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Jain S, LaFrancois JJ, Gerencer K, Botterill JJ, Kennedy M, Criscuolo C, Scharfman HE. Increasing adult-born neurons protects mice from epilepsy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.08.548217. [PMID: 37502909 PMCID: PMC10369878 DOI: 10.1101/2023.07.08.548217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Neurogenesis occurs in the adult brain in the hippocampal dentate gyrus, an area that contains neurons which are vulnerable to insults and injury, such as severe seizures. Previous studies showed that increasing adult neurogenesis reduced neuronal damage after these seizures. Because the damage typically is followed by chronic life-long seizures (epilepsy), we asked if increasing adult-born neurons would prevent epilepsy. Adult-born neurons were selectively increased by deleting the pro-apoptotic gene Bax from Nestin-expressing progenitors. Tamoxifen was administered at 6 weeks of age to conditionally delete Bax in Nestin-CreERT2 Bax fl/fl mice. Six weeks after tamoxifen administration, severe seizures (status epilepticus; SE) were induced by injection of the convulsant pilocarpine. After mice developed epilepsy, seizure frequency was quantified for 3 weeks. Mice with increased adult-born neurons exhibited fewer chronic seizures. Postictal depression was reduced also. These results were primarily in female mice, possibly because they were the more affected by Bax deletion than males, consistent with sex differences in Bax. The female mice with enhanced adult-born neurons also showed less neuronal loss of hilar mossy cells and hilar somatostatin-expressing neurons than wild type females or males, which is notable because these two hilar cell types are implicated in epileptogenesis. The results suggest that selective Bax deletion to increase adult-born neurons can reduce experimental epilepsy, and the effect shows a striking sex difference. The results are surprising in light of past studies showing that suppressing adult-born neurons can also reduce chronic seizures.
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Affiliation(s)
- Swati Jain
- Center for Dementia Research, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962
| | - John J. LaFrancois
- Center for Dementia Research, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962
| | - Kasey Gerencer
- Center for Dementia Research, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962
- Current address: Department of Psychology, The University of Maine, Orono, ME 04469
| | - Justin J. Botterill
- Department of Anatomy, Physiology, & Pharmacology, College of Medicine, Saskatoon, SK S7N 5E5
| | - Meghan Kennedy
- Center for Dementia Research, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962
| | - Chiara Criscuolo
- Center for Dementia Research, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962
- Departments of Child and Adolescent Psychiatry, New York University Grossman School of Medicine, New York, NY 10016
| | - Helen E. Scharfman
- Center for Dementia Research, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962
- Departments of Child and Adolescent Psychiatry, New York University Grossman School of Medicine, New York, NY 10016
- Departments of Neuroscience & Physiology, Psychiatry, and the New York University, Neuroscience Institute, New York University Grossman School of Medicine, New York, NY 10016
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2
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Huang LW, Torelli F, Chen HL, Bartos M. Context and space coding in mossy cell population activity. Cell Rep 2024; 43:114386. [PMID: 38909362 DOI: 10.1016/j.celrep.2024.114386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 05/07/2024] [Accepted: 06/05/2024] [Indexed: 06/25/2024] Open
Abstract
The dentate gyrus plays a key role in the discrimination of memories by segregating and storing similar episodes. Whether hilar mossy cells, which constitute a major excitatory principal cell type in the mammalian hippocampus, contribute to this decorrelation function has remained largely unclear. Using two-photon calcium imaging of head-fixed mice performing a spatial virtual reality task, we show that mossy cell populations robustly discriminate between familiar and novel environments. The degree of discrimination depends on the extent of visual cue differences between contexts. A context decoder revealed that successful environmental classification is explained mainly by activity difference scores of mossy cells. By decoding mouse position, we reveal that in addition to place cells, the coordinated activity among active mossy cells markedly contributes to the encoding of space. Thus, by decorrelating context information according to the degree of environmental differences, mossy cell populations support pattern separation processes within the dentate gyrus.
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Affiliation(s)
- Li-Wen Huang
- Institute for Physiology I, University of Freiburg, Medical Faculty, 79104 Freiburg, Germany
| | - Federico Torelli
- Institute for Physiology I, University of Freiburg, Medical Faculty, 79104 Freiburg, Germany; University of Freiburg, Faculty of Biology, 79104 Freiburg, Germany
| | - Hung-Ling Chen
- Institute for Physiology I, University of Freiburg, Medical Faculty, 79104 Freiburg, Germany; BrainLinks-BrainTools, University of Freiburg, 79104 Freiburg, Germany.
| | - Marlene Bartos
- Institute for Physiology I, University of Freiburg, Medical Faculty, 79104 Freiburg, Germany.
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3
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Jeong M, Won J, Lim KS, Jeon CY, Choe Y, Jang JH, Ha CM, Yoon JH, Lee Y, Oh YS. Comparative Anatomy of the Dentate Mossy Cells in Nonhuman Primates: Their Spatial Distributions and Axonal Projections Compared With Mouse Mossy Cells. eNeuro 2024; 11:ENEURO.0151-24.2024. [PMID: 38688719 DOI: 10.1523/eneuro.0151-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 04/18/2024] [Indexed: 05/02/2024] Open
Abstract
Glutamatergic mossy cells (MCs) mediate associational and commissural connectivity, exhibiting significant heterogeneity along the septotemporal axis of the mouse dentate gyrus (DG). However, it remains unclear whether the neuronal features of MCs are conserved across mammals. This study compares the neuroanatomy of MCs in the DG of mice and monkeys. The MC marker, calretinin, distinguishes two subpopulations: septal and temporal. Dual-colored fluorescence labeling is utilized to compare the axonal projection patterns of these subpopulations. In both mice and monkeys, septal and temporal MCs project axons across the longitudinal axis of the ipsilateral DG, indicating conserved associational projections. However, unlike in mice, no MC subpopulations in monkeys make commissural projections to the contralateral DG. In monkeys, temporal MCs send associational fibers exclusively to the inner molecular layer, while septal MCs give rise to wide axonal projections spanning multiple molecular layers, akin to equivalent MC subpopulations in mice. Despite conserved septotemporal heterogeneity, interspecies differences are observed in the topological organization of septal MCs, particularly in the relative axonal density in each molecular layer along the septotemporal axis of the DG. In summary, this comparative analysis sheds light on both conserved and divergent features of MCs in the DG of mice and monkeys. These findings have implications for understanding functional differentiation along the septotemporal axis of the DG and contribute to our knowledge of the anatomical evolution of the DG circuit in mammals.
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Affiliation(s)
- Minseok Jeong
- Department of Brain Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Jinyoung Won
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Cheongju 28116, Republic of Korea
| | - Kyung Seob Lim
- Futuristic Animal Resource and Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Cheongju 28116, Republic of Korea
| | - Chang-Yeop Jeon
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Cheongju 28116, Republic of Korea
| | - Youngshik Choe
- Developmental Disorders & Rare Diseases Research Group, Korea Brain Research Institute (KBRI), Daegu 41062, Republic of Korea
| | - Jin-Hyeok Jang
- Department of Brain Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Chang Man Ha
- Research Division and Brain Research Core Facilities, Korea Brain Research Institute (KBRI), Daegu 41062, Republic of Korea
| | - Jong Hyuk Yoon
- Neurodegenerative Diseases Research Group, Korea Brain Research Institute (KBRI), Daegu 41062, Republic of Korea
| | - Yongjeon Lee
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Cheongju 28116, Republic of Korea
- Department of Functional Genomics, KRIBB School of Bioscience, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - Yong-Seok Oh
- Department of Brain Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
- Emotion, Cognition & Behavior Research Group, Korea Brain Research Institute (KBRI), Daegu 41062, Republic of Korea
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4
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Botterill JJ, Khlaifia A, Appings R, Wilkin J, Violi F, Premachandran H, Cruz-Sanchez A, Canella AE, Patel A, Zaidi SD, Arruda-Carvalho M. Dorsal peduncular cortex activity modulates affective behavior and fear extinction in mice. Neuropsychopharmacology 2024; 49:993-1006. [PMID: 38233571 PMCID: PMC11039686 DOI: 10.1038/s41386-024-01795-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 12/27/2023] [Accepted: 12/28/2023] [Indexed: 01/19/2024]
Abstract
The medial prefrontal cortex (mPFC) is critical to cognitive and emotional function and underlies many neuropsychiatric disorders, including mood, fear and anxiety disorders. In rodents, disruption of mPFC activity affects anxiety- and depression-like behavior, with specialized contributions from its subdivisions. The rodent mPFC is divided into the dorsomedial prefrontal cortex (dmPFC), spanning the anterior cingulate cortex (ACC) and dorsal prelimbic cortex (PL), and the ventromedial prefrontal cortex (vmPFC), which includes the ventral PL, infralimbic cortex (IL), and in some studies the dorsal peduncular cortex (DP) and dorsal tenia tecta (DTT). The DP/DTT have recently been implicated in the regulation of stress-induced sympathetic responses via projections to the hypothalamus. While many studies implicate the PL and IL in anxiety-, depression-like and fear behavior, the contribution of the DP/DTT to affective and emotional behavior remains unknown. Here, we used chemogenetics and optogenetics to bidirectionally modulate DP/DTT activity and examine its effects on affective behaviors, fear and stress responses in C57BL/6J mice. Acute chemogenetic activation of DP/DTT significantly increased anxiety-like behavior in the open field and elevated plus maze tests, as well as passive coping in the tail suspension test. DP/DTT activation also led to an increase in serum corticosterone levels and facilitated auditory fear extinction learning and retrieval. Activation of DP/DTT projections to the dorsomedial hypothalamus (DMH) acutely decreased freezing at baseline and during extinction learning, but did not alter affective behavior. These findings point to the DP/DTT as a new regulator of affective behavior and fear extinction in mice.
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Affiliation(s)
- Justin J Botterill
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
- Department of Anatomy, Physiology, and Pharmacology, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Abdessattar Khlaifia
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - Ryan Appings
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - Jennifer Wilkin
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - Francesca Violi
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - Hanista Premachandran
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - Arely Cruz-Sanchez
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S3G5, Canada
| | - Anna Elisabete Canella
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - Ashutosh Patel
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - S Danyal Zaidi
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada
| | - Maithe Arruda-Carvalho
- Department of Psychology, University of Toronto Scarborough, Toronto, ON, M1C1A4, Canada.
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S3G5, Canada.
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5
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Hung YC, Wu YJ, Chien ME, Lin YT, Tsai CF, Hsu KS. Loss of oxytocin receptors in hilar mossy cells impairs social discrimination. Neurobiol Dis 2023; 187:106311. [PMID: 37769745 DOI: 10.1016/j.nbd.2023.106311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 09/24/2023] [Accepted: 09/25/2023] [Indexed: 10/02/2023] Open
Abstract
Hippocampal oxytocin receptor (OXTR) signaling is crucial for discrimination of social stimuli to guide social recognition, but circuit mechanisms and cell types involved remain incompletely understood. Here, we report a role for OXTR-expressing hilar mossy cells (MCs) of the dentate gyrus in social stimulus discrimination by regulating granule cell (GC) activity. Using a Cre-loxP recombination approach, we found that ablation of Oxtr from MCs impairs discrimination of social, but not object, stimuli in adult male mice. Ablation of MC Oxtr increases spontaneous firing rate of GCs, synaptic excitation to inhibition ratio of MC-to-GC circuit, and GC firing when temporally associated with the lateral perforant path inputs. Using mouse hippocampal slices, we found that bath application of OXTR agonist [Thr4,Gly7]-oxytocin causes membrane depolarization and increases MC firing activity. Optogenetic activation of MC-to-GC circuit ameliorates social discrimination deficit in MC OXTR deficient mice. Together, our results uncover a previously unknown role of MC OXTR signaling for discrimination of social stimuli and delineate a MC-to-GC circuit responsible for social information processing.
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Affiliation(s)
- Yu-Chieh Hung
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
| | - Yi-Jen Wu
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 70457, Taiwan; Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan
| | - Miao-Er Chien
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 70457, Taiwan
| | - Yu-Ting Lin
- Institute of Systems Neuroscience, College of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Cheng-Fang Tsai
- Department of Physical Medicine and Rehabilitation, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi 60002, Taiwan; Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan.
| | - Kuei-Sen Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan; Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
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6
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Cerroni C, Steiner A, Seanez L, Kwon S, Lewis AS. Effects of repeated developmental GLP-1R agonist exposure on young adult behavior and hippocampal structure in mice. Neurosci Lett 2023; 808:137299. [PMID: 37196974 PMCID: PMC10330515 DOI: 10.1016/j.neulet.2023.137299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/10/2023] [Accepted: 05/11/2023] [Indexed: 05/19/2023]
Abstract
Glucagon-like peptide-1 receptor (GLP-1R) agonists are common type 2 diabetes medications that have been repurposed for adult chronic weight management. Clinical trials suggest this class may also be beneficial for obesity in pediatric populations. Since several GLP-1R agonists cross the blood-brain barrier, it is important to understand how postnatal developmental exposure to GLP-1R agonists might affect brain structure and function later in life. Toward that end, we systemically treated male and female C57BL/6 mice with the GLP-1R agonist exendin-4 (0.5 mg/kg, twice daily) or saline from postnatal day 14 to 21, then allowed uninterrupted development to young adulthood. Beginning at 7 weeks of age, we performed open field and marble burying tests to assess motor behavior and the spontaneous location recognition (SLR) task to assess hippocampal-dependent pattern separation and memory. Mice were sacrificed, and we counted ventral hippocampal mossy cells, as we have recently shown that most murine hippocampal neuronal GLP-1R is expressed in this cell population. We found that GLP-1R agonist treatment did not alter P14-P21 weight gain, but modestly reduced young adult open field distance traveled and marble burying. Despite these motor changes, there was no effect on SLR memory performance or time spent investigating objects. Finally, we did not detect any changes in ventral mossy cell number using two different markers. These data suggest developmental exposure to GLP-1R agonists might have specific rather than global effects on behavior later in life and that extensive additional study is necessary to clarify how drug timing and dose affect distinct constellations of behavior in young adulthood.
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Affiliation(s)
- Catherine Cerroni
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alex Steiner
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Leann Seanez
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sam Kwon
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alan S Lewis
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, USA; Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA.
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7
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Cerroni C, Steiner A, Seanez L, Kwon S, Lewis AS. Effects of repeated developmental GLP-1R agonist exposure on adult behavior and hippocampal structure in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.21.537724. [PMID: 37131808 PMCID: PMC10153236 DOI: 10.1101/2023.04.21.537724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Glucagon-like peptide-1 receptor (GLP-1R) agonists are common type 2 diabetes medications that have been repurposed for adult chronic weight management. Clinical trials suggest this class may also be beneficial for obesity in pediatric populations. Since several GLP-1R agonists cross the blood-brain barrier, it is important to understand how postnatal developmental exposure to GLP-1R agonists might affect brain structure and function in adulthood. Toward that end, we systemically treated male and female C57BL/6 mice with the GLP-1R agonist exendin-4 (0.5 mg/kg, twice daily) or saline from postnatal day 14 to 21, then allowed uninterrupted development to adulthood. Beginning at 7 weeks of age, we performed open field and marble burying tests to assess motor behavior and the spontaneous location recognition (SLR) task to assess hippocampal-dependent pattern separation and memory. Mice were sacrificed, and we counted ventral hippocampal mossy cells, as we have recently shown that most murine hippocampal neuronal GLP-1R is expressed in this cell population. We found that GLP-1R agonist treatment did not alter P14-P21 weight gain, but modestly reduced adult open field distance traveled and marble burying. Despite these motor changes, there was no effect on SLR memory performance or time spent investigating objects. Finally, we did not detect any changes in ventral mossy cell number using two different markers. These data suggest developmental exposure to GLP-1R agonists might have specific rather than global effects on behavior later in life and that extensive additional study is necessary to clarify how drug timing and dose affect distinct constellations of behavior in adulthood.
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8
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Joshi S, Williams CL, Kapur J. Limbic progesterone receptors regulate spatial memory. Sci Rep 2023; 13:2164. [PMID: 36750584 PMCID: PMC9905062 DOI: 10.1038/s41598-023-29100-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/30/2023] [Indexed: 02/09/2023] Open
Abstract
Progesterone and its receptors (PRs) participate in mating and reproduction, but their role in spatial declarative memory is not understood. Male mice expressed PRs, predominately in excitatory neurons, in brain regions that support spatial memory, such as the hippocampus and entorhinal cortex (EC). Furthermore, segesterone, a specific PR agonist, activates neurons in both the EC and hippocampus. We assessed the contribution of PRs in promoting spatial and non-spatial cognitive learning in male mice by examining the performance of mice lacking this receptor (PRKO), in novel object recognition, object placement, Y-maze alternation, and Morris-Water Maze (MWM) tasks. In the recognition test, the PRKO mice preferred the familiar object over the novel object. A similar preference for the familiar object was also seen following the EC-specific deletion of PRs. PRKO mice were also unable to recognize the change in object position. We confirmed deficits in spatial memory of PRKO mice by testing them on the Y-maze forced alternation and MWM tasks; PR deletion affected animal's performance in both these tasks. In contrast to spatial tasks, PR removal did not alter the response to fear conditioning. These studies provide novel insights into the role of PRs in facilitating spatial, declarative memory in males, which may help with finding reproductive partners.
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Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Health Sciences Center, P.O. Box 801330, Charlottesville, VA, 22908, USA.
| | - Cedric L Williams
- Department of Psychology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Health Sciences Center, P.O. Box 801330, Charlottesville, VA, 22908, USA.,Department of Neuroscience, University of Virginia, Charlottesville, VA, 22908, USA.,UVA Brain Institute, University of Virginia, Charlottesville, VA, 22908, USA
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9
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Steiner A, Owen BM, Bauer JP, Seanez L, Kwon S, Biddinger JE, Huffman R, Ayala JE, Nobis WP, Lewis AS. Glucagon-like peptide-1 receptor differentially controls mossy cell activity across the dentate gyrus longitudinal axis. Hippocampus 2022; 32:797-807. [PMID: 36063105 PMCID: PMC9675713 DOI: 10.1002/hipo.23469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 07/27/2022] [Accepted: 08/18/2022] [Indexed: 01/07/2023]
Abstract
Understanding the role of dentate gyrus (DG) mossy cells (MCs) in learning and memory has rapidly evolved due to increasingly precise methods for targeting MCs and for in vivo recording and activity manipulation in rodents. These studies have shown MCs are highly active in vivo, strongly remap to contextual manipulation, and that their inhibition or hyperactivation impairs pattern separation and location or context discrimination. Less well understood is how MC activity is modulated by neurohormonal mechanisms, which might differentially control the participation of MCs in cognitive functions during discrete states, such as hunger or satiety. In this study, we demonstrate that glucagon-like peptide-1 (GLP-1), a neuropeptide produced in the gut and the brain that regulates food consumption and hippocampal-dependent mnemonic function, might regulate MC function through expression of its receptor, GLP-1R. RNA-seq demonstrated that most, though not all, Glp1r in hippocampal principal neurons is expressed in MCs, and in situ hybridization revealed strong expression of Glp1r in hilar neurons. Glp1r-ires-Cre mice crossed with Ai14D reporter mice followed by co-labeling for the MC marker GluR2/3 revealed that almost all MCs in the ventral DG expressed Glp1r and that almost all Glp1r-expressing hilar neurons were MCs. However, only ~60% of dorsal DG MCs expressed Glp1r, and Glp1r was also expressed in small hilar neurons that were not MCs. Consistent with this expression pattern, peripheral administration of the GLP-1R agonist exendin-4 (5 μg/kg) increased cFos expression in ventral but not dorsal DG hilar neurons. Finally, whole-cell patch-clamp recordings from ventral MCs showed that bath application of exendin-4 (200 nM) depolarized MCs and increased action potential firing. Taken together, this study adds to known MC activity modulators a neurohormonal mechanism that may preferentially affect ventral DG physiology and may potentially be targetable by several GLP-1R pharmacotherapies already in clinical use.
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Affiliation(s)
- Alex Steiner
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Benjamin M. Owen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - James P. Bauer
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Leann Seanez
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sam Kwon
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jessica E. Biddinger
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Ragan Huffman
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Julio E. Ayala
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, USA
| | - William P. Nobis
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alan S. Lewis
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, USA
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10
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Kecskés A, Czéh B, Kecskés M. Mossy cells of the dentate gyrus: Drivers or inhibitors of epileptic seizures? BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119279. [PMID: 35526721 DOI: 10.1016/j.bbamcr.2022.119279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 04/22/2022] [Accepted: 04/25/2022] [Indexed: 05/12/2023]
Abstract
Mossy cells (MCs) are glutamatergic cells of the dentate gyrus with an important role in temporal lobe epilepsy. Under physiological conditions MCs can control both network excitations via direct synapses to granule cells and inhibition via connections to GABAergic interneurons innervating granule cells. In temporal lobe epilepsy mossy cell loss is one of the major hallmarks, but whether the surviving MCs drive or inhibit seizure initiation and generalization is still a debate. The aim of the present review is to summarize the latest findings on the role of mossy cells in healthy and overexcited hippocampus.
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Affiliation(s)
- Angéla Kecskés
- Department of Pharmacology and Pharmacotherapy, Medical School & Szentagothai Research Centre, Molecular Pharmacology Research Group, Centre for Neuroscience, University of Pécs, H-7624 Pécs, Hungary
| | - Boldizsár Czéh
- Department of Laboratory Medicine, Medical School & Szentagothai Research Centre, Histology and Light Microscopy Core Facility, Centre for Neuroscience, University of Pécs, H-7624 Pécs, Hungary
| | - Miklós Kecskés
- Institute of Physiology, Medical School & Szentagothai Research Centre, Molecular Neuroendocrinology Research Group, Centre for Neuroscience, University of Pécs, H-7624 Pécs, Hungary.
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11
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Briquet M, Rocher AB, Alessandri M, Rosenberg N, de Castro Abrantes H, Wellbourne-Wood J, Schmuziger C, Ginet V, Puyal J, Pralong E, Daniel RT, Offermanns S, Chatton JY. Activation of lactate receptor HCAR1 down-modulates neuronal activity in rodent and human brain tissue. J Cereb Blood Flow Metab 2022; 42:1650-1665. [PMID: 35240875 PMCID: PMC9441721 DOI: 10.1177/0271678x221080324] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Lactate can be used by neurons as an energy substrate to support their activity. Evidence suggests that lactate also acts on a metabotropic receptor called HCAR1, first described in the adipose tissue. Whether HCAR1 also modulates neuronal circuits remains unclear. In this study, using qRT-PCR, we show that HCAR1 is present in the human brain of epileptic patients who underwent resective surgery. In brain slices from these patients, pharmacological HCAR1 activation using a non-metabolized agonist decreased the frequency of both spontaneous neuronal Ca2+ spiking and excitatory post-synaptic currents (sEPSCs). In mouse brains, we found HCAR1 expression in different regions using a fluorescent reporter mouse line and in situ hybridization. In the dentate gyrus, HCAR1 is mainly present in mossy cells, key players in the hippocampal excitatory circuitry and known to be involved in temporal lobe epilepsy. By using whole-cell patch clamp recordings in mouse and rat slices, we found that HCAR1 activation causes a decrease in excitability, sEPSCs, and miniature EPSCs frequency of granule cells, the main output of mossy cells. Overall, we propose that lactate can be considered a neuromodulator decreasing synaptic activity in human and rodent brains, which makes HCAR1 an attractive target for the treatment of epilepsy.
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Affiliation(s)
- Marc Briquet
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Anne-Bérengère Rocher
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Maxime Alessandri
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Nadia Rosenberg
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | | | - Joel Wellbourne-Wood
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Céline Schmuziger
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Vanessa Ginet
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Julien Puyal
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Etienne Pralong
- Department of Neurosurgery Service, University Hospital of Lausanne and Faculty of Biology and Medicine, UNIL, Lausanne, Switzerland
| | - Roy Thomas Daniel
- Department of Neurosurgery Service, University Hospital of Lausanne and Faculty of Biology and Medicine, UNIL, Lausanne, Switzerland
| | - Stefan Offermanns
- Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Jean-Yves Chatton
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Cellular Imaging Facility, University of Lausanne, Lausanne, Switzerland
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12
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Kwon KM, Pak JH, Jeon CJ. Immunocytochemical localization of the AMPA glutamate receptor subtype GluR2/3 in the squid optic lobe. Acta Histochem 2022; 124:151941. [PMID: 35963117 DOI: 10.1016/j.acthis.2022.151941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/03/2022] [Accepted: 08/03/2022] [Indexed: 11/17/2022]
Abstract
As a major excitatory neurotransmitter in the cephalopod visual system, glutamate signaling is facilitated by ionotropic receptors, such as α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR). In cephalopods with large and well-developed brains, the optic lobes (OL) mainly process visual inputs and are involved in learning and memory. Although the presence of AMPAR in squid OL has been reported, the organization of specific AMPAR-containing neurons remains unknown. This study aimed to investigate the immunocytochemical localization of the AMPA glutamate receptor subtype 2/3-immunoreactive (GluR2/3-IR) neurons in the OL of Pacific flying squid (Tordarodes pacificus). Morphologically diverse GluR2/3-IR neurons were predominantly located in the tangential zone of the medulla. Medium-to-large GluR2/3-IR neurons were also detected. The distribution patterns and cell morphologies of calcium-binding protein (CBP)-IR neurons, specifically calbindin-D28K (CB)-, calretinin (CR)-, and parvalbumin (PV)-IR neurons, were similar to those of GluR2/3-IR neurons. However, two-color immunofluorescence revealed that GluR2/3-IR neurons did not colocalize with the CBP-IR neurons. Furthermore, the specific localizations and diverse types of GluR2/3-IR neurons that do not express CB, CR, or PV in squid OL were determined. These findings further contribute to the existing data on glutamatergic visual systems and provide new insights for understanding the visual processing mechanisms in cephalopods.
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Affiliation(s)
- Kyung-Min Kwon
- Department of Biology, School of Life Sciences, BK21 FOUR KNU Creative BioResearch Group, College of Natural Sciences, Brain Science and Engineering Institute, Kyungpook National University, Daegu 41566, Republic of Korea; Research Institute for Dok-do and Ulleung-do Island, Department of Biology, School of Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jae-Hong Pak
- Research Institute for Dok-do and Ulleung-do Island, Department of Biology, School of Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Chang-Jin Jeon
- Department of Biology, School of Life Sciences, BK21 FOUR KNU Creative BioResearch Group, College of Natural Sciences, Brain Science and Engineering Institute, Kyungpook National University, Daegu 41566, Republic of Korea; Research Institute for Dok-do and Ulleung-do Island, Department of Biology, School of Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea.
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13
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Zirotti Rosenberg A, Méndez-Ruette M, Gorziglia M, Alzerreca B, Cabello J, Kaufmann S, Rambousek L, Iturriaga Jofré A, Wyneken U, Lafourcade CA. Behavioral and Molecular Responses to Exogenous Cannabinoids During Pentylenetetrazol-Induced Convulsions in Male and Female Rats. Front Mol Neurosci 2022; 15:868583. [PMID: 36147210 PMCID: PMC9488559 DOI: 10.3389/fnmol.2022.868583] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 05/13/2022] [Indexed: 11/13/2022] Open
Abstract
Epilepsy is a disabling, chronic brain disease,affecting ~1% of the World’s population, characterized by recurrent seizures (sudden, uncontrolled brain activity), which may manifest with motor symptoms (e.g., convulsions) or non-motor symptoms. Temporal lobe epilepsies (TLE) compromising the hippocampus are the most common form of focal epilepsies. Resistance in ~1/3 of epileptic patients to the first line of treatment, i.e., antiepileptic drugs (AEDs), has been an important motivation to seek alternative treatments. Among these, the plant Cannabis sativa (commonly known as marihuana) or compounds extracted from it (cannabinoids) have gained widespread popularity. Moreover, sex differences have been proposed in epilepsy syndromes and in cannabinoid action. In the hippocampus, cannabinoids interact with the CB1R receptor whose membrane levels are regulated by β-Arrestin2, a protein that promotes its endocytosis and causes its downregulation. In this article, we evaluate the modulatory role of WIN 55,212-2 (WIN), a synthetic exogenous cannabinoid on behavioral convulsions and on the levels of CB1R and β-Arrestin2 in female and male adolescent rats after a single injection of the proconvulsant pentylenetetrazol (PTZ). As epilepsies can have a considerable impact on synaptic proteins that regulate neuronal toxicity, plasticity, and cognition, we also measured the levels of key proteins markers of excitatory synapses, in order to examine whether exogenous cannabinoids may prevent such pathologic changes after acute seizures. We found that the exogenous administration of WIN prevented convulsions of medium severity in females and males and increased the levels of phosphorylated CaMKII in the hippocampus. Furthermore, we observed a higher degree of colocalization between CB1R and β-Arrestin2 in the granule cell layer.
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Affiliation(s)
| | - Maxs Méndez-Ruette
- Centro de investigación e innovación Biomédica (CiiB), Laboratorio de Neurociencias, Universidad de Los Andes, Santiago, Chile
| | - Mario Gorziglia
- Facultad de Medicina, Universidad de Los Andes, Santiago, Chile
| | | | - Javiera Cabello
- Facultad de Medicina, Universidad de Los Andes, Santiago, Chile
| | - Sofía Kaufmann
- Facultad de Medicina, Universidad de Los Andes, Santiago, Chile
| | - Lukas Rambousek
- Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | | | - Ursula Wyneken
- Facultad de Medicina, Universidad de Los Andes, Santiago, Chile
- IMPACT, Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile
| | - Carlos A. Lafourcade
- Department of Biological Sciences, Xi’an Jiaotong-Liverpool University (XJTLU), Suzhou, China
- *Correspondence: Carlos A. Lafourcade
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14
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Zhou Z, Li X, Domel AG, Dennis EL, Georgiadis M, Liu Y, Raymond SJ, Grant G, Kleiven S, Camarillo D, Zeineh M. The Presence of the Temporal Horn Exacerbates the Vulnerability of Hippocampus During Head Impacts. Front Bioeng Biotechnol 2022; 10:754344. [PMID: 35392406 PMCID: PMC8980591 DOI: 10.3389/fbioe.2022.754344] [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] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
Hippocampal injury is common in traumatic brain injury (TBI) patients, but the underlying pathogenesis remains elusive. In this study, we hypothesize that the presence of the adjacent fluid-containing temporal horn exacerbates the biomechanical vulnerability of the hippocampus. Two finite element models of the human head were used to investigate this hypothesis, one with and one without the temporal horn, and both including a detailed hippocampal subfield delineation. A fluid-structure interaction coupling approach was used to simulate the brain-ventricle interface, in which the intraventricular cerebrospinal fluid was represented by an arbitrary Lagrangian-Eulerian multi-material formation to account for its fluid behavior. By comparing the response of these two models under identical loadings, the model that included the temporal horn predicted increased magnitudes of strain and strain rate in the hippocampus with respect to its counterpart without the temporal horn. This specifically affected cornu ammonis (CA) 1 (CA1), CA2/3, hippocampal tail, subiculum, and the adjacent amygdala and ventral diencephalon. These computational results suggest that the presence of the temporal horn exacerbate the vulnerability of the hippocampus, highlighting the mechanobiological dependency of the hippocampus on the temporal horn.
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Affiliation(s)
- Zhou Zhou
- Department of Bioengineering, Stanford University, Stanford, CA, United States
- Neuronic Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Xiaogai Li
- Neuronic Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
| | - August G. Domel
- Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Emily L. Dennis
- TBI and Concussion Center, Department of Neurology, University of Utah, Salt Lake City, UT, United States
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Marios Georgiadis
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Yuzhe Liu
- Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Samuel J. Raymond
- Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Gerald Grant
- Department of Neurosurgery, Stanford University, Stanford, CA, United States
- Department of Neurology, Stanford University, Stanford, CA, United States
| | - Svein Kleiven
- Neuronic Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
| | - David Camarillo
- Department of Bioengineering, Stanford University, Stanford, CA, United States
- Department of Neurosurgery, Stanford University, Stanford, CA, United States
- Department of Mechanical Engineering, Stanford University, Stanford, CA, United States
| | - Michael Zeineh
- Department of Radiology, Stanford University, Stanford, CA, United States
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15
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Ge Y, Wang YT. GluA1-homomeric AMPA receptor in synaptic plasticity and neurological diseases. Neuropharmacology 2021; 197:108708. [PMID: 34274350 DOI: 10.1016/j.neuropharm.2021.108708] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/28/2021] [Accepted: 07/08/2021] [Indexed: 11/17/2022]
Abstract
Synaptic transmission is one of the fundamental processes that all brain functions are based on. Changes in the strength of synaptic transmission among neurons are crucial for information processing in the central nervous system. The α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid subtype of ionotropic glutamate receptors (AMPARs) mediate the majority of the fast excitatory synaptic transmission in the mammalian brain. Rapid trafficking of AMPARs in and out of the postsynaptic membrane is proposed to be a major mechanism for synaptic plasticity, and learning and memory. Defects in the regulated AMPAR trafficking have been shown to be involved in the pathogenesis of certain psychiatric and neurodegenerative diseases. Studies accumulated in the past 30 years have provided a detailed molecular insight on how the trafficking of AMPARs is modulated in a subunit-specific manner. In particular, emerging evidence supports that the regulated expression and trafficking of Ca2+-permeable, GluA1-homomeric subtype of AMPARs mediates diverse types of synaptic plasticity, thereby playing critical roles in brain function and dysfunction. In this review, we will discuss the current knowledge of AMPAR subunit-specific trafficking, with a particular emphasis on the involvement of GluA1-homomeric receptor trafficking in synaptic plasticity and brain disorders.
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Affiliation(s)
- Yuan Ge
- Djavad Mowafaghian Centre for Brain Health and Department of Medicine, University of British Columbia, Vancouver, BC, V6T 2B5, Canada; Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC, V6T 2B5, Canada
| | - Yu Tian Wang
- Djavad Mowafaghian Centre for Brain Health and Department of Medicine, University of British Columbia, Vancouver, BC, V6T 2B5, Canada.
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16
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Henin S, Shankar A, Borges H, Flinker A, Doyle W, Friedman D, Devinsky O, Buzsáki G, Liu A. Spatiotemporal dynamics between interictal epileptiform discharges and ripples during associative memory processing. Brain 2021; 144:1590-1602. [PMID: 33889945 DOI: 10.1093/brain/awab044] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 11/16/2020] [Accepted: 12/06/2020] [Indexed: 12/13/2022] Open
Abstract
We describe the spatiotemporal course of cortical high-gamma activity, hippocampal ripple activity and interictal epileptiform discharges during an associative memory task in 15 epilepsy patients undergoing invasive EEG. Successful encoding trials manifested significantly greater high-gamma activity in hippocampus and frontal regions. Successful cued recall trials manifested sustained high-gamma activity in hippocampus compared to failed responses. Hippocampal ripple rates were greater during successful encoding and retrieval trials. Interictal epileptiform discharges during encoding were associated with 15% decreased odds of remembering in hippocampus (95% confidence interval 6-23%). Hippocampal interictal epileptiform discharges during retrieval predicted 25% decreased odds of remembering (15-33%). Odds of remembering were reduced by 25-52% if interictal epileptiform discharges occurred during the 500-2000 ms window of encoding or by 41% during retrieval. During encoding and retrieval, hippocampal interictal epileptiform discharges were followed by a transient decrease in ripple rate. We hypothesize that interictal epileptiform discharges impair associative memory in a regionally and temporally specific manner by decreasing physiological hippocampal ripples necessary for effective encoding and recall. Because dynamic memory impairment arises from pathological interictal epileptiform discharge events competing with physiological ripples, interictal epileptiform discharges represent a promising therapeutic target for memory remediation in patients with epilepsy.
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Affiliation(s)
- Simon Henin
- NYU Langone Health, Department of Neurology, New York, NY 10017, USA.,NYU Langone Health, Comprehensive Epilepsy Center, New York, NY 10016, USA
| | - Anita Shankar
- NYU Langone Health, Department of Neurology, New York, NY 10017, USA.,NYU Langone Health, Comprehensive Epilepsy Center, New York, NY 10016, USA
| | - Helen Borges
- NYU Langone Health, Department of Neurology, New York, NY 10017, USA.,NYU Langone Health, Comprehensive Epilepsy Center, New York, NY 10016, USA
| | - Adeen Flinker
- NYU Langone Health, Department of Neurology, New York, NY 10017, USA.,NYU Langone Health, Comprehensive Epilepsy Center, New York, NY 10016, USA
| | - Werner Doyle
- NYU Langone Health, Comprehensive Epilepsy Center, New York, NY 10016, USA.,NYU Langone Health, Department of Neurosurgery, New York, NY 10016, USA
| | - Daniel Friedman
- NYU Langone Health, Department of Neurology, New York, NY 10017, USA.,NYU Langone Health, Comprehensive Epilepsy Center, New York, NY 10016, USA
| | - Orrin Devinsky
- NYU Langone Health, Department of Neurology, New York, NY 10017, USA.,NYU Langone Health, Comprehensive Epilepsy Center, New York, NY 10016, USA
| | - György Buzsáki
- NYU Langone Health, Department of Neurology, New York, NY 10017, USA.,New York University, Neuroscience Institute, New York, NY 10016, USA
| | - Anli Liu
- NYU Langone Health, Department of Neurology, New York, NY 10017, USA.,NYU Langone Health, Comprehensive Epilepsy Center, New York, NY 10016, USA.,New York University, Neuroscience Institute, New York, NY 10016, USA
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17
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Houser CR, Peng Z, Wei X, Huang CS, Mody I. Mossy Cells in the Dorsal and Ventral Dentate Gyrus Differ in Their Patterns of Axonal Projections. J Neurosci 2021; 41:991-1004. [PMID: 33268544 PMCID: PMC7880284 DOI: 10.1523/jneurosci.2455-20.2020] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/08/2020] [Accepted: 11/20/2020] [Indexed: 01/22/2023] Open
Abstract
Mossy cells (MCs) of the dentate gyrus (DG) are a major group of excitatory hilar neurons that are important for regulating activity of dentate granule cells. MCs are particularly intriguing because of their extensive longitudinal connections within the DG. It has generally been assumed that MCs in the dorsal and ventral DG have similar patterns of termination in the inner one-third of the dentate molecular layer. Here, we demonstrate that axonal projections of MCs in these two regions are considerably different. MCs in dorsal and ventral regions were labeled selectively with Cre-dependent eYFP or mCherry, using two transgenic mouse lines (including both sexes) that express Cre-recombinase in MCs. At four to six weeks following unilateral labeling of MCs in the ventral DG, a dense band of fibers was present in the inner one-fourth of the molecular layer and extended bilaterally throughout the rostral-caudal extent of the DG, replicating the expected distribution of MC axons. In contrast, following labeling of MCs in the dorsal DG, the projections were more diffusely distributed. At the level of transfection, fibers were present in the inner molecular layer, but they progressively expanded into the middle molecular layer and, most ventrally, formed a distinct band in this region. Optical stimulation of these caudal fibers expressing ChR2 demonstrated robust EPSCs in ipsilateral granule cells and enhanced the effects of perforant path stimulation in the ventral DG. These findings suggest that MCs in the dorsal and ventral DG differ in the distribution of their axonal projections and possibly their function.SIGNIFICANCE STATEMENT Mossy cells (MCs), a major cell type in the hilus of the dentate gyrus (DG), are unique in providing extensive longitudinal and commissural projections throughout the DG. Although it has been assumed that all MCs have similar patterns of termination in the inner molecular layer of the DG, we discovered that the axonal projections of dorsal and ventral MCs differ. While ventral MC projections exhibit the classical pattern, with dense innervation in the inner molecular layer, dorsal MCs have a more diffuse distribution and expand into the middle molecular layer where they overlap and interact with innervation from the perforant path. These distinct locations and patterns of axonal projections suggest that dorsal and ventral MCs may have different functional roles.
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Affiliation(s)
- Carolyn R Houser
- Department of Neurobiology
- Brain Research Institute, David Geffen School of Medicine at the University of California, Los Angeles, Los Angeles, California 90095
| | | | | | | | - Istvan Mody
- Department of Neurology
- Brain Research Institute, David Geffen School of Medicine at the University of California, Los Angeles, Los Angeles, California 90095
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18
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Bernstein HL, Lu YL, Botterill JJ, Scharfman HE. Novelty and Novel Objects Increase c-Fos Immunoreactivity in Mossy Cells in the Mouse Dentate Gyrus. Neural Plast 2019; 2019:1815371. [PMID: 31534449 PMCID: PMC6732597 DOI: 10.1155/2019/1815371] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/05/2019] [Indexed: 02/06/2023] Open
Abstract
The dentate gyrus (DG) and its primary cell type, the granule cell (GC), are thought to be critical to many cognitive functions. A major neuronal subtype of the DG is the hilar mossy cell (MC). MCs have been considered to play an important role in cognition, but in vivo studies to understand the activity of MCs during cognitive tasks are challenging because the experiments usually involve trauma to the overlying hippocampus or DG, which kills hilar neurons. In addition, restraint typically occurs, and MC activity is reduced by brief restraint stress. Social isolation often occurs and is potentially confounding. Therefore, we used c-fos protein expression to understand when MCs are active in vivo in socially housed adult C57BL/6 mice in their home cage. We focused on c-fos protein expression after animals explored novel objects, based on previous work which showed that MCs express c-fos protein readily in response to a novel housing location. Also, MCs are required for the training component of the novel object location task and novelty-encoding during a food-related task. GluR2/3 was used as a marker of MCs. The results showed that MC c-fos protein is greatly increased after exposure to novel objects, especially in ventral DG. We also found that novel objects produced higher c-fos levels than familiar objects. Interestingly, a small subset of neurons that did not express GluR2/3 also increased c-fos protein after novel object exposure. In contrast, GCs appeared relatively insensitive. The results support a growing appreciation of the role of the DG in novelty detection and novel object recognition, where hilar neurons and especially MCs are very sensitive.
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Affiliation(s)
- Hannah L. Bernstein
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
| | - Yi-Ling Lu
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
| | - Justin J. Botterill
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
| | - Helen E. Scharfman
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
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19
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Eyre MD, Bartos M. Somatostatin-Expressing Interneurons Form Axonal Projections to the Contralateral Hippocampus. Front Neural Circuits 2019; 13:56. [PMID: 31507383 PMCID: PMC6716454 DOI: 10.3389/fncir.2019.00056] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 08/08/2019] [Indexed: 12/31/2022] Open
Abstract
Conscious memories are critically dependent upon bilateral hippocampal formation, and interhemispheric commissural projections made by mossy cells and CA3 pyramidal cells. GABAergic interneurons also make long-range axonal projections, but little is known regarding their commissural, inter-hippocampal connections. We used retrograde and adeno-associated viral tracing, immunofluorescence and electron microscopy, and in vitro optogenetics to assess contralateral projections of neurochemically defined interneuron classes. We found that contralateral-projecting interneurons were 24-fold less common compared to hilar mossy cells, and mostly consisted of somatostatin- and parvalbumin-expressing types. Somatostatin-expressing cells made denser contralateral axonal projections than parvalbumin-expressing cells, although this was typically 10-fold less than the ipsilateral projection density. Somatostatin-expressing cells displayed a topographic-like innervation according to the location of their somata, whereas parvalbumin-expressing cells mostly innervated CA1. In the dentate gyrus molecular layer, commissural interneuron post-synaptic targets were predominantly putative granule cell apical dendrites. In the hilus, varicosities in close vicinity to various interneuron subtypes, as well as mossy cells, were observed, but most contralateral axon varicosities had no adjacent immunolabeled structure. Due to the relative sparsity of the connection and the likely distal dendritic location of their synapses, commissural projections made by interneurons were found to be weak. We postulate that these projections may become functionally active upon intense network activity during tasks requiring increased memory processing.
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Affiliation(s)
- Mark D Eyre
- Medical Faculty, Institute for Physiology I, Systemic and Cellular Neurophysiology, University of Freiburg, Freiburg, Germany
| | - Marlene Bartos
- Medical Faculty, Institute for Physiology I, Systemic and Cellular Neurophysiology, University of Freiburg, Freiburg, Germany
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20
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Scharfman HE. Advances in understanding hilar mossy cells of the dentate gyrus. Cell Tissue Res 2018; 373:643-652. [PMID: 29222692 PMCID: PMC5993616 DOI: 10.1007/s00441-017-2750-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 11/21/2017] [Indexed: 02/01/2023]
Abstract
Hilar mossy cells (MCs) of the dentate gyrus (DG) distinguish the DG from other hippocampal subfields (CA1-3) because there are two glutamatergic cell types in the DG rather than one. Thus, in the DG, the main cell types include glutamatergic granule cells (GCs) and MCs, whereas in CA1-3, the only glutamatergic cell type is the pyramidal cell. In contrast to GCs, MCs are different in morphology, intrinsic electrophysiological properties, afferent input and axonal projections, so their function is likely to be very different from GCs. Why are MCs necessary to the DG? In past studies, the answer has been unclear because MCs not only excite GCs directly but also inhibit them disynaptically, by exciting GABAergic neurons that project to GCs. Results of new studies are discussed that shed light on this issue. These studies take advantage of recently available transgenic mice with Cre recombinase expression mostly in MCs and techniques such as optogenetics and DREADDs (designer receptors exclusively activated by designer drugs). The recent studies also address in vivo behavioral functions of MCs. Some of the results support past hypotheses whereas others suggest new conceptualizations of how the MCs contribute to DG circuitry and function. While substantial progess has been made, additional research is still needed to clarify the characteristics and functions of these unique cells.
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Affiliation(s)
- Helen E Scharfman
- Departments of Child & Adolescent Psychiatry, Neuroscience & Physiology, Psychiatry, and the New York University Neuroscience Institute, New York University Langone Medical Center, One Park Avenue, 7th floor, New York, NY, 10016, USA.
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Building 39, Orangeburg, NY, 10962, USA.
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21
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Buckmaster PS, Abrams E, Wen X. Seizure frequency correlates with loss of dentate gyrus GABAergic neurons in a mouse model of temporal lobe epilepsy. J Comp Neurol 2017; 525:2592-2610. [PMID: 28425097 PMCID: PMC5963263 DOI: 10.1002/cne.24226] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 04/11/2017] [Accepted: 04/12/2017] [Indexed: 01/19/2023]
Abstract
Epilepsy occurs in one of 26 people. Temporal lobe epilepsy is common and can be difficult to treat effectively. It can develop after brain injuries that damage the hippocampus. Multiple pathophysiological mechanisms involving the hippocampal dentate gyrus have been proposed. This study evaluated a mouse model of temporal lobe epilepsy to test which pathological changes in the dentate gyrus correlate with seizure frequency and help prioritize potential mechanisms for further study. FVB mice (n = 127) that had experienced status epilepticus after systemic treatment with pilocarpine 31-61 days earlier were video-monitored for spontaneous, convulsive seizures 9 hr/day every day for 24-36 days. Over 4,060 seizures were observed. Seizure frequency ranged from an average of one every 3.6 days to one every 2.1 hr. Hippocampal sections were processed for Nissl stain, Prox1-immunocytochemistry, GluR2-immunocytochemistry, Timm stain, glial fibrillary acidic protein-immunocytochemistry, glutamic acid decarboxylase in situ hybridization, and parvalbumin-immunocytochemistry. Stereological methods were used to measure hilar ectopic granule cells, mossy cells, mossy fiber sprouting, astrogliosis, and GABAergic interneurons. Seizure frequency was not significantly correlated with the generation of hilar ectopic granule cells, the number of mossy cells, the extent of mossy fiber sprouting, the extent of astrogliosis, or the number of GABAergic interneurons in the molecular layer or hilus. Seizure frequency significantly correlated with the loss of GABAergic interneurons in or adjacent to the granule cell layer, but not with the loss of parvalbumin-positive interneurons. These findings prioritize the loss of granule cell layer interneurons for further testing as a potential cause of temporal lobe epilepsy.
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Affiliation(s)
- Paul S. Buckmaster
- Department of Comparative Medicine, Stanford University, Stanford, California
- Department of Neurology & Neurological Sciences, Stanford University, Stanford, California
| | - Emily Abrams
- Department of Comparative Medicine, Stanford University, Stanford, California
| | - Xiling Wen
- Department of Comparative Medicine, Stanford University, Stanford, California
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22
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Ishida K, Kotake Y, Sanoh S, Ohta S. Lead-Induced ERK Activation Is Mediated by GluR2 Non-containing AMPA Receptor in Cortical Neurons. Biol Pharm Bull 2017; 40:303-309. [PMID: 28250271 DOI: 10.1248/bpb.b16-00784] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lead is a persistent environmental pollutant and exposure to high environmental levels causes various deleterious toxicities, especially to the central nervous system (CNS). The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor that is devoid of the glutamate receptor 2 (GluR2) subunit is Ca2+-permeable, which increases the neuronal vulnerability to excitotoxicity. We have previously reported that long-term exposure of rat cortical neurons to lead acetate induces decrease of GluR2 expression. However, it is not clarified whether lead-induced GluR2 decrease is involved in neurotoxicity. Therefore, we investigated the contribution of GluR2 non-containing AMPA receptor to lead-induced neurotoxic events. Although the expression of four AMPA receptor subunits (GluR1, GluR2, GluR3, and GluR4) was decreased by lead exposure, the decrease in GluR2 expression was remarkable among four subunits. Lead-induced neuronal cell death was rescued by three glutamate receptor antagonists, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, a non-selective AMPA receptor blocker), MK-801 (N-methyl-D-aspartate (NMDA) receptor blocker), and 1-naphthyl acetyl spermine (NAS, a specific Ca2+-permeable AMPA receptor blocker). Lead exposure activated extracellular signal-regulated protein kinase (ERK) 1/2, which was significantly ameliorated by CNQX. In addition, lead exposure activated p38 mitogen-activated protein kinase (MAPK p38), and protein kinase C (PKC), which was partially ameliorated by CNQX. Our findings indicate that Ca2+-permeable AMPA receptors resulting from GluR2 decrease may be involved in lead-induced neurotoxicity.
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Affiliation(s)
- Keishi Ishida
- Graduate School of Biomedical and Health Sciences, Hiroshima University
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23
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Moretto JN, Duffy ÁM, Scharfman HE. Acute restraint stress decreases c-fos immunoreactivity in hilar mossy cells of the adult dentate gyrus. Brain Struct Funct 2017; 222:2405-2419. [PMID: 28190104 DOI: 10.1007/s00429-016-1349-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 12/14/2016] [Indexed: 11/29/2022]
Abstract
Although a great deal of information is available about the circuitry of the mossy cells (MCs) of the dentate gyrus (DG) hilus, their activity in vivo is not clear. The immediate early gene c-fos can be used to gain insight into the activity of MCs in vivo, because c-fos protein expression reflects increased neuronal activity. In prior work, it was identified that control rats that were perfusion-fixed after removal from their home cage exhibited c-fos immunoreactivity (ir) in the DG in a spatially stereotyped pattern: ventral MCs and dorsal granule cells (GCs) expressed c-fos protein (Duffy et al., Hippocampus 23:649-655, 2013). In this study, we hypothesized that restraint stress would alter c-fos-ir, because MCs express glucocorticoid type 2 receptors and the DG is considered to be involved in behaviors related to stress or anxiety. We show that acute restraint using a transparent nose cone for just 10 min led to reduced c-fos-ir in ventral MCs compared to control rats. In these comparisons, c-fos-ir was evaluated 30 min after the 10 min-long period of restraint, and if evaluation was later than 30 min c-fos-ir was no longer suppressed. Granule cells (GCs) also showed suppressed c-fos-ir after acute restraint, but it was different than MCs, because the suppression persisted for over 30 min after the restraint. We conclude that c-fos protein expression is rapidly and transiently reduced in ventral hilar MCs after a brief period of restraint, and suppressed longer in dorsal GCs.
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Affiliation(s)
- Jillian N Moretto
- The Nathan Kline Institute of Psychiatric Research, Orangeburg, NY, 10962, USA
| | - Áine M Duffy
- The Nathan Kline Institute of Psychiatric Research, Orangeburg, NY, 10962, USA
| | - Helen E Scharfman
- The Nathan Kline Institute of Psychiatric Research, Orangeburg, NY, 10962, USA. .,Departments of Child and Adolescent Psychiatry, Physiology and Neuroscience, and Psychiatry, New York University Langone Medical Center, New York, NY, 10016, USA.
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24
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GoodSmith D, Chen X, Wang C, Kim SH, Song H, Burgalossi A, Christian KM, Knierim JJ. Spatial Representations of Granule Cells and Mossy Cells of the Dentate Gyrus. Neuron 2017; 93:677-690.e5. [PMID: 28132828 DOI: 10.1016/j.neuron.2016.12.026] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 11/01/2016] [Accepted: 12/12/2016] [Indexed: 01/12/2023]
Abstract
Granule cells in the dentate gyrus of the hippocampus are thought to be essential to memory function by decorrelating overlapping input patterns (pattern separation). A second excitatory cell type in the dentate gyrus, the mossy cell, forms an intricate circuit with granule cells, CA3c pyramidal cells, and local interneurons, but the influence of mossy cells on dentate function is often overlooked. Multiple tetrode recordings, supported by juxtacellular recording techniques, showed that granule cells fired very sparsely, whereas mossy cells in the hilus fired promiscuously in multiple locations and in multiple environments. The activity patterns of these cell types thus represent different environments through distinct computational mechanisms: sparse coding in granule cells and changes in firing field locations in mossy cells.
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Affiliation(s)
- Douglas GoodSmith
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Xiaojing Chen
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Cheng Wang
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sang Hoon Kim
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA
| | - Hongjun Song
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA
| | - Andrea Burgalossi
- Werner-Reichardt Centre for Integrative Neuroscience, 72076 Tübingen, Germany
| | - Kimberly M Christian
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA
| | - James J Knierim
- Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA.
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25
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Abstract
Mossy cells comprise a large fraction of the cells in the hippocampal dentate gyrus, suggesting that their function in this region is important. They are vulnerable to ischaemia, traumatic brain injury and seizures, and their loss could contribute to dentate gyrus dysfunction in such conditions. Mossy cell function has been unclear because these cells innervate both glutamatergic and GABAergic neurons within the dentate gyrus, contributing to a complex circuitry. It has also been difficult to directly and selectively manipulate mossy cells to study their function. In light of the new data generated using methods to preferentially eliminate or activate mossy cells in mice, it is timely to ask whether mossy cells have become any less enigmatic than they were in the past.
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Affiliation(s)
- Helen E Scharfman
- Departments of Child and Adolescent Psychiatry, Physiology and Neuroscience, and Psychiatry, New York University Langone Medical Center, New York 10016, USA.,Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962, USA
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26
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Morrison JH, Siegel SJ, Gazzaley AH, Huntley GW. ■ REVIEW : Glutamate Receptors: Emerging Links Between Subunit Proteins and Specific Excitatory Circuits in Primate Hippocampus and Neocortex. Neuroscientist 2016. [DOI: 10.1177/107385849600200513] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Glutamate receptors (GluRs) are the primary mediators of excitatory neurotransmission in the CNS and play an indispensable role in brain function. Recent molecular advances have revealed an increasingly elaborate panel of GluR subunits that combine to form a variety of heteromeric GluR complexes with distinct functional characteristics determined by the stoichiometry of the subunit composition. Excitatory circuits in hippocampus and neocortex exhibit a complex and highly ordered array of termination patterns that reflect both segregation and convergence at specific target sites. We hypothesize that the molecular diversity of the GluRs will be manifested as circuit-specific profiles that will generate extensive functional diversity in cortical excitatory circuits. To elucidate the link between GluR diversity and neuroanatomical circuitry, immunocytochemical techniques employing subunit-specific antibodies have been used to localize various subunit proteins at the cellular and synaptic level. Such studies have revealed differential subunit parcellation between neocortical neuronal populations, as well as within defined dendritic compartments of hippocampal pyramidal cells. Additionally, the intradendritic parcellation of a specific GluR subunit is modifiable in an age-related and circuit-specific manner. NEUROSCIENTIST 2:272-283, 1996
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Affiliation(s)
- John H. Morrison
- Fishberg Research Center for Neurobiology, Department of Geriatrics and Adult Development, Mount
Sinai School of Medicine New York, New York
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27
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Carceller H, Rovira-Esteban L, Nacher J, Castrén E, Guirado R. Neurochemical Phenotype of Reelin Immunoreactive Cells in the Piriform Cortex Layer II. Front Cell Neurosci 2016; 10:65. [PMID: 27013976 PMCID: PMC4785191 DOI: 10.3389/fncel.2016.00065] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 02/29/2016] [Indexed: 12/29/2022] Open
Abstract
Reelin, a glycoprotein expressed by Cajal-Retzius neurons throughout the marginal layer of developing neocortex, has been extensively shown to play an important role during brain development, guiding neuronal migration and detachment from radial glia. During the adult life, however, many studies have associated Reelin expression to enhanced neuronal plasticity. Although its mechanism of action in the adult brain remains mostly unknown, Reelin is expressed mainly by a subset of mature interneurons. Here, we confirm the described phenotype of this subpopulation in the adult neocortex. We show that these mature interneurons, although being in close proximity, lack polysialylated neural cell adhesion molecule (PSA-NCAM) expression, a molecule expressed by a subpopulation of mature interneurons, related to brain development and involved in neuronal plasticity of the adult brain as well. However, in the layer II of Piriform cortex there is a high density of cells expressing Reelin whose neurochemical phenotype and connectivity has not been described before. Interestingly, in close proximity to these Reelin expressing cells there is a numerous subpopulation of immature neurons expressing PSA-NCAM and doublecortin (DCX) in this layer of the Piriform cortex. Here, we show that Reelin cells express the neuronal marker Neuronal Nuclei (NeuN), but however the majority of neurons lack markers of mature excitatory or inhibitory neurons. A detail analysis of its morphology indicates these that some of these cells might correspond to semilunar neurons. Interestingly, we found that the majority of these cells express T-box brain 1 (TBR-1) a transcription factor found not only in post-mitotic neurons that differentiate to glutamatergic excitatory neurons but also in Cajal-Retzius cells. We suggest that the function of these Reelin expressing cells might be similar to that of the Cajal-Retzius cells during development, having a role in the maintenance of the immature phenotype of the PSA-NCAM/DCX neurons through its receptors apolipoprotein E receptor 2 (ApoER2) and very low density lipoprotein receptor (VLDLR) in the Piriform cortex layer II during adulthood.
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Affiliation(s)
- Hector Carceller
- Departamento de Biologia Celular, Spanish National Network for Research in Mental Health, CIBERSAM, Fundación Investigación Hospital Clínico de Valencia, INCLIVA, Universitat de Valencia Valencia Valencia, Spain
| | - Laura Rovira-Esteban
- Departamento de Biologia Celular, Spanish National Network for Research in Mental Health, CIBERSAM, Fundación Investigación Hospital Clínico de Valencia, INCLIVA, Universitat de Valencia Valencia Valencia, Spain
| | - Juan Nacher
- Departamento de Biologia Celular, Spanish National Network for Research in Mental Health, CIBERSAM, Fundación Investigación Hospital Clínico de Valencia, INCLIVA, Universitat de Valencia Valencia Valencia, Spain
| | - Eero Castrén
- Neuroscience Center, University of Helsinki Helsinki, Finland
| | - Ramon Guirado
- Neuroscience Center, University of Helsinki Helsinki, Finland
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28
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Shisa6 traps AMPA receptors at postsynaptic sites and prevents their desensitization during synaptic activity. Nat Commun 2016; 7:10682. [PMID: 26931375 PMCID: PMC4778035 DOI: 10.1038/ncomms10682] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 01/11/2016] [Indexed: 11/08/2022] Open
Abstract
Trafficking and biophysical properties of AMPA receptors (AMPARs) in the brain depend on interactions with associated proteins. We identify Shisa6, a single transmembrane protein, as a stable and directly interacting bona fide AMPAR auxiliary subunit. Shisa6 is enriched at hippocampal postsynaptic membranes and co-localizes with AMPARs. The Shisa6 C-terminus harbours a PDZ domain ligand that binds to PSD-95, constraining mobility of AMPARs in the plasma membrane and confining them to postsynaptic densities. Shisa6 expressed in HEK293 cells alters GluA1- and GluA2-mediated currents by prolonging decay times and decreasing the extent of AMPAR desensitization, while slowing the rate of recovery from desensitization. Using gene deletion, we show that Shisa6 increases rise and decay times of hippocampal CA1 miniature excitatory postsynaptic currents (mEPSCs). Shisa6-containing AMPARs show prominent sustained currents, indicating protection from full desensitization. Accordingly, Shisa6 prevents synaptically trapped AMPARs from depression at high-frequency synaptic transmission. Auxiliary AMPA receptor subunits can affect gating and surface mobility. Here the authors show that Shisa6 traps AMPA receptors at postsynaptic sites via PSD-95, and keeps them in an activated state in the presence of glutamate, preventing full desensitization and consequently synaptic depression.
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29
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Zhang W, Thamattoor AK, LeRoy C, Buckmaster PS. Surviving mossy cells enlarge and receive more excitatory synaptic input in a mouse model of temporal lobe epilepsy. Hippocampus 2014; 25:594-604. [PMID: 25488607 DOI: 10.1002/hipo.22396] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2014] [Indexed: 11/07/2022]
Abstract
Numerous hypotheses of temporal lobe epileptogenesis have been proposed, and several involve hippocampal mossy cells. Building on previous hypotheses we sought to test the possibility that after epileptogenic injuries surviving mossy cells develop into super-connected seizure-generating hub cells. If so, they might require more cellular machinery and consequently have larger somata, elongate their dendrites to receive more synaptic input, and display higher frequencies of miniature excitatory synaptic currents (mEPSCs). To test these possibilities pilocarpine-treated mice were evaluated using GluR2-immunocytochemistry, whole-cell recording, and biocytin-labeling. Epileptic pilocarpine-treated mice displayed substantial loss of GluR2-positive hilar neurons. Somata of surviving neurons were 1.4-times larger than in controls. Biocytin-labeled mossy cells also were larger in epileptic mice, but dendritic length per cell was not significantly different. The average frequency of mEPSCs of mossy cells recorded in the presence of tetrodotoxin and bicuculline was 3.2-times higher in epileptic pilocarpine-treated mice as compared to controls. Other parameters of mEPSCs were similar in both groups. Average input resistance of mossy cells in epileptic mice was reduced to 63% of controls, which is consistent with larger somata and would tend to make surviving mossy cells less excitable. Other intrinsic physiological characteristics examined were similar in both groups. Increased excitatory synaptic input is consistent with the hypothesis that surviving mossy cells develop into aberrantly super-connected seizure-generating hub cells, and soma hypertrophy is indirectly consistent with the possibility of axon sprouting. However, no obvious evidence of hyperexcitable intrinsic physiology was found. Furthermore, similar hypertrophy and hyper-connectivity has been reported for other neuron types in the dentate gyrus, suggesting mossy cells are not unique in this regard. Thus, findings of the present study reveal epilepsy-related changes in mossy cell anatomy and synaptic input but do not strongly support the hypothesis that mossy cells develop into seizure-generating hub cells.
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Affiliation(s)
- Wei Zhang
- Department of Comparative Medicine, Stanford University, Stanford, California
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30
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Impact of adolescent GluA1 AMPA receptor ablation in forebrain excitatory neurons on behavioural correlates of mood disorders. Eur Arch Psychiatry Clin Neurosci 2014; 264:625-9. [PMID: 24895223 DOI: 10.1007/s00406-014-0509-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 05/24/2014] [Indexed: 12/27/2022]
Abstract
Glutamatergic dysfunctions have recently been postulated to play a considerable role in mood disorders. However, molecular mechanisms underlying these effects have been poorly deciphered. Previous work demonstrated the contribution of GluA1-containing AMPA receptors (AMPAR) to a depression-like and anxiety-like phenotype. Here we investigated the effect of temporally and spatially restricted gene manipulation of GluA1 on behavioural correlates of mood disorders in mice. Here we show that tamoxifen-induced GluA1 deletion restricted to forebrain glutamatergic neurons of post-adolescent mice does not induce depression- and anxiety-like changes. This differs from the phenotype of mice with global AMPAR deletion suggesting that for mood regulation AMPAR may be particularly important on inhibitory interneurons or already early in development.
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31
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Inta D, Vogt MA, Elkin H, Weber T, Lima-Ojeda JM, Schneider M, Luoni A, Riva MA, Gertz K, Hellmann-Regen J, Kronenberg G, Meyer-Lindenberg A, Sprengel R, Gass P. Phenotype of mice with inducible ablation of GluA1 AMPA receptors during late adolescence: relevance for mental disorders. Hippocampus 2013; 24:424-35. [PMID: 24339333 DOI: 10.1002/hipo.22236] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 11/25/2013] [Accepted: 12/02/2013] [Indexed: 12/13/2022]
Abstract
Adolescence is characterized by important molecular and anatomical changes with relevance for the maturation of brain circuitry and cognitive function. This time period is of critical importance in the emergence of several neuropsychiatric disorders accompanied by cognitive impairment, such as affective disorders and schizophrenia. The molecular mechanisms underlying these changes at neuronal level during this specific developmental stage remains however poorly understood. GluA1-containing AMPA receptors, which are located predominantly on hippocampal neurons, are the primary molecular determinants of synaptic plasticity. We investigated here the consequences of the inducible deletion of GluA1 AMPA receptors in glutamatergic neurons during late adolescence. We generated mutant mice with a tamoxifen-inducible deletion of GluA1 under the control of the CamKII promoter for temporally and spatially restricted gene manipulation. GluA1 ablation during late adolescence induced cognitive impairments, but also marked hyperlocomotion and sensorimotor gating deficits. Unlike the global genetic deletion of GluA1, inducible GluA1 ablation during late adolescence resulted in normal sociability. Deletion of GluA1 induced redistribution of GluA2 subunits, suggesting AMPA receptor trafficking deficits. Mutant animals showed increased hippocampal NMDA receptor expression and no change in striatal dopamine concentration. Our data provide new insight into the role of deficient AMPA receptors specifically during late adolescence in inducing several cognitive and behavioral alterations with possible relevance for neuropsychiatric disorders.
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Affiliation(s)
- Dragos Inta
- Department of Psychiatry and Psychotherapy, RG Animal Models in Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
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32
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Duffy AM, Schaner MJ, Chin J, Scharfman HE. Expression of c-fos in hilar mossy cells of the dentate gyrus in vivo. Hippocampus 2013; 23:649-55. [PMID: 23640815 PMCID: PMC3732572 DOI: 10.1002/hipo.22138] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2013] [Indexed: 01/15/2023]
Abstract
Granule cells (GCs) of the dentate gyrus (DG) are considered to be quiescent--they rarely fire action potentials. In contrast, the other glutamatergic cell type in the DG, hilar mossy cells (MCs) often have a high level of spontaneous activity based on recordings in hippocampal slices. MCs project to GCs, so activity in MCs could play an important role in activating GCs. Therefore, we investigated whether MCs were active under basal conditions in vivo, using the immediate early gene c-fos as a tool. We hypothesized that MCs would exhibit c-fos expression even if rats were examined randomly, under normal housing conditions. Therefore, adult male rats were perfused shortly after removal from their home cage and transfer to the laboratory. Remarkably, most c-fos immunoreactivity (ir) was in the hilus, especially temporal hippocampus. C-fos-ir hilar cells co-expressed GluR2/3, suggesting that they were MCs. C-fos-ir MCs were robust even when the animal was habituated to the investigator and laboratory where they were euthanized. However, c-fos-ir in dorsal MCs was reduced under these circumstances, suggesting that ventral and dorsal MCs are functionally distinct. Interestingly, there was an inverse relationship between MC and GC layer c-fos expression, with little c-fos expression in the GC layer in ventral sections where MC expression was strong, and the opposite in dorsal hippocampus. The results support the hypothesis that a subset of hilar MCs are spontaneously active in vivo and provide other DG neurons with tonic depolarizing input.
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Affiliation(s)
- Aine M. Duffy
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Michael J. Schaner
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Jeannie Chin
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107
| | - Helen E. Scharfman
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962
- Department of Child & Adolescent Psychiatry, Psychiatry, Physiology & Neuroscience, New York University Langone, Medical Center, New York, NY 10016
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33
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Jinde S, Zsiros V, Jiang Z, Nakao K, Pickel J, Kohno K, Belforte JE, Nakazawa K. Hilar mossy cell degeneration causes transient dentate granule cell hyperexcitability and impaired pattern separation. Neuron 2013; 76:1189-200. [PMID: 23259953 DOI: 10.1016/j.neuron.2012.10.036] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/15/2012] [Indexed: 02/08/2023]
Abstract
Although excitatory mossy cells of the hippocampal hilar region are known to project both to dentate granule cells and to interneurons, it is as yet unclear whether mossy cell activity's net effect on granule cells is excitatory or inhibitory. To explore their influence on dentate excitability and hippocampal function, we generated a conditional transgenic mouse line, using the Cre/loxP system, in which diphtheria toxin receptor was selectively expressed in mossy cells. One week after injecting toxin into this line, mossy cells throughout the longitudinal axis were degenerated extensively, theta wave power of dentate local field potentials increased during exploration, and deficits occurred in contextual discrimination. By contrast, we detected no epileptiform activity, spontaneous behavioral seizures, or mossy-fiber sprouting 5-6 weeks after mossy cell degeneration. These results indicate that the net effect of mossy cell excitation is to inhibit granule cell activity and enable dentate pattern separation.
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Affiliation(s)
- Seiichiro Jinde
- Unit on Genetics of Cognition and Behavior, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
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Le Roux N, Cabezas C, Böhm UL, Poncer JC. Input-specific learning rules at excitatory synapses onto hippocampal parvalbumin-expressing interneurons. J Physiol 2013; 591:1809-22. [PMID: 23339172 DOI: 10.1113/jphysiol.2012.245852] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Hippocampal parvalbumin-expressing interneurons (PV INs) provide fast and reliable GABAergic signalling to principal cells and orchestrate hippocampal ensemble activities. Precise coordination of principal cell activity by PV INs relies in part on the efficacy of excitatory afferents that recruit them in the hippocampal network. Feed-forward (FF) inputs in particular from Schaffer collaterals influence spike timing precision in CA1 principal cells whereas local feedback (FB) inputs may contribute to pacemaker activities. Although PV INs have been shown to undergo activity-dependent long term plasticity, how both inputs are modulated during principal cell firing is unknown. Here we show that FF and FB synapses onto PV INs are endowed with distinct postsynaptic glutamate receptors which set opposing long-term plasticity rules. Inward-rectifying AMPA receptors (AMPARs) expressed at both FF and FB inputs mediate a form of anti-Hebbian long term potentiation (LTP), relying on coincident membrane hyperpolarization and synaptic activation. In contrast, FF inputs are largely devoid of NMDA receptors (NMDARs) which are more abundant at FB afferents and confer on them an additional form of LTP with Hebbian properties. Both forms of LTP are expressed with no apparent change in presynaptic function. The specific endowment of FF and FB inputs with distinct coincidence detectors allow them to be differentially tuned upon high frequency afferent activity. Thus, high frequency (>20 Hz) stimulation specifically potentiates FB, but not FF afferents. We propose that these differential, input-specific learning rules may allow PV INs to adapt to changes in hippocampal activity while preserving their precisely timed, clockwork operation.
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35
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Scharfman HE, Myers CE. Hilar mossy cells of the dentate gyrus: a historical perspective. Front Neural Circuits 2013; 6:106. [PMID: 23420672 PMCID: PMC3572871 DOI: 10.3389/fncir.2012.00106] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 12/02/2012] [Indexed: 11/24/2022] Open
Abstract
The circuitry of the dentate gyrus (DG) of the hippocampus is unique compared to other hippocampal subfields because there are two glutamatergic principal cells instead of one: granule cells, which are the vast majority of the cells in the DG, and the so-called “mossy cells.” The distinctive appearance of mossy cells, the extensive divergence of their axons, and their vulnerability to excitotoxicity relative to granule cells has led to a great deal of interest in mossy cells. Nevertheless, there is no consensus about the normal functions of mossy cells and the implications of their vulnerability. There even seems to be some ambiguity about exactly what mossy cells are. Here we review initial studies of mossy cells, characteristics that define them, and suggest a practical definition to allow investigators to distinguish mossy cells from other hilar neurons even if all morphological and physiological information is unavailable due to technical limitations of their experiments. In addition, hypotheses are discussed about the role of mossy cells in the DG network, reasons for their vulnerability and their implications for disease.
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Affiliation(s)
- Helen E Scharfman
- New York University Langone Medical Center New York, NY, USA ; Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research Orangeburg, NY, USA
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Czöndör K, Thoumine O. Biophysical mechanisms regulating AMPA receptor accumulation at synapses. Brain Res Bull 2012; 93:57-68. [PMID: 23174308 DOI: 10.1016/j.brainresbull.2012.11.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 11/05/2012] [Indexed: 11/25/2022]
Abstract
Controlling the number of AMPA receptors at synapses is fundamental for fast synaptic transmission as well as for long term adaptations in synaptic strength. In this review, we examine the biophysical mechanisms implicated in regulating AMPAR levels at the cell surface and at synapses. We first describe the structure and function of AMPARs, as well as their interactions with various proteins regulating their traffic and function. Second we review the vesicular trafficking mechanism involving exocytosis and endocytosis, by which AMPARs reach the cell surface and are internalized, respectively. Third, we examine the properties of lateral diffusion of AMPARs and their trapping at post-synaptic densities. Finally, we discuss how these two parallel mechanisms are integrated in time and space to control changes in synaptic AMPAR levels in response to plasticity protocols. This review highlights the important role of the extra-synaptic AMPAR pool, which makes an obligatory link between vesicular trafficking and trapping or release at synapses.
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Piccolini V, Cerri S, Romanelli E, Bernocchi G. Interactions of neurotransmitter systems during postnatal development of the rat hippocampal formation: Effects of cisplatin. Exp Neurol 2012; 234:239-52. [DOI: 10.1016/j.expneurol.2011.12.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 12/21/2011] [Accepted: 12/25/2011] [Indexed: 01/14/2023]
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Weiss JH. Ca permeable AMPA channels in diseases of the nervous system. Front Mol Neurosci 2011; 4:42. [PMID: 22102834 PMCID: PMC3214733 DOI: 10.3389/fnmol.2011.00042] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 10/27/2011] [Indexed: 12/30/2022] Open
Abstract
Since the discovery and molecular characterization of Ca(2+)-permeable AMPA channels just over two decades ago, a large body of evidence has accumulated implicating contributions of these unusual glutamate activated channels to selective neurodegeneration in certain conditions, including ischemia and amyotrophic lateral sclerosis. Factors likely involved in their contributions to disease include their distinct patterns of expression in certain neuronal populations, their upregulation via various mechanisms in response to disease associated stresses, and their high permeability to Zn(2+) as well as to Ca(2+). However, full characterization of their contributions to certain diseases as well as development of therapeutics has been limited by the lack of selective and bioavailable blockers of these channels that can be employed in animals or humans. This review summarizes some of the clues that have emerged over recent years to the contributions of these channels in disease.
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Affiliation(s)
- John H Weiss
- Department of Neurology, University of California Irvine Irvine, CA, USA
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Contextual learning requires synaptic AMPA receptor delivery in the hippocampus. Proc Natl Acad Sci U S A 2011; 108:12503-8. [PMID: 21746893 DOI: 10.1073/pnas.1104558108] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The hippocampus plays a central role in learning and memory. Although synaptic delivery of AMPA-type glutamate receptors (AMPARs) contributes to experience-dependent synaptic strengthening, its role in hippocampus-dependent learning remains elusive. By combining viral-mediated in vivo gene delivery with in vitro patch-clamp recordings, we found that the inhibitory avoidance task, a hippocampus-dependent contextual fear-learning paradigm, delivered GluR1-containing AMPARs into CA3-CA1 synapses of the dorsal hippocampus. To block the synaptic delivery of endogenous AMPARs, we expressed a fragment of the GluR1-cytoplasmic tail (the 14-aa GluR1 membrane-proximal region with two serines mutated to phospho-mimicking aspartates: MPR-DD). MPR-DD prevented learning-driven synaptic AMPAR delivery in CA1 neurons. Bilateral expression of MPR-DD in the CA1 region of the rat impaired inhibitory avoidance learning, indicating that synaptic GluR1 trafficking in the CA1 region of the hippocampus is required for encoding contextual fear memories. The fraction of CA1 neurons that underwent synaptic strengthening positively correlated with the performance in the inhibitory avoidance fear memory task. These data suggest that the robustness of a contextual memory depends on the number of hippocampal neurons that participate in the encoding of a memory trace.
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Deng P, Xu ZC. Contribution of Ih to Neuronal Damage in the Hippocampus after Traumatic Brain Injury in Rats. J Neurotrauma 2011; 28:1173-83. [DOI: 10.1089/neu.2010.1683] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- Ping Deng
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Zao C. Xu
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
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Volz F, Bock HH, Gierthmuehlen M, Zentner J, Haas CA, Freiman TM. Stereologic estimation of hippocampal GluR2/3- and calretinin-immunoreactive hilar neurons (presumptive mossy cells) in two mouse models of temporal lobe epilepsy. Epilepsia 2011; 52:1579-89. [PMID: 21635231 DOI: 10.1111/j.1528-1167.2011.03086.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Hippocampal mossy cells receive dense innervation from dentate granule cells and, in turn, mossy cells innervate both granule cells and interneurons. Mossy cell loss is thought to trigger granule cell mossy fiber sprouting, which may affect granule cell excitability. The aim of this study was to quantify mossy cell loss in two animal models of temporal lobe epilepsy, and determine whether there exists a relationship between mossy cell loss, mossy fiber sprouting, and granule cell dispersion. METHODS Representative hippocampal sections from p35 knockout mice and mice with unilateral intrahippocampal kainate injection were immunolabeled for GluR2/3, two subunits of the amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor and calretinin to identify mossy cells. Mossy fibers were immunostained against synaptoporin. KEY FINDINGS p35 Knockout mice showed no hilar cell death, but moderate mossy fiber sprouting and granule cell dispersion. In the kainate-injected hippocampus, there was an 80% and 85% reduction of GluR2/3- and GluR2/3/calretinin-positive hilar neurons, respectively, and dense mossy fiber sprouting and significant granule cell dispersion. In the contralateral hippocampus there was a 52% loss of GluR2/3-, but only a 20% loss of GluR2/3-calretinin-immunoreactive presumptive mossy cells, and granule cell dispersion; no mossy fiber sprouting was observed. SIGNIFICANCE These results indicate a probable lack of causality between mossy cell death and mossy fiber sprouting.
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Affiliation(s)
- Florian Volz
- Department of Neurosurgery, University Medical Center, Albert-Ludwigs-University, Freiburg, Germany
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Jinno S, Kosaka T. Stereological estimation of numerical densities of glutamatergic principal neurons in the mouse hippocampus. Hippocampus 2010; 20:829-40. [PMID: 19655319 DOI: 10.1002/hipo.20685] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent studies have emphasized functional dissociations between dorsal and ventral hippocampus in learning, emotion, and affect. A rigorous quantitative analysis concerning lamellar cytoarchitecture would be important for promoting further research on the regional differentiation of the hippocampus. Here, we stereologically estimated the numerical densities (NDs) of glutamatergic principal neurons in the mouse hippocampus and encountered the significant differences along the dorsoventral axis. In the CA1 region, the NDs of CA1 pyramidal neurons were almost three times higher at the dorsal level (447.5 x 10(3)/mm(3)) than at the ventral level (180.5 x 10(3)/mm(3)); meanwhile, along the transverse axis, the NDs were significantly higher in the proximal portion than in the distal portion both at the dorsal and ventral levels. An EF-hand calcium-binding protein, calbindin D28K, was expressed in approximately 45% of CA1 pyramidal neurons both at the dorsal and ventral level. In the CA3 region, there were no significant differences in the NDs along the dorsoventral and transverse axes (dorsal, 165.2 x 10(3)/mm(3); ventral, 172.4 x 10(3)/mm(3)). In the dentate gyrus (DG), the NDs of granule cells were significantly higher at the dorsal level (916.7 x 10(3)/mm(3)) than at the ventral level (788.9 x 10(3)/mm(3)). The significant differences were observed only in the suprapyramidal blade, but not in the infrapyramidal blade. Then, we calculated the total neuron numbers contained in a 300-microm-thick hypothetical transverse slice of the hippocampus and found that the ratios of GABAergic to glutamatergic neuron numbers were two to three times higher in the ventral slice than in the dorsal slice. The ratios of numbers of eight GABAergic neuron subtypes to principal cells indicate structural dissociations in the neural network between dorsal and ventral slices. These findings provide an essential quantitative basis for elucidating mechanisms of distinct neural circuits underlying various hippocampal functions.
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Affiliation(s)
- Shozo Jinno
- Department of Anatomy and Neurobiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
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Amrein I, Slomianka L. A morphologically distinct granule cell type in the dentate gyrus of the red fox correlates with adult hippocampal neurogenesis. Brain Res 2010; 1328:12-24. [DOI: 10.1016/j.brainres.2010.02.075] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 02/24/2010] [Accepted: 02/25/2010] [Indexed: 11/25/2022]
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Montgomery KE, Kessler M, Arai AC. Modulation of agonist binding to AMPA receptors by 1-(1,4-benzodioxan-6-ylcarbonyl)piperidine (CX546): differential effects across brain regions and GluA1-4/transmembrane AMPA receptor regulatory protein combinations. J Pharmacol Exp Ther 2009; 331:965-74. [PMID: 19717789 DOI: 10.1124/jpet.109.158014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Ampakines are cognitive enhancers that potentiate alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor currents and synaptic responses by slowing receptor deactivation. Their efficacy varies greatly between classes of neurons and brain regions, but the factor responsible for this effect remains unclear. Ampakines also increase agonist affinity in binding tests in ways that are related to their physiological action. We therefore examined 1) whether ampakine effects on agonist binding vary across brain regions and 2) whether they differ across receptor subunits expressed alone and together with transmembrane AMPA receptor regulatory proteins (TARPs), which associate with AMPA receptors in the brain. We found that the maximal increase in agonist binding (E(max)) caused by the prototypical ampakine 1-(1,4-benzodioxan-6-ylcarbonyl)piperidine (CX546) differs significantly between brain regions, with effects in hippocampus and cerebellum being nearly three times larger than that in thalamus, brainstem, and striatum, and cortex being intermediate. These differences can be explained at least in part by regional variations in receptor subunit and TARP expression because combinations prevalent in hippocampus (GluA2 with TARPs gamma3 and gamma8) exhibited E(max) values nearly twice those of combinations abundant in thalamus (GluA4 with gamma2 or gamma4). TARPs seem to be critical because GluA2 and GluA4 alone had comparable E(max) and also because hippocampal and thalamic receptors had similar E(max) after solubilization with Triton X-100, which probably removes associated proteins. Taken together, our data suggest that variations in physiological drug efficacy, such as the 3-fold difference previously seen in recordings from hippocampus versus thalamus, may be explained by region-specific expression of GluA1-4 as well as TARPs.
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Affiliation(s)
- Kyle E Montgomery
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62794-9629, USA.
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Kienzler F, Norwood BA, Sloviter RS. Hippocampal injury, atrophy, synaptic reorganization, and epileptogenesis after perforant pathway stimulation-induced status epilepticus in the mouse. J Comp Neurol 2009; 515:181-96. [PMID: 19412934 DOI: 10.1002/cne.22059] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Prolonged dentate granule cell discharges produce hippocampal injury and chronic epilepsy in rats. In preparing to study this epileptogenic process in genetically altered mice, we determined whether the background strain used to generate most genetically altered mice, the C57BL/6 mouse, is vulnerable to stimulation-induced seizure-induced injury. This was necessary because C57BL/6 mice are reportedly resistant to the neurotoxic effects of kainate-induced seizures, which we hypothesized to be related to strain differences in kainate's effects, rather than genetic differences in intrinsic neuronal vulnerability. Bilateral perforant pathway stimulation-induced granule cell discharge for 4 hours under urethane anesthesia produced degeneration of glutamate receptor subunit 2 (GluR2)-positive hilar mossy cells and peptide-containing interneurons in both FVB/N (kainate-vulnerable) and C57BL/6 (kainate-resistant) mice, indicating no strain differences in neuronal vulnerability to seizure activity. Granule cell discharge for 2 hours in C57BL/6 mice destroyed most GluR2-positive dentate hilar mossy cells, but not peptide-containing hilar interneurons, indicating that mossy cells are the neurons most vulnerable to this insult. Stimulation for 24 hours caused extensive hippocampal neuron loss and injury to the septum and entorhinal cortex, but no other detectable damage. Mice stimulated for 24 hours developed hippocampal sclerosis, granule cell mossy fiber sprouting, and chronic epilepsy, but not the granule cell layer hypertrophy (granule cell dispersion) produced by intrahippocampal kainate. These results demonstrate that perforant pathway stimulation in mice reliably reproduces the defining features of human mesial temporal lobe epilepsy with hippocampal sclerosis. Experimental studies in transgenic or knockout mice are feasible if electrical stimulation is used to produce controlled epileptogenic insults.
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Affiliation(s)
- Friederike Kienzler
- Departments of Pharmacology and Neurology, University of Arizona College of Medicine, Tucson, Arizona 85724, USA
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Riebe I, Gustafsson B, Hanse E. Silent synapses onto interneurons in the rat CA1 stratum radiatum. Eur J Neurosci 2009; 29:1870-82. [DOI: 10.1111/j.1460-9568.2009.06734.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Augmented hippocampal ripple oscillations in mice with reduced fast excitation onto parvalbumin-positive cells. J Neurosci 2009; 29:2563-8. [PMID: 19244531 DOI: 10.1523/jneurosci.5036-08.2009] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Generation of fast network oscillations in the hippocampus relies on interneurons, but the underlying specific synaptic mechanisms are not established. The excitatory recruitment of fast-spiking interneurons during hippocampal sharp waves has been suggested to be critical for the generation of 140-200 Hz ("ripple") oscillations in the CA1 area. To directly test this, we used genetically modified mice (PV-DeltaGluR-A) with reduced AMPA receptor-mediated excitation onto parvalbumin (PV)-positive interneurons and studied hippocampal oscillations in freely moving animals. In PV-DeltaGluR-A mice, ripple-amplitude and associated rhythmic modulation of pyramidal cells and fast-spiking interneurons were increased. These changes were not accompanied by concurrent alterations of firing rates. Neither theta nor gamma oscillations displayed marked alterations in the mutant. These results provide evidence that fast excitation from pyramidal cells to PV-positive interneurons differentially influences ripple and gamma oscillations in vivo.
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Jinno S, Araki K, Matsumoto Y, Suh YH, Yamamoto T. Selective apoptosis induction in the hippocampal mossy fiber pathway by exposure to CT105, the C-terminal fragment of Alzheimer's amyloid precursor protein. Brain Res 2008; 1249:68-78. [PMID: 19007761 DOI: 10.1016/j.brainres.2008.10.052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 09/29/2008] [Accepted: 10/17/2008] [Indexed: 10/21/2022]
Abstract
Beta-amyloid protein (Abeta), a proteolytic byproduct of Alzheimer's amyloid precursor protein (APP), has been shown to play a central role in the development of Alzheimer's disease (AD). In addition, recent studies strongly suggest that other byproducts of proteolysis, such as C-terminal fragments of APP (APP-CTF), are also critically involved in the AD pathology. To explore this possibility, we investigated the histopathological changes induced by repeated low-dose intrahippocampal injection of a recombinant 105 amino acid C-terminal fragment of APP (CT105). First, we carried out a behavioral analysis by using the three-panel runway task, and found that the working memory was significantly impaired by CT105 exposure. Then, via propidium iodide staining, we encountered a number of cells exhibiting fragmented or shrank nuclei in the mossy fiber pathway (stratum lucidum and dentate hilus) in CT105-treated rats. These cells were positive for single-stranded DNA (ssDNA), an apoptosis-specific marker, and thus were considered to be apoptotic. Some of the ssDNA-positive cells were also positive for somatostatin. But neither ionized calcium-binding adapter molecule 1 (Iba1) nor S100beta occurred in ssDNA-positive cells. These findings suggest that CT105 induces apoptotic changes in cells of neuronal origin. Quantitative analysis showed that the densities of ssDNA-positive cells in the mossy fiber pathway were significantly higher in CT105-treated rats than in control animals. The present results suggest that CT105 causes dysfunction in the hippocampal mossy fiber system, and also provide some key to understand the relationship between APP-CTF and glutamatergic synaptic dysregulation in AD.
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Affiliation(s)
- Shozo Jinno
- Department of Anatomy and Neurobiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
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Seress L, Abrahám H, Czéh B, Fuchs E, Léránth C. Calretinin expression in hilar mossy cells of the hippocampal dentate gyrus of nonhuman primates and humans. Hippocampus 2008; 18:425-34. [PMID: 18189312 DOI: 10.1002/hipo.20403] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Mossy cells, the major excitatory neurons of the hilus of the dentate gyrus constitutively express calretinin in several rodent species, including mouse and hamster, but not in rats. Several studies suggest that mossy cells of the monkey dentate gyrus are calretinin-positive, but others have reported mossy cells in monkeys to be devoid of detectable calretinin-like immunoreactivity. In the present study, the hilar region was investigated throughout the entire longitudinal extent of the hippocampal dentate gyrus in both Old World and New World monkeys, as well as in humans. In the examined four monkey species, mossy cells were found to be calretinin-positive at the uncal pole and at variable length within the main body of the dentate gyrus but not in the tail part. The associational pathway, formed by axons of mossy cells in the inner dentate molecular layer was calretinin-positive in more caudal sections, suggesting that mossy cell axon terminals may contain calretinin, whereas mossy cell somata may contain calretinin in a concentration too low to be detected by immunocytochemistry. In contrast, human mossy cells appear to be devoid of calretinin immunoreactivity in both their somata and their axon terminals. Taken together, mossy cells of nonhuman primates and humans exhibit different expression pattern for calretinin whereas they show similarities in neurochemical content, such as the cocaine and amphetamine-related transcript peptide.
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Affiliation(s)
- László Seress
- Central Electron Microscopic Laboratory, Faculty of Medicine, University of Pécs, Pécs, Hungary.
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