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LIU T, ZHANG X, YANG H, LIN X, LIU J, ZHANG X, GUO D, ZHAO H, ZOU M, LEI C, LONG H, LUO Y, XIANG Y, GE J, WANG Y, MENG P. Luteolin promotes neuronogenesis in hippocampus of chronic unpredictable mild stress rats and primary hippocampus of fetal rats. J TRADIT CHIN MED 2024; 44:670-679. [PMID: 39066527 PMCID: PMC11337264 DOI: 10.19852/j.cnki.jtcm.20240626.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 08/22/2023] [Indexed: 07/28/2024]
Abstract
OBJECTIVE To investigate the effects of luteolin on chronic unpredictable mild stress (CUMS)-induced depressive rats and corticosterone (CORT)-induced depressive primary hippocampal neurons, and to elucidate the mechanism behind the action. METHODS The antidepressant mechanism of luteolin was studied by using CUMS rat model and primary hippocampal neurons in fetal rats. In vivo, novelty suppressed feeding, open-field and sucrose preference tests as well as Morris water maze were evaluated. The content of brain derived neurotrophic factor (BDNF), 5-hydroxytryptamine (5-HT), norepinephrine (NE), and dopamine (DA) in serum were detected by enzyme-linked immunosorbent assay. The mechanisms of luteolin were explored based on neurotrophin and hippocampal neurogenesis, and proliferation. Survival of the septo-temporal axis in hippocampus was assayed using the 5-bromo-2-deoxyuridine (BrdU), the expression of BDNF, neurotrophin-3 (NT-3), and nerve growth factor (NGF) in hippocampus dentate gyrus region were measured by Western-blotting. In vitro, BDNF, NT-3, tropomyosin receptor kinase B (TrkB), and phosphorylated cyclic adenosine monophosphate responsive element binding protein (p-CREB) were detected through the high content analysis (HCA) to investigate neurotrophin and apoptosis. RESULTS Induction of CUMS in rats induced depressive symptoms, while luteolin significantly enhanced sucrose consumption, decreased feeding latency, increased locomotor activity, escape latency, distance of target quadrant and regulated the content of depressive-like biomarkers. Histology analysis revealed that luteolin increased the abundance of new born neurons that had been labeled with BrdU, BrdU + neuronal nuclear antigen, and BrdU + doublecortin in septo-temporal axis of S2 (mid-septal) and T3 (mid-temporal). Moreover, expression of BDNF, NT-3, and NGF increased significantly in the septo-temporal axis of S2 and T3. HCA showed increased expression of BDNF, NT-3, TrkB and p-CREB in primary hippocampal neurons. CONCLUSION The results provided direct evidence that luteolin has an antidepressant effect and could effectively promote the regeneration of the septotemporal axis nerve and hippocampal neuronutrition, which suggested that the antidepressant effect of luteolin may be related to hippocampal neurogenesis.
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Affiliation(s)
- Tongtong LIU
- 1 Institute of Innovation and Applied Research in Chinese Medicine, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Xi ZHANG
- 2 the Second People's Hospital of Hunan Province, Changsha 410007, China
| | - Hui YANG
- 3 The First Affiliated Hospital, Hunan University of Chinese Medicine, Changsha 410007, China
| | - Xiaoyuan LIN
- 3 The First Affiliated Hospital, Hunan University of Chinese Medicine, Changsha 410007, China
| | - Jian LIU
- 3 The First Affiliated Hospital, Hunan University of Chinese Medicine, Changsha 410007, China
| | - Xiuli ZHANG
- 1 Institute of Innovation and Applied Research in Chinese Medicine, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Dongwei GUO
- 2 the Second People's Hospital of Hunan Province, Changsha 410007, China
| | - Hongqing ZHAO
- 1 Institute of Innovation and Applied Research in Chinese Medicine, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Manshu ZOU
- 1 Institute of Innovation and Applied Research in Chinese Medicine, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Chang LEI
- 1 Institute of Innovation and Applied Research in Chinese Medicine, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Hongping LONG
- 3 The First Affiliated Hospital, Hunan University of Chinese Medicine, Changsha 410007, China
| | - Yan LUO
- 1 Institute of Innovation and Applied Research in Chinese Medicine, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Yun XIANG
- 1 Institute of Innovation and Applied Research in Chinese Medicine, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Jinwen GE
- 4 Hunan Academy of Chinese Medicine, Changsha 410013, China
| | - Yuhong WANG
- 1 Institute of Innovation and Applied Research in Chinese Medicine, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Pan MENG
- 1 Institute of Innovation and Applied Research in Chinese Medicine, Hunan University of Chinese Medicine, Changsha 410208, China
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Ku SP, Atucha E, Alavi N, Mulla-Osman H, Kayumova R, Yoshida M, Csicsvari J, Sauvage MM. Phase locking of hippocampal CA3 neurons to distal CA1 theta oscillations selectively predicts memory performance. Cell Rep 2024; 43:114276. [PMID: 38814781 DOI: 10.1016/j.celrep.2024.114276] [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: 06/09/2022] [Revised: 01/09/2024] [Accepted: 05/09/2024] [Indexed: 06/01/2024] Open
Abstract
How the coordination of neuronal spiking and brain rhythms between hippocampal subregions supports memory function remains elusive. We studied the interregional coordination of CA3 neuronal spiking with CA1 theta oscillations by recording electrophysiological signals along the proximodistal axis of the hippocampus in rats that were performing a high-memory-demand recognition memory task adapted from humans. We found that CA3 population spiking occurs preferentially at the peak of distal CA1 theta oscillations when memory was tested but only when previously encountered stimuli were presented. In addition, decoding analyses revealed that only population cell firing of proximal CA3 together with that of distal CA1 can predict performance at test in the present non-spatial task. Overall, our work demonstrates an important role for the synchronization of CA3 neuronal activity with CA1 theta oscillations during memory testing.
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Affiliation(s)
- Shih-Pi Ku
- Leibniz Institute for Neurobiology, Functional Architecture of Memory Department, Magdeburg, Germany.
| | - Erika Atucha
- Leibniz Institute for Neurobiology, Functional Architecture of Memory Department, Magdeburg, Germany
| | - Nico Alavi
- Leibniz Institute for Neurobiology, Functional Architecture of Memory Department, Magdeburg, Germany
| | - Halla Mulla-Osman
- Leibniz Institute for Neurobiology, Functional Architecture of Memory Department, Magdeburg, Germany
| | - Rukhshona Kayumova
- Leibniz Institute for Neurobiology, Functional Architecture of Memory Department, Magdeburg, Germany
| | - Motoharu Yoshida
- Leibniz Institute for Neurobiology, Functional Architecture of Memory Department, Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Jozsef Csicsvari
- Institute of Science and Technology (IST), Klosterneuburg, Austria
| | - Magdalena M Sauvage
- Leibniz Institute for Neurobiology, Functional Architecture of Memory Department, Magdeburg, Germany; Otto von Guericke University, Medical Faculty, Functional Neuroplasticity Department, Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.
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Sun D, Mei L, Xiong WC. Dorsal Dentate Gyrus, a Key Regulator for Mood and Psychiatric Disorders. Biol Psychiatry 2023:S0006-3223(23)00009-4. [PMID: 36894487 DOI: 10.1016/j.biopsych.2023.01.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 12/06/2022] [Accepted: 01/09/2023] [Indexed: 01/18/2023]
Abstract
The dentate gyrus, a "gate" that controls the flow of information into the hippocampus, is critical for learning, memory, spatial navigation, and mood regulation. Several lines of evidence have demonstrated that deficits in dentate granule cells (DGCs) (e.g., loss of DGCs or genetic mutations in DGCs) contribute to the development of various psychiatric disorders, such as depression and anxiety disorders. Whereas ventral DGCs are believed to be critical for mood regulation, the functions of dorsal DGCs in this regard remain elusive. Here, we review the role of DGCs, in particular the dorsal DGCs, in the regulation of mood, their functional relationships with DGC development, and the contributions of dysfunctional DGCs to mental disorders.
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Affiliation(s)
- Dong Sun
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio; National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, Jilin, China
| | - Lin Mei
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Wen-Cheng Xiong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio.
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Silveira‐Rosa T, Mateus‐Pinheiro A, Correia JS, Silva JM, Martins‐Macedo J, Araújo B, Machado‐Santos AR, Alves ND, Silva M, Loureiro‐Campos E, Sotiropoulos I, Bessa JM, Rodrigues AJ, Sousa N, Patrício P, Pinto L. Suppression of adult cytogenesis in the rat brain leads to sex-differentiated disruption of the HPA axis activity. Cell Prolif 2022; 55:e13165. [PMID: 34970787 PMCID: PMC8828259 DOI: 10.1111/cpr.13165] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/21/2021] [Accepted: 11/23/2021] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVES The action of stress hormones, mainly glucocorticoids, starts and coordinates the systemic response to stressful events. The HPA axis activity is predicated on information processing and modulation by upstream centres, such as the hippocampus where adult-born neurons (hABN) have been reported to be an important component in the processing and integration of new information. Still, it remains unclear whether and how hABN regulates HPA axis activity and CORT production, particularly when considering sex differences. MATERIALS AND METHODS Using both sexes of a transgenic rat model of cytogenesis ablation (GFAP-Tk rat model), we examined the endocrinological and behavioural effects of disrupting the generation of new astrocytes and neurons within the hippocampal dentate gyrus (DG). RESULTS Our results show that GFAP-Tk male rats present a heightened acute stress response. In contrast, GFAP-Tk female rats have increased corticosterone secretion at nadir, a heightened, yet delayed, response to an acute stress stimulus, accompanied by neuronal hypertrophy in the basal lateral amygdala and increased expression of the glucocorticoid receptors in the ventral DG. CONCLUSIONS Our results reveal that hABN regulation of the HPA axis response is sex-differentiated.
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Affiliation(s)
- Tiago Silveira‐Rosa
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
| | - António Mateus‐Pinheiro
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
- Department of Internal MedicineCoimbra Hospital and University CenterCoimbraPortugal
- Bn’ML – Behavioral and Molecular LabBragaPortugal
| | - Joana Sofia Correia
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
| | - Joana Margarida Silva
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
| | - Joana Martins‐Macedo
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
- Bn’ML – Behavioral and Molecular LabBragaPortugal
| | - Bruna Araújo
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
| | - Ana Rita Machado‐Santos
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
| | - Nuno Dinis Alves
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
- Present address:
Department of PsychiatryColumbia UniversityNew YorkNew YorkUSA
- Present address:
New York State Psychiatric InstituteNew YorkNew YorkUSA
| | - Mariana Silva
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
| | - Eduardo Loureiro‐Campos
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
| | - Ioannis Sotiropoulos
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
| | - João Miguel Bessa
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
- Bn’ML – Behavioral and Molecular LabBragaPortugal
| | - Ana João Rodrigues
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
- Bn’ML – Behavioral and Molecular LabBragaPortugal
| | - Patrícia Patrício
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
- Bn’ML – Behavioral and Molecular LabBragaPortugal
| | - Luísa Pinto
- Life and Health Sciences Research Institute (ICVS)School of MedicineUniversity of MinhoBragaPortugal
- ICVS/3B’s ‐ PT Government Associate LaboratoryBraga/GuimarãesPortugal
- Bn’ML – Behavioral and Molecular LabBragaPortugal
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Bekiari C, Grivas I, Tsingotjidou A, Papadopoulos GC. Adult neurogenesis and gliogenesis in the dorsal and ventral canine hippocampus. J Comp Neurol 2019; 528:1216-1230. [PMID: 31743444 DOI: 10.1002/cne.24818] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 11/08/2019] [Accepted: 11/08/2019] [Indexed: 12/13/2022]
Abstract
Dentate gyrus (DG) of the mammalian hippocampus gives rise to new neurons and astrocytes all through adulthood. Canine hippocampus presents many similarities in fetal development, anatomy, and physiology with human hippocampus, establishing canines as excellent animal models for the study of adult neurogenesis. In the present study, BrdU-dated cells of the structurally and functionally dissociated dorsal (dDG) and ventral (vDG) adult canine DG were comparatively examined over a period of 30 days. Each part's neurogenic potential, radial glia-like neural stem cells (NSCs) proliferation and differentiation, migration, and maturation of their progenies were evaluated at 2, 5, 14, and 30 days post BrdU administration, with the use of selected markers (glial fibrillary acidic protein, doublecortin, calretinin and calbindin). Co-staining of BrdU+ cells with NeuN or S100B permitted the parallel study of the ongoing neurogenesis and gliogenesis. Our findings reveal the comparatively higher populations of residing granule cells, proliferating NSCs and BrdU+ neurons in the dDG, whereas newborn neurons of the vDG showed a prolonged differentiation, migration, and maturation. Newborn astrocytes were found all along the dorso-ventral axis, counting however for only 11% of newborn cell population. Comparative evaluation of adult canine and rat neurogenesis revealed significant differences in the distribution of resident and newborn granule cells along the dorso-ventral axis, division pattern of adult NSCs, maturation time plan of newborn neurons, and ongoing gliogenesis. Concluding, spatial and temporal features of adult canine neurogenesis are similar to that of other gyrencephalic species, including humans, and justify the comparative examination of adult neurogenesis across mammalian species.
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Affiliation(s)
- Chryssa Bekiari
- Laboratory of Anatomy, Histology & Embryology, Faculty of Veterinary Medicine, School of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Ioannis Grivas
- Laboratory of Anatomy, Histology & Embryology, Faculty of Veterinary Medicine, School of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Anastasia Tsingotjidou
- Laboratory of Anatomy, Histology & Embryology, Faculty of Veterinary Medicine, School of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Georgios C Papadopoulos
- Laboratory of Anatomy, Histology & Embryology, Faculty of Veterinary Medicine, School of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
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6
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Terranova JI, Ogawa SK, Kitamura T. Adult hippocampal neurogenesis for systems consolidation of memory. Behav Brain Res 2019; 372:112035. [DOI: 10.1016/j.bbr.2019.112035] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 06/07/2019] [Accepted: 06/11/2019] [Indexed: 12/11/2022]
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van Dijk RM, Wiget F, Wolfer DP, Slomianka L, Amrein I. Consistent within-group covariance of septal and temporal hippocampal neurogenesis with behavioral phenotypes for exploration and memory retention across wild and laboratory small rodents. Behav Brain Res 2019; 372:112034. [DOI: 10.1016/j.bbr.2019.112034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 05/22/2019] [Accepted: 06/11/2019] [Indexed: 12/20/2022]
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Cahill SP, Yu RQ, Green D, Todorova EV, Snyder JS. Early survival and delayed death of developmentally-born dentate gyrus neurons. Hippocampus 2017; 27:1155-1167. [PMID: 28686814 DOI: 10.1002/hipo.22760] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 06/23/2017] [Accepted: 06/27/2017] [Indexed: 01/20/2023]
Abstract
The storage and persistence of memories depends on plasticity in the hippocampus. Adult neurogenesis produces new neurons that mature through critical periods for plasticity and cellular survival, which determine their contributions to learning and memory. However, most granule neurons are generated prior to adulthood; the maturational timecourse of these neurons is poorly understood compared to adult-born neurons but is essential to identify how the dentate gyrus (DG), as a whole, contributes to behavior. To characterize neurons born in the early postnatal period, we labeled DG neurons born on postnatal day 6 (P6) with BrdU and quantified maturation and survival across early (1 hr to 8 weeks old) and late (2-6 months old) cell ages. We find that the dynamics of developmentally-born neuron survival is essentially the opposite of neurons born in adulthood: P6-born neurons did not go through a period of cell death during their immature stages (from 1 to 8 weeks). In contrast, 17% of P6-born neurons died after reaching maturity, between 2 and 6 months of age. Delayed death was evident from the loss of BrdU+ cells as well as pyknotic BrdU+ caspase3+ neurons within the superficial granule cell layer. Patterns of DCX, NeuN, and activity-dependent Fos expression indicate that developmentally-born neurons mature over several weeks and a sharp peak in zif268 expression at 2 weeks suggests that developmentally-born neurons mature faster than adult-born neurons (which peak at 3 weeks). Collectively, our findings are relevant for understanding how developmentally-born DG neurons contribute to memory and disorders throughout the lifespan. High levels of early survival and zif268 expression may promote learning, while also rendering neurons sensitive to insults at defined stages. Late neuronal death in young adulthood may result in the loss of hundreds of thousands of DG neurons, which could impact memory persistence and contribute to hippocampal/DG atrophy in disorders such as depression.
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Affiliation(s)
- Shaina P Cahill
- Department of Psychology & Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ru Qi Yu
- Department of Psychology & Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Dylan Green
- Department of Psychology & Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Evgenia V Todorova
- Department of Psychology & Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jason S Snyder
- Department of Psychology & Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
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Crescenzi R, DeBrosse C, Nanga RP, Byrne MD, Krishnamoorthy G, D’Aquilla K, Nath H, Morales KH, Iba M, Hariharan H, Lee VM, Detre JA, Reddy R. Longitudinal imaging reveals subhippocampal dynamics in glutamate levels associated with histopathologic events in a mouse model of tauopathy and healthy mice. Hippocampus 2017; 27:285-302. [PMID: 27997993 PMCID: PMC5396955 DOI: 10.1002/hipo.22693] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 12/02/2016] [Accepted: 12/02/2016] [Indexed: 11/08/2022]
Abstract
Tauopathies are neurodegenerative disorders characterized by abnormal intracellular aggregates of tau protein, and include Alzheimer's disease, corticobasal degeneration, frontotemporal dementia, and traumatic brain injury. Glutamate metabolism is altered in neurodegenerative disorders manifesting in higher or lower concentrations of glutamate, its transporters or receptors. Previously, glutamate chemical exchange saturation transfer (GluCEST) magnetic resonance imaging (MRI) demonstrated that glutamate levels are reduced in regions of synapse loss in the hippocampus of a mouse model of late-stage tauopathy. We performed a longitudinal GluCEST imaging experiment paired with a cross-sectional study of histologic markers of tauopathy to determine whether (1) early GluCEST changes are associated with synapse loss before volume loss occurs in the hippocampus, and whether (2) subhippocampal dynamics in GluCEST are associated with histopathologic events related to glutamate alterations in tauopathy. Live imaging of the hippocampus in three serial slices was performed without exogenous contrast agents, and subregions were segmented based on a k-means cluster model. Subregions of the hippocampus were analyzed (cornu ammonis CA1, CA3, dentate gyrus DG, and ventricle) in order to associate local MRI-observable changes in glutamate with histological measures of glial cell proliferation (GFAP), synapse density (synaptophysin, VGlut1) and glutamate receptor (NMDA-NR1) levels. Early differences in GluCEST between healthy and tauopathy mice were measured in the CA1 and DG subregions (30% reduction, P ≤ 0.001). Synapse density was also significantly reduced in every subregion of the hippocampus in tauopathy mice by 6 months. Volume was not significantly reduced in any subregion until 13 months. Further, a gradient in glutamate levels was observed in vivo along hippocampal axes that became polarized as tauopathy progressed. Dynamics in hippocampal glutamate levels throughout lifetime were most closely correlated with combined changes in synaptophysin and GFAP, indicating that GluCEST imaging may be a surrogate marker of glutamate concentration in glial cells and at the synaptic level. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Rachelle Crescenzi
- Department of Biochemistry & Molecular Biophysics (BMB), University of Pennsylvania, Philadelphia, PA, USA
- Center for Magnetic Resonance and Optical Imaging (CMROI), University of Pennsylvania, Philadelphia, PA, USA
| | - Catherine DeBrosse
- Department of Biochemistry & Molecular Biophysics (BMB), University of Pennsylvania, Philadelphia, PA, USA
- Center for Magnetic Resonance and Optical Imaging (CMROI), University of Pennsylvania, Philadelphia, PA, USA
| | - Ravi P.R. Nanga
- Center for Magnetic Resonance and Optical Imaging (CMROI), University of Pennsylvania, Philadelphia, PA, USA
| | - Matthew D. Byrne
- Center for Neurodegenerative Disease Research (CNDR), University of Pennsylvania, Philadelphia, PA, USA
| | - Guruprasad Krishnamoorthy
- Center for Magnetic Resonance and Optical Imaging (CMROI), University of Pennsylvania, Philadelphia, PA, USA
| | - Kevin D’Aquilla
- Center for Magnetic Resonance and Optical Imaging (CMROI), University of Pennsylvania, Philadelphia, PA, USA
| | - Hari Nath
- Center for Magnetic Resonance and Optical Imaging (CMROI), University of Pennsylvania, Philadelphia, PA, USA
| | - Knashawn H. Morales
- Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Michiyo Iba
- Center for Neurodegenerative Disease Research (CNDR), University of Pennsylvania, Philadelphia, PA, USA
| | - Hari Hariharan
- Center for Magnetic Resonance and Optical Imaging (CMROI), University of Pennsylvania, Philadelphia, PA, USA
| | - Virginia M.Y Lee
- Center for Neurodegenerative Disease Research (CNDR), University of Pennsylvania, Philadelphia, PA, USA
| | - John A. Detre
- Center for Functional Neuroimaging (CfN), University of Pennsylvania, Philadelphia, PA, USA
| | - Ravinder Reddy
- Center for Magnetic Resonance and Optical Imaging (CMROI), University of Pennsylvania, Philadelphia, PA, USA
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Effects of neuregulin-1 administration on neurogenesis in the adult mouse hippocampus, and characterization of immature neurons along the septotemporal axis. Sci Rep 2016; 6:30467. [PMID: 27469430 PMCID: PMC4965755 DOI: 10.1038/srep30467] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 07/04/2016] [Indexed: 12/11/2022] Open
Abstract
Adult hippocampal neurogenesis is associated with learning and affective behavioural regulation. Its diverse functionality is segregated along the septotemporal axis from the dorsal to ventral hippocampus. However, features distinguishing immature neurons in these regions have yet to be characterized. Additionally, although we have shown that administration of the neurotrophic factor neuregulin-1 (NRG1) selectively increases proliferation and overall neurogenesis in the mouse ventral dentate gyrus (DG), likely through ErbB3, NRG1's effects on intermediate neurogenic stages in immature neurons are unknown. We examined whether NRG1 administration increases DG ErbB3 phosphorylation. We labeled adultborn cells using BrdU, then administered NRG1 to examine in vivo neurogenic effects on immature neurons with respect to cell survival, morphology, and synaptogenesis. We also characterized features of immature neurons along the septotemporal axis. We found that neurogenic effects of NRG1 are temporally and subregionally specific to proliferation in the ventral DG. Particular morphological features differentiate immature neurons in the dorsal and ventral DG, and cytogenesis differed between these regions. Finally, we identified synaptic heterogeneity surrounding the granule cell layer. These results indicate neurogenic involvement of NRG1-induced antidepressant-like behaviour is particularly associated with increased ventral DG cell proliferation, and identify novel distinctions between dorsal and ventral hippocampal neurogenic development.
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McAvoy K, Russo C, Kim S, Rankin G, Sahay A. Fluoxetine induces input-specific hippocampal dendritic spine remodeling along the septotemporal axis in adulthood and middle age. Hippocampus 2015; 25:1429-46. [PMID: 25850664 DOI: 10.1002/hipo.22464] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2015] [Indexed: 12/15/2022]
Abstract
Fluoxetine, a selective serotonin-reuptake inhibitor (SSRI), is known to induce structural rearrangements and changes in synaptic transmission in hippocampal circuitry. In the adult hippocampus, structural changes include neurogenesis, dendritic, and axonal plasticity of pyramidal and dentate granule neurons, and dedifferentiation of dentate granule neurons. However, much less is known about how chronic fluoxetine affects these processes along the septotemporal axis and during the aging process. Importantly, studies documenting the effects of fluoxetine on density and distribution of spines along different dendritic segments of dentate granule neurons and CA1 pyramidal neurons along the septotemporal axis of hippocampus in adulthood and during aging are conspicuously absent. Here, we use a transgenic mouse line in which mature dentate granule neurons and CA1 pyramidal neurons are genetically labeled with green fluorescent protein (GFP) to investigate the effects of chronic fluoxetine treatment (18 mg/kg/day) on input-specific spine remodeling and mossy fiber structural plasticity in the dorsal and ventral hippocampus in adulthood and middle age. In addition, we examine levels of adult hippocampal neurogenesis, maturation state of dentate granule neurons, neuronal activity, and glutamic acid decarboxylase-67 expression in response to chronic fluoxetine in adulthood and middle age. Our studies reveal that while chronic fluoxetine fails to augment adult hippocampal neurogenesis in middle age, the middle-aged hippocampus retains high sensitivity to changes in the dentate gyrus (DG) such as dematuration, hypoactivation, and increased glutamic acid decarboxylase 67 (GAD67) expression. Interestingly, the middle-aged hippocampus shows greater sensitivity to fluoxetine-induced input-specific synaptic remodeling than the hippocampus in adulthood with the stratum-oriens of CA1 exhibiting heightened structural plasticity. The input-specific changes and circuit-level modifications in middle-age were associated with modest enhancement in contextual fear memory precision, anxiety-like behavior and antidepressant-like behavioral responses.
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Affiliation(s)
- Kathleen McAvoy
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Harvard Stem Cell Institute, Harvard University, Boston, Massachusetts.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Craig Russo
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Harvard Stem Cell Institute, Harvard University, Boston, Massachusetts.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Shannen Kim
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Harvard Stem Cell Institute, Harvard University, Boston, Massachusetts.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Genelle Rankin
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Harvard Stem Cell Institute, Harvard University, Boston, Massachusetts.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Amar Sahay
- Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Harvard Stem Cell Institute, Harvard University, Boston, Massachusetts.,Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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12
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Huang S, Slomianka L, Farmer AJ, Kharlamova AV, Gulevich RG, Herbeck YE, Trut LN, Wolfer DP, Amrein I. Selection for tameness, a key behavioral trait of domestication, increases adult hippocampal neurogenesis in foxes. Hippocampus 2015; 25:963-75. [DOI: 10.1002/hipo.22420] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2015] [Indexed: 01/31/2023]
Affiliation(s)
- Shihhui Huang
- Department of Health Sciences and Technology; Institute of Human Movement Sciences and Sport; ETH Zurich Zürich Switzerland
- Division of Functional Neuroanatomy; Institute of Anatomy, Functional Neuroanatomy, University of Zurich; Zürich Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich; Zürich Switzerland
| | - Lutz Slomianka
- Division of Functional Neuroanatomy; Institute of Anatomy, Functional Neuroanatomy, University of Zurich; Zürich Switzerland
| | | | - Anastasiya V. Kharlamova
- Division of Siberian; Institute of Cytology and Genetics of the Russian Academy of Sciences; Novosibirsk Russia
| | - Rimma G. Gulevich
- Division of Siberian; Institute of Cytology and Genetics of the Russian Academy of Sciences; Novosibirsk Russia
| | - Yury E. Herbeck
- Division of Siberian; Institute of Cytology and Genetics of the Russian Academy of Sciences; Novosibirsk Russia
| | - Lyudmila N. Trut
- Division of Siberian; Institute of Cytology and Genetics of the Russian Academy of Sciences; Novosibirsk Russia
| | - David P. Wolfer
- Department of Health Sciences and Technology; Institute of Human Movement Sciences and Sport; ETH Zurich Zürich Switzerland
- Division of Functional Neuroanatomy; Institute of Anatomy, Functional Neuroanatomy, University of Zurich; Zürich Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich; Zürich Switzerland
- Zurich Center for Integrative Human Physiology ZIHP; University of Zurich; Zurich Switzerland
| | - Irmgard Amrein
- Division of Functional Neuroanatomy; Institute of Anatomy, Functional Neuroanatomy, University of Zurich; Zürich Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich; Zürich Switzerland
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13
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Abstract
New neurons continue to be generated in the dentate gyrus throughout life, providing this region of the hippocampus with exceptional structural plasticity, but the function of this ongoing neurogenesis is unknown. Inhibition of adult neurogenesis produces some behavioral impairments that suggest a role for new neurons in learning and memory; however, other behavioral changes appear inconsistent with this function. A review of studies investigating the function of the hippocampus going back several decades reveals many ideas that seem to converge on a critical role for the hippocampus in stress response and emotion. These potential hippocampal functions provide new avenues for investigating the behavioral functions of adult neurogenesis. And, conversely, studies in animals lacking adult neurogenesis, which are likely to have more limited and more specific impairments than are seen with lesions, may provide valuable new insights into the function of the hippocampus. A complete understanding of the function of the hippocampus must explain its role in emotion and the relationship between its emotional and memory functions.
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Affiliation(s)
- Heather A Cameron
- Section on Neuroplasticity, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892;
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14
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Ransome MI. Could androgens maintain specific domains of mental health in aging men by preserving hippocampal neurogenesis? Neural Regen Res 2014; 7:2227-39. [PMID: 25538744 PMCID: PMC4268723 DOI: 10.3969/j.issn.1673-5374.2012.028.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 07/10/2012] [Indexed: 12/18/2022] Open
Abstract
Interest surrounds the role of sex-hormones in regulating brain function outside of reproductive behaviour. Declining androgen production in aging males has been associated with cognitive impairment, depression and increased risk of developing Alzheimer's disease. Indication for testosterone replacement therapy is based on biochemically determined low circulating testosterone combined with manifest symptoms. However, which aspects of age-related cognitive decline are attributable to low circulating testosterone remain ambiguous. Studies examining cognition in aging men receiving testosterone replacement therapy have yielded equivocal results. The exact role of testosterone in maintaining cognitive function and the underlying neural mechanisms are largely unknown, though it would appear to be domain specific. Clarity in this area will provide clinical direction toward addressing an increasing healthcare burden of mental health decline coincident with increasing longevity. The premise that androgens contribute to maintaining aspects of mental health in aging men by preserving hippocampal neurogenesis will be used as a forum in this review to discuss current knowledge and the need for further studies to better define testosterone replacement strategies for aging male health.
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Affiliation(s)
- Mark I Ransome
- Florey Neurosciences Institute, Melbourne Brain Centre, the University of Melbourne, Parkville, Victoria 3010, Australia
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15
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Bekiari C, Giannakopoulou A, Siskos N, Grivas I, Tsingotjidou A, Michaloudi H, Papadopoulos GC. Neurogenesis in the septal and temporal part of the adult rat dentate gyrus. Hippocampus 2014; 25:511-23. [PMID: 25394554 DOI: 10.1002/hipo.22388] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2014] [Indexed: 12/19/2022]
Abstract
Structural and functional dissociation between the septal and the temporal part of the dentate gyrus predispose for possible differentiations in the ongoing neurogenesis process of the adult hippocampus. In this study, BrdU-dated subpopulations of the rat septal and temporal dentate gyrus (coexpressing GFAP, DCX, NeuN, calretinin, calbindin, S100, caspase-3 or fractin) were quantified comparatively at 2, 5, 7, 14, 21, and 30 days after BrdU administration in order to examine the successive time-frames of the neurogenesis process, the glial or neuronal commitment of newborn cells and the occurring apoptotic cell death. Newborn neurons' migration from the neurogenic subgranular zone to the inner granular cell layer and expression of glutamate NMDA and AMPA receptors were also studied. BrdU immunocytochemistry revealed comparatively higher numbers of BrdU(+) cells in the septal part, but stereological analysis of newborn and total granule cells showed an identical ratio in the two parts, indicating an equivalent neurogenic ability, and a common topographical pattern along each part's longitudinal and transverse axis. Similarly, both parts exhibited extremely low levels of newborn glial and apoptotic cells. However, despite the initially equal division rate and pattern of the septal and temporal proliferating cells, their later proliferative profile diverged in the two parts. Dynamic differences in the differentiation, migration and maturation process of the two BrdU-incorporating subpopulations of newborn neurons were also detected, along with differences in their survival pattern. Therefore, we propose that various factors, including developmental date birth, local DG microenvironment and distinct functionality of the two parts may be the critical regulators of the ongoing neurogenesis process, leading the septal part to a continuous, rapid, and less-disciplined genesis rate, whereas the quiescent temporal microenvironment preserves a quite steady, less-demanding neurogenesis process.
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Affiliation(s)
- Chryssa Bekiari
- Laboratory of Anatomy, Histology and Embryology, Department of Structure and Function of Living Organisms, Faculty of Veterinary Medicine, School of Health Sciences, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece
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16
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Ito H, Morishita R, Iwamoto I, Nagata KI. Establishment of an in vivo electroporation method into postnatal newborn neurons in the dentate gyrus. Hippocampus 2014; 24:1449-57. [DOI: 10.1002/hipo.22325] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 06/04/2014] [Accepted: 06/16/2014] [Indexed: 02/06/2023]
Affiliation(s)
- Hidenori Ito
- Department of Molecular Neurobiology; Institute for Developmental Research; Aichi Human Service Center, 713-8 Kamiya Kasugai Aichi 480-0392 Japan
| | - Rika Morishita
- Department of Molecular Neurobiology; Institute for Developmental Research; Aichi Human Service Center, 713-8 Kamiya Kasugai Aichi 480-0392 Japan
| | - Ikuko Iwamoto
- Department of Molecular Neurobiology; Institute for Developmental Research; Aichi Human Service Center, 713-8 Kamiya Kasugai Aichi 480-0392 Japan
| | - Koh-ichi Nagata
- Department of Molecular Neurobiology; Institute for Developmental Research; Aichi Human Service Center, 713-8 Kamiya Kasugai Aichi 480-0392 Japan
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17
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Sachs BD, Ni JR, Caron M. Sex differences in response to chronic mild stress and congenital serotonin deficiency. Psychoneuroendocrinology 2014; 40:123-9. [PMID: 24485484 PMCID: PMC3918518 DOI: 10.1016/j.psyneuen.2013.11.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 10/25/2013] [Accepted: 11/08/2013] [Indexed: 12/29/2022]
Abstract
Women exhibit a nearly twofold increased risk of developing depression and anxiety disorders when compared to men, a fact that has been hypothesized to result in part from increased stress susceptibility. Here, we used the tryptophan hydroxylase-2 R439H knock-in mouse (Tph2KI) and the chronic unpredictable mild stress (CMS) model to examine sex differences in response to congenital 5-HT deficiency and chronic stress. Our results demonstrate that female mice, but not 5-HT-deficient animals, exhibit significantly increased susceptibility to CMS-induced despair-like behavior in the forced swim test. In addition, female 5-HT-deficient mice exhibit anhedonia-like behavior in the sucrose preference test, whereas male 5-HT-deficient animals do not, suggesting that females exhibit increased sensitivity to at least some of the effects of congenital 5-HT deficiency. Although CMS did not reduce cell proliferation in the hippocampus, low levels of brain 5-HT were associated with increased hippocampal cell proliferation, an effect that was predominantly observed in females. Overall, these results highlight the importance of interactions between psychiatric disease risk factors such as sex, chronic stress and congenital 5-HT deficiency in the development of aberrant emotional behavior.
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Affiliation(s)
| | - Jason R. Ni
- Department of Cell Biology, Duke University, Durham, NC 27710, USA
| | - Marc Caron
- Department of Cell Biology, Duke University, Durham, NC 27710, USA, Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
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18
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Nishijima T, Kawakami M, Kita I. Long-term exercise is a potent trigger for ΔFosB induction in the hippocampus along the dorso-ventral axis. PLoS One 2013; 8:e81245. [PMID: 24282574 PMCID: PMC3840114 DOI: 10.1371/journal.pone.0081245] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 10/21/2013] [Indexed: 01/31/2023] Open
Abstract
Physical exercise improves multiple aspects of hippocampal function. In line with the notion that neuronal activity is key to promoting neuronal functions, previous literature has consistently demonstrated that acute bouts of exercise evoke neuronal activation in the hippocampus. Repeated activating stimuli lead to an accumulation of the transcription factor ΔFosB, which mediates long-term neural plasticity. In this study, we tested the hypothesis that long-term voluntary wheel running induces ΔFosB expression in the hippocampus, and examined any potential region-specific effects within the hippocampal subfields along the dorso–ventral axis. Male C57BL/6 mice were housed with or without a running wheel for 4 weeks. Long-term wheel running significantly increased FosB/ΔFosB immunoreactivity in all hippocampal regions measured (i.e., in the DG, CA1, and CA3 subfields of both the dorsal and ventral hippocampus). Results confirmed that wheel running induced region-specific expression of FosB/ΔFosB immunoreactivity in the cortex, suggesting that the uniform increase in FosB/ΔFosB within the hippocampus is not a non-specific consequence of running. Western blot data indicated that the increased hippocampal FosB/ΔFosB immunoreactivity was primarily due to increased ΔFosB. These results suggest that long-term physical exercise is a potent trigger for ΔFosB induction throughout the entire hippocampus, which would explain why exercise can improve both dorsal and ventral hippocampus-dependent functions. Interestingly, we found that FosB/ΔFosB expression in the DG was positively correlated with the number of doublecortin-immunoreactive (i.e., immature) neurons. Although the mechanisms by which ΔFosB mediates exercise-induced neurogenesis are still uncertain, these data imply that exercise-induced neurogenesis is at least activity dependent. Taken together, our current results suggest that ΔFosB is a new molecular target involved in regulating exercise-induced hippocampal plasticity.
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Affiliation(s)
- Takeshi Nishijima
- Laboratory of Behavioral Physiology, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
- * E-mail:
| | - Masashi Kawakami
- Laboratory of Behavioral Physiology, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Ichiro Kita
- Laboratory of Behavioral Physiology, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
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19
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Gheidi A, Azzopardi E, Adams AA, Marrone DF. Experience-dependent persistent expression of zif268 during rest is preserved in the aged dentate gyrus. BMC Neurosci 2013; 14:100. [PMID: 24028087 PMCID: PMC3848627 DOI: 10.1186/1471-2202-14-100] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 09/10/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Aging is typically accompanied by memory decline and changes in hippocampal function. Among these changes is a decline in the activity of the dentate gyrus (DG) during behavior. Lasting memory, however, is thought to also require recapitulation of recent memory traces during subsequent rest - a phenomenon, termed memory trace reactivation, which is compromised in hippocampal CA1 with progressive age. This process has yet to be assessed in the aged DG, despite its prominent role in age-related memory impairment. Using zif268 transcription to measure granule cell recruitment, DG activity in adult and aged animals was assessed both during spatial exploration and as animals remained at rest in the home cage in order to detect potential memory-related replay. RESULTS Consistent with the observation of memory trace reactivation in DG, the probability that an individual granule cell transcribes zif268 during rest in the animal's home cage is increased by recent experience in a novel environment. Surprisingly, a comparable increase was observed in the probability of granule cells in the aged DG expressing zif268 during rest. Moreover, no significant age-related difference was observed in the number of granule cells expressing zif268 during rest. Thus, the number and pattern of granule cell expression of zif268 during rest is preserved in aged animals, despite a significant decline in exploration-related zif268 expression. CONCLUSIONS These data lead to the hypothesis that the input the aged DG receives from backprojections from CA3 (the region widely hypothesized to mediate reactivation) remains functionally intact despite loss of innervation from the perforant path.
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Affiliation(s)
- Ali Gheidi
- Department of Psychology, Wilfrid Laurier University, 75 University Ave W, Waterloo, ON N2L 3C5, Canada
| | - Erin Azzopardi
- Department of Psychology, Wilfrid Laurier University, 75 University Ave W, Waterloo, ON N2L 3C5, Canada
| | - Allison A Adams
- Department of Psychology, Wilfrid Laurier University, 75 University Ave W, Waterloo, ON N2L 3C5, Canada
| | - Diano F Marrone
- Department of Psychology, Wilfrid Laurier University, 75 University Ave W, Waterloo, ON N2L 3C5, Canada
- McKnight Brain Institute, University of Arizona, Tucson, AZ 85724, USA
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20
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Epp JR, Chow C, Galea LAM. Hippocampus-dependent learning influences hippocampal neurogenesis. Front Neurosci 2013; 7:57. [PMID: 23596385 PMCID: PMC3627134 DOI: 10.3389/fnins.2013.00057] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Accepted: 03/28/2013] [Indexed: 12/26/2022] Open
Abstract
The structure of the mammalian hippocampus continues to be modified throughout life by continuous addition of neurons in the dentate gyrus. Although the existence of adult neurogenesis is now widely accepted the function that adult generated granule cells play is a topic of intense debate. Many studies have argued that adult generated neurons, due to unique physiological characteristics, play a unique role in hippocampus-dependent learning and memory. However, it is not currently clear whether this is the case or what specific capability adult generated neurons may confer that developmentally generated neurons do not. These questions have been addressed in numerous ways, from examining the effects of increasing or decreasing neurogenesis to computational modeling. One particular area of research has examined the effects of hippocampus dependent learning on proliferation, survival, integration and activation of immature neurons in response to memory retrieval. Within this subfield there remains a range of data showing that hippocampus dependent learning may increase, decrease or alternatively may not alter these components of neurogenesis in the hippocampus. Determining how and when hippocampus-dependent learning alters adult neurogenesis will help to further clarify the role of adult generated neurons. There are many variables (such as age of immature neurons, species, strain, sex, stress, task difficulty, and type of learning) as well as numerous methodological differences (such as marker type, quantification techniques, apparatus size etc.) that could all be crucial for a clear understanding of the interaction between learning and neurogenesis. Here, we review these findings and discuss the different conditions under which hippocampus-dependent learning impacts adult neurogenesis in the dentate gyrus.
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Affiliation(s)
- Jonathan R. Epp
- *Correspondence: Jonathan R. Epp, Neurosciences and Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada. e-mail: ;
| | | | - Liisa A. M. Galea
- Department of Psychology, Program in Neuroscience, Brain Research Centre, University of British ColumbiaVancouver, BC, Canada
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21
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Mendez-David I, Hen R, Gardier AM, David DJ. Adult hippocampal neurogenesis: an actor in the antidepressant-like action. ANNALES PHARMACEUTIQUES FRANÇAISES 2013; 71:143-9. [PMID: 23622692 DOI: 10.1016/j.pharma.2013.02.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Revised: 02/23/2013] [Accepted: 02/28/2013] [Indexed: 01/20/2023]
Abstract
Depression and anxiety are psychiatric illnesses that are major burdens in society and affect as much as 7% of the world's population. The heterogeneous nature of depression suggests an involvement of multiple distinct brain regions including amygdala, prefrontal cortex and the hippocampus, which may be responsible for the diversity of the symptoms. Besides its critical role in learning and memory, the hippocampus is one of only two areas in mammalian brain where adult neurogenesis occurs. Of the current leading hypotheses of the pathophysiology and treatment of depression, the neurogenesis hypothesis of depression deserves particular attention because changes in neurogenesis are only seen after chronic, but not acute, antidepressant treatment. This review revisits the role of adult hippocampal neurogenesis in the pathophysiology of mood disorders, especially anxiety/depression, and also in the antidepressant-like responses, especially in stressed rodents.
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Affiliation(s)
- I Mendez-David
- EA 3544 pharmacologie des troubles anxio-dépressifs et neurogenèse, faculté de pharmacie, université Paris-Sud, Tour D1, 2(e) étage, 5, rue J.-B.-Clement, 92296 Chatenay-Malabry cedex, France
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22
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Snyder JS, Ferrante SC, Cameron HA. Late maturation of adult-born neurons in the temporal dentate gyrus. PLoS One 2012; 7:e48757. [PMID: 23144957 PMCID: PMC3492442 DOI: 10.1371/journal.pone.0048757] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 10/02/2012] [Indexed: 12/28/2022] Open
Abstract
Hippocampal function varies along its septotemporal axis, with the septal (dorsal) pole more frequently involved in spatial learning and memory and the temporal (ventral) pole playing a greater role in emotional behaviors. One feature that varies across these subregions is adult neurogenesis. New neurons are more numerous in the septal hippocampus but are more active in the temporal hippocampus during water maze training. However, many other aspects of adult neurogenesis remain unexplored in the context of septal versus temporal subregions. In addition, the dentate gyrus contains another functionally important anatomical division along the transverse axis, with the suprapyramidal blade showing greater experience-related activity than the infrapyramidal blade. Here we ask whether new neurons differ in their rates of survival and maturation along the septotemporal and transverse axes. We found that neurogenesis is initially higher in the infrapyramidal than suprapyramidal blade, but these cells are less likely to survive, resulting in similar densities of neurons in the two blades by four weeks. Across the septotemporal axis, neurogenesis was higher in septal than temporal pole, while the survival rate of new neurons did not differ. Maturation was assessed by immunostaining for the neuronal marker, NeuN, which increases in expression level with maturation, and for the immediate-early gene, Arc, which suggests a neuron is capable of undergoing activity-dependent synaptic plasticity. Maturation occurred approximately 1-2 weeks earlier in the septal pole than in the temporal pole. This suggests that septal neurons may contribute to function sooner; however, the prolonged maturation of new temporal neurons may endow them with a longer window of plasticity during which their functions could be distinct from those of the mature granule cell population. These data point to subregional differences in new neuron maturation and suggest that changes in neurogenesis could alter different hippocampus-dependent behaviors with different time courses.
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Affiliation(s)
- Jason S Snyder
- Unit on Neuroplasticity, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States of America.
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23
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Goodman T, Crandall JE, Nanescu SE, Quadro L, Shearer K, Ross A, McCaffery P. Patterning of retinoic acid signaling and cell proliferation in the hippocampus. Hippocampus 2012; 22:2171-83. [PMID: 22689466 PMCID: PMC3505796 DOI: 10.1002/hipo.22037] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2012] [Indexed: 12/23/2022]
Abstract
The nuclear receptor ligand retinoic acid (RA) has been identified as an endogenous regulatory factor in the hippocampus, acting on pyramidal neurons and granule neuron progenitors, but almost nothing is known about the distribution of RA itself in the hippocampus. This study describes the source of RA for the rodent hippocampus in the meninges via the key RA synthetic enzyme retinaldehyde dehydrogenase 2 (RALDH2). Diffusion of RA from the meninges potentially creates a gradient of RA across the infrapyramidal and suprapyramidal blades of the dentate gyrus, enhanced by the expression of the RA catabolic enzyme Cyp26B1 between the blades, and an infrapyramidal and suprapyramidal blade difference is evident in RA-regulated transcription. This asymmetry may contribute to some of the physiological and molecular differences between the blades, including a disparity in the rates of cell proliferation in the subgranular zone of the two blades through RA inhibition of cell proliferation. Such differences can be altered by either the application of excess RA, its effect dependent on the relative position along the septotemporal axis, or change in RA signaling through mutation of retinol binding protein, while the capacity of RA to inhibit proliferation of cells in the dentate gyrus is demonstrated using in vitro slice culture. Use of synthetic and catabolic enzymes in the hippocampus to create differing zones of RA concentration parallels the mechanisms used in the developing brain to generate patterns of RA-regulated transcription. © 2012 Wiley Periodicals, Inc.
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Affiliation(s)
- Timothy Goodman
- Institute of Medical Sciences, University of Aberdeen, Aberdeenshire, United Kingdom
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24
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Surget A, Tanti A, Leonardo ED, Laugeray A, Rainer Q, Touma C, Palme R, Griebel G, Ibarguen-Vargas Y, Hen R, Belzung C. Antidepressants recruit new neurons to improve stress response regulation. Mol Psychiatry 2011; 16:1177-88. [PMID: 21537331 PMCID: PMC3223314 DOI: 10.1038/mp.2011.48] [Citation(s) in RCA: 338] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Recent research suggests an involvement of hippocampal neurogenesis in behavioral effects of antidepressants. However, the precise mechanisms through which newborn granule neurons might influence the antidepressant response remain elusive. Here, we demonstrate that unpredictable chronic mild stress in mice not only reduces hippocampal neurogenesis, but also dampens the relationship between hippocampus and the main stress hormone system, the hypothalamo-pituitary-adrenal (HPA) axis. Moreover, this relationship is restored by treatment with the antidepressant fluoxetine, in a neurogenesis-dependent manner. Specifically, chronic stress severely impairs HPA axis activity, the ability of hippocampus to modulate downstream brain areas involved in the stress response, the sensitivity of the hippocampal granule cell network to novelty/glucocorticoid effects and the hippocampus-dependent negative feedback of the HPA axis. Remarkably, we revealed that, although ablation of hippocampal neurogenesis alone does not impair HPA axis activity, the ability of fluoxetine to restore hippocampal regulation of the HPA axis under chronic stress conditions, occurs only in the presence of an intact neurogenic niche. These findings provide a mechanistic framework for understanding how adult-generated new neurons influence the response to antidepressants. We suggest that newly generated neurons may facilitate stress integration and that, during chronic stress or depression, enhancing neurogenesis enables a dysfunctional hippocampus to restore the central control on stress response systems, then allowing recovery.
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Affiliation(s)
- A Surget
- U930 Imaging and Brain, Inserm, Tours, France.
| | - A Tanti
- U930 Imaging and Brain, Inserm, Tours, France,Université François Rabelais, Tours, France
| | - E D Leonardo
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY, USA
| | - A Laugeray
- U930 Imaging and Brain, Inserm, Tours, France,Université François Rabelais, Tours, France
| | - Q Rainer
- U930 Imaging and Brain, Inserm, Tours, France,Université François Rabelais, Tours, France
| | - C Touma
- Research Group of Psychoneuroendocrinology, Max Planck Institute of Psychiatry, Munich, Germany
| | - R Palme
- Department of Biomedical Sciences/Biochemistry, University of Veterinary Medicine, Vienna, Austria
| | - G Griebel
- Exploratory Unit, Sanofi-Aventis, Chilly-Mazarin, France
| | - Y Ibarguen-Vargas
- U930 Imaging and Brain, Inserm, Tours, France,Université François Rabelais, Tours, France,Kavli Institute for Systems Neuroscience & Centre for the Biology of Memory, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - R Hen
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY, USA
| | - C Belzung
- U930 Imaging and Brain, Inserm, Tours, France,Université François Rabelais, Tours, France
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25
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Masiulis I, Yun S, Eisch AJ. The interesting interplay between interneurons and adult hippocampal neurogenesis. Mol Neurobiol 2011; 44:287-302. [PMID: 21956642 DOI: 10.1007/s12035-011-8207-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 09/07/2011] [Indexed: 10/17/2022]
Abstract
Adult neurogenesis is a unique form of plasticity found in the hippocampus, a brain region key to learning and memory formation. While many external stimuli are known to modulate the generation of new neurons in the hippocampus, little is known about the local circuitry mechanisms that regulate the process of adult neurogenesis. The neurogenic niche in the hippocampus is highly complex and consists of a heterogeneous population of cells including interneurons. Because interneurons are already highly integrated into the hippocampal circuitry, they are in a prime position to influence the proliferation, survival, and maturation of adult-generated cells in the dentate gyrus. Here, we review the current state of our understanding on the interplay between interneurons and adult hippocampal neurogenesis. We focus on activity- and signaling-dependent mechanisms, as well as research on human diseases that could provide better insight into how interneurons in general might add to our comprehension of the regulation and function of adult hippocampal neurogenesis.
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Affiliation(s)
- Irene Masiulis
- UT Southwestern Medical Center, Dallas, TX 75390-9070, USA.
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26
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Wojtowicz JM. Adult neurogenesis. From circuits to models. Behav Brain Res 2011; 227:490-6. [PMID: 21893104 DOI: 10.1016/j.bbr.2011.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Revised: 08/05/2011] [Accepted: 08/06/2011] [Indexed: 10/17/2022]
Abstract
Our understanding of the hippocampus as a memory-encoding device is greatly helped by our knowledge of neuronal circuits and their plasticity. The trisynaptic hippocampal circuit carrying afferent input from the entorhinal cortex, controlled by a network of inhibitory interneurons and supplemented by modulatory subcortical inputs forms a platform for multiple forms of synaptic plastic mechanisms. Long-term potentiation of synaptic transmission in its various forms is an outstanding example of hippocampal ability to adapt to past neuronal activity. Adult neurogenesis is a profound plastic mechanism incorporating structural and functional changes that were previously thought to be present only in developing neural systems. These powerful forms of plasticity can mask experimental results by compensating for experimentally induced changes in the neurons or circuits. Circuit lesions have been one of the most common techniques in scientific investigations of the hippocampus. Although the effects of such lesions can be quite revealing and ground-breaking, in many cases the results are masked by compensatory mechanisms producing misleading results. This review will highlight such mechanisms and argue that the experimental results, in spite of their shortcomings, can be better understood when viewed in light of our knowledge of the neuronal circuitry, and with guidance by conceptual and computational models. Studies demonstrating a role of neurogenesis in pattern separation and memory interference are a good example of fruitful interaction between modeling and experimental approaches.
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27
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The timing for neuronal maturation in the adult hippocampus is modulated by local network activity. J Neurosci 2011; 31:7715-28. [PMID: 21613484 DOI: 10.1523/jneurosci.1380-11.2011] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The adult hippocampus continuously generates new cohorts of immature neurons with increased excitability and plasticity. The window for the expression of those unique properties in each cohort is determined by the time required to acquire a mature neuronal phenotype. Here, we show that local network activity regulates the rate of maturation of adult-born neurons along the septotemporal axis of the hippocampus. Confocal microscopy and patch-clamp recordings were combined to assess marker expression, morphological development, and functional properties in retrovirally labeled neurons over time. The septal dentate gyrus displayed higher levels of basal network activity and faster rates of newborn neuron maturation than the temporal region. Voluntary exercise enhanced network activity only in the temporal region and, in turn, accelerated neuronal development. Finally, neurons developing within a highly active environment exhibited a delayed maturation when their intrinsic electrical activity was reduced by the cell-autonomous overexpression of Kir2.1, an inward-rectifying potassium channel. Our findings reveal a novel type of activity-dependent plasticity acting on the timing of neuronal maturation and functional integration of newly generated neurons along the longitudinal axis of the adult hippocampus.
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28
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Snyder JS, Cameron HA. Could adult hippocampal neurogenesis be relevant for human behavior? Behav Brain Res 2011; 227:384-90. [PMID: 21736900 DOI: 10.1016/j.bbr.2011.06.024] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 06/02/2011] [Accepted: 06/20/2011] [Indexed: 12/21/2022]
Abstract
Although the function of adult neurogenesis is still unclear, tools for directly studying the behavioral role of new hippocampal neurons now exist in rodents. Since similar studies are impossible to do in humans, it is important to assess whether the role of new neurons in rodents is likely to be similar to that in humans. One feature of adult neurogenesis that varies tremendously across species is the number of neurons that are generated, so a key question is whether there are enough neurons generated in humans to impact function. In this review we examine neuroanatomy and circuit function in the hippocampus to ask how many granule neurons are needed to impact hippocampal function and then discuss what is known about numbers of new neurons produced in adult rats and humans. We conclude that relatively small numbers of neurons could affect hippocampal circuits and that the magnitude of adult neurogenesis in adult rats and humans is probably larger than generally believed.
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Affiliation(s)
- Jason S Snyder
- Unit on Neuroplasticity, National Institute of Mental Health, National Institutes of Health, Building 35/3C911, MSC3718, Bethesda, MD 20892, USA.
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29
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Complementary activation of hippocampal-cortical subregions and immature neurons following chronic training in single and multiple context versions of the water maze. Behav Brain Res 2011; 227:330-9. [PMID: 21736899 DOI: 10.1016/j.bbr.2011.06.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 05/31/2011] [Accepted: 06/20/2011] [Indexed: 11/22/2022]
Abstract
Neurobiological studies of memory typically involve single learning sessions that last minutes or days. In natural settings, however, animals are constantly learning. Here we investigated how several weeks of spatial water maze training influences subsequent activation of neocortical and hippocampal subregions, including adult-born neurons. Mice were either trained in a single context or in a variant of the task in which the spatial cues and platform location changed every 3 days, requiring constant new learning. On the final day, half of the mice in each training group were tested in a novel context and the other half were tested in their previous, familiar context. Two hours later mice were perfused to measure subregion-specific expression of the immediate-early gene zif268, a marker of neuronal activation. None of the training paradigms affected the magnitude of adult neurogenesis. However, different neuronal populations were activated depending on prior training history, final context novelty, or a combination of these 2 factors. The anterior cingulate cortex was more activated by novel context exposure, regardless of the type of prior training. The suprapyramidal blade of the dentate gyrus and region CA3 showed greater activation in mice trained in multiple contexts, primarily after exposure to a familiar context. In immature granule neurons, multiple context training enhanced activation regardless of final context novelty. CA1 showed no significant changes in zif268 expression across any training condition. In naïve control mice, training on the final day increased zif268 expression in CA3, CA1 and the anterior cingulate cortex, but not the dentate gyrus, relative to mice that remained in their cages (transport controls). Unexpectedly, immature granule cells showed a decrease in zif268 expression in naïve learners relative to transport controls. These findings suggest novel and complementary roles for hippocampal, neocortical, and immature neuronal populations in learning and memory.
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30
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Induction of c-Fos, Zif268, and Arc from acute bouts of voluntary wheel running in new and pre-existing adult mouse hippocampal granule neurons. Neuroscience 2011; 184:16-27. [PMID: 21497182 DOI: 10.1016/j.neuroscience.2011.03.072] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 03/30/2011] [Accepted: 03/31/2011] [Indexed: 12/20/2022]
Abstract
The functional significance of newly formed granule neurons in the adult mammalian hippocampus remains a mystery. Recently, it was demonstrated that wheel running increases new neuron survival and c-Fos expression in new and pre-existing granule cells in an activity-dependent manner. It is currently unknown whether other immediate early genes (IEGs) become expressed in granule neurons from running. Further, it is unknown whether locomotor activity in home cages without wheels can influence neurogenesis and IEG expression similar to running. The purpose of this study was three-fold: (1) to determine if Arc and Zif268 expression are also induced from wheel running in both pre-existing and newly formed neurons (2) to determine if neurogenesis and IEG induction is related to horizontal distance traveled in home cages without wheels, and (3) to determine whether IEG induction is related to acute bouts of running or chronic effects. Adult C57BL/6J female mice were placed in cages with or without running wheels for 31 days. The first 10 days, mice received daily injections of 5-Bromo-2'-deoxyuridine (BrdU) to label dividing cells. On day 1, running and non-running animals were euthanized either 2 h after peak activity, or during a period of relative inactivity. Immunohistochemistry was performed on hippocampal sections with antibodies against BrdU, mature neuron marker NeuN, c-Fos, Arc, and Zif268. Results demonstrate that Arc, Zif268, and c-Fos are induced from wheel running but not movement in cages without wheels. All IEGs were expressed in new neurons from running. Further, IEGs were induced acutely by running, as increased expression did not continue into the light cycle, a period of relative inactivity. The results suggest that robust movements, like running, are necessary to stimulate IEG expression and neurogenesis. Moreover, results suggest new neurons from running may be processing information about running behavior itself.
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31
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Burger C. Region-specific genetic alterations in the aging hippocampus: implications for cognitive aging. Front Aging Neurosci 2010; 2:140. [PMID: 21048902 PMCID: PMC2967426 DOI: 10.3389/fnagi.2010.00140] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 08/17/2010] [Indexed: 01/31/2023] Open
Abstract
Aging is associated with cognitive decline in both humans and animals and of all brain regions, the hippocampus appears to be particularly vulnerable to senescence. Age-related spatial learning deficits result from alterations in hippocampal connectivity and plasticity. These changes are differentially expressed in each of the hippocampal fields known as cornu ammonis 1 (CA1), cornu ammonis 3 (CA3), and the dentate gyrus. Each sub-region displays varying degrees of susceptibility to aging. For example, the CA1 region is particularly susceptible in Alzheimer's disease while the CA3 region shows vulnerability to stress and glucocorticoids. Further, in animals, aging is the main factor associated with the decline in adult neurogenesis in the dentate gyrus. This review discusses the relationship between region-specific hippocampal connectivity, morphology, and gene expression alterations and the cognitive deficits associated with senescence. In particular, data are reviewed that illustrate how the molecular changes observed in the CA1, CA3, and dentate regions are associated with age-related learning deficits. This topic is of importance because increased understanding of how gene expression patterns reflect individual differences in cognitive performance is critical to the process of identifying new and clinically useful biomarkers for cognitive aging.
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Affiliation(s)
- Corinna Burger
- Department of Neurology, Medical Sciences Center, University of WisconsinMadison, USA
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32
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Tan YF, Preston E, Wojtowicz JM. Enhanced post-ischemic neurogenesis in aging rats. Front Neurosci 2010; 4. [PMID: 20877422 PMCID: PMC2944628 DOI: 10.3389/fnins.2010.00163] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 08/16/2010] [Indexed: 01/11/2023] Open
Abstract
Hippocampal neurogenesis persists in adult mammals, but its rate declines dramatically with age. Evidence indicates that experimentally-reduced levels of neurogenesis (e.g., by irradiation) in young rats has profound influence on cognition as determined by learning and memory tests. In the present study we asked whether in middle-aged, 10- to 13-months-old rats, cell production can be restored toward the level present in young rats. To manipulate neurogenesis we induced bilateral carotid occlusion with hypotension. This procedure is known to increase neurogenesis in young rats, presumably in a compensatory manner, but until now, has never been tested in aging rats. Cell production was measured at 10, 35, and 90 days after ischemia. The results indicate that neuronal proliferation and differentiation can be transiently restored in middle-aged rats. Furthermore, the effects are more pronounced in the dorsal as opposed to ventral hippocampus thus restoring the dorso-ventral gradient seen in younger rats. Our results support previous findings showing that some of the essential features of the age-dependent decline in neurogenesis are reversible. Thus, it may be possible to manipulate neurogenesis and improve learning and memory in old age.
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Affiliation(s)
- Yao-Fang Tan
- Department of Physiology, University of Toronto Toronto, ON, Canada
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