1
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Vitet H, Bruyère J, Xu H, Séris C, Brocard J, Abada YS, Delatour B, Scaramuzzino C, Venance L, Saudou F. Huntingtin recruits KIF1A to transport synaptic vesicle precursors along the mouse axon to support synaptic transmission and motor skill learning. eLife 2023; 12:e81011. [PMID: 37431882 PMCID: PMC10365837 DOI: 10.7554/elife.81011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 07/06/2023] [Indexed: 07/12/2023] Open
Abstract
Neurotransmitters are released at synapses by synaptic vesicles (SVs), which originate from SV precursors (SVPs) that have traveled along the axon. Because each synapse maintains a pool of SVs, only a small fraction of which are released, it has been thought that axonal transport of SVPs does not affect synaptic function. Here, studying the corticostriatal network both in microfluidic devices and in mice, we find that phosphorylation of the Huntingtin protein (HTT) increases axonal transport of SVPs and synaptic glutamate release by recruiting the kinesin motor KIF1A. In mice, constitutive HTT phosphorylation causes SV over-accumulation at synapses, increases the probability of SV release, and impairs motor skill learning on the rotating rod. Silencing KIF1A in these mice restored SV transport and motor skill learning to wild-type levels. Axonal SVP transport within the corticostriatal network thus influences synaptic plasticity and motor skill learning.
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Affiliation(s)
- Hélène Vitet
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Julie Bruyère
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Hao Xu
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSLParisFrance
| | - Claire Séris
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Jacques Brocard
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Yah-Sé Abada
- Sorbonne Université, Institut du Cerveau, Paris Brain Institute, ICM, Inserm U1127, CNRS UMR7225ParisFrance
| | - Benoît Delatour
- Sorbonne Université, Institut du Cerveau, Paris Brain Institute, ICM, Inserm U1127, CNRS UMR7225ParisFrance
| | - Chiara Scaramuzzino
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Laurent Venance
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSLParisFrance
| | - Frédéric Saudou
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
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2
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VanderZwaag J, Halvorson T, Dolhan K, Šimončičová E, Ben-Azu B, Tremblay MÈ. The Missing Piece? A Case for Microglia's Prominent Role in the Therapeutic Action of Anesthetics, Ketamine, and Psychedelics. Neurochem Res 2023; 48:1129-1166. [PMID: 36327017 DOI: 10.1007/s11064-022-03772-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 08/25/2022] [Accepted: 09/27/2022] [Indexed: 11/06/2022]
Abstract
There is much excitement surrounding recent research of promising, mechanistically novel psychotherapeutics - psychedelic, anesthetic, and dissociative agents - as they have demonstrated surprising efficacy in treating central nervous system (CNS) disorders, such as mood disorders and addiction. However, the mechanisms by which these drugs provide such profound psychological benefits are still to be fully elucidated. Microglia, the CNS's resident innate immune cells, are emerging as a cellular target for psychiatric disorders because of their critical role in regulating neuroplasticity and the inflammatory environment of the brain. The following paper is a review of recent literature surrounding these neuropharmacological therapies and their demonstrated or hypothesized interactions with microglia. Through investigating the mechanism of action of psychedelics, such as psilocybin and lysergic acid diethylamide, ketamine, and propofol, we demonstrate a largely under-investigated role for microglia in much of the emerging research surrounding these pharmacological agents. Among others, we detail sigma-1 receptors, serotonergic and γ-aminobutyric acid signalling, and tryptophan metabolism as pathways through which these agents modulate microglial phagocytic activity and inflammatory mediator release, inducing their therapeutic effects. The current review includes a discussion on future directions in the field of microglial pharmacology and covers bidirectional implications of microglia and these novel pharmacological agents in aging and age-related disease, glial cell heterogeneity, and state-of-the-art methodologies in microglial research.
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Affiliation(s)
- Jared VanderZwaag
- Neuroscience Graduate Program, University of Victoria, Victoria, BC, Canada
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Torin Halvorson
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- BC Children's Hospital Research Institute, Vancouver, BC, Canada
| | - Kira Dolhan
- Department of Psychology, University of Victoria, Vancouver, BC, Canada
- Department of Biology, University of Victoria, Vancouver, BC, Canada
| | - Eva Šimončičová
- Neuroscience Graduate Program, University of Victoria, Victoria, BC, Canada
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Benneth Ben-Azu
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Department of Pharmacology, Faculty of Basic Medical Sciences, College of Health Sciences, Delta State University, Abraka, Delta State, Nigeria
| | - Marie-Ève Tremblay
- Neuroscience Graduate Program, University of Victoria, Victoria, BC, Canada.
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada.
- Département de médecine moléculaire, Université Laval, Québec City, QC, Canada.
- Axe Neurosciences, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada.
- Neurology and Neurosurgery Department, McGill University, Montreal, QC, Canada.
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
- Centre for Advanced Materials and Related Technology (CAMTEC), University of Victoria, Victoria, BC, Canada.
- Institute for Aging and Lifelong Health, University of Victoria, Victoria, BC, Canada.
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3
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Zulkifli NA, Hassan Z, Mustafa MZ, Azman WNW, Hadie SNH, Ghani N, Mat Zin AA. The potential neuroprotective effects of stingless bee honey. Front Aging Neurosci 2023; 14:1048028. [PMID: 36846103 PMCID: PMC9945235 DOI: 10.3389/fnagi.2022.1048028] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 12/29/2022] [Indexed: 02/11/2023] Open
Abstract
Tropical Meliponini bees produce stingless bee honey (SBH). Studies have shown beneficial properties, including antibacterial, bacteriostatic, anti-inflammatory, neurotherapeutic, neuroprotective, wound, and sunburn healing capabilities. High phenolic acid and flavonoid concentrations offer SBH its benefits. SBH can include flavonoids, phenolic acids, ascorbic acid, tocopherol, organic acids, amino acids, and protein, depending on its botanical and geographic origins. Ursolic acid, p-coumaric acid, and gallic acid may diminish apoptotic signals in neuronal cells, such as nuclear morphological alterations and DNA fragmentation. Antioxidant activity minimizes reactive oxygen species (ROS) formation and lowers oxidative stress, inhibiting inflammation by decreasing enzymes generated during inflammation. Flavonoids in honey reduce neuroinflammation by decreasing proinflammatory cytokine and free radical production. Phytochemical components in honey, such as luteolin and phenylalanine, may aid neurological problems. A dietary amino acid, phenylalanine, may improve memory by functioning on brain-derived neurotrophic factor (BDNF) pathways. Neurotrophin BDNF binds to its major receptor, TrkB, and stimulates downstream signaling cascades, which are crucial for neurogenesis and synaptic plasticity. Through BDNF, SBH can stimulate synaptic plasticity and synaptogenesis, promoting learning and memory. Moreover, BDNF contributes to the adult brain's lasting structural and functional changes during limbic epileptogenesis by acting through the cognate receptor tyrosine receptor kinase B (TrkB). Given the higher antioxidants activity of SBH than the Apis sp. honey, it may be more therapeutically helpful. There is minimal research on SBH's neuroprotective effects, and the related pathways contribute to it is unclear. More research is needed to elucidate the underlying molecular process of SBH on BDNF/TrkB pathways in producing neuroprotective effects.
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Affiliation(s)
- Nurdarina Ausi Zulkifli
- Department of Pathology, School of Medical Sciences Universiti Sains Malaysia and Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
| | - Zurina Hassan
- Centre for Drug Research, Universiti Sains Malaysia, Penang, Malaysia
| | - Mohd Zulkifli Mustafa
- Department of Neuroscience, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
| | - Wan Norlina Wan Azman
- Department of Chemical Pathology, School of Medical Sciences, Universiti Sains Malaysia and Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
| | - Siti Nurma Hanim Hadie
- Department of Anatomy, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
| | - Nurhafizah Ghani
- Basic and Medical Sciences Unit, School of Dental Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
| | - Anani Aila Mat Zin
- Department of Pathology, School of Medical Sciences Universiti Sains Malaysia and Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia
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4
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Sharma V, Singh TG, Kaur A, Mannan A, Dhiman S. Brain-Derived Neurotrophic Factor: A Novel Dynamically Regulated Therapeutic Modulator in Neurological Disorders. Neurochem Res 2023; 48:317-339. [PMID: 36308619 DOI: 10.1007/s11064-022-03755-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 09/02/2022] [Accepted: 09/03/2022] [Indexed: 02/04/2023]
Abstract
The growth factor brain-derived neurotrophic factor (BDNF), and its receptor tropomyosin-related kinase receptor type B (TrkB) play an active role in numerous areas of the adult brain, where they regulate the neuronal activity, function, and survival. Upregulation and downregulation of BDNF expression are critical for the physiology of neuronal circuits and functioning in the brain. Loss of BDNF function has been reported in the brains of patients with neurodegenerative or psychiatric disorders. This article reviews the BDNF gene structure, transport, secretion, expression and functions in the brain. This article also implicates BDNF in several brain-related disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, major depressive disorder, schizophrenia, epilepsy and bipolar disorder.
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Affiliation(s)
- Veerta Sharma
- Chitkara College of Pharmacy, Chitkara University, 140401, Rajpura, Punjab, India
| | - Thakur Gurjeet Singh
- Chitkara College of Pharmacy, Chitkara University, 140401, Rajpura, Punjab, India.
| | - Amarjot Kaur
- Chitkara College of Pharmacy, Chitkara University, 140401, Rajpura, Punjab, India
| | - Ashi Mannan
- Chitkara College of Pharmacy, Chitkara University, 140401, Rajpura, Punjab, India
| | - Sonia Dhiman
- Chitkara College of Pharmacy, Chitkara University, 140401, Rajpura, Punjab, India
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5
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Bonansco C, Cerpa W, Inestrosa NC. How Are Synapses Born? A Functional and Molecular View of the Role of the Wnt Signaling Pathway. Int J Mol Sci 2022; 24:ijms24010708. [PMID: 36614149 PMCID: PMC9821221 DOI: 10.3390/ijms24010708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/16/2022] [Accepted: 12/18/2022] [Indexed: 01/03/2023] Open
Abstract
Synaptic transmission is a dynamic process that requires precise regulation. Early in life, we must be able to forge appropriate connections (add and remove) to control our behavior. Neurons must recognize appropriate targets, and external soluble factors that activate specific signaling cascades provide the regulation needed to achieve this goal. Wnt signaling has been implicated in several forms of synaptic plasticity, including functional and structural changes associated with brain development. The analysis of synapses from an electrophysiological perspective allows us to characterize the functional role of cellular signaling pathways involved in brain development. The application of quantal theory to principles of developmental plasticity offers the possibility of dissecting the function of structural changes associated with the birth of new synapses as well as the maturation of immature silent synapses. Here, we focus on electrophysiological and molecular evidence that the Wnt signaling pathway regulates glutamatergic synaptic transmission, specifically N-methyl-d-aspartate receptors (NMDARs), to control the birth of new synapses. We also focus on the role of Wnts in the conversion of silent synapses into functional synapses.
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Affiliation(s)
- Christian Bonansco
- Centro de Neurobiología y Fisiopatología Integrativa (CENFI), Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile
- Correspondence: (C.B.); (N.C.I.)
| | - Waldo Cerpa
- Laboratorio de Función y Patología Neuronal, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
- Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas 6200000, Chile
| | - Nibaldo C. Inestrosa
- Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas 6200000, Chile
- Centro de Envejecimiento y Regeneración (CARE UC), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
- Correspondence: (C.B.); (N.C.I.)
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6
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Kim B, Jha S, Seo JH, Jeong CH, Lee S, Lee S, Seo YH, Park B. MeBib Suppressed Methamphetamine Self-Administration Response via Inhibition of BDNF/ERK/CREB Signal Pathway in the Hippocampus. Biomol Ther (Seoul) 2020; 28:519-526. [PMID: 32466633 PMCID: PMC7585641 DOI: 10.4062/biomolther.2020.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/23/2020] [Accepted: 05/09/2020] [Indexed: 02/01/2023] Open
Abstract
Methamphetamine (MA) is one of the most commonly abused drugs in the world by illegal drug users. Addiction to MA is a serious public health problem and effective therapies do not exist to date. It has also been reported that behavior induced by psychostimulants such as MA is related to histone deacetylase (HDAC). MeBib is an HDAC6 inhibitor derived from a benzimidazole scaffold. Many benzimidazole-containing compounds exhibit a wide range of pharmacological activity. In this study, we investigated whether HDAC6 inhibitor MeBib modulates the behavioral response in MA self-administered rats. Our results demonstrated that the number of active lever presses in MA self-administered rats was reduced by pretreatment with MeBib. In the hippocampus of rats, we also found MA administration promotes GluN2B, an NMDA receptor subunit, expression, which results in sequential activation of ERK/CREB/BDNF pathway, however, MeBib abrogated it. Collectively, we suggest that MeBib prevents the MA seeking response induced by MA administration and therefore, represents a potent candidate as an MA addiction inhibitor.
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Affiliation(s)
- Buyun Kim
- College of Pharmacy, Keimyung University, Daegu 42601, Republic of Korea
| | - Sonam Jha
- College of Pharmacy, Keimyung University, Daegu 42601, Republic of Korea
| | - Ji Hae Seo
- Department of Biochemistry, School of Medicine, Keimyung University, Daegu 42601, Republic of Korea
| | - Chul-Ho Jeong
- College of Pharmacy, Keimyung University, Daegu 42601, Republic of Korea
| | - Sooyeun Lee
- College of Pharmacy, Keimyung University, Daegu 42601, Republic of Korea
| | - Sangkil Lee
- College of Pharmacy, Keimyung University, Daegu 42601, Republic of Korea
| | - Young Ho Seo
- College of Pharmacy, Keimyung University, Daegu 42601, Republic of Korea
| | - Byoungduck Park
- College of Pharmacy, Keimyung University, Daegu 42601, Republic of Korea
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7
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Bosiacki M, Gąssowska-Dobrowolska M, Kojder K, Fabiańska M, Jeżewski D, Gutowska I, Lubkowska A. Perineuronal Nets and Their Role in Synaptic Homeostasis. Int J Mol Sci 2019; 20:ijms20174108. [PMID: 31443560 PMCID: PMC6747153 DOI: 10.3390/ijms20174108] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 08/15/2019] [Accepted: 08/16/2019] [Indexed: 12/17/2022] Open
Abstract
Extracellular matrix (ECM) molecules that are released by neurons and glial cells form perineuronal nets (PNNs) and modulate many neuronal and glial functions. PNNs, whose structure is still not known in detail, surround cell bodies and dendrites, which leaves free space for synapses to come into contact. A reduction in the expression of many neuronal ECM components adversely affects processes that are associated with synaptic plasticity, learning, and memory. At the same time, increased ECM activity, e.g., as a result of astrogliosis following brain damage or in neuroinflammation, can also have harmful consequences. The therapeutic use of enzymes to attenuate elevated neuronal ECM expression after injury or in Alzheimer’s disease has proven to be beneficial by promoting axon growth and increasing synaptic plasticity. Yet, severe impairment of ECM function can also lead to neurodegeneration. Thus, it appears that to ensure healthy neuronal function a delicate balance of ECM components must be maintained. In this paper we review the structure of PNNs and their components, such as hyaluronan, proteoglycans, core proteins, chondroitin sulphate proteoglycans, tenascins, and Hapln proteins. We also characterize the role of ECM in the functioning of the blood-brain barrier, neuronal communication, as well as the participation of PNNs in synaptic plasticity and some clinical aspects of perineuronal net impairment. Furthermore, we discuss the participation of PNNs in brain signaling. Understanding the molecular foundations of the ways that PNNs participate in brain signaling and synaptic plasticity, as well as how they change in physiological and pathological conditions, may help in the development of new therapies for many degenerative and inflammatory diseases of the brain.
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Affiliation(s)
- Mateusz Bosiacki
- Department of Functional Diagnostics and Physical Medicine, Pomeranian Medical University in Szczecin, Żołnierska 54 Str., 71-210 Szczecin, Poland
| | - Magdalena Gąssowska-Dobrowolska
- Department of Cellular Signalling, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego 5 Str., 02-106 Warsaw, Poland
| | - Klaudyna Kojder
- Department of Anaesthesiology and Intensive Care, Pomeranian Medical University in Szczecin, 71-252 Szczecin, Poland
| | - Marta Fabiańska
- Institute of Philosophy, University of Szczecin, Krakowska 71-79 Str., 71-017 Szczecin, Poland
| | - Dariusz Jeżewski
- Department of Neurosurgery and Pediatric Neurosurgery, Department of Applied Neurocognitivistics, Pomeranian Medical University in Szczecin, 71-252 Szczecin, Poland
| | - Izabela Gutowska
- Department of Human Nutrition and Metabolomics, Department of Medical Chemistry, Pomeranian Medical University in Szczecin, Broniewskiego 24 Str., 71-252 Szczecin, Poland
| | - Anna Lubkowska
- Department of Functional Diagnostics and Physical Medicine, Pomeranian Medical University in Szczecin, Żołnierska 54 Str., 71-210 Szczecin, Poland.
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8
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Shahidi S, Komaki A, Sadeghian R, Asl SS. Different doses of methamphetamine alter long-term potentiation, level of BDNF and neuronal apoptosis in the hippocampus of reinstated rats. J Physiol Sci 2019; 69:409-419. [PMID: 30680641 PMCID: PMC10717877 DOI: 10.1007/s12576-019-00660-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 01/05/2019] [Indexed: 12/28/2022]
Abstract
Methamphetamine (METH) is a psychostimulant. The precise mechanisms of its effects remain unknown and current relapse treatments have low efficacy. However, brain-derived neurotrophic factor (BDNF) and neuronal plasticity are essential contributors, despite paradoxical reports and a lack of comprehensive studies. Therefore, we investigated the effects of different doses of METH on long-term potentiation (LTP), BDNF expression and neuronal apoptosis in the hippocampus of reinstated rats. Rats were injected intraperitoneally with METH (1, 5, or 10 mg/kg) or saline, and trained in a conditioned place preference paradigm. Following implementation of the reinstatement model, electrophysiology, western blotting and TUNEL assay were performed to assess behavior, LTP components, BDNF expression, and neuronal apoptosis, respectively. The results demonstrated that the preference scores, population spike amplitude and BDNF expression markedly decreased in the METH (10 mg/kg) group compared with the other groups. In contrast, METH (5 mg/kg) significantly increased these factors more than the control group. There was no change in variables between METH (1 mg/kg) and the control group. Also, apoptosis of the hippocampus was increased in the METH (10 mg/kg) group compared with the METH (5 mg/kg) group. These results suggest that alterations in synaptic plasticity, expression of BDNF and neuronal apoptosis in the hippocampus has a vital role in the context-induced reinstatement of METH seeking.
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Affiliation(s)
- Siamak Shahidi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Alireza Komaki
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Reihaneh Sadeghian
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
- Medical Toxicology and Drug Abuse Research Center, Birjand University of Medical Sciences, Birjand, Iran.
| | - Sara Soleimani Asl
- Anatomy Departments, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
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9
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Gorkhali R, Huang K, Kirberger M, Yang JJ. Defining potential roles of Pb(2+) in neurotoxicity from a calciomics approach. Metallomics 2017; 8:563-78. [PMID: 27108875 DOI: 10.1039/c6mt00038j] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Metal ions play crucial roles in numerous biological processes, facilitating biochemical reactions by binding to various proteins. An increasing body of evidence suggests that neurotoxicity associated with exposure to nonessential metals (e.g., Pb(2+)) involves disruption of synaptic activity, and these observed effects are associated with the ability of Pb(2+) to interfere with Zn(2+) and Ca(2+)-dependent functions. However, the molecular mechanism behind Pb(2+) toxicity remains a topic of debate. In this review, we first discuss potential neuronal Ca(2+) binding protein (CaBP) targets for Pb(2+) such as calmodulin (CaM), synaptotagmin, neuronal calcium sensor-1 (NCS-1), N-methyl-d-aspartate receptor (NMDAR) and family C of G-protein coupled receptors (cGPCRs), and their involvement in Ca(2+)-signalling pathways. We then compare metal binding properties between Ca(2+) and Pb(2+) to understand the structural implications of Pb(2+) binding to CaBPs. Statistical and biophysical studies (e.g., NMR and fluorescence spectroscopy) of Pb(2+) binding are discussed to investigate the molecular mechanism behind Pb(2+) toxicity. These studies identify an opportunistic, allosteric binding of Pb(2+) to CaM, which is distinct from ionic displacement. Together, these data suggest three potential modes of Pb(2+) activity related to molecular and/or neural toxicity: (i) Pb(2+) can occupy Ca(2+)-binding sites, inhibiting the activity of the protein by structural modulation, (ii) Pb(2+) can mimic Ca(2+) in the binding sites, falsely activating the protein and perturbing downstream activities, or (iii) Pb(2+) can bind outside of the Ca(2+)-binding sites, resulting in the allosteric modulation of the protein activity. Moreover, the data further suggest that even low concentrations of Pb(2+) can interfere at multiple points within the neuronal Ca(2+) signalling pathways to cause neurotoxicity.
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Affiliation(s)
- Rakshya Gorkhali
- Department of Chemistry, Center for Diagnostics and Therapeutics, and Drug Design and Biotechnology, Georgia State University, Atlanta, GA 3030, USA.
| | - Kenneth Huang
- Department of Chemistry, Center for Diagnostics and Therapeutics, and Drug Design and Biotechnology, Georgia State University, Atlanta, GA 3030, USA.
| | - Michael Kirberger
- Department of Chemistry and Physics, Clayton State University, Morrow, GA 30260, USA.
| | - Jenny J Yang
- Department of Chemistry, Center for Diagnostics and Therapeutics, and Drug Design and Biotechnology, Georgia State University, Atlanta, GA 3030, USA.
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10
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Gąssowska M, Baranowska-Bosiacka I, Moczydłowska J, Frontczak-Baniewicz M, Gewartowska M, Strużyńska L, Gutowska I, Chlubek D, Adamczyk A. Perinatal exposure to lead (Pb) induces ultrastructural and molecular alterations in synapses of rat offspring. Toxicology 2016; 373:13-29. [DOI: 10.1016/j.tox.2016.10.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 10/22/2016] [Accepted: 10/27/2016] [Indexed: 12/26/2022]
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11
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Bathina S, Das UN. Brain-derived neurotrophic factor and its clinical implications. Arch Med Sci 2015; 11:1164-78. [PMID: 26788077 PMCID: PMC4697050 DOI: 10.5114/aoms.2015.56342] [Citation(s) in RCA: 612] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 08/05/2014] [Indexed: 01/09/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal survival and growth, serves as a neurotransmitter modulator, and participates in neuronal plasticity, which is essential for learning and memory. It is widely expressed in the CNS, gut and other tissues. BDNF binds to its high affinity receptor TrkB (tyrosine kinase B) and activates signal transduction cascades (IRS1/2, PI3K, Akt), crucial for CREB and CBP production, that encode proteins involved in β cell survival. BDNF and insulin-like growth factor-1 have similar downstream signaling mechanisms incorporating both p-CAMK and MAPK that increase the expression of pro-survival genes. Brain-derived neurotrophic factor regulates glucose and energy metabolism and prevents exhaustion of β cells. Decreased levels of BDNF are associated with neurodegenerative diseases with neuronal loss, such as Parkinson's disease, Alzheimer's disease, multiple sclerosis and Huntington's disease. Thus, BDNF may be useful in the prevention and management of several diseases including diabetes mellitus.
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Affiliation(s)
- Siresha Bathina
- Bio-Science Research Center, Gayatri Vidya Parishad College of Engineering, Visakhapatnam, India
| | - Undurti N. Das
- Bio-Science Research Center, Gayatri Vidya Parishad College of Engineering, Visakhapatnam, India
- UND Life Sciences, USA
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12
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Edelmann E, Cepeda-Prado E, Franck M, Lichtenecker P, Brigadski T, Leßmann V. Theta Burst Firing Recruits BDNF Release and Signaling in Postsynaptic CA1 Neurons in Spike-Timing-Dependent LTP. Neuron 2015; 86:1041-1054. [DOI: 10.1016/j.neuron.2015.04.007] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 01/25/2015] [Accepted: 03/31/2015] [Indexed: 01/28/2023]
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13
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Shinoda Y, Ahmed S, Ramachandran B, Bharat V, Brockelt D, Altas B, Dean C. BDNF enhances spontaneous and activity-dependent neurotransmitter release at excitatory terminals but not at inhibitory terminals in hippocampal neurons. Front Synaptic Neurosci 2014; 6:27. [PMID: 25426063 PMCID: PMC4226143 DOI: 10.3389/fnsyn.2014.00027] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Accepted: 10/21/2014] [Indexed: 11/30/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is widely reported to enhance synaptic vesicle (SV) exocytosis and neurotransmitter release. But it is still unclear whether BDNF enhances SV recycling at excitatory terminals only, or at both excitatory and inhibitory terminals. In the present study, in a direct comparison using cultured rat hippocampal neurons, we demonstrate that BDNF enhances both spontaneous and activity-dependent neurotransmitter release from excitatory terminals, but not from inhibitory terminals. BDNF treatment for 5 min or 48 h increased both spontaneous and activity-induced anti-synaptotagmin1 (SYT1) antibody uptake at excitatory terminals marked with vGluT1. Conversely, BDNF treatment did not enhance spontaneous or activity-induced uptake of anti-SYT1 antibodies in inhibitory terminals marked with vGAT. Time-lapse imaging of FM1-43 dye destaining in excitatory and inhibitory terminals visualized by post-hoc immunostaining of vGluT1 and vGAT also showed the same result: The rate of spontaneous and activity-induced destaining was increased by BDNF at excitatory synapses, but not at inhibitory synapses. These data demonstrate that BDNF enhances SV exocytosis in excitatory but not inhibitory terminals. Moreover, BDNF enhanced evoked SV exocytosis, even if vesicles were loaded under spontaneous vesicle recycling conditions. Thus, BDNF enhances both spontaneous and activity-dependent neurotransmitter release on both short and long time-scales, by the same mechanism.
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Affiliation(s)
- Yo Shinoda
- Trans-synaptic Signaling Group, European Neuroscience Institute Goettingen, Germany ; Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science Chiba, Japan
| | - Saheeb Ahmed
- Trans-synaptic Signaling Group, European Neuroscience Institute Goettingen, Germany
| | - Binu Ramachandran
- Trans-synaptic Signaling Group, European Neuroscience Institute Goettingen, Germany
| | - Vinita Bharat
- Trans-synaptic Signaling Group, European Neuroscience Institute Goettingen, Germany
| | - David Brockelt
- Trans-synaptic Signaling Group, European Neuroscience Institute Goettingen, Germany
| | - Bekir Altas
- Trans-synaptic Signaling Group, European Neuroscience Institute Goettingen, Germany
| | - Camin Dean
- Trans-synaptic Signaling Group, European Neuroscience Institute Goettingen, Germany
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Qiao H, An SC, Ren W, Ma XM. Progressive alterations of hippocampal CA3-CA1 synapses in an animal model of depression. Behav Brain Res 2014; 275:191-200. [PMID: 25192638 DOI: 10.1016/j.bbr.2014.08.040] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 08/08/2014] [Accepted: 08/20/2014] [Indexed: 12/11/2022]
Abstract
Major depressive disorder is the most prevalent psychiatric condition, but the cellular and molecular mechanisms underlying this disorder are largely unknown, although multiple hypotheses have been proposed. The aim of this study was to characterize the progressive alteration of neuronal plasticity in the male rat hippocampus during depression induced by chronic unpredictable mild stress (CUMS), an established animal model of depression. The data in the hippocampus were collected on days 7, 14 and 21 after the onset of three-week CUMS. When analyzed on day 21, three-week CUMS induced typically depressive-like behaviors, impaired LTP induction, and decreased basal synaptic transmission at hippocampal CA3-CA1 synapses recorded in vivo, which was accompanied by decreased density of dendritic spines in CA1 and CA3 pyramidal neurons. The levels of both Kalirin-7 and brain-derived neurotrophic factor (BDNF) in the hippocampus were decreased at the same time. On day 14 (middle phase), some depressive-like behaviors were observed, which was accompanied by depressed basal synaptic transmission and enhanced LTP induction at the CA3-CA1 synapses. However, BDNF expression was decreased without alteration of Kalirin7 expression in comparison with no-stress control. Depressed basal synaptic transmission occurred in the middle phase of CUMS may contribute to decreased expression of BDNF. On day 7, depressive-like behaviors were not observed, and LTP induction, spine density, Kalirin-7 and BDNF expression were not altered by CUMS in comparison with no-stress control. These results showed that the functional changes at CA3-CA1synapses occurred earlier than the structural alteration during three-week CUMS as a strategy of neural adaptation, and rats required three weeks to develop depressive-like behaviors during CUMS. Our results suggest an important role of Kalirin-7 in CUMS-mediated alterations in spine density, synaptic function and overall depressive-like behaviors on day 21.
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Affiliation(s)
- Hui Qiao
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi Province 710062, PR China
| | - Shu-Cheng An
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi Province 710062, PR China.
| | - Wei Ren
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi Province 710062, PR China
| | - Xin-Ming Ma
- College of Life Science, Shaanxi Normal University, Xi'an, Shaanxi Province 710062, PR China; University of Connecticut Health Center, Department of Neuroscience, Farmington, CT 06030, USA
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A novel analog of olanzapine linked to sarcosinyl moiety (PGW5) demonstrates high efficacy and good safety profile in mouse models of schizophrenia. Eur Neuropsychopharmacol 2014; 24:425-36. [PMID: 24389121 DOI: 10.1016/j.euroneuro.2013.11.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 11/18/2013] [Accepted: 11/19/2013] [Indexed: 11/22/2022]
Abstract
UNLABELLED Schizophrenia is a chronic mental disorder related to hypo-functioning of glutamatergic neurotransmission. N-methyl-D-aspartate-receptor (NMDA-R) positive modulators were reported to reduce schizophrenia symptoms. However, their efficacy is low and inconsistent. We developed a novel antipsychotic possessing an olanzapine moiety linked to the positive modulator of glutamate NMDA-R sarcosine (PGW5) and characterized the pharmacodynamic properties of the novel molecule in-vivo using MK-801 and in-vitro using receptor binding analysis. We investigated the pharmacological activity of PGW5 (olanzapine linked to sarcosinyl moiety) in male mice (BALB/c or C57BL). In an open field test, up to 50mg/kg PGW5 did not affect motility while higher doses were sedative. PGW5 (25-50mg/kg po) antagonized MK-801 (0.15 mg/kg ip) and amphetamine-induced (5mg/kg ip) hyperactivity. PGW5 (25mg/kg po/d) treatment for 15 or 22 days exhibited antidepressant and anxiolytic activity in mice. Moreover, PGW5, but not olanzapine, attenuated phencyclidine (PCP)-induced deficits of social preference in mice and promoted the expression of brain derived neurotrophic factor (BDNF) in the hippocampus and the frontal cortex and glutamic acid decarboxylase (GAD67) in the hippocampus. Mice treated with PGW5 (25 and 50mg/kg/d) for 28 days did not show toxic effects in terms of weight gain and blood-chemistry analysis. CONCLUSIONS PGW5 is a novel and safe antipsychotic, efficacious against schizophrenia-like positive and negative symptoms at nonsedative doses. The drug shows anxiolytic and antidepressant activity, and improves impaired social performance in phencyclidine (PCP) treated mice. The mechanism underlying its activity seems to involve potentiation of NMDA receptor as well as stimulation of brain BDNF and GAD67 expression.
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16
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Nikolić M, Gardner H, Tucker K. Postnatal neuronal apoptosis in the cerebral cortex: Physiological and pathophysiological mechanisms. Neuroscience 2013; 254:369-78. [DOI: 10.1016/j.neuroscience.2013.09.035] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 09/14/2013] [Accepted: 09/17/2013] [Indexed: 12/15/2022]
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Pre- and postsynaptic twists in BDNF secretion and action in synaptic plasticity. Neuropharmacology 2013; 76 Pt C:610-27. [PMID: 23791959 DOI: 10.1016/j.neuropharm.2013.05.043] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/12/2013] [Accepted: 05/14/2013] [Indexed: 12/30/2022]
Abstract
Overwhelming evidence collected since the early 1990's strongly supports the notion that BDNF is among the key regulators of synaptic plasticity in many areas of the mammalian central nervous system. Still, due to the extremely low expression levels of endogenous BDNF in most brain areas, surprisingly little data i) pinpointing pre- and postsynaptic release sites, ii) unraveling the time course of release, and iii) elucidating the physiological levels of synaptic activity driving this secretion are available. Likewise, our knowledge regarding pre- and postsynaptic effects of endogenous BDNF at the single cell level in mediating long-term potentiation still is sparse. Thus, our review will discuss the data currently available regarding synaptic BDNF secretion in response to physiologically relevant levels of activity, and will discuss how endogenously secreted BDNF affects synaptic plasticity, giving a special focus on spike timing-dependent types of LTP and on mossy fiber LTP. We will attempt to open up perspectives how the remaining challenging questions regarding synaptic BDNF release and action might be addressed by future experiments. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.
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Abstract
Human exposure to neurotoxic metals is a global public health problem. Metals which cause neurological toxicity, such as lead (Pb) and manganese (Mn), are of particular concern due to the long-lasting and possibly irreversible nature of their effects. Pb exposure in childhood can result in cognitive and behavioural deficits in children. These effects are long-lasting and persist into adulthood even after Pb exposure has been reduced or eliminated. While Mn is an essential element of the human diet and serves many cellular functions in the human body, elevated Mn levels can result in a Parkinson's disease (PD)-like syndrome and developmental Mn exposure can adversely affect childhood neurological development. Due to the ubiquitous presence of both metals, reducing human exposure to toxic levels of Mn and Pb remains a world-wide public health challenge. In this review we summarize the toxicokinetics of Pb and Mn, describe their neurotoxic mechanisms, and discuss common themes in their neurotoxicity.
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Affiliation(s)
| | - Tomas R Guilarte
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA.
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19
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Leschik J, Eckenstaler R, Nieweg K, Lichtenecker P, Brigadski T, Gottmann K, Leßmann V, Lutz B. Stably BDNF-GFP expressing embryonic stem cells exhibit a BDNF release-dependent enhancement of neuronal differentiation. J Cell Sci 2013; 126:5062-73. [DOI: 10.1242/jcs.135384] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is known to be a crucial regulator of neuronal survival and synaptic plasticity in the mammalian brain. Furthermore, BDNF positively influences differentiation of embryonic neural precursors as well as of neural stem cells from adult neurogenic niches. To study the impact of cell-released BDNF on neural differentiation of embryonic stem cells (ESCs), which represent an attractive source for cell transplantation studies, we have generated BDNF-GFP overexpressing mouse ESC clones by knock-in technology. After neural differentiation in vitro, we observed that BDNF-GFP overexpressing ESC clones gave rise to an increased number of neurons as compared to control ESCs. Neurons derived from BDNF-GFP expressing ESCs harbored a more complex dendritic morphology and differentiated to a higher extent into the GABAergic lineage than controls. Moreover, we show that ESC-derived neurons released BDNF-GFP in an activity-dependent manner and displayed similar electrophysiological properties as cortical neurons. Thus, our study describes the generation of stably BDNF-GFP overexpressing ESCs which are ideally suited to investigate the ameliorating effects of BDNF in cell transplantation studies for various neuropathological conditions.
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Baranowska-Bosiacka I, Strużyńska L, Gutowska I, Machalińska A, Kolasa A, Kłos P, Czapski GA, Kurzawski M, Prokopowicz A, Marchlewicz M, Safranow K, Machaliński B, Wiszniewska B, Chlubek D. Perinatal exposure to lead induces morphological, ultrastructural and molecular alterations in the hippocampus. Toxicology 2012; 303:187-200. [PMID: 23146751 DOI: 10.1016/j.tox.2012.10.027] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 10/29/2012] [Accepted: 10/30/2012] [Indexed: 11/16/2022]
Abstract
The aim of this paper is to examine if pre- and neonatal exposure to lead (Pb) may intensify or inhibit apoptosis or necroptosis in the developing rat brain. Pregnant experimental females received 0.1% lead acetate (PbAc) in drinking water from the first day of gestation until weaning of the offspring; the control group received distilled water. During the feeding of pups, mothers from the experimental group were still receiving PbAc. Pups were weaned at postnatal day 21 and the young rats of both groups then received only distilled water until postnatal day 28. This treatment protocol resulted in a concentration of Pb in rat offspring whole blood (Pb-B) below the threshold of 10 μg/dL, considered safe for humans.We studied Casp-3 activity and expression, AIF nuclear translocation, DNA fragmentation, as well as Bax, Bcl-2 mRNA and protein expression as well as BDNF concentration in selected structures of the rat brain: forebrain cortex (FC), cerebellum (C) and hippocampus (H). The microscopic examinations showed alterations in hippocampal neurons.Our data shows that pre- and neonatal exposure of rats to Pb, leading to Pb-B below 10 μg/dL, can decrease the number of hippocampus neurons, occurring concomitantly with ultrastructural alterations in this region. We observed no morphological or molecular features of severe apoptosis or necrosis (no active Casp-3 and AIF translocation to nucleus) in young brains, despite the reduced levels of BDNF. The potential protective factor against apoptosis was probably the decreased Bax/Bcl-2 ratio, which requires further investigation. Our findings contribute to further understanding of the mechanisms underlying Pb neurotoxicity and cognition impairment in a Pb-exposed developing brain.
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Affiliation(s)
- I Baranowska-Bosiacka
- Department of Biochemistry and Medical Chemistry, Pomeranian Medical University, Powstańców Wlkp. 72, 70-111 Szczecin, Poland.
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21
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Excitotoxicity in the Pathogenesis of Autism. Neurotox Res 2012; 23:393-400. [DOI: 10.1007/s12640-012-9354-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 09/10/2012] [Accepted: 09/22/2012] [Indexed: 01/29/2023]
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22
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Laudes T, Meis S, Munsch T, Lessmann V. Impaired transmission at corticothalamic excitatory inputs and intrathalamic GABAergic synapses in the ventrobasal thalamus of heterozygous BDNF knockout mice. Neuroscience 2012; 222:215-27. [DOI: 10.1016/j.neuroscience.2012.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 06/27/2012] [Accepted: 07/02/2012] [Indexed: 01/08/2023]
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23
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Neurotoxicity of lead. Hypothetical molecular mechanisms of synaptic function disorders. Neurol Neurochir Pol 2012; 46:569-78. [DOI: 10.5114/ninp.2012.31607] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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24
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Neal AP, Stansfield KH, Guilarte TR. Enhanced nitric oxide production during lead (Pb²⁺) exposure recovers protein expression but not presynaptic localization of synaptic proteins in developing hippocampal neurons. Brain Res 2011; 1439:88-95. [PMID: 22265330 DOI: 10.1016/j.brainres.2011.12.037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 11/28/2011] [Accepted: 12/17/2011] [Indexed: 01/17/2023]
Abstract
We have previously reported that lead (Pb(2+)) exposure results in both presynaptic and postsynaptic changes in developing neurons as a result of inhibition of the N-methyl-d-aspartate receptor (NMDAR). NMDAR inhibition by Pb(2+) during synaptogenesis disrupts downstream trans-synaptic signaling of brain-derived neurotrophic factor (BDNF) and exogenous addition of BDNF can recover the effects of Pb(2+) on both presynaptic protein expression and presynaptic vesicular release. NMDAR activity can modulate other trans-synaptic signaling pathways, such as nitric oxide (NO) signaling. Thus, it is possible that other trans-synaptic pathways in addition to BDNF signaling may be disrupted by Pb(2+) exposure. The current study investigated whether exogenous addition of NO could recover the presynaptic vesicular proteins lost as a result of Pb(2+) exposure during synaptogenesis, namely Synaptophysin (Syn) and Synaptobrevin (Syb). We observed that exogenous addition of NO during Pb(2+) exposure results in complete recovery of whole-cell Syn levels and partial recovery of Syn and Syb synaptic targeting in Pb(2+)-exposed neurons.
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Affiliation(s)
- April P Neal
- Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA.
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25
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Li W, Keifer J. Rapid enrichment of presynaptic protein in boutons undergoing classical conditioning is mediated by brain-derived neurotrophic factor. Neuroscience 2011; 203:50-8. [PMID: 22202461 DOI: 10.1016/j.neuroscience.2011.12.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/28/2011] [Accepted: 12/12/2011] [Indexed: 12/29/2022]
Abstract
Presynaptic structural modifications are thought to accompany activity-dependent synaptic plasticity and learning. This may involve the conversion of nonfunctional synapses into active ones or the generation of entirely new synapses. Here, using an in vitro neural analog of classical conditioning, we investigated presynaptic structural changes restricted to auditory nerve synapses that convey the conditioned stimulus (CS) by tract tracing using fluorescent tracers combined with immunostaining for the synaptic vesicle-associated protein synaptophysin. The results show that the size of presynaptic auditory boutons increased and the area and fluorescence intensity of punctate staining for synaptophysin were enhanced after conditioning. This occurred only for auditory nerve boutons apposed to the dendrites but not the somata of abducens motor neurons. Conditioning increased the percentage of boutons that were immunopositive for synaptophysin and enhanced the number of synaptophysin puncta they contained. Pretreatment with antibodies against brain-derived neurotrophic factor (BDNF) inhibited these conditioning-induced structural changes. There was also a net increase in the number of boutons apposed to abducens motor neurons after conditioning or BDNF treatment. These data indicate that the rapid enrichment of presynaptic boutons with proteins required for neurotransmitter recycling and release occurs during classical conditioning and that these processes are mediated by BDNF.
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Affiliation(s)
- W Li
- Neuroscience Group, Division of Basic Biomedical Sciences, University of South Dakota, Sanford School of Medicine, Vermillion, SD 57010, USA
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26
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An overview of brain-derived neurotrophic factor and implications for excitotoxic vulnerability in the hippocampus. INTERNATIONAL JOURNAL OF PEPTIDES 2011; 2011:654085. [PMID: 21966294 PMCID: PMC3182334 DOI: 10.1155/2011/654085] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 07/26/2011] [Indexed: 01/19/2023]
Abstract
The present paper examines the nature and function of brain-derived neurotrophic factor (BDNF) in the hippocampal formation and the consequences of changes in its expression. The paper focuses on literature describing the role of BDNF in hippocampal development and neuroplasticity. BDNF expression is highly sensitive to developmental and environmental factors, and increased BDNF signaling enhances neurogenesis, neurite sprouting, electrophysiological activity, and other processes reflective of a general enhancement of hippocampal function. Such increases in activity may mediate beneficial effects such as enhanced learning and memory. However, the increased activity also comes at a cost: BDNF plasticity renders the hippocampus more vulnerable to hyperexcitability and/or excitotoxic damage. Exercise dramatically increases hippocampal BDNF levels and produces behavioral effects consistent with this phenomenon. In analyzing the literature regarding exercise-induced regulation of BDNF, this paper provides a theoretical model for how the potentially deleterious consequences of BDNF plasticity may be modulated by other endogenous factors. The peptide galanin may play such a role by regulating hippocampal excitability.
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27
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Molecular neurobiology of lead (Pb(2+)): effects on synaptic function. Mol Neurobiol 2010; 42:151-60. [PMID: 21042954 DOI: 10.1007/s12035-010-8146-0] [Citation(s) in RCA: 143] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 10/13/2010] [Indexed: 12/16/2022]
Abstract
Lead (Pb(2+)) is a ubiquitous environmental neurotoxicant that continues to threaten public health on a global scale. Epidemiological studies have demonstrated detrimental effects of Pb(2+) on childhood IQ at very low levels of exposure. Recently, a mechanistic understanding of how Pb(2+) affects brain development has begun to emerge. The cognitive effects of Pb(2+) exposure are believed to be mediated through its selective inhibition of the N-methyl-D: -aspartate receptor (NMDAR). Studies in animal models of developmental Pb(2+) exposure exhibit altered NMDAR subunit ontogeny and disruption of NMDAR-dependent intracellular signaling. Additional studies have reported that Pb(2+) exposure inhibits presynaptic calcium (Ca(2+)) channels and affects presynaptic neurotransmission, but a mechanistic link between presynaptic and postsynaptic effects has been missing. Recent work has suggested that the presynaptic and postsynaptic effects of Pb(2+) exposure are both due to inhibition of the NMDAR by Pb(2+), and that the presynaptic effects of Pb(2+) may be mediated by disruption of NMDAR activity-dependent signaling of brain-derived neurotrophic factor (BDNF). These findings provide the basis for the first working model to describe the effects of Pb(2+) exposure on synaptic function. Here, we review the neurotoxic effects of Pb(2+) exposure and discuss the known effects of Pb(2+) exposure in light of these recent findings.
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Kuczewski N, Porcher C, Gaiarsa JL. Activity-dependent dendritic secretion of brain-derived neurotrophic factor modulates synaptic plasticity. Eur J Neurosci 2010; 32:1239-44. [DOI: 10.1111/j.1460-9568.2010.07378.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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29
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Neal AP, Stansfield KH, Worley PF, Thompson RE, Guilarte TR. Lead exposure during synaptogenesis alters vesicular proteins and impairs vesicular release: potential role of NMDA receptor-dependent BDNF signaling. Toxicol Sci 2010; 116:249-63. [PMID: 20375082 DOI: 10.1093/toxsci/kfq111] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Lead (Pb(2+)) exposure is known to affect presynaptic neurotransmitter release in both in vivo and cell culture models. However, the precise mechanism by which Pb(2+) impairs neurotransmitter release remains unknown. In the current study, we show that Pb(2+) exposure during synaptogenesis in cultured hippocampal neurons produces the loss of synaptophysin (Syn) and synaptobrevin (Syb), two proteins involved in vesicular release. Pb(2+) exposure also increased the number of presynaptic contact sites. However, many of these putative presynaptic contact sites lack Soluble NSF attachment protein receptor complex proteins involved in vesicular exocytosis. Analysis of vesicular release using FM 1-43 dye confirmed that Pb(2+) exposure impaired vesicular release and reduced the number of fast-releasing sites. Because Pb(2+) is a potent N-methyl-D-aspartate receptor (NMDAR) antagonist, we tested the hypothesis that NMDAR inhibition may be producing the presynaptic effects. We show that NMDAR inhibition by aminophosphonovaleric acid mimics the presynaptic effects of Pb(2+) exposure. NMDAR activity has been linked to the signaling of the transsynaptic neurotrophin brain-derived neurotrophic factor (BDNF), and we observed that both the cellular expression of proBDNF and release of BDNF were decreased during the same period of Pb(2+) exposure. Furthermore, exogenous addition of BDNF rescued the presynaptic effects of Pb(2+). We suggest that the presynaptic deficits resulting from Pb(2+) exposure during synaptogenesis are mediated by disruption of NMDAR-dependent BDNF signaling.
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Affiliation(s)
- April P Neal
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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30
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Properties of glutamatergic synapses in immature layer Vb pyramidal neurons: coupling of pre- and postsynaptic maturational states. Exp Brain Res 2010; 200:169-82. [PMID: 19862508 DOI: 10.1007/s00221-009-2051-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Accepted: 10/06/2009] [Indexed: 01/12/2023]
Abstract
Following initial contact formation, glutamatergic synapses in cortical neurons undergo pronounced functional maturation. These maturational events, occurring both pre- and postsynaptically, have been well described in the developing hippocampus. In this paper, we characterized glutamatergic synapses in immature layer Vb pyramidal neurons of the mouse somatosensory cortex during early postnatal development. At postnatal day 7, a significant subpopulation of glutamatergic synapses exhibited a low release probability that was accompanied by strong paired-pulse facilitation of AMPA EPSCs (paired-pulse ratio C > or = 2). Increasing extracellular Ca(2+) concentration increased release probability and led to paired-pulse depression. During further postnatal development, these functionally immature synapses disappeared. As shown pharmacologically,these synapses expressed postsynaptic NMDA receptors containing NR2B subunits, while NMDA receptors with NR2A subunits were lacking. Taken together, a low release probability presynaptically was coupled to postsynaptic NR2B signaling. This subpopulation of neocortical synapses thus differed from the majority of synapses in the developing hippocampus, where high release probability is coupled to NR2B signaling. The novel type of functionally immature glutamatergic synapse described here might play an important role in early developmental synapse elimination and in the activity-dependent refinement of the neocortical synaptic microcircuitry.
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Cabezas C, Buño W. BDNF is required for the induction of a presynaptic component of the functional conversion of silent synapses. Hippocampus 2010; 21:374-85. [DOI: 10.1002/hipo.20754] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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32
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Jin CH, Shin EJ, Park JB, Jang CG, Li Z, Kim MS, Koo KH, Yoon HJ, Park SJ, Choi WC, Yamada K, Nabeshima T, Kim HC. Fustin flavonoid attenuates β-amyloid (1-42)-induced learning impairment. J Neurosci Res 2009; 87:3658-70. [DOI: 10.1002/jnr.22159] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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33
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BDNF signaling in the formation, maturation and plasticity of glutamatergic and GABAergic synapses. Exp Brain Res 2009; 199:203-34. [PMID: 19777221 DOI: 10.1007/s00221-009-1994-z] [Citation(s) in RCA: 226] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 08/12/2009] [Indexed: 01/17/2023]
Abstract
In the past 15 years numerous reports provided strong evidence that brain-derived neurotrophic factor (BDNF) is one of the most important modulators of glutamatergic and GABAergic synapses. Remarkable progress regarding localization, kinetics, and molecular mechanisms of BDNF secretion has been achieved, and a large number of studies provided evidence that continuous extracellular supply of BDNF is important for the proper formation and functional maturation of glutamatergic and GABAergic synapses. BDNF can play a permissive role in shaping synaptic networks, making them more susceptible for the occurrence of plastic changes. In addition, BDNF appears to be also an instructive factor for activity-dependent long-term synaptic plasticity. BDNF release just in response to synaptic stimulation might be a molecular trigger to convert high-frequency synaptic activity into long-term synaptic memories. This review attempts to summarize the current knowledge in synaptic secretion and synaptic action of BDNF, including both permissive and instructive effects of BDNF in synaptic plasticity.
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Mechanisms, locations, and kinetics of synaptic BDNF secretion: an update. Neurosci Res 2009; 65:11-22. [PMID: 19523993 DOI: 10.1016/j.neures.2009.06.004] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 06/01/2009] [Accepted: 06/03/2009] [Indexed: 01/12/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) and other members of the protein family of neurotrophins have been implicated in a multitude of processes that are important for neuronal development and synaptic plasticity in the rodent central nervous system. In comparison to the wealth of information available with respect to the biological functions of neurotrophins, our knowledge regarding the processes that govern synaptic secretion of neurotrophins is scarce. Using live cell imaging of GFP-tagged neurotrophins in primary neurons, immunocytochemical detection of endogenous BDNF in fixed cells, and by blocking the action of endogenously released BDNF by means of TrkB receptor bodies in living neurons, several studies in recent years have allowed to better understand the time course and the mechanisms of synaptic secretion of neurotrophins. This review will summarize the current knowledge regarding the intracellular processing of proneurotrophins, the targeting of neurotrophin vesicles to axons and dendrites, and the mechanisms of activity-dependent secretion of BDNF at synapses. Since these processes are known to be cell type dependent, special emphasis is given to observations gained from experiments in primary neurons.
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Activity-dependent dendritic release of BDNF and biological consequences. Mol Neurobiol 2009; 39:37-49. [PMID: 19156544 DOI: 10.1007/s12035-009-8050-7] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 01/07/2009] [Indexed: 01/08/2023]
Abstract
Network construction and reorganization is modulated by the level and pattern of synaptic activity generated in the nervous system. During the past decades, neurotrophins, and in particular brain-derived neurotrophic factor (BDNF), have emerged as attractive candidates for linking synaptic activity and brain plasticity. Thus, neurotrophin expression and secretion are under the control of activity-dependent mechanisms and, besides their classical role in supporting neuronal survival neurotrophins, modulate nearly all key steps of network construction from neuronal migration to experience-dependent refinement of local connections. In this paper, we provide an overview of recent findings showing that BDNF can serve as a target-derived messenger for activity-dependent synaptic plasticity and development at the single cell level.
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Backpropagating action potentials trigger dendritic release of BDNF during spontaneous network activity. J Neurosci 2008; 28:7013-23. [PMID: 18596175 DOI: 10.1523/jneurosci.1673-08.2008] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is a major regulator of activity-dependent synapse development and plasticity. Because BDNF is a secreted protein, it has been proposed that BDNF is released from target neurons in an activity-dependent manner. However, direct evidence for postsynaptic release of BDNF triggered by ongoing network activity is still lacking. Here we transfected cultures of dissociated hippocampal neurons with green fluorescent protein (GFP)-tagged BDNF and combined whole-cell recording, time-lapse fluorescent imaging, and immunostaining to monitor activity-dependent dendritic release of BDNF. We found that spontaneous backpropagating action potentials, but not synaptic activity alone, led to a Ca2+-dependent dendritic release of BDNF-GFP. Moreover, we provide evidence that endogenous BDNF released from a single neuron can phosphorylate CREB (cAMP response element-binding protein) in neighboring neurons, an important step of immediate early gene activation. Therefore, together, our results support the hypothesis that BDNF might act as a target-derived messenger of activity-dependent synaptic plasticity and development.
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Corner MA. Spontaneous neuronal burst discharges as dependent and independent variables in the maturation of cerebral cortex tissue cultured in vitro: a review of activity-dependent studies in live 'model' systems for the development of intrinsically generated bioelectric slow-wave sleep patterns. ACTA ACUST UNITED AC 2008; 59:221-44. [PMID: 18722470 DOI: 10.1016/j.brainresrev.2008.08.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 08/01/2008] [Accepted: 08/05/2008] [Indexed: 10/21/2022]
Abstract
A survey is presented of recent experiments which utilize spontaneous neuronal spike trains as dependent and/or independent variables in developing cerebral cortex cultures when synaptic transmission is interfered with for varying periods of time. Special attention is given to current difficulties in selecting suitable preparations for carrying out biologically relevant developmental studies, and in applying spike-train analysis methods with sufficient resolution to detect activity-dependent age and treatment effects. A hierarchy of synchronized nested burst discharges which approximate early slow-wave sleep patterns in the intact organism is established as a stable basis for isolated cortex function. The complexity of reported long- and short-term homeostatic responses to experimental interference with synaptic transmission is reviewed, and the crucial role played by intrinsically generated bioelectric activity in the maturation of cortical networks is emphasized.
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Affiliation(s)
- Michael A Corner
- Netherlands Institute for Brain Research, Amsterdam, The Netherlands.
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Xu Y, Cui C, Pang C, Christen Y, Luo Y. Restoration of impaired phosphorylation of cyclic AMP response element-binding protein (CREB) by EGb 761 and its constituents in Abeta-expressing neuroblastoma cells. Eur J Neurosci 2008; 26:2931-9. [PMID: 18001288 DOI: 10.1111/j.1460-9568.2007.05905.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cyclic AMP response element-binding protein (CREB) plays important roles in neuronal plasticity and amyloid beta-peptide (Abeta)-induced cognitive impairment in Alzheimer's disease (AD). Here we demonstrated that Ginkgo biloba extract, EGb 761, displayed the neuron protective effect by activating the CREB signaling pathway. Wild-type neuroblastoma cells cultured in a conditioned medium containing cell-secreted Alphabeta exhibited reduced levels of phosphorylated CREB (pCREB). Addition of EGb 761 (100 microg/mL) or an anti-oligomer-specific antibody (A-11) to the conditioned medium could restore pCREB level. In a neuroblastoma cell line expressing Alphabeta, treatment with EGb 761 increased levels of pCREB and brain-derived neurotrophic factor. Furthermore, CREB phosphorylation induced by EGb 761 was blocked by inhibitors of several upstream signaling pathways of CREB, including protein kinase C, ERK, ribosomal S6 kinase(RSK)90 and nitric oxide pathway. Moreover, these inhibitors differentially blocked the effects of individual components of EGb 761, ginkgolide C, quercetin and bilobalide, which suggest diverse effects of the EGb 761 individual components. Actions of individual EGb 761 components provide further insights into direct mechanisms underlying the effect of EGb 761 on enhancing the cognitive performance of patients with AD.
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Affiliation(s)
- Yanan Xu
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, MD 21201, USA
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Kolarow R, Brigadski T, Lessmann V. Postsynaptic secretion of BDNF and NT-3 from hippocampal neurons depends on calcium calmodulin kinase II signaling and proceeds via delayed fusion pore opening. J Neurosci 2007; 27:10350-64. [PMID: 17898207 PMCID: PMC6673152 DOI: 10.1523/jneurosci.0692-07.2007] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The mammalian neurotrophins (NTs) NGF, BDNF, NT-3, and NT-4 constitute a family of secreted neuronal growth factors. In addition, NTs are implicated in several forms of activity-dependent synaptic plasticity. Although synaptic secretion of NTs has been described, the intracellular signaling cascades that regulate synaptic secretion of NTs are far from being understood. Analysis of NT secretion at the subcellular level is thus required to resolve the role of presynaptic and postsynaptic NT secretion for synaptic plasticity. Here, we transfected cultures of dissociated rat hippocampal neurons with green fluorescent protein-tagged versions of BDNF and NT-3, respectively, and identified NT vesicles at glutamatergic synapses by colocalization with the cotransfected postsynaptic marker PSD-95 (postsynaptic density-95)-DsRed. Depolarization-induced secretion of BDNF and NT-3 was monitored with live cell imaging. Direct postsynaptic depolarization with elevated K+ in the presence of blockers of synaptic transmission allowed us to investigate the signaling cascades that are involved in the postsynaptic NT vesicle secretion process. We show that depolarization-induced postsynaptic NT secretion is elicited by Ca2+ influx, either via L-type voltage-gated calcium channels or via NMDA receptors. Subsequent release of Ca2+ from internal stores via ryanodine receptors is required for the secretion process. Postsynaptic NT secretion is inhibited in the presence of KN-62 ([4(2S)-2-[(5-isoquinolinylsulfonyl)methylamino]-3-oxo-3-(4-phenyl-1-piperazinyl)propyl] phenyl isoquinolinesulfonic acid ester) and KN-93 (N-[2-[[[3-(4-chlorophenyl)-2-propenyl]methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulfonamide), indicating a critical dependence on the activation of alpha-calcium-calmodulin-dependent protein kinase II (CaMKII). The cAMP/protein kinase A (PKA) signaling inhibitor Rp-cAMP-S impaired NT secretion, whereas elevation of intracellular cAMP levels was without effect. Using the Trk inhibitor k252a, we show that NT-induced NT secretion does not contribute to the NT release process at synapses, and BDNF does not induce its own secretion at postsynaptic sites. Release experiments in the presence of the fluorescence quencher bromphenol blue provide evidence for asynchronous and prolonged fusion pore opening of NT vesicles during secretion. Because fusion pore opening is fast compared with compound release, the speed of NT release seems to be limited by diffusion of NTs out of the vesicle. Together, our results reveal a strong dependence of activity-dependent postsynaptic NT secretion on Ca2+ influx, Ca2+ release from internal stores, activation of CaMKII, and intact PKA signaling, whereas Trk signaling and activation of Na+ channels is not required.
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Affiliation(s)
- Richard Kolarow
- Institute of Physiology and Pathophysiology, Johannes Gutenberg-University, 55128 Mainz, Germany, and
| | - Tanja Brigadski
- Institute of Physiology and Pathophysiology, Johannes Gutenberg-University, 55128 Mainz, Germany, and
- Institute of Physiology, Otto-von-Guericke-University, 39120 Magdeburg, Germany
| | - Volkmar Lessmann
- Institute of Physiology and Pathophysiology, Johannes Gutenberg-University, 55128 Mainz, Germany, and
- Institute of Physiology, Otto-von-Guericke-University, 39120 Magdeburg, Germany
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Heck N, Golbs A, Riedemann T, Sun JJ, Lessmann V, Luhmann HJ. Activity-Dependent Regulation of Neuronal Apoptosis in Neonatal Mouse Cerebral Cortex. Cereb Cortex 2007; 18:1335-49. [DOI: 10.1093/cercor/bhm165] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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Lang SB, Stein V, Bonhoeffer T, Lohmann C. Endogenous brain-derived neurotrophic factor triggers fast calcium transients at synapses in developing dendrites. J Neurosci 2007; 27:1097-105. [PMID: 17267564 PMCID: PMC6673203 DOI: 10.1523/jneurosci.3590-06.2007] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is involved in many aspects of the formation of functional neuronal networks. BDNF signaling regulates neuronal development not only globally, at the level of entire neurons or networks, but also at a subcellular level and with high temporal specificity; however, the spatiotemporal characteristics of intrinsic BDNF signaling are essentially unknown. Here, we used calcium imaging to directly observe intrinsic BDNF signaling in developing hippocampal neurons. We found that blocking intrinsic BDNF signaling with function-blocking BDNF antibodies (alphaBDNF) or K252-a reduced the frequency of spontaneously occurring fast and localized calcium rises in dendrites. Conversely, focal application of BDNF evoked fast and local dendritic calcium transients, which required activation of TrkB (tropomyosin-related kinase B) receptors as well as activation of voltage-gated sodium and calcium channels. Virus-mediated expression of PSD-95:CFP (postsynaptic density-95 tagged with cyan fluorescent protein) revealed that spontaneous local calcium transients occurred frequently at postsynaptic sites along the dendrite. The frequency of synaptically localized calcium transients was specifically reduced by blocking intrinsic BDNF signaling, whereas nonsynaptic calcium rises were not affected. Furthermore, focal BDNF delivery evoked localized and fast calcium elevations specifically at postsynaptic sites. Together, our results demonstrate that BDNF-dependent calcium signaling in developing hippocampal neurons is fast and occurs at synapses. These temporal and spatial characteristics of intrinsic BDNF signaling as well as its relative abundance renders BDNF an ideal signaling molecule in the establishment of specific synaptic connectivity and functional neuronal networks.
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Affiliation(s)
- Susanne B. Lang
- Max Planck Institute of Neurobiology, 82152 Martinsried-München, Germany
| | - Valentin Stein
- Max Planck Institute of Neurobiology, 82152 Martinsried-München, Germany
| | - Tobias Bonhoeffer
- Max Planck Institute of Neurobiology, 82152 Martinsried-München, Germany
| | - Christian Lohmann
- Max Planck Institute of Neurobiology, 82152 Martinsried-München, Germany
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