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Raven F, Bolsius YG, Renssen LV, Meijer EL, Zee EA, Meerlo P, Havekes R. Elucidating the role of protein synthesis in hippocampus‐dependent memory consolidation across the day and night. Eur J Neurosci 2020; 54:6972-6981. [PMID: 31965655 PMCID: PMC8596627 DOI: 10.1111/ejn.14684] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 01/08/2020] [Accepted: 01/13/2020] [Indexed: 01/11/2023]
Abstract
It is widely acknowledged that de novo protein synthesis is crucial for the formation and consolidation of long‐term memories. While the basal activity of many signaling cascades that modulate protein synthesis fluctuates in a circadian fashion, it is unclear whether the temporal dynamics of protein synthesis‐dependent memory consolidation vary depending on the time of day. More specifically, it is unclear whether protein synthesis inhibition affects hippocampus‐dependent memory consolidation in rodents differentially across the day (i.e., the inactive phase with an abundance of sleep) and night (i.e., the active phase with little sleep). To address this question, male and female C57Bl6/J mice were trained in a contextual fear conditioning task at the beginning or the end of the light phase. Animals received a single systemic injection with the protein synthesis inhibitor anisomycin or vehicle directly, 4, 8 hr, or 11.5 hr following training, and memory was assessed after 24 hr. Here, we show that protein synthesis inhibition impaired the consolidation of context–fear memories selectively when the protein synthesis inhibitor was administered at the first three time points, irrespective of timing of training. Even though the basal activity of signaling pathways regulating de novo protein synthesis may fluctuate across the 24‐hr cycle, these results suggest that the temporal dynamics of protein synthesis‐dependent memory consolidation are similar for day‐time and night‐time learning.
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Affiliation(s)
- Frank Raven
- Groningen Institute for Evolutionary Life Sciences (GELIFES) University of Groningen Groningen The Netherlands
| | - Youri G. Bolsius
- Groningen Institute for Evolutionary Life Sciences (GELIFES) University of Groningen Groningen The Netherlands
| | - Lara V. Renssen
- Groningen Institute for Evolutionary Life Sciences (GELIFES) University of Groningen Groningen The Netherlands
| | - Elroy L. Meijer
- Groningen Institute for Evolutionary Life Sciences (GELIFES) University of Groningen Groningen The Netherlands
| | - Eddy A. Zee
- Groningen Institute for Evolutionary Life Sciences (GELIFES) University of Groningen Groningen The Netherlands
| | - Peter Meerlo
- Groningen Institute for Evolutionary Life Sciences (GELIFES) University of Groningen Groningen The Netherlands
| | - Robbert Havekes
- Groningen Institute for Evolutionary Life Sciences (GELIFES) University of Groningen Groningen The Netherlands
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Overtraining modifies spatial memory susceptibility to corticosterone administration. Neurobiol Learn Mem 2017; 145:232-239. [DOI: 10.1016/j.nlm.2017.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 09/28/2017] [Accepted: 10/07/2017] [Indexed: 12/20/2022]
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González-Salinas S, Medina AC, Marín-Vignando V, Ruiz-López CX, Quirarte GL, Prado-Alcalá RA. Protein synthesis is not required for acquisition, consolidation, and extinction of high foot-shock active avoidance training. Behav Brain Res 2015; 287:8-14. [DOI: 10.1016/j.bbr.2015.03.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 03/11/2015] [Accepted: 03/16/2015] [Indexed: 01/01/2023]
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Almeida-Corrêa S, Moulin TC, Carneiro CFD, Gonçalves MMC, Junqueira LS, Amaral OB. Calcineurin inhibition blocks within-, but not between-session fear extinction in mice. Learn Mem 2015; 22:159-69. [PMID: 25691516 PMCID: PMC4340130 DOI: 10.1101/lm.037770.114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 01/02/2015] [Indexed: 01/11/2023]
Abstract
Memory extinction involves the formation of a new associative memory that inhibits a previously conditioned association. Nonetheless, it could also depend on weakening of the original memory trace if extinction is assumed to have multiple components. The phosphatase calcineurin (CaN) has been described as being involved in extinction but not in the initial consolidation of fear learning. With this in mind, we set to study whether CaN could have different roles in distinct components of extinction. Systemic treatment with the CaN inhibitors cyclosporin A (CsA) or FK-506, as well as i.c.v. administration of CsA, blocked within-session, but not between-session extinction or initial learning of contextual fear conditioning. Similar effects were found in multiple-session extinction of contextual fear conditioning and in auditory fear conditioning, indicating that CaN is involved in different types of short-term extinction. Meanwhile, inhibition of protein synthesis by cycloheximide (CHX) treatment did not affect within-session extinction, but disrupted fear acquisition and slightly impaired between-session extinction. Our results point to a dissociation of within- and between-session extinction of fear conditioning, with the former being more dependent on CaN activity and the latter on protein synthesis. Moreover, the modulation of within-session extinction did not affect between-session extinction, suggesting that these components are at least partially independent.
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Affiliation(s)
- Suellen Almeida-Corrêa
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, RJ, 22290-290, Brazil
| | - Thiago C Moulin
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, RJ, 22290-290, Brazil
| | - Clarissa F D Carneiro
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, RJ, 22290-290, Brazil
| | - Marina M C Gonçalves
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, RJ, 22290-290, Brazil
| | - Lara S Junqueira
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, RJ, 22290-290, Brazil
| | - Olavo B Amaral
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, RJ, 22290-290, Brazil
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Increasing CRTC1 function in the dentate gyrus during memory formation or reactivation increases memory strength without compromising memory quality. J Neurosci 2013; 32:17857-68. [PMID: 23223304 DOI: 10.1523/jneurosci.1419-12.2012] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Memory stabilization following encoding (synaptic consolidation) or memory reactivation (reconsolidation) requires gene expression and protein synthesis (Dudai and Eisenberg, 2004; Tronson and Taylor, 2007; Nader and Einarsson, 2010; Alberini, 2011). Although consolidation and reconsolidation may be mediated by distinct molecular mechanisms (Lee et al., 2004), disrupting the function of the transcription factor CREB impairs both processes (Kida et al., 2002; Mamiya et al., 2009). Phosphorylation of CREB at Ser133 recruits CREB binding protein (CBP)/p300 coactivators to activate transcription (Chrivia et al., 1993; Parker et al., 1996). In addition to this well known mechanism, CREB regulated transcription coactivators (CRTCs), previously called transducers of regulated CREB (TORC) activity, stimulate CREB-mediated transcription, even in the absence of CREB phosphorylation. Recently, CRTC1 has been shown to undergo activity-dependent trafficking from synapses and dendrites to the nucleus in excitatory hippocampal neurons (Ch'ng et al., 2012). Despite being a powerful and specific coactivator of CREB, the role of CRTC in memory is virtually unexplored. To examine the effects of increasing CRTC levels, we used viral vectors to locally and acutely increase CRTC1 in the dorsal hippocampus dentate gyrus region of mice before training or memory reactivation in context fear conditioning. Overexpressing CRTC1 enhanced both memory consolidation and reconsolidation; CRTC1-mediated memory facilitation was context specific (did not generalize to nontrained context) and long lasting (observed after virally expressed CRTC1 dissipated). CREB overexpression produced strikingly similar effects. Therefore, increasing CRTC1 or CREB function is sufficient to enhance the strength of new, as well as established reactivated, memories without compromising memory quality.
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Stafford JM, Raybuck JD, Ryabinin AE, Lattal KM. Increasing histone acetylation in the hippocampus-infralimbic network enhances fear extinction. Biol Psychiatry 2012; 72:25-33. [PMID: 22290116 PMCID: PMC3352991 DOI: 10.1016/j.biopsych.2011.12.012] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 12/13/2011] [Accepted: 12/15/2011] [Indexed: 10/14/2022]
Abstract
BACKGROUND A key finding from recent studies of epigenetic mechanisms of memory is that increasing histone acetylation after a learning experience enhances memory consolidation. This has been demonstrated in several preparations, but little is known about whether excitatory and inhibitory memories are equally sensitive to drugs that promote histone acetylation and how transcriptional changes in the hippocampal-medial prefrontal cortex network contribute to these drug effects. METHODS We compare the long-term behavioral consequences of systemic, intrahippocampal and intra-medial prefrontal cortex administration of the histone deacetylase inhibitor sodium butyrate (NaB) after contextual fear conditioning and extinction 1 and/or 14 days later in male c57BL/6J mice (n = 302). Levels of histone acetylation and expression of the product of the immediate-early gene c-Fos were assessed by immunohistochemistry following infusion of NaB into the hippocampus (n = 26). RESULTS Across a variety of conditions, the effects of NaB on extinction were larger and more persistent compared to the effects on initial memory formation. NaB administered following weak extinction induced behavioral extinction, infralimbic histone acetylation and c-Fos expression consistent with strong extinction. No similar effect was seen in the prelimbic cortex. The involvement of the infralimbic cortex was confirmed as infusions of NaB into the infralimbic, but not prelimbic cortex, induced extinction enhancements. CONCLUSIONS These studies show that the memory modulating ability of drugs that enhance acetylation is sensitive to a variety of behavioral and molecular conditions. We further identify transcriptional changes in the hippocampal-infralimbic circuit associated with extinction enhancements induced by the histone deacetylase inhibitor NaB.
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da Silva WCN, Köhler CC, Radiske A, Cammarota M. D1/D5 dopamine receptors modulate spatial memory formation. Neurobiol Learn Mem 2012; 97:271-5. [PMID: 22266268 DOI: 10.1016/j.nlm.2012.01.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 12/19/2011] [Accepted: 01/04/2012] [Indexed: 10/14/2022]
Abstract
We investigated the effect of the intra-CA1 administration of the D1/D5 receptor antagonist SCH23390 and the D1/D5 receptor agonist SKF38393 on spatial memory in the water maze. When given immediately, but not 3h after training, SCH23390 hindered long-term spatial memory formation without affecting non-spatial memory or the normal functionality of the hippocampus. On the contrary, post-training infusion of SKF38393 enhanced retention and facilitated the spontaneous recovery of the original spatial preference after reversal learning. Our findings demonstrate that hippocampal D1/D5 receptors play an essential role in spatial memory processing.
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Affiliation(s)
- Weber C N da Silva
- Laboratório de Neuroquímica & Neurofisiologia da Memória, Centro de Memória, Instituto do Cérebro, Pontifícia Universidade Católica de Rio Grande do Sul, Av. Ipiranga, 6690-2nd floor, 90610-000 Porto Alegre, RS, Brazil
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Hong I, Kim J, Song B, Park S, Lee J, Kim J, An B, Lee S, Choi S. Modulation of fear memory by retrieval and extinction: a clue for memory deconsolidation. Rev Neurosci 2011; 22:205-29. [PMID: 21476941 DOI: 10.1515/rns.2011.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Memories are fragile and easily forgotten at first, but after a consolidation period of hours to weeks, are inscribed in our brains as stable traces, no longer vulnerable to conventional amnesic treatments. Retrieval of a memory renders it labile, akin to the early stages of consolidation. This phenomenon has been explored as memory reactivation, in the sense that the memory is temporarily 'deconsolidated', allowing a short time window for amnesic intervention. This window closes again after reconsolidation, which restores the stability of the memory. In contrast to this 'transient deconsolidation' and the short-spanned amnesic effects of consolidation blockers, some specific treatments can disrupt even consolidated memory, leading to apparent amnesia. We propose the term 'amnesic deconsolidation' to describe such processes that lead to disruption of consolidated memory and/or consolidated memory traces. We review studies of these 'amnesic deconsolidation' treatments that enhance memory extinction, alleviate relapse, and reverse learning-induced plasticity. The transient deconsolidation that memory retrieval induces and the amnesic deconsolidation that these regimes induce both seem to dislodge a component that stabilizes consolidated memory. Characterizing this component, at both molecular and network levels, will provide a key to developing clinical treatments for memory-related disorders and to defining the consolidated memory trace.
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Affiliation(s)
- Ingie Hong
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-742, Republic of Korea
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Méndez M, Méndez-López M, López L, Aller MA, Arias J, Arias JL. Portosystemic hepatic encephalopathy model shows reversal learning impairment and dysfunction of neural activity in the prefrontal cortex and regions involved in motivated behavior. J Clin Neurosci 2011; 18:690-4. [PMID: 21371891 DOI: 10.1016/j.jocn.2010.09.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 09/15/2010] [Accepted: 09/22/2010] [Indexed: 11/16/2022]
Abstract
Hepatic encephalopathy (HE) is a neurological complication that affects attention and memory. Experimental animal models have been used to study HE, the most frequent being the portacaval shunt (PCS). In order to investigate learning impairment and brain functional alterations in this model, we assessed reversal learning and neural metabolic activity in a PCS rat model. PCS and sham-operated rats were tested for reversal learning in the Morris water maze. Brains were then processed for cytochrome oxidase (CO) histochemistry. The PCS group had reversal learning impairment and a reduction in CO activity in the prefrontal cortex, ventral tegmental area and accumbens shell nucleus. These results suggest that this model of portosystemic HE shows learning impairments that could be linked to dysfunction in neural activity in the prefrontal cortex and regions involved in motivated behavior.
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Affiliation(s)
- M Méndez
- Laboratorio de Neurociencias, Departamento de Psicología, Universidad de Oviedo, Plaza Feijoo s/n. 33003, Oviedo, Spain.
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Boccia M, Blake M, Krawczyk M, Baratti C. Hippocampal alpha7 nicotinic receptors modulate memory reconsolidation of an inhibitory avoidance task in mice. Neuroscience 2010; 171:531-43. [DOI: 10.1016/j.neuroscience.2010.08.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 08/12/2010] [Accepted: 08/13/2010] [Indexed: 01/06/2023]
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Porte Y, Trifilieff P, Wolff M, Micheau J, Buhot M, Mons N. Extinction of spatial memory alters CREB phosphorylation in hippocampal CA1. Hippocampus 2010; 21:1169-79. [DOI: 10.1002/hipo.20844] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2010] [Indexed: 01/07/2023]
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Vargas-López V, Lamprea MR, Múnera A. Characterizing spatial extinction in an abbreviated version of the Barnes maze. Behav Processes 2010; 86:30-8. [PMID: 20708660 DOI: 10.1016/j.beproc.2010.08.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 07/31/2010] [Accepted: 08/03/2010] [Indexed: 01/13/2023]
Abstract
Adult male Wistar rats were trained to find an escape box in the Barnes maze in order to characterize the extinction process of a learned spatial preference. To do so, once they had fully acquired the spatial task, they were repeatedly exposed to the maze without the escape box. Multiple behavioral measurements (grouped into motor skill and spatial preference indicators) were followed up throughout the complete training process. Animals gained efficiency in finding the escape box during acquisition, as indicated by the reduction in the time spent escaping from the maze, the number of errors, the length of the traveled path, and by the increase in exploration accuracy and execution speed. When their retention and preference were tested 24h later, all the subjects retained their enhanced performance efficiency and accuracy and displayed a clear-cut preference for the escape hole and its adjacent holes. Almost all motor skill indicators followed an inverse, though not monotonic, pattern during the extinction training, returning to basal levels after three trials without escape box, displaying a transient relapse during the fifth extinction trial. Preference indicators also followed a reverse pattern; however, it took seven trials for them to return to basal levels, relapsing during the eighth extinction trial. The abbreviated Barnes maze acquisition, evaluation, and extinction procedures described herein are useful tools for evaluating the effects of behavioral and/or pharmacological treatment on different stages of spatial memory, and could also be used for studying the neurophysiological and neurobiological underpinnings of this kind of memory.
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Affiliation(s)
- Viviana Vargas-López
- Behavioral Neurophysiology Laboratory, Universidad Nacional de Colombia, Bogotá, Colombia
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Kozlovsky N, Kaplan Z, Zohar J, Matar MA, Shimon H, Cohen H. Protein synthesis inhibition before or after stress exposure results in divergent endocrine and BDNF responses disassociated from behavioral responses. Depress Anxiety 2008; 25:E24-34. [PMID: 17828750 DOI: 10.1002/da.20366] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
This study aimed to assess the effects of anisomycin, a protein synthesis inhibitor, on behavioral responses, brain-derived neurotrophic factor (BDNF) and TrkB mRNA levels, and circulating corticosterone in rats-when administered before or after initial exposure to a predator scent stress stimulus. Magnitude of changes in prevalence of anxiety-like behaviors on the elevated plus-maze and exaggerated startle reaction as well as corticosterone levels and mRNA BDNF and TrkB were compared in rats exposed to predator stress, microinjected with anisomycin before or after stress exposure. Administration of anisomycin before or after stress exposure reduced anxiety-like behavior in the elevated plus-maze and reduced the mean startle amplitude 7 days postexposure. Although the behavioral responses were similar when anisomycin was microinjected before or after stress exposure, the levels of mRNAs for BDNF and TrkB, which play a role in modulation of synaptic plasticity and the consolidation process, showed varying responses.
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Affiliation(s)
- Nitsan Kozlovsky
- Ministry of Health Beer-Sheva Mental Health Center, Anxiety and Stress Research Unit, Ben-Gurion University of the Negev, Beer Sheva, Israel
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Baratti CM, Boccia MM, Blake MG, Acosta GB. Reactivated memory of an inhibitory avoidance response in mice is sensitive to a nitric oxide synthase inhibitor. Neurobiol Learn Mem 2008; 89:426-40. [DOI: 10.1016/j.nlm.2007.11.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2007] [Revised: 11/08/2007] [Accepted: 11/09/2007] [Indexed: 10/22/2022]
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Xia S, Li Y, Rosen EM, Laterra J. Ribotoxic stress sensitizes glioblastoma cells to death receptor induced apoptosis: requirements for c-Jun NH2-terminal kinase and Bim. Mol Cancer Res 2007; 5:783-92. [PMID: 17699104 DOI: 10.1158/1541-7786.mcr-06-0433] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A prominent feature of glioblastoma is its resistance to death receptor-mediated apoptosis. In this study, we explored the possibility of modulating death receptor-induced cell death with the c-Jun-NH2-terminal kinase (JNK) activator anisomycin. Anisomycin activates JNK by inactivating the ribosome and inducing "ribotoxic stress." We found that anisomycin and death receptor ligand anti-Fas antibody CH-11 or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) synergistically induce apoptosis in multiple human glioblastoma cell lines. For example, in U87 cells, anisomycin reduced the IC50 of CH-11 by more than 20-fold (from 500 to 25 ng/mL). Cell viability in response to anisomycin, CH-11, and their combination was 79%, 91%, and 28% (P<0.001), respectively. Anisomycin and TRAIL were found to be similarly synergistic in glioblastoma cells maintained as tumor xenografts. The potentiation of death receptor-dependent cell death by anisomycin was specific because emetine, another ribosome inhibitor that does not induce ribotoxic stress or activate JNK, did not have a similar effect. Synergistic cell death was predominantly apoptotic involving both extrinsic and intrinsic pathways. Expression of Fas, FasL, FLIP, and Fas-associated death domain (FADD) was not changed following treatment with anisomycin+CH-11. JNK was activated 10- to 22-fold by anisomycin+CH-11 in U87 cells. Inhibiting JNK activation with pharmacologic inhibitors of JNKK and JNK or with dominant negative mitogen-activated protein kinase (MAPK) kinase kinase 2 (MEKK2) significantly prevented cell death induced by the combination of anisomycin+CH-11. We further found that anisomycin+CH-11 up-regulated the proapoptotic protein Bim by approximately 14-fold. Simultaneously inhibiting Bim expression and JNK activation additively desensitized U87 cells to anisomycin+CH-11. These findings show that anisomycin-induced ribotoxic stress sensitizes glioblastoma cells to death receptor-induced apoptosis via a specific mechanism requiring both JNK activation and Bim induction.
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Affiliation(s)
- Shuli Xia
- Kennedy Krieger Research Institute, Department of Neurology, School of Medicine, Johns Hopkins University, 707 N. Broadway, Baltimore, MD 21205, USA
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Artinian J, De Jaeger X, Fellini L, de Saint Blanquat P, Roullet P. Reactivation with a simple exposure to the experimental environment is sufficient to induce reconsolidation requiring protein synthesis in the hippocampal CA3 region in mice. Hippocampus 2007; 17:181-91. [PMID: 17294462 DOI: 10.1002/hipo.20256] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Our understanding of the memory reconsolidation process is at an earlier stage than that of consolidation. For example, it is unclear if, as for memory consolidation, reconsolidation of a memory trace necessitates protein synthesis. In fact, conflicting results appear in the literature and this discrepancy may be due to differences in the experimental reactivation procedure. Here, we addressed the question of whether protein synthesis in the CA3 hippocampal region is crucial in memory consolidation and reconsolidation of allocentric knowledge after reactivation in different experimental conditions in the Morris water maze. We showed (1) that an injection of the protein synthesis inhibitor anisomycin in the CA3 region during consolidation or after a single reactivation trial disrupted performance and (2) that protein synthesis is required even after a simple contextual reactivation without any learning trial and independently of the presence of the reinforcement. This work demonstrates that a simple exposure to the spatial environment is sufficient to reactivate the memory trace, to make it labile, and that reconsolidation of this trace requires de novo protein synthesis.
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Affiliation(s)
- Julien Artinian
- Centre de Recherches sur la Cognition Animale, CNRS 5169, Université Paul Sabatier, Toulouse, France
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Abstract
Memory reconsolidation has been argued to be a distinct process that serves to maintain, strengthen or modify memories. Specifically, the retrieval of a previously consolidated memory has been hypothesized to induce an additional activity-dependent labile period during which the memory can be modified. Understanding the molecular mechanisms of reconsolidation could provide crucial insights into the dynamic aspects of normal mnemonic function and psychiatric disorders that are characterized by exceptionally strong and salient emotional memories.
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Affiliation(s)
- Natalie C Tronson
- Department of Psychiatry, Division of Molecular Psychiatry, Center for Genes and Behavior, Yale University School of Medicine, Abraham Ribicoff Research Facilities, Connecticut Mental Health Center, 34 Park Street, New Haven, Connecticut 06508, USA
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Abstract
Excessive fear and anxiety are hallmarks of a variety of disabling anxiety disorders that affect millions of people throughout the world. Hence, a greater understanding of the brain mechanisms involved in the inhibition of fear and anxiety is attracting increasing interest in the research community. In the laboratory, fear inhibition most often is studied through a procedure in which a previously fear conditioned organism is exposed to a fear-eliciting cue in the absence of any aversive event. This procedure results in a decline in conditioned fear responses that is attributed to a process called fear extinction. Extensive empirical work by behavioral psychologists has revealed basic behavioral characteristics of extinction, and theoretical accounts have emphasized extinction as a form of inhibitory learning as opposed to an erasure of acquired fear. Guided by this work, neuroscientists have begun to dissect the neural mechanisms involved, including the regions in which extinction-related plasticity occurs and the cellular and molecular processes that are engaged. The present paper will cover behavioral, theoretical and neurobiological work, and will conclude with a discussion of clinical implications.
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Affiliation(s)
- K M Myers
- Center for Behavioral Neuroscience, Emory University, Atlanta, GA, USA.
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Colón-Cesario WI, Martínez-Montemayor MM, Morales S, Félix J, Cruz J, Adorno M, Pereira L, Colón N, Maldonado-Vlaar CS, Peña de Ortiz S. Knockdown of Nurr1 in the rat hippocampus: implications to spatial discrimination learning and memory. Learn Mem 2006; 13:734-44. [PMID: 17142303 PMCID: PMC1783627 DOI: 10.1101/lm.407706] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Accepted: 09/01/2006] [Indexed: 02/04/2023]
Abstract
Nurr1 expression is up-regulated in the brain following associative learning experiences, but its relevance to cognitive processes remains unclear. In these studies, rats initially received bilateral hippocampal infusions of control or antisense oligodeoxynucleotides (ODNs) 1 h prior to training in a holeboard spatial discrimination task. Such pre-training infusions of nurr1 antisense ODNs caused a moderate effect in learning the task and also impaired LTM tested 7 d later. In a second experiment, ODN infusions were given immediately after the animals had received two sessions of training, during which all animals showed normal learning. Although antisense treated rats were significantly impaired during the post-infusion stages of acquisition of the task, no group differences were observed during the LTM test given 7 d later. These animals were subjected 3 d later to reversal training in the same maze in the absence of any additional treatments. Remarkably, rats previously treated with antisense ODNs displayed perseveration: The animals were fixated with the previously learned pattern of baited holes, causing them to be significantly impaired in the extinction of acquired spatial preferences and future learning. We postulate that Nurr1 function in the hippocampus is important for normal cognitive processes.
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Affiliation(s)
| | | | - Sohaira Morales
- Department of Biology, University of Puerto Rico, San Juan 00931-3360, Puerto Rico
| | - Jahaira Félix
- Department of Biology, University of Puerto Rico, San Juan 00931-3360, Puerto Rico
| | - Juan Cruz
- Department of Biology, University of Puerto Rico, San Juan 00931-3360, Puerto Rico
| | - Monique Adorno
- Department of Biology, University of Puerto Rico, San Juan 00931-3360, Puerto Rico
| | - Lixmar Pereira
- Department of Biology, University of Puerto Rico, San Juan 00931-3360, Puerto Rico
| | - Nydia Colón
- Department of Biology, University of Puerto Rico, San Juan 00931-3360, Puerto Rico
| | | | - Sandra Peña de Ortiz
- Department of Biology, University of Puerto Rico, San Juan 00931-3360, Puerto Rico
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Rossato JI, Bevilaqua LRM, Medina JH, Izquierdo I, Cammarota M. Retrieval induces hippocampal-dependent reconsolidation of spatial memory. Learn Mem 2006; 13:431-40. [PMID: 16882860 PMCID: PMC1538920 DOI: 10.1101/lm.315206] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Nonreinforced retrieval can cause extinction and/or reconsolidation, two processes that affect subsequent retrieval in opposite ways. Using the Morris water maze task we show that, in the rat, repeated nonreinforced expression of spatial memory causes extinction, which is unaffected by inhibition of protein synthesis within the CA1 region of the dorsal hippocampus. However, if the number of nonreinforced retrieval trials is insufficient to induce long-lasting extinction, then a hippocampal protein synthesis-dependent reconsolidation process recovers the original memory. Inhibition of hippocampal protein synthesis after reversal learning sessions impairs retention of the reversed preference and blocks persistence of the original one, suggesting that reversal learning involves reconsolidation rather than extinction of the original memory. Our results suggest the existence of a hippocampal protein synthesis-dependent reconsolidation process that operates to recover or update retrieval-weakened memories from incomplete extinction.
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Affiliation(s)
- Janine I Rossato
- Centro de Memória, Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brasil
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Cohen H, Kaplan Z, Matar MA, Loewenthal U, Kozlovsky N, Zohar J. Anisomycin, a protein synthesis inhibitor, disrupts traumatic memory consolidation and attenuates posttraumatic stress response in rats. Biol Psychiatry 2006; 60:767-76. [PMID: 16735032 DOI: 10.1016/j.biopsych.2006.03.013] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 09/05/2005] [Accepted: 03/06/2006] [Indexed: 11/27/2022]
Abstract
BACKGROUND Paradoxical changes in memory represent a troublesome characteristic of posttraumatic stress disorder (PTSD). Exceptionally vivid intrusive memories of some aspects of the trauma are mingled with patchy amnesia regarding other important aspects. Molecular studies of the memory process suggest that the conversion from labile short-term memory into long-term fixed traces involves protein synthesis. This study assessed the effects of administration of anisomycin, a protein synthesis inhibitor, after initial exposure, after exposure to a cue associated with triggering experience, and after reexposure to the triggering trauma in an animal model of PTSD. METHOD Magnitude of changes in prevalence of anxiety-like behaviors on the elevated plus-maze and nonhabituated exaggerated startle reaction were compared in rats that were exposed to predator stress, with and without microinjection of anisomycin. RESULTS Microinjection of anisomycin before and after stress exposure reduced anxiety-like and avoidant behavior, reduced the mean startle amplitude, and reversed the stress-induced habituation deficit 7 days later. The persistent anxiety-like behaviors that were seen after stress exposure do not appear to be sensitive to anisomycin after reexposure to a cue associated with the event or after reexposure to the index experience. CONCLUSIONS Disruption of the process of traumatic memory consolidation may be useful for mitigating PTSD symptoms.
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Affiliation(s)
- Hagit Cohen
- Ministry of Health Mental Health Center, Anxiety and Stress Research Unit, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel.
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Lattal KM, Radulovic J, Lukowiak K. Extinction: [corrected] does it or doesn't it? The requirement of altered gene activity and new protein synthesis. Biol Psychiatry 2006; 60:344-51. [PMID: 16919523 PMCID: PMC2761679 DOI: 10.1016/j.biopsych.2006.05.038] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Revised: 05/02/2006] [Accepted: 05/26/2006] [Indexed: 12/16/2022]
Abstract
Many accounts of memory suggest that an initial learning experience initiates a cascade of cellular and molecular events that are required for the consolidation of memory from a labile into a more permanent state. Studies of memory in many species have routinely found that altered gene activity and new protein synthesis are the critical components of this memory consolidation process. During extinction, when organisms learn that previously established relations between stimuli have been severed, new memories are formed and consolidated. However, the nature of the learning that underlies extinction remains unclear and there are many processes that may contribute to the weakening of behavior that occurs during extinction. In this review, we suggest that the molecular mechanisms that underlie extinction may differ depending on the learning process that is engaged by extinction. We review evidence that extinction, like initial learning, requires transcription and translation, as well as evidence that extinction occurs when protein synthesis is inhibited. We suggest that extinction occurs through the interaction of multiple behavioral and molecular mechanisms.
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Affiliation(s)
- K Matthew Lattal
- Department of Behavioral Neuroscience and Portland Alcohol Research Center, Oregon Health & Science University, Portland, Oregon 97239, USA.
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Izquierdo I, Bevilaqua LRM, Rossato JI, Bonini JS, Da Silva WC, Medina JH, Cammarota M. The connection between the hippocampal and the striatal memory systems of the brain: A review of recent findings. Neurotox Res 2006; 10:113-21. [PMID: 17062373 DOI: 10.1007/bf03033240] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Two major memory systems have been recognized over the years (Squire, in Memory and Brain, 1987): the declarative memory system, which is under the control of the hippocampus and related temporal lobe structures, and the procedural or habit memory system, which is under the control of the striatum and its connections (Mishkin et al., in Neurobiology of Learning by G Lynch et al., 1984; Knowlton et al., Science 273:1399, 1996). Most if not all learning tasks studied in animals, however, involve either the performance or the suppression of movement. Animals acquire connections between environmental or discrete sensory cues (conditioned stimuli, CSs) and emotionally or otherwise significant stimuli (unconditioned stimuli, USs). As a result, they learn to perform or to inhibit the performance of certain motor responses to the CS which, when learned well, become what can only be called habits (Mishkin et al., 1984): to regularly walk or swim to a place or away from a place, or to inhibit one or several forms of movement. These responses can be viewed as conditioned responses (CRs) and may sometimes be very complex. This is of course also seen in humans: people learn how to play on a keyboard in response to a mental or written script and perform the piano or write a text; with practice, the performance improves and eventually reaches a high criterion and becomes a habit, performed almost if not completely without awareness. Commuting to school in a big city in the shortest possible time and eschewing the dangers is a complex learning that children acquire to the point of near-perfection. It is agreed that the rules that connect the perception of the CS and the expression of the CR change from their first association to those that take place when the task is mastered. Does this change of rules involve a switch from one memory system to another? Are different brain systems used the first time one plays a sonata or goes to school as compared with the 100th time? Here we will comment on: 1) reversal learning in the Morris water maze (MWM), in which the declarative or spatial component of a task is changed but the procedural component (to swim) persists and needs to be re-linked with a different set of spatial cues; and 2) a series of observations on an inhibitory avoidance task that indicate that the brain systems involved change with further learning.
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Affiliation(s)
- I Izquierdo
- Centro de Memoria, Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Andar (90610-000) Porto Alegre, RS, Brasil
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Myers KM, Ressler KJ, Davis M. Different mechanisms of fear extinction dependent on length of time since fear acquisition. Learn Mem 2006; 13:216-23. [PMID: 16585797 PMCID: PMC1409828 DOI: 10.1101/lm.119806] [Citation(s) in RCA: 241] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Accepted: 12/18/2005] [Indexed: 11/24/2022]
Abstract
Fear extinction is defined as a decline in conditioned fear responses (CRs) following nonreinforced exposure to a feared conditioned stimulus (CS). Behavioral evidence indicates that extinction is a form of inhibitory learning: Extinguished fear responses reappear with the passage of time (spontaneous recovery), a shift of context (renewal), and unsignaled presentations of the unconditioned stimulus (reinstatement). However, there also is evidence to suggest that extinction is an "unlearning" process corresponding to depotentiation of potentiated synapses within the amygdala. Because depotentiation is induced more readily at short intervals following LTP induction and is not inducible at all at a sufficient delay, it may be that extinction initiated shortly following fear acquisition preferentially engages depotentiation/"unlearning," whereas extinction initiated at longer delays recruits a different mechanism. We investigated this possibility through a series of behavioral experiments examining the recoverability of conditioned fear following extinction. Consistent with an inhibitory learning mechanism of extinction, rats extinguished 24-72 h following acquisition exhibited moderate to strong reinstatement, renewal, and spontaneous recovery. In contrast, and consistent with an erasure mechanism, rats extinguished 10 min to 1 h after acquisition exhibited little or no reinstatement, renewal, or spontaneous recovery. These data support a model in which different neural mechanisms are recruited depending on the temporal delay of fear extinction.
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Affiliation(s)
- Karyn M Myers
- Center for Behavioral Neuroscience, Emory University Atlanta, Georgia 30329, USA.
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Power AE, Berlau DJ, McGaugh JL, Steward O. Anisomycin infused into the hippocampus fails to block "reconsolidation" but impairs extinction: the role of re-exposure duration. Learn Mem 2006; 13:27-34. [PMID: 16452651 PMCID: PMC1360130 DOI: 10.1101/lm.91206] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Accepted: 11/03/2005] [Indexed: 11/25/2022]
Abstract
Recent studies have reported new evidence consistent with the hypothesis that reactivating a memory by re-exposure to a training context destabilizes the memory and induces "reconsolidation." In the present experiments, rats' memory for inhibitory avoidance (IA) training was tested 6 h (Test 1), 2 d (Test 2), and 6 d (Test 3) after training. On Test 1 the rats were either removed from the shock compartment immediately after entry or retained in the shock context for 200 sec, and intrahippocampal infusions of the protein synthesis inhibitor anisomycin (75 microg/side) were administered immediately after the test. Anisomycin infusions administered after Test 1 impaired IA performance on Test 2 in animals given the brief re-exposure, but impaired extinction in animals exposed to the context for 200 sec. Rats with anisomycin-induced retention impairment on Test 2 demonstrated spontaneous recovery of retention performance on Test 3, whereas rats showing extinction on Test 2 showed further extinction on Test 3. The findings indicate that post-retrieval administration of anisomycin impairs subsequent retention performance only in the absence of extinction and that this impairment is temporary.
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Affiliation(s)
- Ann E Power
- Department of Anatomy and Neurobiology, Reeve-Irvine Research Center, University of California-Irvine, California 92697, USA.
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Abstract
Research on the neural systems underlying emotion in animal models over the past two decades has implicated the amygdala in fear and other emotional processes. This work stimulated interest in pursuing the brain mechanisms of emotion in humans. Here, we review research on the role of the amygdala in emotional processes in both animal models and humans. The review is not exhaustive, but it highlights five major research topics that illustrate parallel roles for the amygdala in humans and other animals, including implicit emotional learning and memory, emotional modulation of memory, emotional influences on attention and perception, emotion and social behavior, and emotion inhibition and regulation.
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Affiliation(s)
- Elizabeth A Phelps
- Department of Psychology, New York University, 4-6 Washington Place, New York, New York 10003, USA.
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