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Scienza-Martin K, Lotz FN, Zanona QK, Santana-Kragelund F, Crestani AP, Boos FZ, Calcagnotto ME, Quillfeldt JA. Memory consolidation depends on endogenous hippocampal levels of anandamide: CB1 and M4, but possibly not TRPV1 receptors mediate AM404 effects. Neuroscience 2022; 497:53-72. [DOI: 10.1016/j.neuroscience.2022.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/14/2022] [Accepted: 04/08/2022] [Indexed: 11/15/2022]
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Belén Sanz-Martos A, Fernández-Felipe J, Merino B, Cano V, Ruiz-Gayo M, Del Olmo N. Butyric Acid Precursor Tributyrin Modulates Hippocampal Synaptic Plasticity and Prevents Spatial Memory Deficits: Role of PPARγ and AMPK. Int J Neuropsychopharmacol 2022; 25:498-511. [PMID: 35152284 PMCID: PMC9211015 DOI: 10.1093/ijnp/pyac015] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 01/31/2022] [Accepted: 02/10/2022] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Short chain fatty acids (SCFA), such as butyric acid (BA), derived from the intestinal fermentation of dietary fiber and contained in dairy products, are gaining interest in relation to their possible beneficial effects on neuropsychological disorders. METHODS C57BL/6J male mice were used to investigate the effect of tributyrin (TB), a prodrug of BA, on hippocampus (HIP)-dependent spatial memory, HIP synaptic transmission and plasticity mechanisms, and the expression of genes and proteins relevant to HIP glutamatergic transmission. RESULTS Ex vivo studies, carried out in HIP slices, revealed that TB can transform early-LTP into late-LTP (l-LTP) and to rescue LTP-inhibition induced by scopolamine. The facilitation of l-LTP induced by TB was blocked both by GW9662 (a PPARγ antagonist) and C-Compound (an AMPK inhibitor), suggesting the involvement of both PPARγ and AMPK on TB effects. Moreover, 48-hour intake of a diet containing 1% TB prevented, in adolescent but not in adult mice, scopolamine-induced impairment of HIP-dependent spatial memory. In the adolescent HIP, TB upregulated gene expression levels of Pparg, leptin, and adiponectin receptors, and that of the glutamate receptor subunits AMPA-2, NMDA-1, NMDA-2A, and NMDA-2B. CONCLUSIONS Our study shows that TB has a positive influence on LTP and HIP-dependent spatial memory, which suggests that BA may have beneficial effects on memory.
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Affiliation(s)
- Ana Belén Sanz-Martos
- Department of Health and Pharmaceutical Sciences, School of Pharmacy, Universidad CEU-San Pablo, CEU Universities, Madrid, Spain
| | - Jesús Fernández-Felipe
- Department of Health and Pharmaceutical Sciences, School of Pharmacy, Universidad CEU-San Pablo, CEU Universities, Madrid, Spain
| | - Beatriz Merino
- Department of Health and Pharmaceutical Sciences, School of Pharmacy, Universidad CEU-San Pablo, CEU Universities, Madrid, Spain
| | - Victoria Cano
- Department of Health and Pharmaceutical Sciences, School of Pharmacy, Universidad CEU-San Pablo, CEU Universities, Madrid, Spain
| | | | - Nuria Del Olmo
- Correspondence: Nuria Del Olmo, PhD, Department of Psychobiology, School of Psychology, National University for Distance Education (UNED), C/ Juan del Rosal 10, 28040 Madrid, Spain ()
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Van Baelen AC, Robin P, Kessler P, Maïga A, Gilles N, Servent D. Structural and Functional Diversity of Animal Toxins Interacting With GPCRs. Front Mol Biosci 2022; 9:811365. [PMID: 35198603 PMCID: PMC8859281 DOI: 10.3389/fmolb.2022.811365] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/05/2022] [Indexed: 12/12/2022] Open
Abstract
Peptide toxins from venoms have undergone a long evolutionary process allowing host defense or prey capture and making them highly selective and potent for their target. This has resulted in the emergence of a large panel of toxins from a wide diversity of species, with varied structures and multiple associated biological functions. In this way, animal toxins constitute an inexhaustible reservoir of druggable molecules due to their interesting pharmacological properties. One of the most interesting classes of therapeutic targets is the G-protein coupled receptors (GPCRs). GPCRs represent the largest family of membrane receptors in mammals with approximately 800 different members. They are involved in almost all biological functions and are the target of almost 30% of drugs currently on the market. Given the interest of GPCRs in the therapeutic field, the study of toxins that can interact with and modulate their activity with the purpose of drug development is of particular importance. The present review focuses on toxins targeting GPCRs, including peptide-interacting receptors or aminergic receptors, with a particular focus on structural aspects and, when relevant, on potential medical applications. The toxins described here exhibit a great diversity in size, from 10 to 80 amino acids long, in disulfide bridges, from none to five, and belong to a large panel of structural scaffolds. Particular toxin structures developed here include inhibitory cystine knot (ICK), three-finger fold, and Kunitz-type toxins. We summarize current knowledge on the structural and functional diversity of toxins interacting with GPCRs, concerning first the agonist-mimicking toxins that act as endogenous agonists targeting the corresponding receptor, and second the toxins that differ structurally from natural agonists and which display agonist, antagonist, or allosteric properties.
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Affiliation(s)
- Anne-Cécile Van Baelen
- CEA, Département Médicaments et Technologies pour La Santé (DMTS), SIMoS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Philippe Robin
- CEA, Département Médicaments et Technologies pour La Santé (DMTS), SIMoS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Pascal Kessler
- CEA, Département Médicaments et Technologies pour La Santé (DMTS), SIMoS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Arhamatoulaye Maïga
- CEA, Département Médicaments et Technologies pour La Santé (DMTS), SIMoS, Université Paris-Saclay, Gif-sur-Yvette, France
- CHU Sainte Justine, Université de Montréal, Montreal, QC, Canada
| | - Nicolas Gilles
- CEA, Département Médicaments et Technologies pour La Santé (DMTS), SIMoS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Denis Servent
- CEA, Département Médicaments et Technologies pour La Santé (DMTS), SIMoS, Université Paris-Saclay, Gif-sur-Yvette, France
- *Correspondence: Denis Servent,
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Quillfeldt JA. Temporal Flexibility of Systems Consolidation and the Synaptic Occupancy/Reset Theory (SORT): Cues About the Nature of the Engram. Front Synaptic Neurosci 2019; 11:1. [PMID: 30814946 PMCID: PMC6381034 DOI: 10.3389/fnsyn.2019.00001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 01/14/2019] [Indexed: 11/24/2022] Open
Abstract
The ability to adapt to new situations involves behavioral changes expressed either from an innate repertoire, or by acquiring experience through memory consolidation mechanisms, by far a much richer and flexible source of adaptation. Memory formation consists of two interrelated processes that take place at different spatial and temporal scales, Synaptic Consolidation, local plastic changes in the recruited neurons, and Systems Consolidation, a process of gradual reorganization of the explicit/declarative memory trace between hippocampus and the neocortex. In this review, we summarize some converging experimental results from our lab that support a normal temporal framework of memory systems consolidation as measured both from the anatomical and the psychological points of view, and propose a hypothetical model that explains these findings while predicting other phenomena. Then, the same experimental design was repeated interposing additional tasks between the training and the remote test to verify for any interference: we found that (a) when the animals were subject to a succession of new learnings, systems consolidation was accelerated, with the disengagement of the hippocampus taking place before the natural time point of this functional switch, but (b) when a few reactivation sessions reexposed the animal to the training context without the shock, systems consolidation was delayed, with the hippocampus prolonging its involvement in retrieval. We hypothesize that new learning recruits from a fixed number of plastic synapses in the CA1 area to store the engram index, while reconsolidation lead to a different outcome, in which additional synapses are made available. The first situation implies the need of a reset mechanism in order to free synapses needed for further learning, and explains the acceleration observed under intense learning activity, while the delay might be explained by a different process, able to generate extra free synapses: depending on the cognitive demands, it deals either with a fixed or a variable pool of available synapses. The Synaptic Occupancy/Reset Theory (SORT) emerged as an explanation for the temporal flexibility of systems consolidation, to encompass the two different dynamics of explicit memories, as well as to bridge both synaptic and systems consolidation in one single mechanism.
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Affiliation(s)
- Jorge Alberto Quillfeldt
- Psychobiology and Neurocomputation Lab, Department of Biophysics, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Neurosciences Graduate Program, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Department of Psychology, McGill University, Montreal, QC, Canada
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Dobryakova YV, Ivanova OY, Markevich VA. Administration of muscarinic antagonists induce changes in passive avoidance learning and in synaptic transmission in the CA1 area of the hippocampus. Acta Neurobiol Exp (Wars) 2018. [DOI: 10.21307/ane-2018-012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Thorn CA, Popiolek M, Stark E, Edgerton JR. Effects of M1 and M4 activation on excitatory synaptic transmission in CA1. Hippocampus 2017; 27:794-810. [PMID: 28422371 PMCID: PMC5573954 DOI: 10.1002/hipo.22732] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 02/24/2017] [Accepted: 03/31/2017] [Indexed: 01/23/2023]
Abstract
Hippocampal networks are particularly susceptible to dysfunction in many neurodegenerative diseases and neuropsychiatric disorders including Alzheimer's disease, Lewy body dementia, and schizophrenia. CA1, a major output region of the hippocampus, receives glutamatergic input from both hippocampal CA3 and entorhinal cortex, via the Schaffer collateral (SC) and temporoammonic (TA) pathways, respectively. SC and TA inputs to CA1 are thought to be differentially involved in the retrieval of previously stored memories versus the encoding of novel information, and switching between these two crucial hippocampal functions is thought to critically depend on acetylcholine (ACh) acting at muscarinic receptors. In this study, we aimed to determine the roles of specific subtypes of muscarinic receptors in mediating the neuromodulatory effects of ACh on glutamatergic synaptic transmission in the SC and TA pathways of CA1. Using selective pharmacological activation of M1 or M4 receptors along with extracellular and intracellular electrophysiology recordings from adult rat hippocampal slices, we demonstrate that activation of M1 receptors increases spontaneous spike rates of neuronal ensembles in CA1 and increases the intrinsic excitability of pyramidal neurons and interneurons. Selective activation of M4 receptors inhibits glutamate release in the SC pathway, while leaving synaptic transmission in the TA pathway comparatively intact. These results suggest specific mechanisms by which M1 and M4 activation may normalize CA1 circuit activity following disruptions of signaling that accompany neurodegenerative dementias or neuropsychiatric disorders. These findings are of particular interest in light of clinical findings that xanomeline, an M1/M4 preferring agonist, was able to improve cognitive and behavioral symptoms in patients with Alzheimer's disease or schizophrenia.
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Affiliation(s)
| | - Michael Popiolek
- Pfizer Internal Medicine Research UnitCambridgeMassachusetts02139
| | - Eda Stark
- Pfizer Internal Medicine Research UnitCambridgeMassachusetts02139
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Mahboob A, Farhat SM, Iqbal G, Babar MM, Zaidi NUSS, Nabavi SM, Ahmed T. Alpha-lipoic acid-mediated activation of muscarinic receptors improves hippocampus- and amygdala-dependent memory. Brain Res Bull 2016; 122:19-28. [PMID: 26912408 DOI: 10.1016/j.brainresbull.2016.02.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 02/12/2016] [Accepted: 02/15/2016] [Indexed: 12/30/2022]
Abstract
Aluminum (Al) is a neurotoxic agent which readily crosses the blood-brain-barrier (BBB) and accumulates in the brain leading to neurodegenerative disorders, characterised by cognitive impairment. Alpha-lipoic acid (ALA) is an antioxidant and has a potential to improve cognitive functions. This study aimed to evaluate the neuroprotective effect of ALA in AlCl3-induced neurotoxicity mouse model. Effect of ALA (25mg/kg/day) was evaluated in the AlCl3-induced neurotoxicity (AlCl3 150 mg/kg/day) mouse model on learning and memory using behaviour tests and on the expression of muscarinic receptor genes (using RT-PCR), in hippocampus and amygdala. Following ALA treatment, the expression of muscarinic receptor genes M1, M2 and choline acetyltransferase (ChaT) were significantly improved (p<0.05) relative to AlCl3-treated group. ALA enhanced fear memory (p<0.01) and social novelty preference (p<0.001) comparative to the AlCl3-treated group. Fear extinction memory was remarkably restored (p<0.001) in ALA-treated group demonstrated by reduced freezing response as compared to the AlCl3-treated group which showed higher freezing. In-silico analysis showed that racemic mixture of ALA has higher binding affinity for M1 and M2 compared to acetylcholine. These novel findings highlight the potential role of ALA in cognitive functions and cholinergic system enhancement thus presenting it an enviable therapeutic candidate for the treatment of neurodegenerative disorders.
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Affiliation(s)
- Aamra Mahboob
- Neurobiology Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Sector H-12, Islamabad 44000, Pakistan
| | - Syeda Mehpara Farhat
- Neurobiology Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Sector H-12, Islamabad 44000, Pakistan
| | - Ghazala Iqbal
- Neurobiology Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Sector H-12, Islamabad 44000, Pakistan
| | - Mustafeez Mujtaba Babar
- Department of Industrial Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Sector H-12, Islamabad 44000, Pakistan
| | - Najam-us-Sahar Sadaf Zaidi
- Department of Industrial Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Sector H-12, Islamabad 44000, Pakistan
| | - Seyed Mohammad Nabavi
- Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Touqeer Ahmed
- Neurobiology Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Sector H-12, Islamabad 44000, Pakistan.
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8
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Portero-Tresserra M, Del Olmo N, Martí-Nicolovius M, Guillazo-Blanch G, Vale-Martínez A. D-cycloserine prevents relational memory deficits and suppression of long-term potentiation induced by scopolamine in the hippocampus. Eur Neuropsychopharmacol 2014; 24:1798-807. [PMID: 25453488 DOI: 10.1016/j.euroneuro.2014.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 10/01/2014] [Accepted: 10/11/2014] [Indexed: 01/31/2023]
Abstract
Previous research has demonstrated that systemic D-cycloserine (DCS), a partial agonist of the N-methyl-D-aspartate receptor (NMDAR), enhances memory processes in different learning paradigms and attenuates mnemonic deficits produced by diverse pharmacological manipulations. In the present study two experiments were conducted in rats to investigate whether DCS administered in the hippocampus may rescue relational memory deficits and improve deficient synaptic plasticity, both induced by an intracerebral injection of the muscarinic receptor antagonist scopolamine (SCOP). In experiment 1, we assessed whether DCS would prevent SCOP-induced amnesia in an olfactory learning paradigm requiring the integrity of the cholinergic system, the social transmission of food preference (STFP). The results showed that DCS (10 μg/site) injected into the ventral hippocampus (vHPC) before STFP acquisition compensated the 24-h retention deficit elicited by post-training intra-vHPC SCOP (40 μg/site), although it did not affect memory expression in non-SCOP treated rats. In experiment 2, we evaluated whether the perfusion of DCS in hippocampal slices may potentiate synaptic plasticity in CA1 synapses and thus recover SCOP-induced deficits in long-term potentiation (LTP). We found that DCS (50 µM and 100 µM) was able to rescue SCOP (100 µM)-induced LTP maintenance impairment, in agreement with the behavioral findings. Additionally, DCS alone (50 µM and 100 µM) enhanced field excitatory postsynaptic potentials prior to high frequency stimulation, although it did not significantly potentiate LTP. Our results suggest that positive modulation of the NMDAR, by activation of the glycine-binding site, may compensate relational memory impairments due to hippocampal muscarinic neurotransmission dysfunction possibly through enhancements in LTP maintenance.
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Colettis NC, Snitcofsky M, Kornisiuk EE, Gonzalez EN, Quillfeldt JA, Jerusalinsky DA. Amnesia of inhibitory avoidance by scopolamine is overcome by previous open-field exposure. ACTA ACUST UNITED AC 2014; 21:634-45. [PMID: 25322799 PMCID: PMC4201807 DOI: 10.1101/lm.036210.114] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The muscarinic cholinergic receptor (MAChR) blockade with scopolamine either extended or restricted to the hippocampus, before or after training in inhibitory avoidance (IA) caused anterograde or retrograde amnesia, respectively, in the rat, because there was no long-term memory (LTM) expression. Adult Wistar rats previously exposed to one or two open-field (OF) sessions of 3 min each (habituated), behaved as control animals after a weak though over-threshold training in IA. However, after OF exposure, IA LTM was formed and expressed in spite of an extensive or restricted to the hippocampus MAChR blockade. It was reported that during and after OF exposure and reexposure there was an increase in both hippocampal and cortical ACh release that would contribute to “prime the substrate,” e.g., by lowering the synaptic threshold for plasticity, leading to LTM consolidation. In the frame of the “synaptic tagging and capture” hypothesis, plasticity-related proteins synthesized during/after the previous OF could facilitate synaptic plasticity for IA in the same structure. However, IA anterograde amnesia by hippocampal protein synthesis inhibition with anisomycin was also prevented by two OF exposures, strongly suggesting that there would be alternative interpretations for the role of protein synthesis in memory formation and that another structure could also be involved in this “OF effect.”
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Affiliation(s)
- Natalia C Colettis
- Laboratorio de Neuroplasticidad y Neurotoxinas (LaNyN), Instituto de Biología Celular y Neurociencias (IBCN), UBA-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina
| | - Marina Snitcofsky
- Laboratorio de Neuroplasticidad y Neurotoxinas (LaNyN), Instituto de Biología Celular y Neurociencias (IBCN), UBA-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina
| | - Edgar E Kornisiuk
- Laboratorio de Neuroplasticidad y Neurotoxinas (LaNyN), Instituto de Biología Celular y Neurociencias (IBCN), UBA-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina
| | - Emilio N Gonzalez
- Laboratorio de Neuroplasticidad y Neurotoxinas (LaNyN), Instituto de Biología Celular y Neurociencias (IBCN), UBA-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina
| | - Jorge A Quillfeldt
- Laboratório de Psicobiologia e Neurocomputação, Depto. de Biofísica, UFRGS, Porto Alegre 91501-970, Brazil
| | - Diana A Jerusalinsky
- Laboratorio de Neuroplasticidad y Neurotoxinas (LaNyN), Instituto de Biología Celular y Neurociencias (IBCN), UBA-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires 1121, Argentina
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Zanona QK, Boos FZ, Crestani AP, Duran JM, Calcagnotto ME, Quillfeldt JA. Muscarynic metabotropic receptor M4 modulates the hippocampal CA1 LTP possibly through local GABAergic interneurons. BMC Neurosci 2014. [PMCID: PMC4126527 DOI: 10.1186/1471-2202-15-s1-p63] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Increased Noradrenaline Levels in the Rostral Pons can be Reversed by M1 Antagonist in a Rat Model of Post-traumatic Stress Disorder. Neurochem Res 2013; 38:1726-33. [DOI: 10.1007/s11064-013-1076-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/09/2013] [Accepted: 05/11/2013] [Indexed: 10/26/2022]
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Hunt PS. Supplemental choline during the periweaning period protects against trace conditioning impairments attributable to post-training ethanol exposure in adolescent rats. Behav Neurosci 2012; 126:593-8. [PMID: 22687150 DOI: 10.1037/a0028878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Supplemental choline during early stages of development can result in long-lasting improvements to memory function. In addition, pre- or postnatal choline has been shown to be protective against some of the adverse effects of early alcohol exposure. The present experiment examined whether supplemental choline given to rats would protect against the effects of posttraining alcohol administration on trace fear conditioning. Posttraining alcohol exposure in adolescent rats results in poor performance in this hippocampus-dependent task, although delay conditioning is unaffected. Here, rats were given an s.c. injection of either saline or choline chloride daily on postnatal days (PD) 15-26. On PD 30 subjects were trained in a trace fear conditioning procedure. For the next 3 days animals were administered 2.5 g/kg ethanol or water control, and conditional stimulus (CS)-elicited freezing was measured on PD 34. Results indicated that posttraining alcohol disrupted the expression of trace conditioning and that supplemental choline on PD 15-26 was protective against this effect. That is, choline-treated animals subsequently given posttraining ethanol performed as well as animals not given ethanol. These results indicate that supplemental choline given during the periweaning period protects against ethanol-induced impairments in a hippocampus-dependent learning task. Findings contribute to the growing literature showing improvements in learning and memory in subjects given extra dietary choline during critical periods of brain development.
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Affiliation(s)
- Pamela S Hunt
- Department of Psychology, College of William & Mary, Williamsburg, VA 23187-8795, USA.
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Aykaç A, Aydın B, Cabadak H, Gören MZ. The change in muscarinic receptor subtypes in different brain regions of rats treated with fluoxetine or propranolol in a model of post-traumatic stress disorder. Behav Brain Res 2012; 232:124-9. [PMID: 22522023 DOI: 10.1016/j.bbr.2012.04.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 03/28/2012] [Accepted: 04/02/2012] [Indexed: 01/08/2023]
Abstract
This study shows the possible contribution of muscarinic receptors in the pathophysiology of post-traumatic stress disorder. Sprague-Dawley rats of both sexes were exposed to dirty cat litter (trauma) for 10 min and the protocol was repeated 1 week later with a trauma reminder (clean litter). The rats also received intraperitoneal fluoxetine (2.5, 5 or 10 mg/kg/day), propranolol (10 mg/kg/day) or saline for 7 days between two exposure sessions. Functional behavioral experiments were performed using elevated plus maze, following exposure to trauma reminder. Western blot analyses for M(1), M(2), M(3), M(4) and M(5) receptor proteins were employed in the homogenates of the hippocampus, the frontal cortex and the amygdaloid complex. The anxiety indices increased from 0.63±0.02 to 0.89±0.04 in rats exposed to the trauma reminder. The freezing times were also recorded as 47±6 and 133±12 s, in control and test animals respectively. Fluoxetine or propranolol treatments restored the increases in the anxiety indices and the freezing times. Female rats had higher anxiety indices compared to males. Western blot data showed increases in M(2) and M(5) expression in the frontal cortex. Expression of M(1) receptors increased and M(4) subtype decreased in the hippocampus. In the amygdaloid complex of rats, we also detected a down-regulation of M(4) receptors. Fluoxetine and propranolol only corrected the changes occurred in the frontal cortex. These results may imply that muscarinic receptors are involved in this experimental model of post-traumatic stress disorder.
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Affiliation(s)
- Aslı Aykaç
- Department of Biophysics, Marmara University, School of Medicine, Haydarpaşa Istanbul 34668, Turkey
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Näreoja K, Näsman J. Selective targeting of G-protein-coupled receptor subtypes with venom peptides. Acta Physiol (Oxf) 2012; 204:186-201. [PMID: 21481193 DOI: 10.1111/j.1748-1716.2011.02305.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The G-protein-coupled receptor (GPCR) family is one of the largest gene superfamilies with approx. 370 members responding to endogenous ligands in humans and a roughly equal amount of receptors sensitive to external stimuli from the surrounding. A number of receptors from this superfamily are well recognized targets for medical treatment of various disease conditions, whereas for many others the potential medical benefit of interference is still obscure. A general problem associated with GPCR research and therapeutics is the insufficient specificity of available ligands to differentiate between closely homologous receptor subtypes. In this context, venom peptides could make a significant contribution to the development of more specific drugs. Venoms from certain animals specialized in biochemical hunting contain a mixture of molecules that are directed towards a variety of membrane proteins. Peptide toxins isolated from these mixtures usually exhibit high specificity for their targets. Muscarinic toxins found from mamba snakes attracted much attention during the 1990s. These are 65-66 amino acid long peptides with a structural three-finger folding similar to the α-neurotoxins and they target the muscarinic acetylcholine receptors in a subtype-selective manner. Recently, several members of the three-finger toxins from mamba snakes as well as conotoxins from marine cone snails have been shown to selectively interact with subtypes of adrenergic receptors. In this review, we will discuss the GPCR-directed peptide toxins found from different venoms and how some of these can be useful in exploring specific roles of receptor subtypes.
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Affiliation(s)
- K Näreoja
- Department of Biosciences, Biochemistry, Åbo Akademi University, Turku, Finland
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Dontigny E, Patenaude C, Cyr M, Massicotte G. Sphingomyelinase selectively reduces M1 muscarinic receptors in rat hippocampal membranes. Hippocampus 2012; 22:1589-96. [PMID: 22228652 DOI: 10.1002/hipo.21001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2011] [Indexed: 01/20/2023]
Abstract
Although there is evidence that nicotinic acetylcholine (Ach) receptors are influenced by ceramides, we do not currently know whether or not these sphingolipids can also regulate the muscarinic subtypes of Ach receptors. Using the whole-cell patch technique, we demonstrated that the effectiveness of the muscarinic receptor agonist pilocarpine, in enhancing spontaneous inhibitory postsynaptic currents in CA1 pyramidal cells, was completely abolished in hippocampal slices pre-exposed to the ceramide-generating enzyme sphingomyelinase (SMase). Western blot experiments, performed with biotinylated hippocampal membranes, showed that this electrophysiological defect possibly relies on the loss of M1 muscarinic Ach receptors at the cell surface. However, the effect appears to be relatively specific as the cell-surface expression of M4 muscarinic receptors was not found to be impacted by SMase treatment. Interestingly, we observed that G protein-coupled receptor kinases 2 and β-arrestin1/2 interactions with M1-immunoprecipitated proteins were substantially augmented in SMase-treated slices and that the reduction of cell-surface M1 muscarinic receptor expression generated was completely suppressed by the muscarinic antagonist atropine. Collectively, our data suggest that selective internalization of M1 muscarinic receptors can be accentuated in neurons subjected to high ceramide levels. The potential physiopathological implications of this finding are presented.
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Affiliation(s)
- Eve Dontigny
- Groupe de recherche en Neuroscience, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
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16
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Abstract
Schizophrenia is a devastating disease with several broad symptom clusters and the current monoamine-based treatments do not adequately treat the disease, especially negative and cognitive symptoms. A proposed alternative approach for treating schizophrenia is through the use of compounds that activate certain muscarinic receptor subtypes, the so-called muscarinic cholinergic hypothesis theory. This theory has been revitalized with a number of recent and provocative findings including postmortem reports in schizophrenia patients showing decreased numbers of muscarinic M(1) and M(4) receptors in brain regions associated with schizophrenia as well as decreased muscarinic receptors in an in vivo imaging study. Studies with M(4) knockout mice have shown that there is a reciprocal relationship between M(4) and dopamine receptor function, and a number of muscarinic agonists have shown antidopaminergic activity in a variety of preclinical assays predictive of antipsychotic efficacy in the clinic. Furthermore, the M(1)/M(4) preferring partial agonist xanomeline has been shown to have antipsychotic-like and pro-cognitive activity in preclinical models and in clinical trials to decrease psychotic-like behaviors in Alzheimer's patients and positive, negative, and cognitive symptoms in patients with schizophrenia. Therefore, we propose that an agonist with M(1) and M(4) interactions would effectively treat core symptom clusters associated with schizophrenia. Currently, research is focused on developing subtype-selective muscarinic agonists and positive allosteric modulators that have reduced propensity for parasympathetic side-effects, but retain the therapeutic benefit observed with their less selective predecessors.
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Affiliation(s)
- David L McKinzie
- Lilly Research Laboratories, Eli Lilly and Co., Indianapolis, IN 46285, USA.
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Servent D, Blanchet G, Mourier G, Marquer C, Marcon E, Fruchart-Gaillard C. Muscarinic toxins. Toxicon 2011; 58:455-63. [PMID: 21906611 DOI: 10.1016/j.toxicon.2011.08.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 07/12/2011] [Accepted: 08/08/2011] [Indexed: 12/15/2022]
Abstract
Muscarinic toxins isolated from the venom of Dendroaspis snakes may interact with a high affinity, large selectivity and various functional properties with muscarinic receptors. Therefore, these toxins are invaluable tools for studying the physiological role, molecular functioning and structural organization of the five subtypes of these G-Protein Coupled Receptors. We review the data on the most relevant results dealing with the isolation/identification, mode of action, structure/function and exploitation of these toxins and finally highlight the unresolved issues related to their pharmacological studies.
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Affiliation(s)
- Denis Servent
- CEA, Institute of Biology and Technology, Service d'Ingénierie Moléculaire des Protéines, Gif-sur-Yvette 91191, France.
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18
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Dasari S, Gulledge AT. M1 and M4 receptors modulate hippocampal pyramidal neurons. J Neurophysiol 2010; 105:779-92. [PMID: 21160001 DOI: 10.1152/jn.00686.2010] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acetylcholine (ACh), acting at muscarinic ACh receptors (mAChRs), modulates the excitability and synaptic connectivity of hippocampal pyramidal neurons. CA1 pyramidal neurons respond to transient ("phasic") mAChR activation with biphasic responses in which inhibition is followed by excitation, whereas prolonged ("tonic") mAChR activation increases CA1 neuron excitability. Both phasic and tonic mAChR activation excites pyramidal neurons in the CA3 region, yet ACh suppresses glutamate release at the CA3-to-CA1 synapse (the Schaffer-collateral pathway). Using mice genetically lacking specific mAChRs (mAChR knockout mice), we identified the mAChR subtypes responsible for cholinergic modulation of hippocampal pyramidal neuron excitability and synaptic transmission. Knockout of M1 receptors significantly reduced, or eliminated, most phasic and tonic cholinergic responses in CA1 and CA3 pyramidal neurons. On the other hand, in the absence of other G(q)-linked mAChRs (M3 and M5), M1 receptors proved sufficient for all postsynaptic cholinergic effects on CA1 and CA3 pyramidal neuron excitability. M3 receptors were able to participate in tonic depolarization of CA1 neurons, but otherwise contributed little to cholinergic responses. At the Schaffer-collateral synapse, bath application of the cholinergic agonist carbachol suppressed stratum radiatum-evoked excitatory postsynaptic potentials (EPSPs) in wild-type CA1 neurons and in CA1 neurons from mice lacking M1 or M2 receptors. However, Schaffer-collateral EPSPs were not significantly suppressed by carbachol in neurons lacking M4 receptors. We therefore conclude that M1 and M4 receptors are the major mAChR subtypes responsible for direct cholinergic modulation of the excitatory hippocampal circuit.
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Affiliation(s)
- Sameera Dasari
- Dartmouth Medical School, Department of Physiology and Neurobiology, One Medical Center Drive, Lebanon, NH 03756-0001, USA
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19
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Devi L, Ohno M. Phospho-eIF2α level is important for determining abilities of BACE1 reduction to rescue cholinergic neurodegeneration and memory defects in 5XFAD mice. PLoS One 2010; 5:e12974. [PMID: 20886088 PMCID: PMC2944882 DOI: 10.1371/journal.pone.0012974] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 08/30/2010] [Indexed: 01/08/2023] Open
Abstract
β-Site APP-cleaving enzyme 1 (BACE1) initiates amyloid-β (Aβ) generation and thus represents a prime therapeutic target in treating Alzheimer's disease (AD). Notably, increasing evidence indicates that BACE1 levels become elevated in AD brains as disease progresses; however, it remains unclear how the BACE1 upregulation may affect efficacies of therapeutic interventions including BACE1-inhibiting approaches. Here, we crossed heterozygous BACE1 knockout mice with AD transgenic mice (5XFAD model) and compared the abilities of partial BACE1 reduction to rescue AD-like phenotypes at earlier (6-month-old) and advanced (15–18-month-old) stages of disease, which expressed normal (∼100%) and elevated (∼200%) levels of BACE1, respectively. BACE1+/− deletion rescued memory deficits as tested by the spontaneous alternation Y-maze task in 5XFAD mice at the earlier stage and prevented their septohippocampal cholinergic deficits associated with significant neuronal loss. Importantly, BACE1+/− deletion was no longer able to rescue memory deficits or cholinergic neurodegeneration in 5XFAD mice at the advanced stage. Moreover, BACE1+/− deletion significantly reduced levels of Aβ42 and the β-secretase-cleaved C-terminal fragment (C99) in 6-month-old 5XFAD mouse brains, while these neurotoxic β-cleavage products dramatically elevated with age and were not affected by BACE1+/− deletion in 15–18-month-old 5XFAD brains. Interestingly, although BACE1+/− deletion lowered BACE1 expression by ∼50% in 5XFAD mice irrespective of age in concordance with the reduction in gene copy number, BACE1 equivalent to wild-type controls remained in BACE1+/−·5XFAD mice at the advanced age. In accord, phosphorylation of the translation initiation factor eIF2α, an important mediator of BACE1 elevation, was dramatically increased (∼9-fold) in 15–18-month-old 5XFAD mice and remained highly upregulated (∼6-fold) in age-matched BACE1+/−·5XFAD mice. Together, our results indicate that partial reduction of BACE1 is not sufficient to block the phospho-eIF2α-dependent BACE1 elevation during the progression of AD, thus limiting its abilities to reduce cerebral Aβ/C99 levels and rescue memory deficits and cholinergic neurodegeneration.
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Affiliation(s)
- Latha Devi
- Center for Dementia Research, Nathan Kline Institute, New York University School of Medicine, Orangeburg, New York, United States of America
| | - Masuo Ohno
- Center for Dementia Research, Nathan Kline Institute, New York University School of Medicine, Orangeburg, New York, United States of America
- * E-mail:
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Kini RM, Doley R. Structure, function and evolution of three-finger toxins: mini proteins with multiple targets. Toxicon 2010; 56:855-67. [PMID: 20670641 DOI: 10.1016/j.toxicon.2010.07.010] [Citation(s) in RCA: 252] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 07/19/2010] [Indexed: 12/15/2022]
Abstract
Snake venoms are complex mixtures of pharmacologically active peptides and proteins. These protein toxins belong to a small number of superfamilies of proteins. Three-finger toxins belong to a superfamily of non-enzymatic proteins found in all families of snakes. They have a common structure of three beta-stranded loops extending from a central core containing all four conserved disulphide bonds. Despite the common scaffold, they bind to different receptors/acceptors and exhibit a wide variety of biological effects. Thus, the structure-function relationships of this group of toxins are complicated and challenging. Studies have shown that the functional sites in these 'sibling' toxins are located on various segments of the molecular surface. Targeting to a wide variety of receptors and ion channels and hence distinct functions in this group of mini proteins is achieved through a combination of accelerated rate of exchange of segments as well as point mutations in exons. In this review, we describe the structural and functional diversity, structure-function relationships and evolution of this group of snake venom toxins.
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Affiliation(s)
- R Manjunatha Kini
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore.
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Kumar A. Carbachol-induced long-term synaptic depression is enhanced during senescence at hippocampal CA3-CA1 synapses. J Neurophysiol 2010; 104:607-16. [PMID: 20505129 DOI: 10.1152/jn.00278.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Dysregulation of the cholinergic transmitter system is a hallmark of Alzheimer's disease and contributes to an age-associated decline in memory performance. The current study examined the influence of carbachol, a cholinergic receptor agonist, on synaptic transmission over the course of aging. Extracellular excitatory postsynaptic field potentials were recorded from CA3-CA1 synapses in acute hippocampal slices obtained from young adult (5-8 mo) and aged (22-24 mo) male Fischer 344 rats. Bath application of carbachol elicited a transient depression of synaptic transmission, which was followed by a long-lasting depression (CCh-LTD) observed 90 min after carbachol cessation in both age groups. However, the magnitude of CCh-LTD was significantly larger in senescent animals and was attenuated by N-methyl-D-aspartate receptor blockade in aged animals. Blockade of L-type Ca(2+) channels inhibited CCh-LTD to a greater extent in aged animals compared to young adults. Finally, the expression of CCh-LTD was dependent on protein synthesis. The results indicate that altered Ca(2+) homeostasis or muscarinic activation of Ca(2+) signaling contribute to the enhanced CCh-LTD during senescence.
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Affiliation(s)
- Ashok Kumar
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, Florida 32610-0244, USA.
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22
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Saraf MK, Anand A, Prabhakar S. Scopolamine Induced Amnesia is Reversed by Bacopa monniera Through Participation of Kinase-CREB Pathway. Neurochem Res 2009; 35:279-87. [DOI: 10.1007/s11064-009-0051-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 08/13/2009] [Indexed: 11/30/2022]
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23
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Sánchez G, Colettis N, Vázquez P, Cerveñansky C, Aguirre A, Quillfeldt JA, Jerusalinsky D, Kornisiuk E. Muscarinic inhibition of hippocampal and striatal adenylyl cyclase is mainly due to the M(4) receptor. Neurochem Res 2009; 34:1363-71. [PMID: 19191026 DOI: 10.1007/s11064-009-9916-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2009] [Indexed: 10/21/2022]
Abstract
The five muscarinic acetylcholine receptors (M(1)-M(5)) are differentially expressed in the brain. M(2) and M(4) are coupled to inhibition of stimulated adenylyl cyclase, while M(1), M(3) and M(5) are mainly coupled to the phosphoinositide pathway. We studied the muscarinic receptor regulation of adenylyl cyclase activity in the rat hippocampus, compared to the striatum and amygdala. Basal and forskolin-stimulated adenylyl cyclase activity was higher in the striatum but the muscarinic inhibition was much lower. Highly selective muscarinic toxins MT1 and MT2-affinity order M(1) > or = M(4) >> others-and MT3-highly selective M(4) antagonist-did not show significant effects on basal or forskolin-stimulated cyclic AMP production but, like scopolamine, counteracted oxotremorine inhibition. Since MTs have negligible affinity for M(2), M(4) would be the main subtype responsible for muscarinic inhibition of forskolin-stimulated enzyme. Dopamine stimulated a small fraction of the enzyme (3.1% in striatum, 1.3% in the hippocampus). Since MT3 fully blocked muscarinic inhibition of dopamine-stimulated enzyme, M(4) receptor would be responsible for this regulation.
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Affiliation(s)
- Gonzalo Sánchez
- Instituto de Biología Celular & Neurociencia "Prof. Eduardo De Robertis", Facultad de Medicina, Universidad de Buenos Aires-CONICET, Paraguay 2155, 2Do piso, 1121 Buenos Aires, Argentina
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