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Muscarinic antagonists impair multiple aspects of operant discrimination learning and performance. Neurosci Lett 2023; 794:137025. [PMID: 36529388 PMCID: PMC9812939 DOI: 10.1016/j.neulet.2022.137025] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Acetylcholine signaling can strengthen associations between environmental cues and reward availability. Diverse subtypes (M1-M5) of the muscarinic acetylcholine receptor (mAChR) family may have distinct roles in different learning and memory processes, such as encoding cue-reward associations and consolidating these associations in long-term memory. Using an operant discrimination learning task in which mice are trained to nose poke during a tone to receive a food reward, we found that acquisition of the task requires mAChR signaling in the central nervous system. In addition, post-session injections of a broad mAChR antagonist, scopolamine impaired consolidation of the cue-reward memory. Further, after successful learning of a cue-reward contingency across multiple training sessions, mice that received a single pre-session injection of scopolamine were unable to use the learned cue association to receive rewards. Taken together, these data demonstrate distinct roles for muscarinic signaling in acquisition, consolidation and recall of the operant discrimination learning task. Understanding mechanisms underlying natural reward-related responding may provide insight into other maladaptive forms of reward learning such as addiction.
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2
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Blokland A. Cholinergic models of memory impairment in animals and man: scopolamine vs. biperiden. Behav Pharmacol 2022; 33:231-237. [PMID: 35621168 DOI: 10.1097/fbp.0000000000000670] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Scopolamine has been used as a pharmacologic model for cognitive impairments in dementia and Alzheimer's disease. The validity of this model seems to be limited because findings in animals do not readily translate to novel treatments in humans. Biperiden is also a cholinergic deficit model for cognitive impairments but specifically blocks muscarinic M1 receptors. The effects of scopolamine and biperiden (and pirenzepine) are compared in animal studies and related to findings in humans. It is concluded that the effects on cognitive functions are different for scopolamine and biperiden, and they should be considered as different cognitive deficit models. Scopolamine may model more advanced stages of Alzheimer's disease whereas biperiden may model the early deficits in declarative memory in aging and mild cognitive impairment.
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Affiliation(s)
- Arjan Blokland
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
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3
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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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4
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Muscarinic M1, but not M4, receptor antagonism impairs divided attention in male rats. Pharmacol Biochem Behav 2021; 205:173184. [PMID: 33836220 DOI: 10.1016/j.pbb.2021.173184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 03/29/2021] [Accepted: 03/30/2021] [Indexed: 11/21/2022]
Abstract
Divided attention may be more important than ever to comprehend, given ubiquitous distractors in modern living. In humans, concern has been expressed about the negative impact of distraction in education, the home, and the workplace. While acetylcholine supports divided attention, in part via muscarinic receptors, little is known about the specific muscarinic subtypes that may contribute. We designed a novel, high-response rate test of auditory sustained attention, in which rats complete variable-ratio runs on one of two levers, rather than emitting a single response. By doing this, we can present a secondary visual distractor task during some trials, for which a correct nosepoke response is reinforced with a more palatable food pellet. The nonspecific muscarinic antagonist scopolamine impaired performance, and slowed and reduced lever press activity. We then explored antagonists that preferentially block the M1 and M4 subtypes, because these receptors are potential therapeutic targets for cognitive enhancers. Telenzepine, an M1-preferring antagonist, impaired divided attention performance, but not performance of the attention task without distraction. Telenzepine also had fewer nonspecific effects than scopolamine. In contrast, the M4-preferring antagonist tropicamide had no effects. Analysis of overall behavior also indicated that accuracy in the main attention task decreased as a function of engagement with the distractor task. These results implicate the M1 receptor in divided attention.
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Vaseghi S, Nasehi M, Zarrindast MR. How do stupendous cannabinoids modulate memory processing via affecting neurotransmitter systems? Neurosci Biobehav Rev 2020; 120:173-221. [PMID: 33171142 DOI: 10.1016/j.neubiorev.2020.10.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/17/2020] [Accepted: 10/26/2020] [Indexed: 12/27/2022]
Abstract
In the present study, we wanted to review the role of cannabinoids in learning and memory in animal models, with respect to their interaction effects with six principal neurotransmitters involved in learning and memory including dopamine, glutamate, GABA (γ-aminobutyric acid), serotonin, acetylcholine, and noradrenaline. Cannabinoids induce a wide-range of unpredictable effects on cognitive functions, while their mechanisms are not fully understood. Cannabinoids in different brain regions and in interaction with different neurotransmitters, show diverse responses. Previous findings have shown that cannabinoids agonists and antagonists induce various unpredictable effects such as similar effect, paradoxical effect, or dualistic effect. It should not be forgotten that brain neurotransmitter systems can also play unpredictable roles in mediating cognitive functions. Thus, we aimed to review and discuss the effect of cannabinoids in interaction with neurotransmitters on learning and memory. In addition, we mentioned to the type of interactions between cannabinoids and neurotransmitter systems. We suggested that investigating the type of interactions is a critical neuropharmacological issue that should be considered in future studies.
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Affiliation(s)
- Salar Vaseghi
- Cognitive and Neuroscience Research Center (CNRC), Amir-Almomenin Hospital, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran; Department of Cognitive Neuroscience, Institute for Cognitive Science Studies (ICSS), Tehran, Iran
| | - Mohammad Nasehi
- Cognitive and Neuroscience Research Center (CNRC), Amir-Almomenin Hospital, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.
| | - Mohammad-Reza Zarrindast
- Department of Cognitive Neuroscience, Institute for Cognitive Science Studies (ICSS), Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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6
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Dos Santos RTF, Silva MFP, Porto RM, Lebrun I, Gonçalves LRDC, Batista IDFC, Sandoval MRL, Abdalla FMF. Effects of Mlx-8, a phospholipase A 2 from Brazilian coralsnake Micrurus lemniscatus venom, on muscarinic acetylcholine receptors in rat hippocampus. J Venom Anim Toxins Incl Trop Dis 2020; 26:e20190041. [PMID: 32063920 PMCID: PMC6986814 DOI: 10.1590/1678-9199-jvatitd-2019-0041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 12/04/2019] [Indexed: 11/22/2022] Open
Abstract
Background: Here, we described the presence of a neurotoxin with phospholipase
A2 activity isolated from Micrurus
lemniscatus venom (Mlx-8) with affinity for muscarinic
acetylcholine receptors (mAChRs). Methods: The purification, molecular mass determination, partial amino acid
sequencing, phospholipase A2 activity determination, inhibition
of the binding of the selective muscarinic ligand [3H]QNB and
inhibition of the total [3H]inositol phosphate accumulation in
rat hippocampus of the Mlx-8 were determined. Results: Thirty-one fractions were collected from HPLC chromatography, and the Mlx-8
toxin was used in this work. The molecular mass of Mlx-8 is 13.628 Da. Edman
degradation yielded the following sequence:
NLYQFKNMIQCTNTRSWL-DFADYG-CYCGRGGSGT. The Mlx-8 had phospholipase
A2 enzymatic activity. The pKi values were
determined for Mlx-8 toxin and the M1 selective muscarinic
antagonist pirenzepine in hippocampus membranes via [3H]QNB
competition binding assays. The pKi values obtained from the
analysis of Mlx-8 and pirenzepine displacement curves were 7.32 ± 0.15, n =
4 and 5.84 ± 0.18, n = 4, respectively. These results indicate that Mlx-8
has affinity for mAChRs. There was no effect on the inhibition ability of
the [3H]QNB binding in hippocampus membranes when 1 µM Mlx-8 was
incubated with 200 µM DEDA, an inhibitor of phospholipase A2.
This suggests that the inhibition of the phospholipase A2
activity of the venom did not alter its ability to bind to displace
[3H]QNB binding. In addition, the Mlx-8 toxin caused a
blockade of 43.31 ± 8.86%, n = 3 and 97.42 ± 2.02%, n = 3 for 0.1 and 1 µM
Mlx-8, respectively, on the total [3H]inositol phosphate content
induced by 10 µM carbachol. This suggests that Mlx-8 inhibits the
intracellular signaling pathway linked to activation of mAChRs in
hippocampus. Conclusion: The results of the present work show, for the first time, that muscarinic
receptors are also affected by the Mlx-8 toxin, a muscarinic ligand with
phospholipase A2 characteristics, obtained from the venom of the
Elapidae snake Micrurus lemniscatus, since this toxin was
able to compete with muscarinic ligand [3H]QNB in hippocampus of
rats. In addition, Mlx-8 also blocked the accumulation of total
[3H]inositol phosphate induced by muscarinic agonist
carbachol. Thus, Mlx-8 may be a new pharmacological tool for examining
muscarinic cholinergic function.
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Affiliation(s)
| | | | - Rafael Marques Porto
- Laboratory of Biochemistry and Biophysics, Butantan Institute, São Paulo, SP, Brazil
| | - Ivo Lebrun
- Laboratory of Biochemistry and Biophysics, Butantan Institute, São Paulo, SP, Brazil
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The Impact of Removal of Ovarian Hormones on Cholinergic Muscarinic Receptors: Examining Prepulse Inhibition and Receptor Binding. Brain Sci 2020; 10:brainsci10020106. [PMID: 32079174 PMCID: PMC7071400 DOI: 10.3390/brainsci10020106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/10/2020] [Accepted: 02/13/2020] [Indexed: 12/23/2022] Open
Abstract
Ovarian hormones, such as estrogens and progesterone, are known to exert beneficial effects on cognition and some psychiatric disorders. The basis of these effects is not fully understood, but may involve altered cholinergic neurotransmission. This study aimed to investigate how a lack of ovarian hormones would impact muscarinic receptor-induced deficits in prepulse inhibition (PPI) and muscarinic receptor density in several brain regions. Adult female rats were either ovariectomized, to remove the source of ovarian hormones, or left intact (sham-operated). PPI is a measure of sensorimotor gating that is typically impaired in schizophrenia patients, and similar deficits can be induced in rats by administering scopolamine, a muscarinic receptor antagonist. Our results revealed no significant effects of ovariectomy on PPI after saline or scopolamine treatment. Autoradiography was performed to measure cholinergic muscarinic receptor binding density using [3H]-pirenzepine, [3H]-AF-DX, and [3H]-4-DAMP, to label M1, M2/M4, and M3 receptors, respectively. We examined the amygdala, caudate putamen, dorsal hippocampus, motor cortex, retrosplenial cortex, and ventromedial hypothalamus. There were no significant group differences in any region for any muscarinic receptor type. These results suggest that removing peripheral ovarian hormones does not influence the cholinergic muscarinic receptor system in the context of PPI or receptor binding density.
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8
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Neuromodulators and Long-Term Synaptic Plasticity in Learning and Memory: A Steered-Glutamatergic Perspective. Brain Sci 2019; 9:brainsci9110300. [PMID: 31683595 PMCID: PMC6896105 DOI: 10.3390/brainsci9110300] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 10/24/2019] [Accepted: 10/29/2019] [Indexed: 12/19/2022] Open
Abstract
The molecular pathways underlying the induction and maintenance of long-term synaptic plasticity have been extensively investigated revealing various mechanisms by which neurons control their synaptic strength. The dynamic nature of neuronal connections combined with plasticity-mediated long-lasting structural and functional alterations provide valuable insights into neuronal encoding processes as molecular substrates of not only learning and memory but potentially other sensory, motor and behavioural functions that reflect previous experience. However, one key element receiving little attention in the study of synaptic plasticity is the role of neuromodulators, which are known to orchestrate neuronal activity on brain-wide, network and synaptic scales. We aim to review current evidence on the mechanisms by which certain modulators, namely dopamine, acetylcholine, noradrenaline and serotonin, control synaptic plasticity induction through corresponding metabotropic receptors in a pathway-specific manner. Lastly, we propose that neuromodulators control plasticity outcomes through steering glutamatergic transmission, thereby gating its induction and maintenance.
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9
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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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10
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Grape Seed Proanthocyanidin and Swimming Exercise Protects Against Cognitive Decline: A Study on M1 Acetylcholine Receptors in Aging Male Rat Brain. Neurochem Res 2017; 42:3573-3586. [DOI: 10.1007/s11064-017-2406-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 09/01/2017] [Accepted: 09/21/2017] [Indexed: 12/21/2022]
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11
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Hadar A, Milanesi E, Squassina A, Niola P, Chillotti C, Pasmanik-Chor M, Yaron O, Martásek P, Rehavi M, Weissglas-Volkov D, Shomron N, Gozes I, Gurwitz D. RGS2 expression predicts amyloid-β sensitivity, MCI and Alzheimer's disease: genome-wide transcriptomic profiling and bioinformatics data mining. Transl Psychiatry 2016; 6:e909. [PMID: 27701409 PMCID: PMC5315547 DOI: 10.1038/tp.2016.179] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 05/26/2016] [Accepted: 06/15/2016] [Indexed: 12/30/2022] Open
Abstract
Alzheimer's disease (AD) is the most frequent cause of dementia. Misfolded protein pathological hallmarks of AD are brain deposits of amyloid-β (Aβ) plaques and phosphorylated tau neurofibrillary tangles. However, doubts about the role of Aβ in AD pathology have been raised as Aβ is a common component of extracellular brain deposits found, also by in vivo imaging, in non-demented aged individuals. It has been suggested that some individuals are more prone to Aβ neurotoxicity and hence more likely to develop AD when aging brains start accumulating Aβ plaques. Here, we applied genome-wide transcriptomic profiling of lymphoblastoid cells lines (LCLs) from healthy individuals and AD patients for identifying genes that predict sensitivity to Aβ. Real-time PCR validation identified 3.78-fold lower expression of RGS2 (regulator of G-protein signaling 2; P=0.0085) in LCLs from healthy individuals exhibiting high vs low Aβ sensitivity. Furthermore, RGS2 showed 3.3-fold lower expression (P=0.0008) in AD LCLs compared with controls. Notably, RGS2 expression in AD LCLs correlated with the patients' cognitive function. Lower RGS2 expression levels were also discovered in published expression data sets from postmortem AD brain tissues as well as in mild cognitive impairment and AD blood samples compared with controls. In conclusion, Aβ sensitivity phenotyping followed by transcriptomic profiling and published patient data mining identified reduced peripheral and brain expression levels of RGS2, a key regulator of G-protein-coupled receptor signaling and neuronal plasticity. RGS2 is suggested as a novel AD biomarker (alongside other genes) toward early AD detection and future disease modifying therapeutics.
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Affiliation(s)
- A Hadar
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - E Milanesi
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - A Squassina
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - P Niola
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - C Chillotti
- Unit of Clinical Pharmacology, University Hospital of Cagliari, Cagliari, Italy
| | - M Pasmanik-Chor
- Bioinformatics Unit, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - O Yaron
- The Genomic Analysis Laboratory, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - P Martásek
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
| | - M Rehavi
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
| | - D Weissglas-Volkov
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - N Shomron
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel,Adams Super Center for Brain Studies, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - I Gozes
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel,Adams Super Center for Brain Studies, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel,Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel. E-mail: or
| | - D Gurwitz
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel,Adams Super Center for Brain Studies, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel,Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel. E-mail: or
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12
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Aitken P, Benoit A, Zheng Y, Philoxene B, Le Gall A, Denise P, Besnard S, Smith PF. Hippocampal and striatal M1-muscarinic acetylcholine receptors are down-regulated following bilateral vestibular loss in rats. Hippocampus 2016; 26:1509-1514. [DOI: 10.1002/hipo.22651] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/17/2016] [Accepted: 08/25/2016] [Indexed: 12/21/2022]
Affiliation(s)
- Phillip Aitken
- Department of Pharmacology and Toxicology; Brain Health Research Centre University of Otago; Dunedin New Zealand
| | - Alice Benoit
- Normandie Univ, UNICAEN, INSERM, COMETE, CHU Caen; 14000 Caen France
| | - Yiwen Zheng
- Department of Pharmacology and Toxicology; Brain Health Research Centre University of Otago; Dunedin New Zealand
- Brain Research New Zealand Centre of Research Excellence; New Zealand
| | - Bruno Philoxene
- Normandie Univ, UNICAEN, INSERM, COMETE, CHU Caen; 14000 Caen France
| | - Anne Le Gall
- Normandie Univ, UNICAEN, INSERM, COMETE, CHU Caen; 14000 Caen France
| | - Pierre Denise
- Normandie Univ, UNICAEN, INSERM, COMETE, CHU Caen; 14000 Caen France
| | - Stephane Besnard
- Normandie Univ, UNICAEN, INSERM, COMETE, CHU Caen; 14000 Caen France
| | - Paul F. Smith
- Department of Pharmacology and Toxicology; Brain Health Research Centre University of Otago; Dunedin New Zealand
- Brain Research New Zealand Centre of Research Excellence; New Zealand
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13
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de Vin F, Choi SM, Bolognesi ML, Lefebvre RA. Presynaptic M3 muscarinic cholinoceptors mediate inhibition of excitatory synaptic transmission in area CA1 of rat hippocampus. Brain Res 2015; 1629:260-9. [DOI: 10.1016/j.brainres.2015.10.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 10/11/2015] [Accepted: 10/16/2015] [Indexed: 11/26/2022]
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14
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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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15
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Abstract
AbstractMemory consolidation is the process by which relevant information is selected and transferred from a short-term, fragile state, into a stable, longer term domain from which it can be recalled. Effective memory underpins our ability to carry out everyday activities. When memory consolidation fails, such as in Alzheimer’s disease, the consequences can be devastating. Understanding the neurobiology of memory will help develop treatments for patients with memory loss. Here we describe the myriad processes involved in memory consolidation, including cholinergic and dopaminergic neurotransmission predominantly in hippocampal networks. We discuss established therapies as well as potential novel strategies for boosting cognition. Future approaches to enhancement of memory consolidation include not only pharmacological and neurosurgical treatments, but also lifestyle interventions — for example, modifications to sleep, exercise and diet.
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Robinson AM, Mangini DF, Burk JA. Task demands dissociate the effects of muscarinic M1 receptor blockade and protein kinase C inhibition on attentional performance in rats. J Psychopharmacol 2012; 26:1143-50. [PMID: 21890584 PMCID: PMC3251644 DOI: 10.1177/0269881111415732] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The cholinergic system is known to be necessary for normal attentional processing. However, the receptors and mechanisms mediating the effects of acetylcholine on attention remain unclear. Previous work in our laboratory suggested that cholinergic muscarinic receptors are critical for maintaining performance in an attention-demanding task in rats. We examined the role of the muscarinic M(1) receptor and protein kinase C (PKC), which is activated by the M(1) receptor, in attention task performance. Rats were trained in an attention-demanding task requiring discrimination of brief (500, 100, 25 ms) visual signals from trials with no signal presentation. The effects of muscarinic M(1) receptor blockade were assessed by administering dicyclomine (0-5.0 mg/kg). The effects of PKC inhibition were assessed by administering chelerythrine chloride (0-2.0 mg/kg). Dicyclomine decreased the accuracy of detecting longer signals in this attention task, including when attentional demands were increased by flashing a houselight throughout the session. Chelerythrine chloride decreased the accuracy of signal detection in the standard version of the task but not when the houselight was flashed throughout the session. The present findings indicate that muscarinic M(1) receptors are critical for maintaining performance when attentional demands are increased, and that PKC activity may contribute to some aspects of attentional performance.
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Affiliation(s)
- Andrea M Robinson
- Department of Psychology, College of William and Mary, Williamsburg, VA, USA
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17
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Parfitt GM, Campos RC, Barbosa ÂK, Koth AP, Barros DM. Participation of hippocampal cholinergic system in memory persistence for inhibitory avoidance in rats. Neurobiol Learn Mem 2012; 97:183-8. [DOI: 10.1016/j.nlm.2011.12.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 11/23/2011] [Accepted: 12/01/2011] [Indexed: 10/14/2022]
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18
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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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19
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Veeraragavan S, Bui N, Perkins JR, Yuva-Paylor LA, Paylor R. The modulation of fragile X behaviors by the muscarinic M4 antagonist, tropicamide. Behav Neurosci 2011; 125:783-90. [PMID: 21942438 PMCID: PMC3183989 DOI: 10.1037/a0025202] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Muscarinic acetylcholine receptors (mAChR) are G protein-coupled receptors (M1-M5), grouped together into two functional classes, based on their G protein interaction. Although ubiquitously expressed in the CNS, the M4 protein shows highest expression in the neostriatum, cortex, and hippocampus. Electrophysiological and biochemical studies have provided evidence for overactive mAChR signaling in the fragile X knock-out (Fmr1KO) mouse model, and this has been hypothesized to contribute to the phenotypes seen in Fmr1KO mice. To address this hypothesis we used an M4 antagonist, tropicamide, to reduce the activity through the M4 mAChR and investigated the behavioral response in the Fmr1KO animals. Data from the marble-burying assay have shown that tropicamide treatment resulted in a decreased number of marbles buried in the wild-type (WT) and in the knockout (KO) animals. Results from the open field assay indicated that tropicamide increases activity in both the WT and KO mice. In the passive avoidance assay, tropicamide treatment resulted in the improvement of performance in both the WT and the KO animals at the lower doses (2 and 5 mg/kg), and the drug was shown to be important for the acquisition and not the consolidation process. Lastly, we observed that tropicamide causes a significant decrease in the percentage of audiogenic seizures in the Fmr1KO animals. These results suggest that pharmacological antagonism of the M4 receptor modulates select behavioral responses in the Fmr1KO mice.
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Affiliation(s)
- Surabi Veeraragavan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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20
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Robinson L, Platt B, Riedel G. Involvement of the cholinergic system in conditioning and perceptual memory. Behav Brain Res 2011; 221:443-65. [PMID: 21315109 DOI: 10.1016/j.bbr.2011.01.055] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 01/29/2011] [Indexed: 01/07/2023]
Abstract
The cholinergic systems play a pivotal role in learning and memory, and have been the centre of attention when it comes to diseases containing cognitive deficits. It is therefore not surprising, that the cholinergic transmitter system has experienced detailed examination of its role in numerous behavioural situations not least with the perspective that cognition may be rescued with appropriate cholinergic 'boosters'. Here we reviewed the literature on (i) cholinergic lesions, (ii) pharmacological intervention of muscarinic or nicotinic system, or (iii) genetic deletion of selective receptor subtypes with respect to sensory discrimination and conditioning procedures. We consider visual, auditory, olfactory and somatosensory processing first before discussing more complex tasks such as startle responses, latent inhibition, negative patterning, eye blink and fear conditioning, and passive avoidance paradigms. An overarching reoccurring theme is that lesions of the cholinergic projection neurones of the basal forebrain impact negatively on acquisition learning in these paradigms and blockade of muscarinic (and to a lesser extent nicotinic) receptors in the target structures produce similar behavioural deficits. While these pertain mainly to impairments in acquisition learning, some rare cases extend to memory consolidation. Such single case observations warranted replication and more in-depth studies. Intriguingly, receptor blockade or receptor gene knockout repeatedly produced contradictory results (for example in fear conditioning) and combined studies, in which genetically altered mice are pharmacological manipulated, are so far missing. However, they are desperately needed to clarify underlying reasons for these contradictions. Consistently, stimulation of either muscarinic (mainly M(1)) or nicotinic (predominantly α7) receptors was beneficial for learning and memory formation across all paradigms supporting the notion that research into the development and mechanisms of novel and better cholinomimetics may prove useful in the treatment of neurodegenerative or psychiatric disorders with cognitive endophenotypes.
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Affiliation(s)
- Lianne Robinson
- School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
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21
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Huang ZB, Wang H, Rao XR, Zhong GF, Hu WH, Sheng GQ. Different effects of scopolamine on the retrieval of spatial memory and fear memory. Behav Brain Res 2010; 221:604-9. [PMID: 20553767 DOI: 10.1016/j.bbr.2010.05.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 03/10/2010] [Accepted: 05/19/2010] [Indexed: 11/25/2022]
Abstract
Retrieval of memory is fundamental for our life as individuals. The participation of cholinergic system in memory consolidation process has been extensively studied, but there are few data concerning the function of this system in memory retrieval process. In the current study, we inject non-selective muscarinic antagonist scopolamine peripherally 20 min before training or testing to see whether cholinergic modulation has effects on the acquisition or retrieval of spatial memory by water maze task and fear memory by inhibitory avoidance task. We find that the cholinergic system is essential for the acquisition of both spatial memory and fear memory. As for the memory retrieval, the cholinergic system has a positive role in the retrieval of spatial memory, because mice injected with scopolamine 20 min before the testing in the water maze show impaired spatial memory retrieval. Whereas injection of scopolamine 20 min before the testing in the inhibitory avoidance task does not cause memory retrieval deficits. That indicates the cholinergic system is not essential for the retrieval of fear memory.
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Affiliation(s)
- Zhen-Bo Huang
- CAS Key Laboratory of Regenerative Biology, South China Institute of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, People's Republic of China
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22
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Lecourtier L, de Vasconcelos AP, Cosquer B, Cassel JC. Combined lesions of GABAergic and cholinergic septal neurons increase locomotor activity and potentiate the locomotor response to amphetamine. Behav Brain Res 2010; 213:175-82. [PMID: 20450937 DOI: 10.1016/j.bbr.2010.04.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 04/24/2010] [Accepted: 04/28/2010] [Indexed: 10/19/2022]
Abstract
Potentiated locomotor response to amphetamine has been associated with an increased sensitivity of the dopaminergic system and used as a model of the positive symptoms of schizophrenia in rodents. The hippocampus, through the subiculum, modulates dopamine transmission and hippocampal or subicular lesions potentiate the locomotor response to amphetamine. However, little is known about the upstream structures controlling hippocampal/subicular activity towards the regulation of dopamine transmission. The main modulatory input to the hippocampus is the septal area, composed of the medial septum and vertical limb of the diagonal band of Broca (MS/vDBB). The so-called septohippocampal pathway includes cholinergic and GABAergic fibers reaching the hippocampus through the fimbria-fornix. While electrolytic lesions of the MS/vDBB potentiate the locomotor response to amphetamine, cholinergic damage in the MS/vDBB does not affect this response. Moreover, the role of the GABAergic connections has never been investigated. Therefore, we performed in rats lesions of cholinergic or/and GABAergic septal neurons and assessed locomotor activity, (i) in an unfamiliar environment, (ii) under baseline conditions (separating light-on and light-off periods) and (iii) in response to an amphetamine challenge. While single lesions had no effects, rats with combined lesions were hyperactive in all three conditions. Thus, damage to cholinergic and GABAergic septohippocampal neurons induced locomotor alterations qualitatively comparable to those produced by hippocampal and/or subicular lesions. Our results further suggest that the septum, through both cholinergic and GABAergic fibers, modulates the functional contribution of the hippocampus/subiculum in the regulation of mesolimbic dopamine transmission.
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Affiliation(s)
- Lucas Lecourtier
- Laboratoire d'Imagerie et de Neurosciences Cognitives, FRE 3289, Université de Strasbourg-CNRS, 12 rue Goethe, Strasbourg, France
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23
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Sánchez G, de Oliveira Alvares L, Oberholzer MV, Genro B, Quillfeldt J, da Costa JC, Cerveñansky C, Jerusalinsky D, Kornisiuk E. M4muscarinic receptors are involved in modulation of neurotransmission at synapses of Schaffer collaterals on CA1 hippocampal neurons in rats. J Neurosci Res 2009; 87:691-700. [DOI: 10.1002/jnr.21876] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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24
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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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25
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Allosteric modulation of the muscarinic M4 receptor as an approach to treating schizophrenia. Proc Natl Acad Sci U S A 2008; 105:10978-83. [PMID: 18678919 DOI: 10.1073/pnas.0800567105] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Current antipsychotics provide symptomatic relief for patients suffering from schizophrenia and related psychoses; however, their effectiveness is variable and many patients discontinue treatment due to side effects. Although the etiology of schizophrenia is still unclear, a leading hypothesis implicates an imbalanced dopaminergic system. Muscarinic acetylcholine (ACh) receptors regulate dopamine levels in key areas of the brain involved in psychosis, with the M(4) subtype emerging as a key regulator of dopaminergic hyperactivity. Unfortunately, no selective small molecule tools exist to provide pharmacological validation of this hypothesis. Here, we describe the discovery of a small molecule modulator, LY2033298, that is highly selective for human M(4) receptors by virtue of targeting an allosteric site on this receptor. Pharmacological assays confirmed the selectivity of LY2033298 for the M(4) receptor and revealed the highest degree of positive allosteric enhancement of ACh potency thus far identified. Radioligand binding assays also show this compound to directly potentiate agonist binding while having minimal effects on antagonist binding. Mutational analysis identified a key amino acid (D(432)) in the third extracellular loop of the human M(4) receptor to be critical for selectivity and agonist potentiation by LY2033298. Importantly, LY2033298 was active in animal models predictive of clinical antipsychotic drug efficacy indicating its potential use as a first-in-class, selective, allosteric muscarinic antipsychotic agent.
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26
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De Oliveira Alvares L, Genro BP, Diehl F, Quillfeldt JA. Differential role of the hippocampal endocannabinoid system in the memory consolidation and retrieval mechanisms. Neurobiol Learn Mem 2008; 90:1-9. [DOI: 10.1016/j.nlm.2008.01.009] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 01/01/2008] [Accepted: 01/18/2008] [Indexed: 11/16/2022]
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McCool MF, Patel S, Talati R, Ragozzino ME. Differential involvement of M1-type and M4-type muscarinic cholinergic receptors in the dorsomedial striatum in task switching. Neurobiol Learn Mem 2007; 89:114-24. [PMID: 17709264 PMCID: PMC2293307 DOI: 10.1016/j.nlm.2007.06.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 06/26/2007] [Accepted: 06/30/2007] [Indexed: 11/26/2022]
Abstract
Previous experiments have demonstrated that the rat dorsomedial striatum is one brain area that plays a crucial role in learning when conditions require a shift in strategies. Further evidence indicates that muscarinic cholinergic receptors in this brain area support adaptations in behavioral responses. Unknown is whether specific muscarinic receptor subtypes in the dorsomedial striatum contribute to a flexible shift in response patterns. The present experiments investigated whether blockade of M1-type and/or M4-type cholinergic receptors in the dorsomedial striatum underlie place reversal learning. Experiment 1 investigated the effects of the M1-type muscarinic cholinergic antagonist, muscarinic-toxin 7 (MT-7) infused into the dorsomedial striatum in place acquisition and reversal learning. Experiment 2 investigated the effects of the M4-type muscarinic cholinergic antagonist, muscarinic-toxin 3 (MT-3) injected into the dorsomedial striatum in place acquisition and reversal learning. All testing occurred in a modified cross-maze across two consecutive sessions. Bilateral injections of MT-7 into the dorsomedial striatum at 1 or 2 microg, but not 0.05 microg impaired place reversal learning. Analysis of the errors revealed that MT-7 at 1 and 2 microg significantly increased regressive errors, but not perseverative errors. An injection of MT-7 2 microg into the dorsomedial striatum prior to place acquisition did not affect learning. Experiment 2 revealed that dorsomedial striatal injections of MT-3 (0.05, 1 or 2 microg) did not affect place acquisition or reversal learning. The findings suggest that activation of M1-type muscarinic cholinergic receptors in the dorsomedial striatum, but not M4-type muscarinic cholinergic receptors facilitate the flexible shifting of response patterns by maintaining or learning a new choice pattern once selected.
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Affiliation(s)
| | | | | | - Michael E. Ragozzino
- Department of Psychology
- Center for Cognitive Medicine
- Laboratory of Integrative Neuroscience
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28
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Valvassori SS, Fortunato JJ, Gomes KM, Réus GZ, Martins MR, Gavioli EC, Schetinger MRC, Dal-Pizzol F, Quevedo J. Acute and subacute exposure to malathion impairs aversive but not non-associative memory in rats. Neurotox Res 2007; 12:71-9. [PMID: 17513201 DOI: 10.1007/bf03033902] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Malathion [S-(1,2-dicarbethoxy) ethyl-0,0-dimethyl-phosphorodithioate] is an organophosphorus compound that is widely used as pesticide especially in developing countries. This pesticide affects the central nervous system by inhibiting acetylcholinesterase, leading to an increase of acetylcholine in the synaptic cleft, and subsequent activation of cholinergic muscarinic and nicotinic receptors. In humans, intoxication with organophosphates causes a wide range of neurological symptoms, including memory deficits. The present study was aimed to investigate the effects of the acute (1 h prior the test) and subacute (once a day for 28 days) exposure to malathion at doses of 25, 50, 100 and 150 mg/kg in rats tested in the step-down inhibitory avoidance task, open-field habituation and elevated plus-maze tests. Interestingly, the acute and subacute treatment with malathion impaired aversive-memory in the step-down inhibitory avoidance task, but did not alter the animal performance in the elevated plus-maze and in the habituation to the open-field tests, and neither modified spontaneous locomotion. The activity of acetylcholinesterase enzyme was significantly reduced after subacute, but not acute, treatment with malathion (25, 100 and 150 mg/kg). Our results suggest that malathion impairs aversive-memory retention but not non-associative memory, without affecting anxiety-related behaviors. These findings support the view that the inhibition of acetylcholinesterase enzyme is not correlated with cognitive deficits observed in acute and subacute malathion-treated rats.
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Affiliation(s)
- Samira S Valvassori
- Laboratório de Neurociencias, Programa de Pós-Graduacao em Ciencias da Saúde, Universidade do Extremo Sul Catrinense, 88806-000 Criciúma, SC, Brazil
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29
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Li S, Cullen WK, Anwyl R, Rowan MJ. Muscarinic acetylcholine receptor-dependent induction of persistent synaptic enhancement in rat hippocampus in vivo. Neuroscience 2007; 144:754-61. [PMID: 17101232 DOI: 10.1016/j.neuroscience.2006.10.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2006] [Revised: 09/30/2006] [Accepted: 10/02/2006] [Indexed: 11/23/2022]
Abstract
Presynaptic terminal autoinhibitory muscarinic acetylcholine (ACh) receptors are predominantly of the M2/M4 subtypes and antagonists at these receptors may facilitate cognitive processes by increasing ACh release. The present study examined the ability of the M2/M4 muscarinic ACh receptor antagonist N,N'-bis [6-[[(2-methoxyphenyl)methyl]amino]hexyl]-1,8-octane diamine tetrahydrochloride (methoctramine) to induce and modulate synaptic plasticity in the CA1 area of the hippocampus in urethane-anesthetized rats. Both methoctramine and another M2/M4 antagonist, {11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepin-6-one} (AF-DX 116), caused a rapid onset and persistent increase in baseline synaptic transmission after i.c.v. injection. Consistent with a requirement for activation of non-M2 receptors by endogenously released ACh, the M1/M3 receptor selective antagonists 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) and 4,9-dihydro-3-methyl-4-[(4-methyl-1-piperazinyl)acetyl]-10H-thieno[3,4-b][1,5]benzodiazepin-10-one dihydrochloride (telenzepine) prevented the induction of the persistent synaptic enhancement by methoctramine. The requirement for cholinergic activation was transient and independent of nicotinic ACh receptor stimulation. The synaptic enhancement was inhibited by the prior induction of long-term potentiation (LTP) by high frequency stimulation but induction of the synaptic enhancement by methoctramine before high frequency stimulation did not inhibit LTP. Unlike high frequency stimulation-evoked LTP, the synaptic enhancement induced by methoctramine appeared to be NMDA receptor-independent. The present studies provide evidence for the rapid induction of a persistent potentiation at hippocampal glutamatergic synapses by endogenous ACh in vivo following disinhibition of inhibitory M2 muscarinic autoreceptors.
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Affiliation(s)
- S Li
- Department of Pharmacology and Therapeutics, Biotechnology Building, Trinity College Institute of Neuroscience, Trinity College, Dublin 2, Ireland
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30
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Nissen C, Power AE, Nofzinger EA, Feige B, Voderholzer U, Kloepfer C, Waldheim B, Radosa MP, Berger M, Riemann D. M1 Muscarinic Acetylcholine Receptor Agonism Alters Sleep without Affecting Memory Consolidation. J Cogn Neurosci 2006; 18:1799-807. [PMID: 17069471 DOI: 10.1162/jocn.2006.18.11.1799] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract
Preclinical studies have implicated cholinergic neurotransmission, specifically M1 muscarinic acetylcholine receptor (mAChR) activation, in sleep-associated memory consolidation. In the present study, we investigated the effects of administering the direct M1 mAChR agonist RS-86 on pre-post sleep memory consolidation. Twenty healthy human participants were tested in a declarative word-list task and a procedural mirror-tracing task. RS-86 significantly reduced rapid eye movement (REM) sleep latency and slow wave sleep (SWS) duration in comparison with placebo. Presleep acquisition and postsleep recall rates were within the expected ranges. However, recall rates in both tasks were almost identical for the RS-86 and placebo conditions. These results indicate that selective M1 mAChR activation in healthy humans has no clinically relevant effect on pre-post sleep consolidation of declarative or procedural memories at a dose that reduces REM sleep latency and SWS duration.
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Mulugeta E, Chandranath I, Karlsson E, Winblad B, Adem A. Temporal and region-dependent changes in muscarinic M4 receptors in the hippocampus and entorhinal cortex of adrenalectomized rats. Exp Brain Res 2006; 173:309-17. [PMID: 16676164 DOI: 10.1007/s00221-006-0490-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2006] [Accepted: 04/01/2006] [Indexed: 10/24/2022]
Abstract
Long-term adrenalectomy induces a dramatic loss of cells in the dentate gyrus and CA1-CA4 fields of the hippocampus resulting in an impairment of cognitive functions such as spatial learning, memory and exploratory behaviour. Muscarinic M1 and M4 receptor levels in the hippocampus and entorhinal cortex of adult male Wistar rats were examined 3, 14, 30, 90, and 150 days after adrenalectomy. Receptor levels in the entorhinal cortex and the hippocampus were determined by quantitative autoradiography using 125I-M1-toxin-1 and 125I-M4-toxin-1, M1 and M4 subtype selective antagonists, respectively. Moreover, the level of hippocampal M1 and M4 muscarinic receptors were evaluated 1 month after adrenalectomy by immunoblot analysis. Adrenalectomy induced apoptotic processes were examined by analysing apoptotic markers using Western blot analysis. No significant changes were observed in the level of muscarinic M1 receptors in the entorhinal cortex, the dentate gyrus and in the different CA fields of the hippocampus of adrenalectomized (ADX) rats. However, M4 receptors showed a significant decrease in the entorhinal cortex (at 3 days), dentate gyrus and CA4 (at 14 days), CA3 (at 30 days), and CA2 and CA1 (at 90 days) after adrenalectomy. Moreover, a decrease in the level of M4 receptors was detected in ADX rats 1 month after adrenalectomy as compared with sham groups using M4 specific antibody. Apoptotic markers such as PARP and p53 were significantly increased whereas Bcl-2 marker was decreased in ADX rat brain homogenates compared to controls. Our results show that M1 and M4 receptors are differentially affected by adrenalectomy and indicate that these subtypes have different functions in the hippocampus. Our data on time and region-dependent decreases in hippocampal M4 receptors indicate that the M4 receptor subtype is influenced by adrenal hormones and suggest that the M4 receptor might be linked to memory function in the hippocampus.
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Affiliation(s)
- Ezra Mulugeta
- Section of Experimental Geriatrics, NEUROTEC, Karolinska Institute, 141 86, Huddinge, Sweden
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32
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Millan MJ. Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application. Pharmacol Ther 2006; 110:135-370. [PMID: 16522330 DOI: 10.1016/j.pharmthera.2005.11.006] [Citation(s) in RCA: 388] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 12/20/2022]
Abstract
Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.
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Affiliation(s)
- Mark J Millan
- Institut de Recherches Servier, Centre de Recherches de Croissy, Psychopharmacology Department, 125, Chemin de Ronde, 78290-Croissy/Seine, France.
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33
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Pych JC, Chang Q, Colon-Rivera C, Haag R, Gold PE. Acetylcholine release in the hippocampus and striatum during place and response training. Learn Mem 2006; 12:564-72. [PMID: 16322358 PMCID: PMC1356173 DOI: 10.1101/lm.33105] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
These experiments examined the release of acetylcholine in the hippocampus and striatum when rats were trained, within single sessions, on place or response versions of food-rewarded mazes. Microdialysis samples of extra-cellular fluid were collected from the hippocampus and striatum at 5-min increments before, during, and after training. These samples were later analyzed for ACh content using HPLC methods. In Experiment 1, ACh release in both the hippocampus and striatum increased during training on both the place and response tasks. The magnitude of increase of training-related ACh release in the striatum was greater in rats trained on the response task than in rats trained on the place task, while the magnitude of ACh release in the hippocampus was comparable in the two tasks. Experiment 2 tested the possibility that the hippocampus was engaged and participated in learning the response task, as well as the place task, because of the availability of extra-maze cues. Rats were trained on a response version of a maze under either cue-rich or cue-poor conditions. The findings indicate that ACh release in the hippocampus increased similarly under both cue conditions, but declined during training on the cue-poor condition, when spatial processing by the hippocampus would not be suitable for solving the maze. In addition, high baseline levels of ACh release in the hippocampus predicted rapid learning in the cue-rich condition and slow learning in the cue-poor condition. These findings suggest that ACh release in the hippocampus augments response learning when extra-maze cues can be used to solve the maze but impairs response learning when extra-maze cues are not available for use in solving the maze.
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Affiliation(s)
- Jason C Pych
- Department of Psychology, University of Illinois at Urbana-Champaign, Illinois 61820, USA
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Mohapel P, Leanza G, Kokaia M, Lindvall O. Forebrain acetylcholine regulates adult hippocampal neurogenesis and learning. Neurobiol Aging 2005; 26:939-46. [PMID: 15718053 DOI: 10.1016/j.neurobiolaging.2004.07.015] [Citation(s) in RCA: 242] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2004] [Revised: 07/19/2004] [Accepted: 07/30/2004] [Indexed: 01/09/2023]
Abstract
Hippocampus-mediated learning enhances neurogenesis in the adult dentate gyrus (DG), and this process has been suggested to be involved in memory formation. The hippocampus receives abundant cholinergic innervation and acetylcholine (ACh) plays an important role in learning and Alzheimer's disease (AD) pathophysiology. Here, we show that a selective neurotoxic lesion of forebrain cholinergic input with 192 IgG-saporin reduces DG neurogenesis with a concurrent impairment in spatial memory. Conversely, systemic administration of the cholinergic agonist physostigmine increases DG neurogenesis. We find that changes of forebrain ACh levels primarily influence the proliferation and/or the short-term survival rather than the long-term survival or differentiation of the new neurons. We further demonstrate that these newly born cells express the muscarinic receptor subtypes M1 and M4. Our data provide evidence that forebrain ACh promotes neurogenesis, and suggest that the impaired cholinergic function in AD may in part contribute to deficits in learning and memory through reductions in the formation of new hippocampal neurons.
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Affiliation(s)
- Paul Mohapel
- Section of Restorative Neurology, Wallenberg Neuroscience Centre, BMC A11, SE-221 84 Lund, Sweden.
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Tzavos A, Jih J, Ragozzino ME. Differential effects of M1 muscarinic receptor blockade and nicotinic receptor blockade in the dorsomedial striatum on response reversal learning. Behav Brain Res 2004; 154:245-53. [PMID: 15302131 PMCID: PMC3206590 DOI: 10.1016/j.bbr.2004.02.011] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Revised: 01/06/2004] [Accepted: 02/18/2004] [Indexed: 11/26/2022]
Abstract
The present studies determined whether blockade of M(1)-like muscarinic or nicotinic cholinergic receptors in the dorsomedial striatum affects acquisition or reversal learning of a response discrimination. Testing occurred in a modified cross-maze across two consecutive sessions. In the acquisition phase, a rat learned to turn to the left or to the right. In the reversal learning phase, a rat learned to turn in the opposite direction as required during acquisition. Experiment 1 investigated the effects of the M(1)-like muscarinic receptor antagonist, pirenzepine infused into the dorsomedial striatum on acquisition and reversal learning. Experiment 2 examined the effects of the nicotinic cholinergic antagonist, mecamylamine injected into the dorsomedial striatum on acquisition and reversal learning. Bilateral injections of pirenzepine at 10 microg, but not 1 microg, selectively impaired reversal learning. Analysis of the errors indicated that pirenzepine treatment did not impair the initial shift, but increased reversions back to the original response choice following the initial shift. Bilateral injections of mecamylamine, 6 or 18 microg, did not affect acquisition or reversal learning. The results suggest that activation of M(1) muscarinic cholinergic receptors, but not nicotinic cholinergic receptors, in the dorsomedial striatum is important for facilitating the flexible shifting of response patterns.
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Affiliation(s)
- Arianna Tzavos
- Laboratory of Integrative Neuroscience, Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA
| | - Jane Jih
- Laboratory of Integrative Neuroscience, Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA
| | - Michael E. Ragozzino
- Laboratory of Integrative Neuroscience, Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA
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