the ligand and voltage-gated calcium channels and proteins involved in synaptic transmission including NMDA 1 receptor subunit, alpha 1A-voltage-dependent calcium channel, synaptotagmin-17, and synaptojanin-2 were downregulated in CYP-treated cells. After 48h of CYP exposure, cell viability was reduced with flattened and enlarged morphology. The levels of 23 proteins regulating cell cycle processes were altered in CYP-treated cells, according to a proteomic study. The cell cycle analysis showed elevated G0/G1 cell cycle arrest and DNA fragmentation at the sub-G0 stage after CYP exposure. CYP treatment also increased senescence-associated β-galactosidase positive cells, DNA damage, and apoptotic markers. Taken together, the current study showed that cypermethrin exposure caused DNA damage and hastened cellular senescence and apoptosis via disrupting cell cycle regulation. In addition, despite its primary target sodium channel, CYP might cause synaptic dysfunction via the downregulation of synaptic proteins and dysregulation of synapse-associated ion channels.
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Social Transmission and Buffering of Hippocampal Metaplasticity after Stress in Mice. J Neurosci 2020; 41:1317-1330. [PMID: 33310752 DOI: 10.1523/jneurosci.1751-20.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 11/16/2020] [Accepted: 11/30/2020] [Indexed: 11/21/2022] Open
Abstract
In social animals, the behavioral and hormonal responses to stress can be transmitted from one individual to another through a social transmission process, and, conversely, social support ameliorates stress responses, a phenomenon referred to as social buffering. Metaplasticity represents activity-dependent synaptic changes that modulate the ability to elicit subsequent synaptic plasticity. Authentic stress can induce hippocampal metaplasticity, but whether transmitted stress has the same ability remains unknown. Here, using an acute restraint-tailshock stress paradigm, we report that both authentic and transmitted stress in adult male mice trigger metaplastic facilitation of long-term depression (LTD) induction at hippocampal CA1 synapses. Using LTD as a readout of persistent synaptic consequences of stress, our findings demonstrate that, in a male-male dyad, stress transmission happens in nearly half of naive partners and stress buffering occurs in approximately half of male stressed mice that closely interact with naive partners. By using a social-confrontation tube test to assess the dominant-subordinate relationship in a male-male dyad, we found that stressed subordinate mice are not buffered by naive dominant partners and that stress transmission is exhibited in ∼60% of dominant naive partners. Furthermore, the appearance of stress transmission correlates with more time spent in sniffing the anogenital area of stressed mice, and the appearance of stress buffering correlates with more time engaged in allogrooming from naive partners. Chemical ablation of the olfactory epithelium with dichlobenil or physical separation between social contacts diminishes stress transmission. Together, our data demonstrate that transmitted stress can elicit metaplastic facilitation of LTD induction as authentic stress.SIGNIFICANCE STATEMENT Social animals can acquire information about their environment through interactions with conspecifics. Stress can induce enduring changes in neural activity and synaptic function. Current studies are already unraveling the transmission and buffering of stress responses between individuals, but little is known about the relevant synaptic changes associated with social transmission and buffering of stress. Here, we show that authentic and transmitted stress can prime glutamatergic synapses onto hippocampal CA1 neurons to undergo long-term depression. This hippocampal metaplasticity is bufferable following social interactions with naive partners. Hierarchical status of naive partners strongly affects the social buffering effect on synaptic consequences of stress. This work provides novel insights into the conceptual framework for synaptic changes with social transmission and buffering of stress.
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Pagani MR, Merlo E. Kinase and Phosphatase Engagement Is Dissociated Between Memory Formation and Extinction. Front Mol Neurosci 2019; 12:38. [PMID: 30842725 PMCID: PMC6391346 DOI: 10.3389/fnmol.2019.00038] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 01/31/2019] [Indexed: 01/18/2023] Open
Abstract
Associative long-term memories (LTMs) support long-lasting behavioral changes resulting from sensory experiences. Retrieval of a stable LTM by means of a large number of conditioned stimulus (CS) alone presentations produces inhibition of the original memory through extinction. Currently, there are two opposing hypotheses to account for the neural mechanisms supporting extinction. The unlearning hypothesis posits that extinction affects the original memory trace by reverting the synaptic changes supporting LTM. On the contrary, the new learning hypothesis proposes that extinction is simply the formation of a new associative memory that inhibits the expression of the original one. We propose that detailed analysis of extinction-associated molecular mechanisms could help distinguish between these hypotheses. Here we will review experimental evidence regarding the role of protein kinases and phosphatases (K&P) on LTM formation and extinction. Even though K&P regulate both memory processes, their participation appears to be dissociated. LTM formation recruits kinases, but is constrained by phosphatases. Memory extinction presents a more diverse molecular landscape, requiring phosphatases and some kinases, but also being constrained by kinase activity. Based on the available evidence, we propose a new theoretical model for memory extinction: a neuronal segregation of K&P supports a combination of time-dependent reversible inhibition of the original memory [CS-unconditioned stimulus (US)], with establishment of a new associative memory trace (CS-noUS).
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Affiliation(s)
- Mario Rafael Pagani
- Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO)-Houssay, Facultad de Medicina, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Emiliano Merlo
- Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO)-Houssay, Facultad de Medicina, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.,Department of Psychology, University of Cambridge, Cambridge, United Kingdom
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Saavedra A, Fernández-García S, Cases S, Puigdellívol M, Alcalá-Vida R, Martín-Flores N, Alberch J, Ginés S, Malagelada C, Pérez-Navarro E. Chelerythrine promotes Ca2+-dependent calpain activation in neuronal cells in a PKC-independent manner. Biochim Biophys Acta Gen Subj 2017; 1861:922-935. [DOI: 10.1016/j.bbagen.2017.01.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 12/20/2016] [Accepted: 01/06/2017] [Indexed: 11/26/2022]
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Lombroso PJ, Ogren M, Kurup P, Nairn AC. Molecular underpinnings of neurodegenerative disorders: striatal-enriched protein tyrosine phosphatase signaling and synaptic plasticity. F1000Res 2016; 5. [PMID: 29098072 PMCID: PMC5642311 DOI: 10.12688/f1000research.8571.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/20/2016] [Indexed: 12/22/2022] Open
Abstract
This commentary focuses on potential molecular mechanisms related to the dysfunctional synaptic plasticity that is associated with neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. Specifically, we focus on the role of striatal-enriched protein tyrosine phosphatase (STEP) in modulating synaptic function in these illnesses. STEP affects neuronal communication by opposing synaptic strengthening and does so by dephosphorylating several key substrates known to control synaptic signaling and plasticity. STEP levels are elevated in brains from patients with Alzheimer's and Parkinson's disease. Studies in model systems have found that high levels of STEP result in internalization of glutamate receptors as well as inactivation of ERK1/2, Fyn, Pyk2, and other STEP substrates necessary for the development of synaptic strengthening. We discuss the search for inhibitors of STEP activity that may offer potential treatments for neurocognitive disorders that are characterized by increased STEP activity. Future studies are needed to examine the mechanisms of differential and region-specific changes in STEP expression pattern, as such knowledge could lead to targeted therapies for disorders involving disrupted STEP activity.
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Affiliation(s)
- Paul J Lombroso
- Child Study Center, Yale University School of Medicine, New Haven, Connecticut, 06520, USA.,Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, 06520, USA.,Department of Neuroscience, Yale University School of Medicine, New Haven, Connecticut, 06520, USA
| | - Marilee Ogren
- Department of Psychology, Boston College, Chestnut Hill, MA, 02467, USA
| | - Pradeep Kurup
- Child Study Center, Yale University School of Medicine, New Haven, Connecticut, 06520, USA
| | - Angus C Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, 06520, USA
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Uribe-Mariño A, Gassen NC, Wiesbeck MF, Balsevich G, Santarelli S, Solfrank B, Dournes C, Fries GR, Masana M, Labermeier C, Wang XD, Hafner K, Schmid B, Rein T, Chen A, Deussing JM, Schmidt MV. Prefrontal Cortex Corticotropin-Releasing Factor Receptor 1 Conveys Acute Stress-Induced Executive Dysfunction. Biol Psychiatry 2016; 80:743-753. [PMID: 27318500 DOI: 10.1016/j.biopsych.2016.03.2106] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 03/30/2016] [Accepted: 03/31/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND The medial prefrontal cortex (mPFC) subserves complex cognition and is impaired by stress. Corticotropin-releasing factor (CRF), through CRF receptor 1 (CRFR1), constitutes a key element of the stress response. However, its contribution to the effects of stress in the mPFC remains unclear. METHODS Mice were exposed to acute social defeat stress and subsequently to either the temporal order memory (n = 11-12) or reversal learning (n = 9-11) behavioral test. Changes in mPFC Crhr1 messenger RNA levels were measured in acutely stressed mice (n = 12). Crhr1loxP/loxP mice received either intra-mPFC adeno-associated virus-Cre or empty microinjections (n = 17-20) and then were submitted to acute stress and later to the behavioral tests. Co-immunoprecipitation was used to detect activation of the protein kinase A (PKA) signaling pathway in the mPFC of acutely stressed mice (n = 8) or intra-mPFC CRF injected mice (n = 7). Finally, mice received intra-mPFC CRF (n = 11) and/or Rp-isomer cyclic adenosine 3',5' monophosphorothioate (Rp-cAMPS) (n = 12) microinjections and underwent behavioral testing. RESULTS We report acute stress-induced effects on mPFC-mediated cognition, identify CRF-CRFR1-containing microcircuits within the mPFC, and demonstrate stress-induced changes in Crhr1 messenger RNA expression. Importantly, intra-mPFC CRFR1 deletion abolishes acute stress-induced executive dysfunction, whereas intra-mPFC CRF mimics acute stress-induced mPFC dysfunction. Acute stress and intra-mPFC CRF activate the PKA signaling pathway in the mPFC, leading to cyclic AMP response element binding protein phosphorylation in intra-mPFC CRFR1-expressing neurons. Finally, PKA blockade reverses the intra-mPFC CRF-induced executive dysfunction. CONCLUSIONS Taken together, these results unravel a molecular mechanism linking acute stress to executive dysfunction via CRFR1. This will aid in the development of novel therapeutic targets for stress-induced cognitive dysfunction.
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Affiliation(s)
- Andrés Uribe-Mariño
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Nils C Gassen
- Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany
| | - Maximilian F Wiesbeck
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Georgia Balsevich
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Sara Santarelli
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Beate Solfrank
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Carine Dournes
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Gabriel R Fries
- Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany; INCT for Translational Medicine, Porto Alegre, Brazil
| | - Merce Masana
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Christiana Labermeier
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Xiao-Dong Wang
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany; Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Kathrin Hafner
- Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany
| | - Bianca Schmid
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Theo Rein
- Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany
| | - Alon Chen
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Jan M Deussing
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Mathias V Schmidt
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany.
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Role of Striatal-Enriched Tyrosine Phosphatase in Neuronal Function. Neural Plast 2016; 2016:8136925. [PMID: 27190655 PMCID: PMC4844879 DOI: 10.1155/2016/8136925] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/27/2016] [Indexed: 11/18/2022] Open
Abstract
Striatal-enriched protein tyrosine phosphatase (STEP) is a CNS-enriched protein implicated in multiple neurologic and neuropsychiatric disorders. STEP regulates key signaling proteins required for synaptic strengthening as well as NMDA and AMPA receptor trafficking. Both high and low levels of STEP disrupt synaptic function and contribute to learning and behavioral deficits. High levels of STEP are present in human postmortem samples and animal models of Alzheimer's disease, Parkinson's disease, and schizophrenia and in animal models of fragile X syndrome. Low levels of STEP activity are present in additional disorders that include ischemia, Huntington's chorea, alcohol abuse, and stress disorders. Thus the current model of STEP is that optimal levels are required for optimal synaptic function. Here we focus on the role of STEP in Alzheimer's disease and the mechanisms by which STEP activity is increased in this illness. Both genetic lowering of STEP levels and pharmacological inhibition of STEP activity in mouse models of Alzheimer's disease reverse the biochemical and cognitive abnormalities that are present. These findings suggest that STEP is an important point for modulation of proteins required for synaptic plasticity.
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Zhang JJ, Han J, Sui N. Okadaic acid blocks the effects of 5-aza-2-deoxycytidine on consolidation, acquisition and retrieval of morphine-induced place preference in rats. Neuropharmacology 2014; 86:282-93. [DOI: 10.1016/j.neuropharm.2014.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 07/18/2014] [Accepted: 08/05/2014] [Indexed: 12/22/2022]
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10
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Huang CC, Chu CY, Yeh CM, Hsu KS. Acute hypernatremia dampens stress-induced enhancement of long-term potentiation in the dentate gyrus of rat hippocampus. Psychoneuroendocrinology 2014; 46:129-40. [PMID: 24882165 DOI: 10.1016/j.psyneuen.2014.04.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 04/22/2014] [Accepted: 04/22/2014] [Indexed: 01/09/2023]
Abstract
Stress often occurs within the context of homeostatic threat, requiring integration of physiological and psychological demands to trigger appropriate behavioral, autonomic and endocrine responses. However, the neural mechanism underlying stress integration remains elusive. Using an acute hypernatremic challenge (2.0M NaCl subcutaneous), we assessed whether physical state may affect subsequent responsiveness to psychogenic stressors. We found that experienced forced swimming (FS, 15min in 25°C), a model of psychogenic stress, enhanced long-term potentiation (LTP) induction in the dentate gyrus (DG) of the rat hippocampus ex vivo. The effect of FS on LTP was prevented when the animals were adrenalectomized or given mineralocorticoid receptor antagonist RU28318 before experiencing stress. Intriguingly, relative to normonatremic controls, hypernatremic challenge effectively elevated plasma sodium concentration and dampened FS-induced enhancement of LTP, which was prevented by adrenalectomy. In addition, acute hypernatremic challenge resulted in increased extracellular signal-regulated kinase (ERK)1/2 phosphorylation in the DG and occluded the subsequent activation of ERK1/2 by FS. Moreover, stress response dampening effects by acute hypernatremic challenge remained intact in conditional oxytocin receptor knockout mice. These results suggest that acute hypernatremic challenge evokes a sustained increase in plasma corticosterone concentration, which in turn produces stress-like changes in the DG, thereby occluding subsequent responsiveness to psychogenetic stress. They also fit into the general concept of "metaplasticity" - that is, the responsiveness to stress is not fixed but appears to be governed by the recent history of prior physical state.
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Affiliation(s)
- Chiung-Chun Huang
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chiao-Yin Chu
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Che-Ming Yeh
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Kuei-Sen Hsu
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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Bukalo O, Pinard CR, Holmes A. Mechanisms to medicines: elucidating neural and molecular substrates of fear extinction to identify novel treatments for anxiety disorders. Br J Pharmacol 2014; 171:4690-718. [PMID: 24835117 DOI: 10.1111/bph.12779] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/28/2014] [Accepted: 05/04/2014] [Indexed: 12/11/2022] Open
Abstract
The burden of anxiety disorders is growing, but the efficacy of available anxiolytic treatments remains inadequate. Cognitive behavioural therapy for anxiety disorders focuses on identifying and modifying maladaptive patterns of thinking and behaving, and has a testable analogue in rodents in the form of fear extinction. A large preclinical literature has amassed in recent years describing the neural and molecular basis of fear extinction in rodents. In this review, we discuss how this work is being harnessed to foster translational research on anxiety disorders and facilitate the search for new anxiolytic treatments. We begin by summarizing the anatomical and functional connectivity of a medial prefrontal cortex (mPFC)-amygdala circuit that subserves fear extinction, including new insights from optogenetics. We then cover some of the approaches that have been taken to model impaired fear extinction and associated impairments with mPFC-amygdala dysfunction. The principal goal of the review is to evaluate evidence that various neurotransmitter and neuromodulator systems mediate fear extinction by modulating the mPFC-amygdala circuitry. To that end, we describe studies that have tested how fear extinction is impaired or facilitated by pharmacological manipulations of dopamine, noradrenaline, 5-HT, GABA, glutamate, neuropeptides, endocannabinoids and various other systems, which either directly target the mPFC-amygdala circuit, or produce behavioural effects that are coincident with functional changes in the circuit. We conclude that there are good grounds to be optimistic that the progress in defining the molecular substrates of mPFC-amygdala circuit function can be effectively leveraged to identify plausible candidates for extinction-promoting therapies for anxiety disorders.
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Affiliation(s)
- Olena Bukalo
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
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12
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Jin F, Li L, Shi M, Li Z, Zhou J, Chen L. The longitudinal study of rat hippocampus influenced by stress: Early adverse experience enhances hippocampal vulnerability and working memory deficit in adult rats. Behav Brain Res 2013; 246:116-24. [DOI: 10.1016/j.bbr.2013.02.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 02/19/2013] [Accepted: 02/24/2013] [Indexed: 11/16/2022]
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Baumgärtel K, Mansuy IM. Neural functions of calcineurin in synaptic plasticity and memory. Learn Mem 2012; 19:375-84. [PMID: 22904368 DOI: 10.1101/lm.027201.112] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Major brain functions depend on neuronal processes that favor the plasticity of neuronal circuits while at the same time maintaining their stability. The mechanisms that regulate brain plasticity are complex and engage multiple cascades of molecular components that modulate synaptic efficacy. Protein kinases (PKs) and phosphatases (PPs) are among the most important of these components that act as positive and negative regulators of neuronal signaling and plasticity, respectively. In these cascades, the PP protein phosphatase 2B or calcineurin (CaN) is of particular interest because it is the only Ca(2+)-activated PP in the brain and a major regulator of key proteins essential for synaptic transmission and neuronal excitability. This review describes the primary properties of CaN and illustrates its functions and modes of action by focusing on several representative targets, in particular glutamate receptors, striatal enriched protein phosphatase (STEP), and neuromodulin (GAP43), and their functional significance for synaptic plasticity and memory.
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Affiliation(s)
- Karsten Baumgärtel
- Dorris Neuroscience Center, Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037-1000, USA
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A critical role for protein tyrosine phosphatase nonreceptor type 5 in determining individual susceptibility to develop stress-related cognitive and morphological changes. J Neurosci 2012; 32:7550-62. [PMID: 22649233 DOI: 10.1523/jneurosci.5902-11.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
While stressful life events confer increased risk for the development of psychopathology, most individuals experiencing adversity maintain normal psychological functioning, suggesting that individual differences may influence the susceptibility to develop stress-related psychiatric disorders. However, little is known about what determines this difference between individuals at the molecular level. In the present study, we identify that protein tyrosine phosphatase nonreceptor type 5 (PTPN5) (also known as STEP) is a critical determinant of differences in individual susceptibility to develop stress-related cognitive and morphological changes in rats. Our data demonstrate that ablation of PTPN5 expression delays physiological recovery from stress and augments the development of stress-related cognitive and morphological changes, whereas overexpression of a constitutively active variant of PTPN5 enhances the individual's resilience to stress. Our data also reveal that reduced PTPN5 expression prolongs the duration of extracellular signal-regulated kinase activation, leading to an elevation of Ca(V)1.2 channel expression and a recovery delay of K(V)4.2 channels from inactivation, which in turn heightens neuronal vulnerability to glutamate toxicity. Moreover, intraperitoneal injections of L-type Ca(2+) channel blocker nifedipine after stress resulted in a significantly lower rate for developing stress-related cognitive and morphological changes seen in PTPN5 knockdown rats. Together, these results identify a novel role for PTPN5 in mediating the development of stress-related cognitive and morphological changes and suggest that people with PTPN5 deficiency may have a greater susceptibility to capture the deleterious effects of stress.
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15
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Qi Y, Hu NW, Rowan MJ. Switching off LTP: mGlu and NMDA receptor-dependent novelty exploration-induced depotentiation in the rat hippocampus. Cereb Cortex 2012; 23:932-9. [PMID: 22490551 DOI: 10.1093/cercor/bhs086] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Both electrically induced synaptic long-term potentiation (LTP) and long-term depression have been extensively studied as models of the cellular basis of learning and memory mechanisms. Recently, considerable interest has been generated by the possibility that the activity-dependent persistent reversal of previously established synaptic LTP (depotentiation) may play a role in the time- and state-dependent erasure of memory. Here, we examined the requirement for glutamate receptor activation in experience-induced reversal of previously established LTP in the CA1 area of the hippocampus of freely behaving rats. Continuous exploration of non-aversive novelty for ~30 min, which was associated with hippocampal activation as measured by increased theta power in the electroencephalogram, triggered a rapid and persistent reversal of high frequency stimulation-induced LTP both at apical and basal synapses. Blockade of metabotropic glutamate (mGlu) receptors with mGlu5 subtype-selective antagonists, or N-methyl-D-aspartate (NMDA) receptors with GluN2B subunit-selective antagonists, prevented novelty-induced depotentiation. These findings strongly indicate that activation of both mGlu5 receptors and GluN2B-containing NMDA receptors is required for experience-triggered induction of depotentiation at CA3-CA1 synapses. The mechanistic concordance of the present and previous studies of experience-induced and electrically induced synaptic depotentiation helps to integrate our understanding of the neurophysiological underpinnings of learning and memory.
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Affiliation(s)
- Yingjie Qi
- Department of Pharmacology and Therapeutics, Trinity College, Dublin 2, Ireland
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Foster TC. Dissecting the age-related decline on spatial learning and memory tasks in rodent models: N-methyl-D-aspartate receptors and voltage-dependent Ca2+ channels in senescent synaptic plasticity. Prog Neurobiol 2012; 96:283-303. [PMID: 22307057 DOI: 10.1016/j.pneurobio.2012.01.007] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 01/09/2012] [Accepted: 01/19/2012] [Indexed: 10/14/2022]
Abstract
In humans, heterogeneity in the decline of hippocampal-dependent episodic memory is observed during aging. Rodents have been employed as models of age-related cognitive decline and the spatial water maze has been used to show variability in the emergence and extent of impaired hippocampal-dependent memory. Impairment in the consolidation of intermediate-term memory for rapidly acquired and flexible spatial information emerges early, in middle-age. As aging proceeds, deficits may broaden to include impaired incremental learning of a spatial reference memory. The extent and time course of impairment has been be linked to senescence of calcium (Ca²⁺) regulation and Ca²⁺-dependent synaptic plasticity mechanisms in region CA1. Specifically, aging is associated with altered function of N-methyl-D-aspartate receptors (NMDARs), voltage-dependent Ca²⁺ channels (VDCCs), and ryanodine receptors (RyRs) linked to intracellular Ca²⁺ stores (ICS). In young animals, NMDAR activation induces long-term potentiation of synaptic transmission (NMDAR-LTP), which is thought to mediate the rapid consolidation of intermediate-term memory. Oxidative stress, starting in middle-age, reduces NMDAR function. In addition, VDCCs and ICS can actively inhibit NMDAR-dependent LTP and oxidative stress enhances the role of VDCC and RyR-ICS in regulating synaptic plasticity. Blockade of L-type VDCCs promotes NMDAR-LTP and memory in older animals. Interestingly, pharmacological or genetic manipulations to reduce hippocampal NMDAR function readily impair memory consolidation or rapid learning, generally leaving incremental learning intact. Finally, evidence is mounting to indicate a role for VDCC-dependent synaptic plasticity in associative learning and the consolidation of remote memories. Thus, VDCC-dependent synaptic plasticity and extrahippocampal systems may contribute to incremental learning deficits observed with advanced aging.
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Affiliation(s)
- Thomas C Foster
- Department of Neuroscience, Evelyn F. and William L. McKnight Brain Institute, University of Florida, PO Box 100244, Gainesville, FL 32610-0244, USA. ,
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Zorumski CF, Izumi Y. NMDA receptors and metaplasticity: mechanisms and possible roles in neuropsychiatric disorders. Neurosci Biobehav Rev 2012; 36:989-1000. [PMID: 22230702 DOI: 10.1016/j.neubiorev.2011.12.011] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/14/2011] [Accepted: 12/22/2011] [Indexed: 02/08/2023]
Abstract
N-methyl-D-aspartate receptors (NMDARs) are key components of neural signaling, playing roles in synaptic transmission and in the synaptic plasticity thought to underlie learning and memory. NMDAR activation can also have neurotoxic consequences contributing to several forms of neurodegeneration. Additionally, NMDARs can modulate neuronal function and regulate the ability of synapses to undergo synaptic plasticity. Evidence gathered over the past 20 years strongly supports the idea that untimely activation of NMDARs impairs the induction of long-term potentiation (LTP) by a form of metaplasticity. This metaplasticity can be triggered by multiple stimuli including physiological receptor activation, and metabolic and behavioral stressors. These latter findings raise the possibility that NMDARs contribute to cognitive dysfunction associated with neuropsychiatric disorders. This paper examines NMDAR metaplasticity and its potential role in cognition. Recent studies using NMDAR antagonists for therapeutic purposes also raise the possibility that metaplasticity may contribute to clinical effects of certain drugs.
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Affiliation(s)
- Charles F Zorumski
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Satb1 ablation alters temporal expression of immediate early genes and reduces dendritic spine density during postnatal brain development. Mol Cell Biol 2011; 32:333-47. [PMID: 22064485 DOI: 10.1128/mcb.05917-11] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Complex behaviors, such as learning and memory, are associated with rapid changes in gene expression of neurons and subsequent formation of new synaptic connections. However, how external signals are processed to drive specific changes in gene expression is largely unknown. We found that the genome organizer protein Satb1 is highly expressed in mature neurons, primarily in the cerebral cortex, dentate hilus, and amygdala. In Satb1-null mice, cortical layer morphology was normal. However, in postnatal Satb1-null cortical pyramidal neurons, we found a substantial decrease in the density of dendritic spines, which play critical roles in synaptic transmission and plasticity. Further, we found that in the cerebral cortex, Satb1 binds to genomic loci of multiple immediate early genes (IEGs) (Fos, Fosb, Egr1, Egr2, Arc, and Bdnf) and other key neuronal genes, many of which have been implicated in synaptic plasticity. Loss of Satb1 resulted in greatly alters timing and expression levels of these IEGs during early postnatal cerebral cortical development and also upon stimulation in cortical organotypic cultures. These data indicate that Satb1 is required for proper temporal dynamics of IEG expression. Based on these findings, we propose that Satb1 plays a critical role in cortical neurons to facilitate neuronal plasticity.
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Kumar A, Rani A, Tchigranova O, Lee WH, Foster TC. Influence of late-life exposure to environmental enrichment or exercise on hippocampal function and CA1 senescent physiology. Neurobiol Aging 2011; 33:828.e1-17. [PMID: 21820213 DOI: 10.1016/j.neurobiolaging.2011.06.023] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 06/13/2011] [Accepted: 06/23/2011] [Indexed: 01/11/2023]
Abstract
Aged (20-22 months) male Fischer 344 rats were randomly assigned to sedentary (A-SED), environmentally-enriched (A-ENR), or exercise (A-EX) conditions. After 10-12 weeks of differential experience, the 3 groups of aged rats and young sedentary controls were tested for physical and cognitive function. Spatial discrimination learning and memory consolidation, tested on the water maze, were enhanced in environmentally-enriched compared with sedentary. A-EX exhibited improved and impaired performance on the cue and spatial task, respectively. Impaired spatial learning in A-EX was likely due to a bias in response selection associated with exercise training, as object recognition memory improved for A-EX rats. An examination of senescent hippocampal physiology revealed that enrichment and exercise reversed age-related changes in long-term depression (LTD) and long-term potentiation (LTP). Rats in the enrichment group exhibited an increase in cell excitability compared with the other 2 groups of aged animals. The results indicate that differential experience biased the selection of a spatial or a response strategy and factors common across the 2 conditions, such as increased hippocampal activity associated with locomotion, contribute to reversal of senescent synaptic plasticity.
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Affiliation(s)
- Ashok Kumar
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610-0244, USA
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Motanis H, Maroun M. Exposure to a novel context following contextual fear conditioning enhances the induction of hippocampal long-term potentiation. Eur J Neurosci 2010; 32:840-6. [DOI: 10.1111/j.1460-9568.2010.07334.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Chen CC, Yang CH, Huang CC, Hsu KS. Acute stress impairs hippocampal mossy fiber-CA3 long-term potentiation by enhancing cAMP-specific phosphodiesterase 4 activity. Neuropsychopharmacology 2010; 35:1605-17. [PMID: 20237461 PMCID: PMC3055459 DOI: 10.1038/npp.2010.33] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The mossy fiber synapses onto hippocampal CA3 neurons show unique molecular features and a wide dynamic range of plasticity. Although acute stress has been well recognized to alter bidirectional long-term synaptic plasticity in the hippocampal CA1 region and dentate gyrus, it remains unclear whether the same effect may also occur at the mossy fiber-CA3 synapses. Here, we report that hippocampal slices prepared from adult mice that had experienced an acute unpredictable and inescapable restraint tail-shock stress showed a marked impairment of long-term potentiation (LTP) induced by high-frequency stimulation or adenylyl cyclase activator forskolin. This effect was prevented when animals were submitted to bilateral adrenalectomy or given the glucocorticoid receptor antagonist RU38486 before experiencing stress. In contrast, stress has no effect on synaptic potentiation induced by the non-hydrolysable and membrane-permeable cyclic adenosine 5'-monophosphate (cAMP) analog Sp-8-bromo-cAMPS. No obvious differences were observed between control and stressed mice in the basal synaptic transmission, paired-pulse facilitation, or frequency facilitation at the mossy fiber-CA3 synapses. We also found that the inhibitory effect of stress on mossy fiber LTP was obviated by the adenosine A(1) receptor antagonist 8-cyclopentyl-1,3,-dipropylxanthine, the non-specific phosphodiesterase (PDE) inhibitor 3-isobutyl-methylxanthine, and the specific PDE4 inhibitor 4-(3-butoxy-4-methoxyphenyl)methyl-2-imidazolidone. In addition, stress induces a sustained and profound increase in cAMP-specific PDE4 activity. These results suggest that the inhibition of mossy fiber LTP by acute stress treatment seems originating from a corticosterone-induced sustained increase in the PDE4 activity to accelerate the metabolism of cAMP to adenosine, in turn triggering an adenosine A(1) receptor-mediated impairment of transmitter release machinery.
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Affiliation(s)
- Chien-Chung Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chih-Hao Yang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chiung-Chun Huang
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Kuei-Sen Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan,Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan,Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University, Tainan, Taiwan,Department of Pharmacology, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan, Tel: +886 6235 3535 ext: 5498, Fax: +886 6274 9296, E-mail:
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Ryan BK, Vollmayr B, Klyubin I, Gass P, Rowan MJ. Persistent inhibition of hippocampal long-term potentiation in vivo by learned helplessness stress. Hippocampus 2009; 20:758-67. [DOI: 10.1002/hipo.20677] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Adaptations of striatal endocannabinoid system during stress. Mol Neurobiol 2009; 39:178-84. [PMID: 19267225 DOI: 10.1007/s12035-009-8061-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Accepted: 02/18/2009] [Indexed: 01/24/2023]
Abstract
The endocannabinoid system (ECS) plays a fundamental role in the regulation of synaptic transmission. Exposure to stressful events triggers synaptic adaptations in many brain areas. The activity of the ECS in stress-responsive neural circuits suggests that it may be involved in the behavioral responses and synaptic effects typical of stress. In this review, we discuss evidence demonstrating that striatal ECS is modulated by stress. Chronic stress exposure alters endocannabinoid levels, cannabinoid CB1 receptor binding and cannabinoid CB1 receptor-mediated control of inhibitory synaptic transmission in the striatum. Recent studies have shown that impairment of endocannabinoid signalling is associated with inability to adapt to chronic stress and to the development of maladaptive behaviors. The ECS represents a novel potential pharmacological target to treat stress-associated neuropsychiatric conditions.
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Sierra-Mercado D, Dieguez D, Barea-Rodriguez EJ. Brief novelty exposure facilitates dentate gyrus LTP in aged rats. Hippocampus 2008; 18:835-43. [PMID: 18481283 DOI: 10.1002/hipo.20447] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Aging is associated with a decreased capacity for dentate gyrus (DG) granule cell depolarization as well as reduced perforant path activation. Although it is well established that the maintenance of DG long-term potentiation (LTP) over days is impaired in aged, as compared to young animals, the threshold for inducing this LTP has never been investigated in aged, awake animals. In addition, although exposure to novelty prior to theta-burst stimulation (TBS) increases both the induction and longevity of DG LTP in adult rats, the effects of exposure to novelty on LTP in aged rats have never been investigated. Here, we report that although TBS delivered in the home cage induces robust and long-lasting DG LTP in young rats, TBS fails to induce DG LTP in aged rats. Interestingly, delivery of TBS to aged rats exploring novel environments induces robust and long-lasting LTP, with the induction, but not the longevity, of this LTP being similar in magnitude to that observed in young rats delivered TBS in the home cage. These results indicate that although TBS-induced DG LTP is impaired in aged, as compared to young rats, TBS during exploration of novel environments is sufficient to rescue age-related deficits in DG LTP. We discuss these observations in the context of previous findings suggesting that the facilitation of LTP by exposure to novel environments results as a consequence of reduced network inhibition in the DG and we suggest that, in spite of age-related changes in the DG, this capacity persists in aged rats and represents a nondietary and nonpharmacological way to facilitate DG LTP during aging.
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Affiliation(s)
- Demetrio Sierra-Mercado
- Neurobiology of Aging Laboratory, Department of Biology, The University of Texas, San Antonio, Texas 78249-0662, USA
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Synaptic plasticity in learning and memory: stress effects in the hippocampus. PROGRESS IN BRAIN RESEARCH 2008; 169:145-58. [PMID: 18394472 DOI: 10.1016/s0079-6123(07)00008-8] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Synaptic plasticity has often been argued to play an important role in learning and memory. The discovery of long-term potentiation (LTP) and long-term depression (LTD), the two most widely cited cellular models of synaptic plasticity, significantly spurred research in this field. Although correlative evidence suggesting a role for synaptic changes such as those seen in LTP and LTD in learning and memory has been gained in a number of studies, definitive demonstrations of a specific role for either LTP or LTD in learning and memory are lacking. In this review, we discuss a number of recent advancements in the understanding of the mechanisms that mediate LTP and LTD in the rodent hippocampus and focus on the use of subunit-specific N-methyl-d-aspartate receptor antagonists and interference peptides as potential tools to study the role of synaptic plasticity in learning and memory. By using the modulation of synaptic plasticity and hippocampal-dependent learning and memory by acute stress as an example, we review a large body of convincing evidence indicating that alterations in synaptic plasticity underlie the changes in learning and memory produced by acute stress.
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Chronic psychoemotional stress impairs cannabinoid-receptor-mediated control of GABA transmission in the striatum. J Neurosci 2008; 28:7284-92. [PMID: 18632932 DOI: 10.1523/jneurosci.5346-07.2008] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Exposure to stressful events has a myriad of consequences in animals and in humans, and triggers synaptic adaptations in many brain areas. Stress might also alter cannabinoid-receptor-mediated transmission in the brain, but no physiological study has addressed this issue so far. In the present study, we found that social defeat stress, induced in mice by exposure to aggression, altered cannabinoid CB(1)-receptor-mediated control of synaptic transmission in the striatum. In fact, the presynaptic inhibition of GABAergic IPSCs induced by the cannabinoid CB(1) receptor agonist HU210 [(6aR)-trans-3-(1,1-dimethylheptyl)-6a,7,10,10a-tetrahydro-1-hydroxy-6,6-dimethyl-6H-dibenzo[b,d]pyran-9-methanol] was reduced after a single stressful episode and fully abolished after 3 and 7 d of stress exposure. Repeated psychoemotional stress also impaired the sensitivity of GABA synapses to endocannabinoids mobilized by group I metabotropic glutamate receptor stimulation, whereas the cannabinoid CB(1)-mediated control of glutamate transmission was unaffected by repeated exposure to an aggressor. Corticosteroids released in response to the activation of the hypothalamic-pituitary-adrenal axis played a major role in the synaptic defects observed in stressed animals, because these alterations were fully prevented by pharmacological blockade of glucocorticoid receptors and were mimicked by corticosterone injections. The recovery of stress-induced synaptic defects was favored when stressed mice were given access to a running wheel or to sucrose consumption, which function as potent natural rewards. A similar rescuing effect was obtained by a single injection of cocaine, a psychostimulant with strong rewarding properties. Targeting cannabinoid CB(1) receptors or endocannabinoid metabolism might be a valuable option to treat stress-associated neuropsychiatric conditions.
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Chewing ameliorates stress-induced suppression of hippocampal long-term potentiation. Neuroscience 2008; 154:1352-9. [DOI: 10.1016/j.neuroscience.2008.04.057] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Revised: 04/09/2008] [Accepted: 04/28/2008] [Indexed: 11/21/2022]
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Yang CH, Huang CC, Hsu KS. Differential roles of basolateral and central amygdala on the effects of uncontrollable stress on hippocampal synaptic plasticity. Hippocampus 2008; 18:548-63. [DOI: 10.1002/hipo.20414] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Alvarez EO, Alvarez PA. Motivated exploratory behaviour in the rat: The role of hippocampus and the histaminergic neurotransmission. Behav Brain Res 2008; 186:118-25. [PMID: 17825439 DOI: 10.1016/j.bbr.2007.07.038] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 07/26/2007] [Accepted: 07/30/2007] [Indexed: 11/25/2022]
Abstract
Exploration is one of most basic adaptive behavioural responses, giving the animal an important evolutionary advantage to survive in a changing environment. Inspection of novel environments might be come with motivated exploratory behaviour. In spite that this type of exploration in the rat is known for many years, little attention has been given to the intrinsic mechanisms or the brain structures that are involved in. In the present work the hippocampus, the neurotransmitter histamine, and the geometrical features of novel objects were examined in a model of conflictive and non-conflictive exploration in the rat which evaluates incentive-motivated exploration. Young adult intact rats were tested in a neutral non-conflictive behavioural activity detector (OVM), with (eOVM) or without (sOVM) novel objects. Three different objects were used: a box, a toy duck, and a tower. Results show that animals decrease its general motor activity (horizontal, ambulatory and non-ambulatory activity) in favor to exploration of the objects. Motivated exploration was not the same for all three objects. Rats explored significantly more the Tower and the Box objects than the Duck item. Behavioral patterns of hippocampus-implanted rats showed decreased scores in motor activity but maintained the difference in the relation of "without/with objects" exploration. When hippocampus-implanted rats were tested in a conflictive exploration device (the elevated asymmetric plus-maze), exploration of the No Wall arm, considered the most fear-inducing environment, was significantly more explored by the animal when the tower object was positioned at its end than when it was absent. Microinjection into the ventral hippocampus of histamine abolished this motivated exploratory response. Pre-treatment with pyrilamine, and not with ranitidine, was effective to block the inhibitory effect of histamine on the object motivated exploration. Results confirm that the hippocampus is involved on incentive motivated exploration, and suggest that histamine is part of an analyzing neuronal circuit of novelty incentivating behavioural responses in rats.
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Affiliation(s)
- Edgardo O Alvarez
- Area de Farmacología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, IMBECU-CONICET, Mendoza, Argentina.
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Yang PC, Yang CH, Huang CC, Hsu KS. Phosphatidylinositol 3-kinase activation is required for stress protocol-induced modification of hippocampal synaptic plasticity. J Biol Chem 2007; 283:2631-43. [PMID: 18057005 DOI: 10.1074/jbc.m706954200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stress dramatically affects the induction of hippocampal synaptic plasticity; however, the molecular details of how it does so remain unclear. Phosphatidylinositol 3-kinase (PI3K) signaling plays a crucial role in promoting neuronal survival and neuroplasticity, but its role, if any, in stress-induced alterations of long term potentiation (LTP) and long term depression (LTD) is unknown. We found here that inhibitors of PI3K signaling blocked the effects of acute restraint-tail shock stress protocol on LTP and LTD. Therefore, the purpose of the present study is to explore the signaling events involving PI3K in terms of its role in mediating stress protocol-induced alterations of LTP and LTD. We found that stress protocol-induced PI3K activation can be blocked by various inhibitors, including RU38486 for glucocorticoid receptors, LY294002 for PI3K, and dl-2-amino-5-phosphonopentanoic acid for N-methyl-D-aspartate receptors or brain-derived neurotrophic factor antisense oligonucleotides. Also, immunoblotting analyses revealed that stress protocol induced a profound and prolonged phosphorylation of numbers of PI3K downstream effectors, including 3-phosphoinositide-dependent protein kinase-1, protein kinase B, mammalian target of rapamycin (mTOR), p70 S6 kinase, and eukaryotic initiation factor 4B in hippocampal CA1 homogenate, which was prevented by the PI3K inhibitor pretreatment. More importantly, we found that stress protocol significantly increased the protein expression of dendritic scaffolding protein PSD-95 (postsynaptic density-95), which is known to be involved in LTP and LTD, in an mTOR-dependent manner. These results identify a key role of PI3K signaling in mediating the stress protocol-induced modification of hippocampal synaptic plasticity and further suggest that PI3K may do so by invoking the protein expression of PSD-95.
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Affiliation(s)
- Ping-Chun Yang
- Department of Pharmacology, College of Medicine, National Cheng-Kung University, 1 University Road, Tainan, Taiwan
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