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Kim B, Yang M, Lee J, Kim JS, Hyun SH, Moon C. Upregulation of γ-synuclein in the prefrontal cortex and hippocampus following dopamine depletion: A study using the striatal 6-hydroxydopamine hemiparkinsonian rat model. Neurosci Lett 2024; 839:137936. [PMID: 39151573 DOI: 10.1016/j.neulet.2024.137936] [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: 04/26/2024] [Revised: 07/16/2024] [Accepted: 08/12/2024] [Indexed: 08/19/2024]
Abstract
Synucleins, including α-synuclein (α-syn), β-syn, and γ-syn, have been implicated in various synucleinopathies, notably Parkinson's disease (PD), which has generated increased interest in understanding their roles. Although α-syn and β-syn have contrasting neuropathological consequences, the precise role of γ-syn remains unclear. This study validated non-motor symptoms, specifically anxiety-like behavior, along with the degradation of dopaminergic (DAergic) neurons in the nigrostriatal system and DAergic neurites in the prefrontal cortex and hippocampus of rats infused with striatal 6-hydroxydopamine (6-OHDA). Our study further investigated the alterations in γ-syn expression levels in the prefrontal cortices and hippocampi of these 6-OHDA-treated rats, aiming to establish foundational insights into the neuropathophysiology of DA depletion, a central feature of PD. Our findings revealed a significant increase in the expression of γ-syn mRNA and protein in these brain regions, in contrast to unaltered α- and β-syn expression levels. This suggests a distinct role of γ-syn within the neurobiological milieu under conditions of DA deficiency. Overall, our data shed light on the neurobiological changes observed in the hemiparkinsonian rat model induced with 6-OHDA, underscoring the potential significance of γ-syn in PD pathology.
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Affiliation(s)
- Bohye Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Miyoung Yang
- Department of Anatomy, Wonkwang University School of Medicine, Iksan, Republic of Korea
| | - Jeongmin Lee
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Joong-Sun Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Sang-Hwan Hyun
- Laboratory of Veterinary Embryology and Biotechnology (VETEMBIO), College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Republic of Korea.
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Sharma M, Pal P, Gupta SK, Potdar MB, Belgamwar AV. Microglial-mediated immune mechanisms in autoimmune uveitis: Elucidating pathogenic pathways and targeted therapeutics. J Neuroimmunol 2024; 395:578433. [PMID: 39168018 DOI: 10.1016/j.jneuroim.2024.578433] [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: 12/18/2023] [Revised: 07/26/2024] [Accepted: 08/13/2024] [Indexed: 08/23/2024]
Abstract
This review offers a comprehensive examination of the role of microglia in the pathogenesis of autoimmune uveitis, an inflammatory eye disease with significant potential for vision impairment. Central to our discussion is the dual nature of microglial cells, which act as both protectors and potential perpetrators in the immune surveillance of the retina. We explore the mechanisms of microglial activation, highlighting the key signaling pathways involved, such as NF-κB, JAK/STAT, MAPK, and PI3K/Akt. The review also delves into the genetic and environmental factors influencing microglial behavior, underscoring their complex interaction in disease manifestation. Advanced imaging techniques and emerging biomarkers for microglial activation, pivotal in diagnosing and monitoring the disease, are critically assessed. Additionally, we discuss current and novel therapeutic strategies targeting microglial activity, emphasizing the shift towards more precise and personalized interventions. This article aims to provide a nuanced understanding of microglial dynamics in autoimmune uveitis, offering insights into potential avenues for effective treatment and management.
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Affiliation(s)
- Monika Sharma
- Department of Pharmacy, Banasthali Vidyapith, Rajasthan, India
| | - Pankaj Pal
- Department of Pharmacy, Banasthali Vidyapith, Rajasthan, India; IIMT College of Pharmacy, IIMT Group of Colleges, Greater Noida, Uttar Pradesh, India.
| | - Sukesh Kumar Gupta
- KIET School of Pharmacy, KIET Group of Institutions, Ghaziabad, Uttar Pradesh, India; Department of Ophthalmology, Visual and Anatomical Sciences (OVAS), School of Medicine, Wayne State University, USA.
| | - Mrugendra B Potdar
- Department of Pharmaceutics, Shri Vile Parle Kelvani Mandal's Institute of Pharmacy, Dhule, Maharashtra, India
| | - Aarti V Belgamwar
- Department of Pharmaceutics, Shri Vile Parle Kelvani Mandal's Institute of Pharmacy, Dhule, Maharashtra, India
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HONG S, AHN M, MOON C, ORTIZ-LEAL I, SANCHEZ-QUINTEIRO P, KANG T, SHIN T. Histological evaluation of the alpaca (Vicugna pacos) vomeronasal organ. J Vet Med Sci 2024; 86:458-462. [PMID: 38508726 PMCID: PMC11144526 DOI: 10.1292/jvms.23-0430] [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: 10/16/2023] [Accepted: 03/05/2024] [Indexed: 03/22/2024] Open
Abstract
Little is known about the neuronal structure of the vomeronasal organ (VNO), a receptor organ responsible for pheromone perception, in the alpaca (Vicugna pacos). This study was performed to determine the localization of neuronal elements, including protein gene product 9.5 (PGP 9.5), a pan-neuronal marker, olfactory marker protein (OMP), a marker of mature olfactory receptor cells, and phospholipase C beta 2 (PLC-β2), a marker of solitary chemoreceptor cells (SCCs), in the VNO. OMP was identified in receptor cells of the vomeronasal sensory epithelium (VSE), while PGP 9.5 and PLC-β2 were localized in both the VSE and vomeronasal non-sensory epithelium. Collectively, these results suggested that the alpaca VNO possesses SCCs and olfactory receptor cells, which recognize both harmful substances and pheromones.
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Affiliation(s)
- Sungmoo HONG
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
| | - Meejung AHN
- Department of Animal Science, College of Life Science, Sangji University, Wonju, Republic of Korea
| | - Changjong MOON
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 Plus Project Team, Chonnam National University, Gwangju, Republic
of Korea
| | - Irene ORTIZ-LEAL
- Department of Anatomy, Animal Production and Clinical Veterinary Sciences, Faculty of Veterinary, University of Santiago de Compostela, Lugo, Spain
| | - Pablo SANCHEZ-QUINTEIRO
- Department of Anatomy, Animal Production and Clinical Veterinary Sciences, Faculty of Veterinary, University of Santiago de Compostela, Lugo, Spain
| | - Taeyoung KANG
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
| | - Taekyun SHIN
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
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Hong S, Kim J, Jung K, Ahn M, Moon C, Nomura Y, Matsuda H, Tanaka A, Jeong H, Shin T. Histopathological evaluation of the lungs in experimental autoimmune encephalomyelitis. J Vet Sci 2024; 25:e35. [PMID: 38834505 PMCID: PMC11156594 DOI: 10.4142/jvs.23302] [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: 12/01/2023] [Revised: 02/29/2024] [Accepted: 03/07/2024] [Indexed: 06/06/2024] Open
Abstract
IMPORTANCE Experimental autoimmune encephalomyelitis (EAE) is an animal model of multiple sclerosis characterized by inflammation within the central nervous system. However, inflammation in non-neuronal tissues, including the lungs, has not been fully evaluated. OBJECTIVE This study evaluated the inflammatory response in lungs of EAE mice by immunohistochemistry and histochemistry. METHODS Eight adult C57BL/6 mice were injected with myelin oligodendrocyte glycoprotein35-55 to induce the EAE. Lungs and spinal cords were sampled from the experimental mice at the time of sacrifice and used for the western blotting, histochemistry, and immunohistochemistry. RESULTS Histopathological examination revealed inflammatory lesions in the lungs of EAE mice, characterized by infiltration of myeloperoxidase (MPO)- and galectin-3-positive cells, as determined by immunohistochemistry. Increased numbers of collagen fibers in the lungs of EAE mice were confirmed by histopathological analysis. Western blotting revealed significantly elevated level of osteopontin (OPN), cluster of differentiation 44 (CD44), MPO and galectin-3 in the lungs of EAE mice compared with normal controls (p < 0.05). Immunohistochemical analysis revealed both OPN and CD44 in ionized calcium-binding adapter molecule 1-positive macrophages within the lungs of EAE mice. CONCLUSIONS AND RELEVANCE Taken together, these findings suggest that the increased OPN level in lungs of EAE mice led to inflammation; concurrent increases in proinflammatory factors (OPN and galectin-3) caused pulmonary impairment.
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Affiliation(s)
- Sungmoo Hong
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju 63243, Korea
| | - Jeongtae Kim
- Department of Anatomy, Kosin University College of Medicine, Busan 49267, Korea
| | - Kyungsook Jung
- Functional Biomaterials Research Center, Korea Research Institute of Bioscience and Biotechnology, Jeongeup 56212, Korea
| | - Meejung Ahn
- Department of Animal Science, College of Life Science, Sangji University, Wonju 26339, Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Korea
| | - Yoshihiro Nomura
- Scleroprotein and Leather Research Institute, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Hiroshi Matsuda
- Laboratory of Comparative Animal Medicine, Division of Animal Life Science, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Akane Tanaka
- Laboratory of Comparative Animal Medicine, Division of Animal Life Science, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Hyohoon Jeong
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju 63243, Korea.
| | - Taekyun Shin
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju 63243, Korea.
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Kim B, Hong S, Lee J, Kang S, Kim JS, Jung C, Shin T, Youn B, Moon C. Identifying candidate genes associated with hippocampal dysfunction in a hemiparkinsonian rat model by transcriptomic profiling. Anim Cells Syst (Seoul) 2024; 28:198-215. [PMID: 38693920 PMCID: PMC11062273 DOI: 10.1080/19768354.2024.2348671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 03/12/2024] [Indexed: 05/03/2024] Open
Abstract
Parkinson's disease (PD) often results in hippocampal dysfunction, which leads to cognitive and emotional challenges and synaptic irregularities. This study attempted to assess behavioral anomalies and identify differentially expressed genes (DEGs) within the hippocampus of a hemiparkinsonian rat model to potentially uncover novel genetic candidates linked to hippocampal dysfunction. Striatal 6-hydroxydopamine (6-OHDA) infusions were performed unilaterally in the brains of adult SD rats, while dopaminergic impairments were verified in rats with 6-OHDA-lesioned striata. RNA sequencing and gene expression analysis unveiled 1018 DEGs in the ipsilateral rat hippocampus following 6-OHDA infusion: 631 genes exhibited upregulation, while 387 genes were downregulated (with FDR-adjusted p-value < 0.05 and absolute fold-change > 1.5). Gene ontology analysis of DEGs indicated that alterations in the hippocampi of 6-OHDA-lesioned rats were primarily associated with synaptic signaling, axon development, behavior, postsynaptic membrane, synaptic membrane, neurotransmitter receptor activity, and peptide receptor activity. The Kyoto Encyclopedia of Genes and Genomes analysis of DEGs demonstrated significant enrichment of the neuroactive ligand-receptor interaction, calcium signaling pathway, cAMP signaling pathway, axon guidance, and notch signaling pathway in rat hippocampi that had been subjected to striatal 6-OHDA infusion. STRING analysis confirmed a notable upregulation of eight hub genes (Notch3, Gng4, Itga3, Grin2d, Hgf, Fgf11, Htr3a, and Col6a2), along with a significant downregulation of two hub genes (Itga11 and Plp1), as validated by reverse transcription-quantitative polymerase chain reaction. This study provides a comprehensive transcriptomic profile of the hippocampi in a hemiparkinsonian rat model, thereby offering insights into the signaling pathways underlying hippocampal dysfunction.
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Affiliation(s)
- Bohye Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
| | - Sungmoo Hong
- Department of Veterinary Anatomy, College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
| | - Jeongmin Lee
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
| | - Sohi Kang
- Department of Anatomy and Convergence Medical Science, College of Medicine, Institute of Health Sciences, Gyeongsang National University, Jinju, Republic of Korea
| | - Joong-Sun Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
| | - Chaeyong Jung
- Department of Anatomy, Chonnam National University Medical School, Gwangju, Korea
| | - Taekyun Shin
- Department of Veterinary Anatomy, College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
| | - BuHyun Youn
- Department of Biological Science, Pusan National University, Busan, Republic of Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
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Weerasinghe-Mudiyanselage PDE, Kang S, Kim JS, Kim SH, Wang H, Shin T, Moon C. Changes in structural plasticity of hippocampal neurons in an animal model of multiple sclerosis. Zool Res 2024; 45:398-414. [PMID: 38485508 PMCID: PMC11017077 DOI: 10.24272/j.issn.2095-8137.2023.309] [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: 12/04/2023] [Accepted: 12/25/2023] [Indexed: 03/19/2024] Open
Abstract
Structural plasticity is critical for the functional diversity of neurons in the brain. Experimental autoimmune encephalomyelitis (EAE) is the most commonly used model for multiple sclerosis (MS), successfully mimicking its key pathological features (inflammation, demyelination, axonal loss, and gliosis) and clinical symptoms (motor and non-motor dysfunctions). Recent studies have demonstrated the importance of synaptic plasticity in EAE pathogenesis. In the present study, we investigated the features of behavioral alteration and hippocampal structural plasticity in EAE-affected mice in the early phase (11 days post-immunization, DPI) and chronic phase (28 DPI). EAE-affected mice exhibited hippocampus-related behavioral dysfunction in the open field test during both early and chronic phases. Dendritic complexity was largely affected in the cornu ammonis 1 (CA1) and CA3 apical and dentate gyrus (DG) subregions of the hippocampus during the chronic phase, while this effect was only noted in the CA1 apical subregion in the early phase. Moreover, dendritic spine density was reduced in the hippocampal CA1 and CA3 apical/basal and DG subregions in the early phase of EAE, but only reduced in the DG subregion during the chronic phase. Furthermore, mRNA levels of proinflammatory cytokines ( Il1β, Tnfα, and Ifnγ) and glial cell markers ( Gfap and Cd68) were significantly increased, whereas the expression of activity-regulated cytoskeleton-associated protein (ARC) was reduced during the chronic phase. Similarly, exposure to the aforementioned cytokines in primary cultures of hippocampal neurons reduced dendritic complexity and ARC expression. Primary cultures of hippocampal neurons also showed significantly reduced extracellular signal-regulated kinase (ERK) phosphorylation upon treatment with proinflammatory cytokines. Collectively, these results suggest that autoimmune neuroinflammation alters structural plasticity in the hippocampus, possibly through the ERK-ARC pathway, indicating that this alteration may be associated with hippocampal dysfunctions in EAE.
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Affiliation(s)
- Poornima D E Weerasinghe-Mudiyanselage
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Sohi Kang
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Republic of Korea
- Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, Republic of Korea
| | - Joong-Sun Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Sung-Ho Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Hongbing Wang
- Department of Physiology and Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
| | - Taekyun Shin
- Department of Veterinary Anatomy, College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju 63243, Republic of Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju 61186, Republic of Korea. E-mail:
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Lee SK, Kim SH, Ahnn J. "A broken heart" becomes sleepless, literally. Mol Cells 2024; 47:100009. [PMID: 38211721 PMCID: PMC11004403 DOI: 10.1016/j.mocell.2024.100009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/02/2024] [Indexed: 01/13/2024] Open
Affiliation(s)
- Sun-Kyung Lee
- Department of Life Sciences, Research Institute for Natural Sciences, Research Institute for Convergence of Basic Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea.
| | - Seung Hyun Kim
- Department of Life Sciences, Research Institute for Natural Sciences, Research Institute for Convergence of Basic Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea
| | - Joohong Ahnn
- Department of Life Sciences, Research Institute for Natural Sciences, Research Institute for Convergence of Basic Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea.
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Hong S, Jung K, Ahn M, Kim J, Moon C, Shin T. Eugenol ameliorates uveitis in mice with experimental autoimmune encephalomyelitis through the suppression of key inflammatory genes. Anim Cells Syst (Seoul) 2024; 28:37-44. [PMID: 38249123 PMCID: PMC10798281 DOI: 10.1080/19768354.2024.2304557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 01/08/2024] [Indexed: 01/23/2024] Open
Abstract
Visual impairment associated with uveitis is among the potential complications in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Bioinformatics analyses have shown that some hub genes are closely associated with the molecular mechanisms underlying uveitis in EAE. This study evaluated whether 4-allyl-2-methoxyphenol (eugenol) can mitigate the pathogenesis of uveitis in EAE through the interruption of key uveitogenic gene expression. Myelin oligodendrocyte glycoprotein35-55 (MOG) peptide-immunized C57BL/6 mice were injected intraperitoneally with eugenol. The eyeballs and spinal cords of EAE mice with or without eugenol treatment were collected simultaneously and immunohistochemical and molecular biological analyses were conducted. Eugenol treatment significantly ameliorated hindlimb paralysis. Ionized calcium-binding adapter molecule 1 (Iba-1) immunohistochemistry showed that the inflammatory response was significantly reduced in the uvea of eugenol-treated EAE mice compared with vehicle-treated controls. Eugenol also significantly reduced the expression of key uveitogenic genes including C1qb and Tyrobp. The suppressive effect of eugenol on inflammation was also observed in the spinal cord, as determined by the suppression of Iba-1-positive microglial cells. Together, these results suggest that the ameliorative effect of eugenol against EAE uveitis is associated with the suppression of key proinflammatory genes, which may represent targets for the treatment of uveitis.
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Affiliation(s)
- Sungmoo Hong
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
| | - Kyungsook Jung
- Functional Biomaterials Research Center, Korea Research Institute of Bioscience and Biotechnology, Jeongeup-si, Republic of Korea
| | - Meejung Ahn
- Department of Animal Science, College of Life Science, Sangji University, Wonju, Republic of Korea
| | - Jeongtae Kim
- Department of Anatomy, Kosin University College of Medicine, Busan, Republic of Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 Plus Project Team, Chonnam National University, Gwangju, Republic of Korea
| | - Taekyun Shin
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
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Kim B, Kim JS, Youn B, Moon C. Dopamine depletion alters neuroplasticity-related signaling in the rat hippocampus. Anim Cells Syst (Seoul) 2023; 27:436-446. [PMID: 38125760 PMCID: PMC10732217 DOI: 10.1080/19768354.2023.2294308] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 12/08/2023] [Indexed: 12/23/2023] Open
Abstract
Dopamine (DA) plays a significant role in regulating hippocampal function, particularly in modulating synaptic plasticity. Despite this, a comprehensive understanding of the molecular mechanisms involved in neuroplasticity-related signaling influenced by DA remains incomplete. This study aimed to elucidate the changes in the expression of key molecules related to hippocampal neuroplasticity following DA depletion in rats. To induce DA depletion, unilateral striatal infusions of 6-hydroxydopamine (6-OHDA) were administered to adult Sprague-Dawley rats. The subsequent loss of nigrostriatal DAergic signaling in these 6-OHDA-lesioned rats was confirmed using an apomorphine-induced rotation test at 4 weeks post-infusion and by assessing the expression levels of tyrosine hydroxylase (TH) through immunohistochemistry and western blotting at 7 weeks post-infusion. A decrease in DAergic signaling, evidenced by reduced TH-positive immunoreactivity, was also noted in the ipsilateral hippocampus of the lesioned rats. Interestingly, 6-OHDA infusion led to increased phosphorylation of pivotal hippocampal plasticity-related proteins, including extracellular signal-regulated kinase (ERK), protein kinase B (Akt), glycogen synthase kinase 3β (GSK3β), and cAMP response element-binding protein (CREB), in the ipsilateral hippocampus 7 weeks following the infusion. To extend these findings, in vitro experiments were conducted on primary hippocampal neurons exposed to DA and/or the active D1/D2 DA receptor antagonist, flupentixol (Flux). DA inhibited the constitutive phosphorylation of ERK, Akt, GSK3, and CREB, while Flux restored these phosphorylation levels. Taken together, these findings indicate that DA depletion triggers an increase in plasticity-related signaling in the hippocampus, suggesting a possible compensatory mechanism that promotes activity-independent neuroplasticity following DA depletion.
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Affiliation(s)
- Bohye Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
| | - Joong-Sun Kim
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
| | - BuHyun Youn
- Department of Biological Science, Pusan National University, Busan, Republic of Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National University, Gwangju, Republic of Korea
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