151
|
Klintsova AY, Dickson E, Yoshida R, Greenough WT. Altered expression of BDNF and its high-affinity receptor TrkB in response to complex motor learning and moderate exercise. Brain Res 2005; 1028:92-104. [PMID: 15518646 DOI: 10.1016/j.brainres.2004.09.003] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2004] [Indexed: 11/22/2022]
Abstract
We report that rats learning complex motor skills or exercising moderately show changes in expression of brain-derived neurotrophic factor (BDNF) and its receptor, TrkB protein, in cerebellum and motor cortex. It is now known that physical activity increases expression of some neurotrophins. We examined the time course of BDNF and TrkB expression after 1, 3, 5, 7 or 14 days in one of three conditions: (1) an "acrobatic" motor skill learning condition (AC), (2) a motor activity condition (moderately paced running on a flat track; MC) and (3) an inactive social-only control (SC) that served as a baseline group. Expression levels of BDNF and TrkB were evaluated by measuring relative optical density of the immunocytochemical reaction product. In cerebellar molecular layer, expression of BDNF correlated significantly with time spent in AC and MC over the first 7 days of training and remained elevated after 14 days of AC but not of MC. Changes in TrkB protein expression in cerebellar molecular layer mirrored those for BDNF during the first 7 days of training, but subsequently its expression subsided to the control level. In motor cortex, a significant increase in BDNF and TrkB protein expression was detected in the upper layers after 14 days in AC. Increased expression of BDNF, but not of TrkB, was observed in upper motor cortical layers after 14 days of MC. These data indicate that complex motor learning and moderate physical activity with little learning produce different effects on the expression pattern of BDNF and its receptor and may have implications for neural plasticity arising from such experiences.
Collapse
Affiliation(s)
- Anna Y Klintsova
- Department of Psychology, Binghamton University, P.O. Box 6000, NY 13902, USA.
| | | | | | | |
Collapse
|
152
|
Takayama C. GABAergic signaling in the developing cerebellum. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 71:63-94. [PMID: 16512346 DOI: 10.1016/s0074-7742(05)71003-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Chitoshi Takayama
- Department of Molecular Neuroanatomy, Hokkaido University School of Medicine, Sapporo, Japan
| |
Collapse
|
153
|
Henneberger C, Kirischuk S, Grantyn R. Brain-derived neurotrophic factor modulates GABAergic synaptic transmission by enhancing presynaptic glutamic acid decarboxylase 65 levels, promoting asynchronous release and reducing the number of activated postsynaptic receptors. Neuroscience 2005; 135:749-63. [PMID: 16154289 DOI: 10.1016/j.neuroscience.2005.06.044] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 06/10/2005] [Accepted: 06/14/2005] [Indexed: 11/28/2022]
Abstract
Brain-derived neurotrophic factor is known to modulate the function of GABAergic synapses, but the site of brain-derived neurotrophic factor action is still a matter of controversy. This study was aimed at further dissecting the functional alterations produced by brain-derived neurotrophic factor treatment of GABAergic synaptic connections in cultures of the murine superior colliculus. The functional consequences of long-term brain-derived neurotrophic factor treatment were assessed by analysis of unitary evoked and delayed inhibitory postsynaptic currents in response to high frequency stimulation of single axons. It was found that brain-derived neurotrophic factor facilitated the asynchronous release, but had no effect on the probability of evoked release, the size of the readily releasable pool, and the paired-pulse behavior of evoked inhibitory postsynaptic currents. However, the amplitudes of evoked inhibitory postsynaptic currents, delayed inhibitory postsynaptic currents and miniature inhibitory postsynaptic currents were significantly reduced. Non-stationary fluctuation analysis revealed a decrease in the open channel number at the miniature/evoked inhibitory postsynaptic current peak, but no effect on the mean GABA(A) receptor single channel conductance. Quantitative immunocytochemistry uncovered a significant elevation of presynaptic levels of glutamic acid decarboxylase 65. Together, these findings indicate that brain-derived neurotrophic factor treatment induces pre- as well as postsynaptic changes. What effect predominates will depend on the presynaptic activity pattern: at low activation rates brain-derived neurotrophic factor-treated synapses display a pronounced postsynaptic depression, but at high frequencies this depression is fully compensated by an enhancement of asynchronous release.
Collapse
Affiliation(s)
- C Henneberger
- Sensory and Developmental Physiology Group, Institute of Neurophysiology, Johannes-Mueller-Center of Physiology, Charité-University Medicine Berlin, Tucholskystr. 2, D-10117 Berlin, Germany
| | | | | |
Collapse
|
154
|
SWANWICK CATHERINECROFT, HARRISON MADALINEB, KAPUR JAIDEEP. Synaptic and extrasynaptic localization of brain-derived neurotrophic factor and the tyrosine kinase B receptor in cultured hippocampal neurons. J Comp Neurol 2004; 478:405-17. [PMID: 15384067 PMCID: PMC2892721 DOI: 10.1002/cne.20295] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) regulates synapses, but the distribution of BDNF and its receptor TrkB relative to the location of glutamatergic and gamma-aminobutyric acidergic (GABAergic) synapses is presently unknown. Immunocytochemistry was performed in primary hippocampal neuron cultures to determine whether BDNF and TrkB are preferentially localized to excitatory or inhibitory markers at 7, 14, and 21 days in vitro (DIV). Glutamatergic sites were localized with vesicular glutamate transporter type 1 (VGLUT1) as presynaptic marker and the NR1 subunit of the NMDA receptor and the GluR1 subunit of the AMPA receptor as receptor markers. GABAergic sites were labeled with the 65-kDa isoform of glutamic acid decarboxylase (GAD-65) as presynaptic marker and the gamma2 subunit of the GABAA receptor as receptor marker. During development, <30% of BDNF punctae and TrkB clusters were localized to glutamatergic and GABAergic markers. Because their rates of colocalization did not change from 7 to 21 DIV, this study details the distribution of BDNF and TrkB at 14 DIV. BDNF was preferentially colocalized with glutamatergic markers VGLUT1 and NR1 ( approximately 30% each). TrkB was also relatively highly colocalized with VGLUT1 and NR1 ( approximately 20% each) but was additionally highly colocalized with GABAergic markers GAD-65 ( approximately 20%) and gamma2 ( approximately 30%). NR1 clusters colocalized with BDNF puncta and TrkB clusters were mostly extrasynaptic, as were gamma2 clusters colocalized with TrkB clusters. These results show that, whereas most BDNF and TrkB protein is extrasynaptic, BDNF is preferentially associated with excitatory markers and that TrkB is associated equally with excitatory and inhibitory markers.
Collapse
Affiliation(s)
| | - MADALINE B. HARRISON
- Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22908
- Department of Neurology, University of Virginia, Charlottesville, Virginia 22908
| | - JAIDEEP KAPUR
- Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22908
- Department of Neurology, University of Virginia, Charlottesville, Virginia 22908
- Correspondence to: Jaideep Kapur, Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22908.
| |
Collapse
|
155
|
Pang PT, Lu B. Regulation of late-phase LTP and long-term memory in normal and aging hippocampus: role of secreted proteins tPA and BDNF. Ageing Res Rev 2004; 3:407-30. [PMID: 15541709 DOI: 10.1016/j.arr.2004.07.002] [Citation(s) in RCA: 230] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Accepted: 07/20/2004] [Indexed: 10/26/2022]
Abstract
Long-lasting forms of memory are generally believed to be mediated by protein synthesis-dependent, late-phase long-term potentiation (L-LTP). L-LTP exhibits at least two distinctive characteristics compared with early phase LTP (E-LTP): synaptic growth and requirement of gene transcription and new protein synthesis. In this review, we discuss the cellular and molecular mechanisms underlying the structural and functional changes of hippocampal synapses during L-LTP, in the context of long-term memory. We describe experiments that reveal the critical role of cAMP/protein kinase A and MAP kinase pathways, and the downstream transcription factor CREB. Because transcription-dependent long-term changes are input specific, we also discuss the role of "local protein synthesis" and "synaptic tagging" mechanisms that may confer synapse specificity. We then focus on brain-derived neurotrophic factor (BDNF) and tissue plasminogen activator (tPA), two secreted proteins that have been repeatedly implicated in L-LTP. Biochemical and molecular biology experiments indicate that the expression and secretion of both factors are enhanced by strong tetanic stimulation that induces L-LTP as well as by training in hippocampal-dependent memory tasks. Inhibition of either tPA or BDNF by gene knockout and specific inhibitors results in a significant impairments in L-LTP and long-term memory. Further work will be required to address the relationship between BDNF and tPA in various forms of synaptic plasticity, and the mechanisms by which BDNF/tPA achieves synapse-specific modulation. Finally, we discuss how the aging process affects L-LTP and long-term memory.
Collapse
Affiliation(s)
- Petti T Pang
- Section on Neural Development and Plasticity, NICHD, NIH, Building 49, Rm. 6A80, 49 Convent Dr., MSC4480 Bethesda, MD 20892-4480, USA
| | | |
Collapse
|
156
|
Givalois L, Naert G, Rage F, Ixart G, Arancibia S, Tapia-Arancibia L. A single brain-derived neurotrophic factor injection modifies hypothalamo–pituitary–adrenocortical axis activity in adult male rats. Mol Cell Neurosci 2004; 27:280-95. [PMID: 15519243 DOI: 10.1016/j.mcn.2004.07.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Revised: 07/05/2004] [Accepted: 07/08/2004] [Indexed: 01/11/2023] Open
Abstract
Immobilization stress induces in adult male rats rapid activation of brain derived neurotrophic factor (BDNF) expression in the hypothalamic paraventricular nucleus (PVN) preceding the increases in corticotropin releasing hormone (CRH) and arginin-vasopressin (AVP) expression. The BDNF mRNA signal belatedly co-localizes with CRH and AVP mRNA signals in the PVN, as determined by in situ hybridization. Intracerebroventricular BDNF injections (5 microg/rat) in non-anesthetized adult male rats induce a gradual increase in the CRH mRNA signal whereas AVP mRNA signal progressively decreases in the parvocellular and magnocellular PVN portions. At the same time, the CRH hypothalamic content decreases while the AVP content increases. These variations are accompanied by increases in ACTH and corticosterone plasma concentrations. These results strongly suggest that BDNF could be a stress-responsive intercellular messenger since when it is exogenously administered acts as an important and early component in the activation and recruitment of hypothalamic CRH and AVP neurons.
Collapse
Affiliation(s)
- Laurent Givalois
- Cerebral Plasticity Laboratory, FRE 2693 CNRS, University of Montpellier II, 34095 Montpellier, France.
| | | | | | | | | | | |
Collapse
|
157
|
Benítez-Temiño B, de la Cruz RR, Tena JJ, Pastor AM. Cerebellar grafting in the oculomotor system as a model to study target influence on adult neurons. ACTA ACUST UNITED AC 2004; 49:317-29. [PMID: 16111559 DOI: 10.1016/j.brainresrev.2004.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Revised: 08/31/2004] [Accepted: 09/15/2004] [Indexed: 11/19/2022]
Abstract
In the last decades, there have been many efforts directed to gain a better understanding on adult neuron-target cell relationships. Embryonic grafts have been used for the study of neural circuit rewiring. Thus, using several donor neuronal tissues, such as cerebellum or striatum, developing grafted cells have been shown to have the capability of substituting neural cell populations and establishing reciprocal connections with the host. In addition, different lesion paradigms have also led to a better understanding of target dependence in neuronal cells. Thus, for example, axotomy induces profound morphofunctional changes in adult neurons, including the loss of synaptic inputs and discharge alterations. These alterations are probably due to trophic factor loss in response to target disconnection. In this review, we summarize the different strategies performed to disconnect neurons from their targets, and the effects of target substitution, performed by tissue grafting, upon neural properties. Using the oculomotor system-and more precisely the abducens internuclear neurons-as a model, we describe herein the effects of disconnecting a population of central neurons from its natural target (i.e., the medial rectus motoneurons at the mesencephalic oculomotor nucleus). We also analyze target-derived influences in the structure and physiology of these neurons by using cerebellar embryonic grafts as a new target for the axotomized abducens internuclear neurons.
Collapse
Affiliation(s)
- Beatriz Benítez-Temiño
- Dept. Fisiología y Zoología, Facultad de Biología, Universidad de Sevilla, Av. Reina Mercedes, 6 41012 Sevilla, E-41012, Spain
| | | | | | | |
Collapse
|
158
|
Control of axonal branching and synapse formation by focal adhesion kinase. Nat Neurosci 2004; 7:1059-69. [PMID: 15378065 DOI: 10.1038/nn1317] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Accepted: 08/09/2004] [Indexed: 11/08/2022]
Abstract
The formation of neuronal networks in the central nervous system (CNS) requires precise control of axonal branch development and stabilization. Here we show that cell-specific ablation of the murine gene Ptk2 (more commonly known as fak), encoding focal adhesion kinase (FAK), increases the number of axonal terminals and synapses formed by neurons in vivo. Consistent with this, fak mutant neurons also form greater numbers of axonal branches in culture because they have increased branch formation and reduced branch retraction. Expression of wild-type FAK, but not that of several FAK variants that prevent interactions with regulators of Rho family GTPases including the p190 Rho guanine nuclear exchange factor (p190RhoGEF), rescues the axonal arborization phenotype observed in fak mutant neurons. In addition, expression of a mutant p190RhoGEF that cannot associate with FAK results in a phenotype very similar to that of neurons lacking FAK. Thus, FAK functions as a negative regulator of axonal branching and synapse formation, and it seems to exert its actions, in part, through Rho family GTPases.
Collapse
|
159
|
Bibel M, Richter J, Schrenk K, Tucker KL, Staiger V, Korte M, Goetz M, Barde YA. Differentiation of mouse embryonic stem cells into a defined neuronal lineage. Nat Neurosci 2004; 7:1003-9. [PMID: 15332090 DOI: 10.1038/nn1301] [Citation(s) in RCA: 337] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Accepted: 07/14/2004] [Indexed: 01/08/2023]
Abstract
Although it has long been known that cultured embryonic stem cells can generate neurons, the lineage relationships with their immediate precursors remain unclear. We report here that selection of highly proliferative stem cells followed by treatment with retinoic acid generated essentially pure precursors that markers identified as Pax-6-positive radial glial cells. As they do in vivo, these cells went on to generate neurons with remarkably uniform biochemical and electrophysiological characteristics.
Collapse
Affiliation(s)
- Miriam Bibel
- Friedrich Miescher Institute, CH-4058 Basel, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
160
|
Abstract
While the development and plasticity of excitatory synaptic connections have been studied into detail, little is known about the development of inhibitory synapses. As proposed for excitatory synapses, recent studies have indicated that activity-dependent forms of synaptic plasticity, such as long-term potentiation and long-term depression, may play a role in the establishment of functional inhibitory synaptic connections. Here, I review these different forms of plasticity and focus on their possible role in the developing neuronal network.
Collapse
Affiliation(s)
- J-L Gaïarsa
- Institut de Neurobiologie de la Méditerranée (INMED), Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 29, Marseille, France.
| |
Collapse
|
161
|
Dezawa M, Kanno H, Hoshino M, Cho H, Matsumoto N, Itokazu Y, Tajima N, Yamada H, Sawada H, Ishikawa H, Mimura T, Kitada M, Suzuki Y, Ide C. Specific induction of neuronal cells from bone marrow stromal cells and application for autologous transplantation. J Clin Invest 2004. [PMID: 15199405 DOI: 10.1172/jci200420935] [Citation(s) in RCA: 468] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Bone marrow stromal cells (MSCs) have the capability under specific conditions of differentiating into various cell types such as osteocytes, chondrocytes, and adipocytes. Here we demonstrate a highly efficient and specific induction of cells with neuronal characteristics, without glial differentiation, from both rat and human MSCs using gene transfection with Notch intracellular domain (NICD) and subsequent treatment with bFGF, forskolin, and ciliary neurotrophic factor. MSCs expressed markers related to neural stem cells after transfection with NICD, and subsequent trophic factor administration induced neuronal cells. Some of them showed voltage-gated fast sodium and delayed rectifier potassium currents and action potentials compatible with characteristics of functional neurons. Further treatment of the induced neuronal cells with glial cell line-derived neurotrophic factor (GDNF) increased the proportion of tyrosine hydroxylase-positive and dopamine-producing cells. Transplantation of these GDNF-treated cells showed improvement in apomorphine-induced rotational behavior and adjusting step and paw-reaching tests following intrastriatal implantation in a 6-hydroxy dopamine rat model of Parkinson disease. This study shows that a population of neuronal cells can be specifically generated from MSCs and that induced cells may allow for a neuroreconstructive approach.
Collapse
Affiliation(s)
- Mari Dezawa
- Department of Anatomy and Neurobiology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
162
|
Molteni R, Zheng JQ, Ying Z, Gómez-Pinilla F, Twiss JL. Voluntary exercise increases axonal regeneration from sensory neurons. Proc Natl Acad Sci U S A 2004; 101:8473-8. [PMID: 15159540 PMCID: PMC420418 DOI: 10.1073/pnas.0401443101] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Recent advances in understanding the role of neurotrophins on activity-dependent plasticity have provided insight into how behavior can affect specific aspects of neuronal biology. We present evidence that voluntary exercise can prime adult dorsal root ganglion neurons for increased axonal regeneration through a neurotrophin-dependent mechanism. Dorsal root ganglion neurons showed an increase in neurite outgrowth when cultured from animals that had undergone 3 or 7 days of exercise compared with sedentary animals. Neurite length over 18-22 h in culture correlated directly with the distance that animals ran. The exercise-conditioned animals also showed enhanced regrowth of axons after an in vivo nerve crush injury. Sensory ganglia from the 3- and 7-day-exercised animals contained higher brain-derived neurotrophic factor, neurotrophin 3, synapsin I, and GAP43 mRNA levels than those from sedentary animals. Consistent with the rise in brain-derived neurotrophic factor and neurotrophin 3 during exercise, the increased growth potential of the exercise-conditioned animals required activation of the neurotrophin signaling in vivo during the exercise period but did not require new mRNA synthesis in culture.
Collapse
Affiliation(s)
- Raffaella Molteni
- Department of Neurosurgery, University of California, Los Angeles, CA 90095, USA
| | | | | | | | | |
Collapse
|
163
|
Affiliation(s)
- Carlos Vicario‐Abejón
- Centro de Investigaciones Biológicas, Censejo Superior de Investigaciones Cientificas Madrid Spain
| |
Collapse
|
164
|
Hans A, Bajramovic JJ, Syan S, Perret E, Dunia I, Brahic M, Gonzalez-Dunia D. Persistent, non‐cytolytic infection of neurons by Borna disease virus interferes with ERK 1/2 signaling and abrogates BDNF‐induced synaptogenesis. FASEB J 2004; 18:863-5. [PMID: 15033926 DOI: 10.1096/fj.03-0764fje] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Infection of the central nervous system by Borna disease virus (BDV) provides a unique model to study the mechanisms whereby a persistent viral infection can impair neuronal function and cause behavioral diseases reminiscent of mood disorders, schizophrenia, or autism in humans. In the present work, we studied the effect of BDV infection on the response of hippocampal neurons, the main target for this virus, to the neurotrophin BDNF. We showed that persistent infection did not affect neuronal survival or morphology. However, it blocked BDNF-induced ERK 1/2 phosphorylation, despite normal expression of the TrkB BDNF receptor. In addition, BDNF-induced expression of synaptic vesicle proteins was abrogated, which resulted in severely impaired synaptogenesis and defects in synaptic organization. Thus, we provide the first evidence that a virus can interfere specifically with neurotrophin-regulated neuroplasticity, thereby hampering proper neuronal connectivity. These results may help to understand the behavioral disorders associated with BDV infection.
Collapse
Affiliation(s)
- Aymeric Hans
- Unité des Virus Lents, CNRS URA 1930, Institut Pasteur, Paris, France
| | | | | | | | | | | | | |
Collapse
|
165
|
Palizvan MR, Sohya K, Kohara K, Maruyama A, Yasuda H, Kimura F, Tsumoto T. Brain-derived neurotrophic factor increases inhibitory synapses, revealed in solitary neurons cultured from rat visual cortex. Neuroscience 2004; 126:955-66. [PMID: 15207329 DOI: 10.1016/j.neuroscience.2004.03.053] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2004] [Indexed: 11/30/2022]
Abstract
To elucidate chronic actions of brain-derived neurotrophic factor (BDNF) on GABAergic synapses, we examined effects of a long-term application of BDNF for 10-15 days on autapses (synapses) of solitary GABAergic neurons cultured from rat visual cortex. Solitary neuron preparations were used to exclude a possible contamination of BDNF actions on excitatory neurons in dissociated neuron culture or slice preparations. Neurons were confirmed to be GABAergic pharmacologically with bicuculline, a selective antagonist for GABAA receptors and immunocytochemically with antibody against glutamic acid decarboxylase 65, a GABA synthesizing enzyme. To evaluate GABAergic synaptic function, evoked and/or miniature inhibitory postsynaptic currents (IPSCs) were recorded in the whole-cell voltage-clamp mode. The treatment with BDNF at a concentration of 100 ng/ml enhanced the amplitude of evoked IPSCs and the frequency of miniature IPSCs. In contrast, BDNF did not have a detectable effect on the amplitude of miniature IPSCs and the paired pulse ratio of IPSCs evoked by two, successive activations. To evaluate morphological changes, neurons were immunocytochemically stained with antibodies against microtubule-associated protein 2, to visualize somatodendritic region and synapsin I, to visualize presynaptic sites. The quantitative analysis indicated that BDNF increased the area of soma, the numbers of primary dendrites and dendritic branching points, the total length of dendrites and the number of synaptic sites. Such an action of BDNF was seen in both subgroups of GABAergic neurons, parvalbumin-positive and -negative neurons. To visualize functionally active presynaptic sites, neurons were stained with a styryl dye, FM1-43. BDNF increased the number of stained sites that was correlated with the frequency of miniature IPSCs. These results suggest that the chronic treatment with BDNF promotes dendritic and synaptic development of GABAergic neurons in visual cortex.
Collapse
Affiliation(s)
- M R Palizvan
- Division of Neurophysiology, Osaka University Graduate School of Medicine (D-14), Suita, Japan
| | | | | | | | | | | | | |
Collapse
|
166
|
Abstract
While it has now been well accepted that neurotrophins play an important role in synapse development and plasticity, the specific effects of each neurotrophin on different populations of neurons at different developmental stages have just begun to be worked out. Moreover, the cellular and molecular mechanisms underlying the synaptic function of neurotrophins remain poorly understood. In general, synaptic effects of neurotrophins could be divided into two categories: acute effect on synaptic transmission and plasticity occurring within seconds or minutes after cells are exposed to a neurotrophin, and long-term effect on synaptic structures and function that takes days to accomplish. In this review I have considered the previous findings on neurotrophic regulation of synapses in view of these two categories. Acute and long-term effects of neurotrophins are reexamined in detail in three model systems: the neuromuscular junction, the hippocampus and the visual cortex. Potential molecular mechanisms that mediate the acute or long-term neurotrophic regulation are discussed. Efforts are made to understand the mechanistic differences between the two effects and their relationships. Further study of these mechanisms will help us better understand how neurotrophins can achieve diverse and synapse-specific modulation.
Collapse
Affiliation(s)
- Bai Lu
- Section on Neural Development and Plasticity, NICHD, NIH, Building 49, Rm. 6A80, 49 Convent Dr., MSC4480, Bethesda, MD 20892-4480, USA.
| |
Collapse
|
167
|
Guillin O, Griffon N, Bezard E, Leriche L, Diaz J, Gross C, Sokoloff P. Brain-derived neurotrophic factor controls dopamine D3 receptor expression: therapeutic implications in Parkinson's disease. Eur J Pharmacol 2003; 480:89-95. [PMID: 14623353 DOI: 10.1016/j.ejphar.2003.08.096] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) belongs to a family of proteins related to nerve growth factor, which are responsible for neuron proliferation, survival and differentiation. A more diverse role for BDNF as a neuronal extracellular transmitter has, nevertheless, been proposed. Here we show that BDNF synthesized by dopamine neurons is responsible for the appearance of the dopamine D3 receptor during development and maintains its expression in adults. Moreover, BDNF triggers behavioral sensitization to levodopa in hemiparkinsonian rats. In monkeys rendered parkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which develop levodopa-induced dyskinesia, we show an overexpression of this receptor. Administration of a dopamine D3 receptor-selective partial agonist strongly attenuated levodopa-induced dyskinesia, while leaving unaffected the therapeutic effect of levodopa. These results suggest that the dopamine D3 receptor participates in both dyskinesia and the therapeutic action of levodopa and that partial agonists may normalize dopamine D3 receptor function and correct side-effects of levodopa therapy in PD patients.
Collapse
Affiliation(s)
- Olivier Guillin
- Unité de Neurobiologie et Pharmacologie Moléculaire, INSERM U 573, Centre Paul Broca, 2 ter rue d'Alésia, 75014, Paris, France.
| | | | | | | | | | | | | |
Collapse
|
168
|
Abstract
The mechanisms that govern synapse formation and elimination are fundamental to our understanding of neural development and plasticity. The wiring of neural circuitry requires that vast numbers of synapses be formed in a relatively short time. The subsequent refinement of neural circuitry involves the formation of additional synapses coincident with the disassembly of previously functional synapses. There is increasing evidence that activity-dependent plasticity also involves the formation and disassembly of synapses. While we are gaining insight into the mechanisms of both synapse assembly and disassembly, we understand very little about how these phenomena are related to each other and how they might be coordinately controlled to achieve the precise patterns of synaptic connectivity in the nervous system. Here, we review our current understanding of both synapse assembly and disassembly in an effort to unravel the relationship between these fundamental developmental processes.
Collapse
Affiliation(s)
- Yukiko Goda
- MRC Cell Biology Unit and Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom.
| | | |
Collapse
|
169
|
Kohara K, Kitamura A, Adachi N, Nishida M, Itami C, Nakamura S, Tsumoto T. Inhibitory but not excitatory cortical neurons require presynaptic brain-derived neurotrophic factor for dendritic development, as revealed by chimera cell culture. J Neurosci 2003; 23:6123-31. [PMID: 12853431 PMCID: PMC6740357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
To address questions of whether endogenous BDNF acts differentially on inhibitory and excitatory neurons, and through what routes, we used chimera culture of cerebral cortical neurons derived from BDNF-/- mice and another type of transgenic mice that express green fluorescence protein and BDNF. Presynaptic BDNF transferred to both types of neurons, GABA-synthesizing enzyme-positive and -negative neurons. The latter neurons were confirmed to be glutamatergic with immunocytochemistry. Dendritic development of the former inhibitory neurons was promoted by endogenous BDNF transferred from presynaptic, excitatory neurons. In contrast, dendritic development of excitatory neurons was not related to the presence or absence of presynaptic BDNF, suggesting that BDNF acts on inhibitory neurons through an anterograde, transsynaptic route so as to promote dendritic development, whereas this is not the case in excitatory neurons.
Collapse
Affiliation(s)
- Keigo Kohara
- Division of Neurophysiology, Osaka University Graduate School of Medicine, Suita 565-0871, Japan
| | | | | | | | | | | | | |
Collapse
|
170
|
Jin X, Hu H, Mathers PH, Agmon A. Brain-derived neurotrophic factor mediates activity-dependent dendritic growth in nonpyramidal neocortical interneurons in developing organotypic cultures. J Neurosci 2003; 23:5662-73. [PMID: 12843269 PMCID: PMC6741232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) promotes postnatal maturation of GABAergic inhibition in the cerebral and cerebellar cortices, and its expression and release are enhanced by neuronal activity, suggesting that it acts in a feedback manner to maintain a balance between excitation and inhibition during development. BDNF promotes differentiation of cerebellar, hippocampal, and neostriatal inhibitory neurons, but its effects on the dendritic development of neocortical inhibitory interneurons remain unknown. Here, we show that BDNF mediates depolarization-induced dendritic growth and branching in neocortical interneurons. To visualize inhibitory interneurons, we biolistically transfected organotypic cortical slice cultures from neonatal mice with green fluorescent protein (GFP) driven by the glutamic acid decarboxylase (GAD)67 promoter. Nearly all GAD67-GFP-expressing neurons were nonpyramidal, many contained GABA, and some expressed markers of neurochemically defined GABAergic subtypes, indicating that GAD67-GFP-expressing neurons were GABAergic. We traced dendritic trees from confocal images of the same GAD67-GFP-expressing neurons before and after a 5 d growth period, and quantified the change in total dendritic length (TDL) and total dendritic branch points (TDBPs) for each neuron. GAD67-GFP-expressing neurons growing in control medium exhibited a 20% increase in TDL, but in 200 ng/ml BDNF or 10 mm KCl, this increase nearly doubled and was accompanied by a significant increase in TDBPs. Blocking action potentials with TTX did not prevent the BDNF-induced growth, but antibodies against BDNF blocked the growth-promoting effect of KCl. We conclude that BDNF, released by neocortical pyramidal neurons in response to depolarization, enhances dendritic growth and branching in nearby inhibitory interneurons.
Collapse
Affiliation(s)
- Xiaoming Jin
- Department of Neurobiology and Anatomy, West Virginia University, Morgantown, West Virginia 26506-9128, USA
| | | | | | | |
Collapse
|
171
|
Lu D, Mahmood A, Chopp M. Biologic Transplantation and Neurotrophin-Induced Neuroplasticity After Traumatic Brain Injury. J Head Trauma Rehabil 2003; 18:357-76. [PMID: 16222130 DOI: 10.1097/00001199-200307000-00006] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVE In this review, we analyze progress in the treatment of traumatic brain injury with neurotrophins, growth factors and cell and tissue neurotransplantation. The primary objective of these therapies is to reduce neurologic deficits associated with the trauma by inducing neuroplasticity. These therapies are restorative and not necessarily neuroprotective. MAIN OUTCOME MEASURES An extensive literature on administration of neurotrophics factors and cell and tissue cerebral transplantation is reviewed. The effects of these therapeutic approaches on brain biochemical, molecular, cellular, and tissue responses are summarized. CONCLUSION The cumulative data indicate that cell therapy shows substantial promise in the treatment of neural injury.
Collapse
Affiliation(s)
- Dunyue Lu
- Department of Neurosurgery, Henry Ford Health System, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI 48202, USA
| | | | | |
Collapse
|
172
|
Duan W, Guo Z, Jiang H, Ware M, Mattson MP. Reversal of behavioral and metabolic abnormalities, and insulin resistance syndrome, by dietary restriction in mice deficient in brain-derived neurotrophic factor. Endocrinology 2003; 144:2446-53. [PMID: 12746306 DOI: 10.1210/en.2002-0113] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Dietary restriction (DR) extends life span and improves glucose metabolism in mammals. Recent studies have shown that DR stimulates the production of brain-derived neurotrophic factor (BDNF) in brain cells, which may mediate neuroprotective and neurogenic actions of DR. Other studies have suggested a role for central BDNF signaling in the regulation of glucose metabolism and body weight. BDNF heterozygous knockout (BDNF+/-) mice are obese and exhibit features of insulin resistance. We now report that an intermittent fasting DR regimen reverses several abnormal phenotypes of BDNF(+/-) mice including obesity, hyperphagia, and increased locomotor activity. DR increases BDNF levels in the brains of BDNF(+/-) mice to the level of wild-type mice fed ad libitum. BDNF(+/-) mice exhibit an insulin-resistance syndrome phenotype characterized by elevated levels of circulating glucose, insulin, and leptin; DR reduces levels of each of these three factors. DR normalizes blood glucose responses in glucose tolerance and insulin tolerance tests in the BDNF(+/-) mice. These findings suggest that BDNF is a major regulator of energy metabolism and that beneficial effects of DR on glucose metabolism are mediated, in part, by BDNF signaling. Dietary and pharmacological manipulations of BDNF signaling may prove useful in the prevention and treatment of obesity and insulin resistance syndrome-related diseases.
Collapse
Affiliation(s)
- Wenzhen Duan
- Laboratory of Neurosciences, National Institute on Aging Gerontology Research Center, Baltimore, Maryland 21224, USA
| | | | | | | | | |
Collapse
|
173
|
Segal M, Greenberger V, Korkotian E. Formation of dendritic spines in cultured striatal neurons depends on excitatory afferent activity. Eur J Neurosci 2003; 17:2573-85. [PMID: 12823464 DOI: 10.1046/j.1460-9568.2003.02696.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The role of afferent innervation in the formation of dendritic spines was studied in cultured rat striatum. The striatum is a unique structure in that it contains highly spiny GABAergic projection neurons, with no known local excitation. Grown alone in culture, striatal neurons did not express spontaneous network activity and were virtually devoid of dendritic spines. Adding GFP-expressing mouse cortical neurons to the striatal culture caused the appearance of spontaneous and evoked excitatory synaptic currents in the striatal neurons and a 10-fold increase in the density of spines on their dendrites. This effect was blocked by a continuous presence of TTX in the growth medium, while removal of the drug caused a rapid appearance of spines. Exposure to glutamate, or the presence of cortex-conditioned medium did not mimic the effect of cortical neurons on formation of spines in the striatal neurons. Also, the cortical innervation did not cause a selective enhancement of survival of specific subtypes of spiny striatal neurons. These experiments demonstrate that excitatory afferents are necessary for the formation of dendritic spines in striatal neurons.
Collapse
Affiliation(s)
- Menahem Segal
- Department of Neurobiology, The Weizmann Institute, Rehovot 76100, Israel.
| | | | | |
Collapse
|
174
|
Munno DW, Prince DJ, Syed NI. Synapse number and synaptic efficacy are regulated by presynaptic cAMP and protein kinase A. J Neurosci 2003; 23:4146-55. [PMID: 12764102 PMCID: PMC6741068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023] Open
Abstract
The mechanisms by which neurons regulate the number and strength of synapses during development and synaptic plasticity have not yet been defined fully. This lack of fundamental knowledge in the fields of neurodevelopment and synaptic plasticity can be attributed, in part, to compensatory mechanisms by which neurons accommodate for the loss of function in their synaptic partners. This is generally achieved either by scaling up neuronal transmitter release capabilities or by enhancing the postsynaptic responsiveness. Here, we demonstrate that regulation of synaptic strength and number between identified Lymnaea neurons visceral dorsal 4 (VD4, the presynaptic cell) and left pedal dorsal 1 (LPeD1, the postsynaptic cell) requires presynaptic activation of a cAMP-PKA-dependent signal. Experimental activation of the cAMP-PKA pathway resulted in reduced synaptic efficacy, whereas inhibition of the cAMP-PKA cascade permitted hyperinnervation and an overall enhancement of synaptic strength. Because synaptic transmission between VD4 and LPeD1 does not require a cAMP-PKA pathway, our data show that these messengers may play a novel role in regulating the synaptic efficacy during early synaptogenesis and plasticity.
Collapse
Affiliation(s)
- David W Munno
- Respiratory Research Group, Faculty of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1 Canada
| | | | | |
Collapse
|
175
|
Abstract
The mammalian cerebral cortex requires the proper formation of exquisitely precise circuits to function correctly. These neuronal circuits are assembled during development by the formation of synaptic connections between hundreds of thousands of differentiating neurons. Although the development of the cerebral cortex has been well described anatomically, the cellular and molecular mechanisms that guide neuronal differentiation and formation of connections are just beginning to be understood. Moreover, despite evidence that coordinated patterns of activity underlie reorganization of brain circuits during critical periods of development, the molecular signals that translate activity into structural and functional changes in connections remain unknown. Recently, the neurotrophins have emerged as attractive candidates not only for regulating neuronal differentiation in the developing brain, but also for mediating activity-dependent synaptic plasticity. The neurotrophins meet many of the criteria required for molecular signals involved in neuronal differentiation and plasticity. They are present in the cerebral cortex during development and their expression is regulated by synaptic activity. In turn, the neurotrophins themselves strongly influence both short-term synaptic plasticity and long-term potentiation and depression. In addition to their functional effects, the neurotrophins also profoundly regulate the structural changes that underlie axonal and dendritic differentiation. Finally, the neurotrophins have been implicated in mediating synaptic competition required for activity-dependent plasticity during the critical period. This chapter presents and discusses the rapidly accumulating evidence that the neurotrophins are critical for neuronal differentiation and that they may be involved in activity-dependent synaptic refinement in the developing cerebral cortex.
Collapse
Affiliation(s)
- A Kimberley McAllister
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, California 95616, USA
| |
Collapse
|
176
|
Aguado F, Carmona MA, Pozas E, Aguiló A, Martínez-Guijarro FJ, Alcantara S, Borrell V, Yuste R, Ibañez CF, Soriano E. BDNF regulates spontaneous correlated activity at early developmental stages by increasing synaptogenesis and expression of the K+/Cl- co-transporter KCC2. Development 2003; 130:1267-80. [PMID: 12588844 DOI: 10.1242/dev.00351] [Citation(s) in RCA: 216] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Spontaneous neural activity is a basic property of the developing brain, which regulates key developmental processes, including migration, neural differentiation and formation and refinement of connections. The mechanisms regulating spontaneous activity are not known. By using transgenic embryos that overexpress BDNF under the control of the nestin promoter, we show here that BDNF controls the emergence and robustness of spontaneous activity in embryonic hippocampal slices. Further, BDNF dramatically increases spontaneous co-active network activity, which is believed to synchronize gene expression and synaptogenesis in vast numbers of neurons. In fact, BDNF raises the spontaneous activity of E18 hippocampal neurons to levels that are typical of postnatal slices. We also show that BDNF overexpression increases the number of synapses at much earlier stages (E18) than those reported previously. Most of these synapses were GABAergic, and GABAergic interneurons showed hypertrophy and a 3-fold increase in GAD expression. Interestingly, whereas BDNF does not alter the expression of GABA and glutamate ionotropic receptors, it does raise the expression of the recently cloned K(+)/Cl(-) KCC2 co-transporter, which is responsible for the conversion of GABA responses from depolarizing to inhibitory, through the control of the Cl(-) potential. Together, results indicate that both the presynaptic and postsynaptic machineries of GABAergic circuits may be essential targets of BDNF actions to control spontaneous activity. The data indicate that BDNF is a potent regulator of spontaneous activity and co-active networks, which is a new level of regulation of neurotrophins. Given that BDNF itself is regulated by neuronal activity, we suggest that BDNF acts as a homeostatic factor controlling the emergence, complexity and networking properties of spontaneous networks.
Collapse
Affiliation(s)
- Fernando Aguado
- Department of Cell Biology Faculty of Biology, and Barcelona Science Park, University of Barcelona, Barcelona 08028, Spain
| | | | | | | | | | | | | | | | | | | |
Collapse
|
177
|
Abstract
1. Neural stem cells can be cultured from the CNS of different mammalian species at many stages of development. They have an extensive capacity for self-renewal and will proliferate ex vivo in response to mitogenic growth factors or following genetic modification with immortalising oncogenes. Neural stem cells are multipotent since their differentiating progeny will give rise to the principal cellular phenotypes comprising the mature CNS: neurons, astrocytes and oligodendrocytes. 2. Neural stem cells can also be derived from more primitive embryonic stem (ES) cells cultured from the blastocyst. ES cells are considered to be pluripotent since they can give rise to the full cellular spectrum and will, therefore, contribute to all three of the embryonic germ layers: endoderm, mesoderm and ectoderm. However, pluripotent cells have also been derived from germ cells and teratocarcinomas (embryonal carcinomas) and their progeny may also give rise to the multiple cellular phenotypes contributing to the CNS. In a recent development, ES cells have also been isolated and grown from human blastocysts, thus raising the possibility of growing autologous stem cells when combined with nuclear transfer technology. 3. There is now an emerging recognition that the adult mammalian brain, including that of primates and humans, harbours stem cell populations suggesting the existence of a previously unrecognised neural plasticity to the mature CNS, and thereby raising the possibility of promoting endogenous neural reconstruction. 4. Such reports have fuelled expectations for the clinical exploitation of neural stem cells in cell replacement or recruitment strategies for the treatment of a variety of human neurological conditions including Parkinson's disease (PD), Huntington's disease, multiple sclerosis and ischaemic brain injury. Owing to their migratory capacity within the CNS, neural stem cells may also find potential clinical application as cellular vectors for widespread gene delivery and the expression of therapeutic proteins. In this regard, they may be eminently suitable for the correction of genetically-determined CNS disorders and in the management of certain tumors responsive to cytokines. Since large numbers of stem cells can be generated efficiently in culture, they may obviate some of the technical and ethical limitations associated with the use of fresh (primary) embryonic neural tissue in current transplantation strategies. 5. While considerable recent progress has been made in terms of developing new techniques allowing for the long-term culture of human stem cells, the successful clinical application of these cells is presently limited by our understanding of both (i) the intrinsic and extrinsic regulators of stem cell proliferation and (ii) those factors controlling cell lineage determination and differentiation. Although such cells may also provide accessible model systems for studying neural development, progress in the field has been further limited by the lack of suitable markers needed for the identification and selection of cells within proliferating heterogeneous populations of precursor cells. There is a further need to distinguish between the committed fate (defined during normal development) and the potential specification (implying flexibility of fate through manipulation of its environment) of stem cells undergoing differentiation. 6. With these challenges lying ahead, it is the opinion of the authors that stem-cell therapy is likely to remain within the experimental arena for the foreseeable future. In this regard, few (if any) of the in vivo studies employing neural stem cell grafts have shown convincingly that behavioural recovery can be achieved in the various model paradigms. Moreover, issues relating to the quality control of cultured cells and their safety following transplantation have only begun to be addressed. 7. While on the one hand cell biotechnologists have been quick to realise the potential commercial value, human stem cell research and its clinical applications has been the subject of intense ethical and legislative considerations. The present chapter aims to review some recent aspects of stem cell research applicable to developmental neurobiology and the potential applications in clinical neuroscience.
Collapse
Affiliation(s)
- T Ostenfeld
- MRC Centre for Brain Repair, University of Cambridge, Cambridge, UK
| | | |
Collapse
|
178
|
Abstract
It is widely accepted that neuronal activity plays a pivotal role in synaptic plasticity. Neurotrophins have emerged recently as potent factors for synaptic modulation. The relationship between the activity and neurotrophic regulation of synapse development and plasticity, however, remains unclear. A prevailing hypothesis is that activity-dependent synaptic modulation is mediated by neurotrophins. An important but unresolved issue is how diffusible molecules such as neurotrophins achieve local and synapse-specific modulation. In this review, I discuss several potential mechanisms with which neuronal activity could control the synapse-specificity of neurotrophin regulation, with particular emphasis on BDNF. Data accumulated in recent years suggest that neuronal activity regulates the transcription of BDNF gene, the transport of BDNF mRNA and protein into dendrites, and the secretion of BDNF protein. There is also evidence for activity-dependent regulation of the trafficking of the BDNF receptor, TrkB, including its cell surface expression and ligand-induced endocytosis. Further study of these mechanisms will help us better understand how neurotrophins could mediate activity-dependent plasticity in a local and synapse-specific manner.
Collapse
Affiliation(s)
- Bai Lu
- Section on Neural Development and Plasticity, National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland 20892-4480, USA.
| |
Collapse
|
179
|
Carmona MA, Martínez A, Soler A, Blasi J, Soriano E, Aguado F. Ca(2+)-evoked synaptic transmission and neurotransmitter receptor levels are impaired in the forebrain of trkb (-/-) mice. Mol Cell Neurosci 2003; 22:210-26. [PMID: 12676531 DOI: 10.1016/s1044-7431(03)00038-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
To determine the in vivo targets of long-lasting actions of TrkB signaling on synaptic function we analyze synaptic components of excitatory and inhibitory circuits in the cerebral cortex of trkB (-/-) mice. First, we show that K(+)-evoked glutamate and GABA release from forebrain mutant synaptosomes was decreased. Moreover, the dependence of regulated exocytosis on the SNARE SNAP-25 and the Ca(2+)-dependent neurotransmitter release were also impaired in trkB (-/-) mice. We also analyzed postsynaptic glutamate and GABA(A) ionotropic receptors in cortical areas of trkB mutant mice. By using Western blot we observed decreased levels of the AMPA receptor subunits GluR2/3 and GluR4 in trkB (-/-) forebrains. In contrast, the forebrain of mutant mice exhibited increased levels of the GABA(A) receptor subunit alpha3 and alpha5 and a reduction of the gamma2 subunit. Immunocytochemical analysis showed that the hippocampus and neocortex of mutant mice exhibited decreased numbers of interneurons positive for distinct AMPA and GABA(A) receptor subunits. Furthermore, alteration of inhibitory circuits in trkB (-/-) mice was also shown by the low expression of the GABA-synthesizing enzyme glutamic acid decarboxylase in mutant cortical areas. The present results indicate that long-lasting TrkB signaling is required for the precise adjustment of neurotransmitter release and for the correct composition of the fast glutamatergic and GABAergic receptor subunits in vivo.
Collapse
MESH Headings
- Animals
- Calcium Signaling/drug effects
- Calcium Signaling/genetics
- Female
- Glutamate Decarboxylase/genetics
- Glutamic Acid/metabolism
- Immunohistochemistry
- Interneurons/drug effects
- Interneurons/metabolism
- Male
- Membrane Proteins/drug effects
- Membrane Proteins/metabolism
- Mice
- Mice, Knockout
- Microscopy, Electron
- Nerve Tissue Proteins/drug effects
- Nerve Tissue Proteins/metabolism
- Neural Inhibition/drug effects
- Neural Inhibition/genetics
- Potassium/pharmacology
- Presynaptic Terminals/drug effects
- Presynaptic Terminals/metabolism
- Presynaptic Terminals/ultrastructure
- Prosencephalon/drug effects
- Prosencephalon/metabolism
- Prosencephalon/ultrastructure
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Receptor, trkB/deficiency
- Receptor, trkB/genetics
- Receptors, AMPA/drug effects
- Receptors, AMPA/metabolism
- Receptors, GABA-A/drug effects
- Receptors, GABA-A/metabolism
- Receptors, Neurotransmitter/metabolism
- Synaptic Membranes/drug effects
- Synaptic Membranes/metabolism
- Synaptic Membranes/ultrastructure
- Synaptic Transmission/drug effects
- Synaptic Transmission/genetics
- Synaptosomal-Associated Protein 25
- Synaptosomes
- gamma-Aminobutyric Acid/metabolism
Collapse
Affiliation(s)
- Maria A Carmona
- Department of Cell Biology and Barcelona Science Park, University of Barcelona, 08028, Barcelona, Spain
| | | | | | | | | | | |
Collapse
|
180
|
Moriguchi A, Nakano K, Yamaguchi I, Sano K, Noda K, Hashimoto M, Ohara K, Matsuoka N, Goto T. FK960, a potential anti-dementia drug, increases synaptic density in the hippocampal CA3 region of aged rats. Brain Res 2002; 958:381-9. [PMID: 12470874 DOI: 10.1016/s0006-8993(02)03686-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
There is accumulating evidence suggesting that synapse formation in the adult brain is dynamically regulated, and that this regulation plays a role in cognitive function. A decrease in synaptic density is reportedly related to memory deficits in aged animals as well as in Alzheimer's patients. FK960 [N-(4-acetyl-1-piperazinyl)-p-fluorobenzamide monohydrate], a novel anti-dementia drug, has been shown to ameliorate experimental amnesia in rats and monkeys through activation of the somatostatinergic nervous system in the hippocampus. Furthermore, FK960 has been shown to be considerably more effective in a model of spontaneous amnesia in aged rats than cholinesterase inhibitors. In the present electron microscopy study, we demonstrated that the density of axodendritic and axosomatic synapses in the hippocampal CA3 region of aged rats was reduced compared to young rats, and that repeated treatment with FK960 for either 3 or 21 days dose-dependently reversed these deficits in aged rats. This FK960-induced increase in synaptic density was transient and density returned to basal levels at 8 days after the final dose. In contrast, FK960 did not alter synaptic density in the cingulate cortex or hippocampal CA1 region in aged rats, nor the CA3 region of young rats. Collectively, these results suggest that FK960 can selectively and reversibly increase synaptic density in the hippocampal CA3 region of aged rats, and that this activity may play a role in its cognitive-enhancing action.
Collapse
Affiliation(s)
- Akira Moriguchi
- Medicinal Biology Research Laboratories, Fujisawa Pharmaceutical Co Ltd, 2-1-6 Kashima, Yodogawa-ku, Osaka 532-8514, Japan.
| | | | | | | | | | | | | | | | | |
Collapse
|
181
|
Segal M. Dendritic spines: elementary structural units of neuronal plasticity. PROGRESS IN BRAIN RESEARCH 2002; 138:53-9. [PMID: 12432762 DOI: 10.1016/s0079-6123(02)38070-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- Menahem Segal
- Department of Neurobiology, Weizmann Institute, Rehovot 76100, Israel.
| |
Collapse
|
182
|
Huberman AD, McAllister AK. Neurotrophins and visual cortical plasticity. PROGRESS IN BRAIN RESEARCH 2002; 138:39-51. [PMID: 12432761 DOI: 10.1016/s0079-6123(02)38069-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Andrew D Huberman
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95616, USA
| | | |
Collapse
|
183
|
Vicario-Abejón C, Owens D, McKay R, Segal M. Role of neurotrophins in central synapse formation and stabilization. Nat Rev Neurosci 2002; 3:965-74. [PMID: 12461553 DOI: 10.1038/nrn988] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Carlos Vicario-Abejón
- Group of Growth Factors in Vertebrate Development, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, E-28006 Madrid, Spain.
| | | | | | | |
Collapse
|
184
|
Baldelli P, Novara M, Carabelli V, Hernández-Guijo JM, Carbone E. BDNF up-regulates evoked GABAergic transmission in developing hippocampus by potentiating presynaptic N- and P/Q-type Ca2+ channels signalling. Eur J Neurosci 2002; 16:2297-310. [PMID: 12492424 DOI: 10.1046/j.1460-9568.2002.02313.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Chronic application of brain-derived neurotrophic factor (BDNF) induces new selective synthesis of non-L-type Ca2+ channels (N, P/Q, R) at the soma of cultured hippocampal neurons. As N- and P/Q-channels support neurotransmitter release in the hippocampus, this suggests that BDNF-treatment may enhance synaptic transmission by increasing the expression of presynaptic Ca2+ channels as well. To address this issue we studied the long-term effects of BDNF on miniature and stimulus-evoked GABAergic transmission in rat embryo hippocampal neurons. We found that BDNF increased the frequency of miniature currents (mIPSCs) by approximately 40%, with little effects on their amplitude. BDNF nearly doubled the size of evoked postsynaptic currents (eIPSCs) with a marked increase of paired-pulse depression, which is indicative of a major increase in presynaptic activity. The potentiation of eIPSCs was more relevant during the first two weeks in culture, when GABAergic transmission is depolarizing. BDNF action was mediated by TrkB-receptors and had no effects on: (i) the amplitude and dose-response of GABA-evoked IPSCs and (ii) the number of GABA(A) receptor clusters and the total functioning synapses, suggesting that the neurotrophin unlikely acted postsynaptically. In line with this, BDNF affected the contribution of voltage-gated Ca2+ channels mediating evoked GABAergic transmission. BDNF drastically increased the fraction of evoked IPSCs supported by N- and P/Q-channels while it decreased the contribution associated with R- and L-types. This selective action resembles the previously observed up-regulatory effects of BDNF on somatic Ca2+ currents in developing hippocampus, suggesting that potentiation of presynaptic N- and P/Q-channel signalling belongs to a manifold mechanism by which BDNF increases the efficiency of stimulus-evoked GABAergic transmission.
Collapse
MESH Headings
- Animals
- Brain-Derived Neurotrophic Factor/metabolism
- Brain-Derived Neurotrophic Factor/pharmacology
- Calcium Channel Blockers/pharmacology
- Calcium Channels/drug effects
- Calcium Channels/metabolism
- Calcium Channels, N-Type/drug effects
- Calcium Channels, N-Type/metabolism
- Calcium Channels, P-Type/drug effects
- Calcium Channels, P-Type/metabolism
- Calcium Channels, Q-Type/drug effects
- Calcium Channels, Q-Type/metabolism
- Cell Differentiation/drug effects
- Cell Differentiation/physiology
- Cells, Cultured
- Female
- Fetus
- GABA Antagonists/pharmacology
- Hippocampus/drug effects
- Hippocampus/embryology
- Hippocampus/metabolism
- Neural Inhibition/drug effects
- Neural Inhibition/physiology
- Potassium Chloride/pharmacology
- Pregnancy
- Presynaptic Terminals/drug effects
- Presynaptic Terminals/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, trkB/drug effects
- Receptor, trkB/metabolism
- Receptors, GABA-A/drug effects
- Receptors, GABA-A/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- Up-Regulation/drug effects
- Up-Regulation/physiology
- gamma-Aminobutyric Acid/metabolism
Collapse
Affiliation(s)
- P Baldelli
- INFM Research Unit, University of Turin, I-10125 Turin, Italy
| | | | | | | | | |
Collapse
|
185
|
Richardson CA, Leitch B. Cerebellar Golgi, Purkinje, and basket cells have reduced gamma-aminobutyric acid immunoreactivity in stargazer mutant mice. J Comp Neurol 2002; 453:85-99. [PMID: 12357434 DOI: 10.1002/cne.10406] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The stargazer mutant mouse has characteristic ataxia and head-tossing traits coupled with a severe impairment in the acquisition of classical eye-blink conditioning (Qiao et al. [1996] J. Neurosci. 16:640-648; Qiao et al. [ 1998] J. Neurosci. 18:6990-6999). These phenotypes are thought to be cerebellar mediated and have been attributed to the specific reduction in brain-derived neurotrophic factor (BDNF). The granule cells in the cerebellum of the stargazer mouse exhibit a near-total and exclusive ablation of BDNF mRNA expression and a consequent defect in TrkB receptor signalling. To investigate whether the stargazer mutation and lack of availability of BDNF in the granule cells compromise the phenotype of the cerebellar inhibitory neurons, specifically their immunoreactivity for gamma-aminobutyric acid (GABA); the levels of GABA neurotransmitter expressed in Golgi, Purkinje, and basket cells; and the density of their synaptic contacts were compared in stargazer and wild-type controls using electron microscopy and quantitative immunogold labelling. The data presented in this study clearly show that, in the spontaneous ataxic mutant mouse stargazer, the cerebellar inhibitory neurons have significantly reduced levels of GABA immunoreactivity indicative of a significant decrease in their GABA content compared with wild-type controls. Furthermore, the density of inhibitory synapses between Golgi interneurons and granule cells and also between basket and Purkinje cells in stargazer mutants is reduced to approximately half that in wild-type controls. Whether this reduction in GABA content and inhibitory synapse density is directly attributable to the lack of BDNF in the cerebellum of the stargazer mutant is yet to be proved.
Collapse
Affiliation(s)
- Christine A Richardson
- Department of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, United Kingdom
| | | |
Collapse
|
186
|
Schwyzer L, Mateos JM, Abegg M, Rietschin L, Heeb L, Thompson SM, Lüthi A, Gähwiler BH, McKinney RA. Physiological and morphological plasticity induced by chronic treatment with NT-3 or NT-4/5 in hippocampal slice cultures. Eur J Neurosci 2002; 16:1939-48. [PMID: 12453058 DOI: 10.1046/j.1460-9568.2002.02259.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Expression of neurotrophins (NTs) and their receptors is elevated in the adult CNS under several neuropathological conditions. We have investigated the anatomical and electrophysiological consequences of chronic NT-3 or NT-4/5 treatment on established organotypic hippocampal slice cultures maintained in vitro for > 14 days. Both NT-3 and NT-4/5 increased spontaneous, action potential-dependent excitatory synaptic activity (sEPSCs), but only NT-3 increased inhibitory synaptic activity (sIPSCs) in CA3 pyramidal cells. Both NTs strongly promoted spontaneous synaptic bursting activity. Spontaneous bursts of EPSCs were observed after either NT treatment but only NT-3-treated cultures exhibited an increase in spontaneous bursts of IPSCs. In addition, sIPSC bursts were eliminated by blocking glutamatergic excitation. The frequency of miniature inhibitory postsynaptic currents, but not miniature excitatory postsynaptic currents, was also increased by both NT-3 and NT-4/5. Furthermore, NT-3 and NT-4/5 induced an up-regulation of the growth-associated protein GAP-43, suggesting that neurotrophins may be able to induce axonal reorganization in established neuronal networks. CA1 pyramidal cells exhibited slight alterations in dendritic branching after NT-4/5, but not NT-3 treatment. We conclude that chronic treatment with NT-3 or NT-4/5 can affect an established hippocampal network by elevating spontaneous inhibitory and excitatory synaptic activity and inducing coordinated pre- and postsynaptic structural changes.
Collapse
Affiliation(s)
- Lucia Schwyzer
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | | | | | | | | | | | | | | | | |
Collapse
|
187
|
Sokoloff P, Guillin O, Diaz J, Carroll P, Griffon N. Brain-derived neurotrophic factor controls dopamine D3 receptor expression: implications for neurodevelopmental psychiatric disorders. Neurotox Res 2002; 4:671-678. [PMID: 12709305 DOI: 10.1080/1029842021000045499] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) belongs to a family of proteins related to nerve growth factor, which are responsible for neuron proliferation, survival and differentiation. A more diverse role for BDNF as a neuronal extracellular transmitter has, nevertheless, been proposed. The dopamine D(3) receptor has been implicated in neuropsychiatric disorders including schizophrenia, drug addiction, depression and Parkinson's disease. Its expression during development and in adulthood is highly dependent on dopaminergic innervation. Here we show that BDNF synthesized by dopamine neurons is responsible for the appearance of the D(3) receptor during development and maintains D(3) receptor expression in adults. Moreover, BDNF triggers D(3) receptor overexpression and behavioral sensitization to levodopa in denervated animals. These results suggest that BDNF, by controlling the expression of specific genes such as the D(3) receptor gene, may be an important factor in neurodevelopmental psychiatric diseases.
Collapse
Affiliation(s)
- Pierre Sokoloff
- Unite de Neurobiologie et Pharmacologie Moleculaire, INSERM U 573, Centre Paul Broca, 2ter rue d' Alesia, 75014 Paris, France
| | | | | | | | | |
Collapse
|
188
|
Abstract
Synapse formation and stabilization in the vertebrate central nervous system is a dynamic process, requiring bi-directional communication between pre- and postsynaptic partners. Numerous mechanisms coordinate where and when synapses are made in the developing brain. This review discusses cellular and activity-dependent mechanisms that control the development of synaptic connectivity.
Collapse
Affiliation(s)
- Susana Cohen-Cory
- Mental Retardation Research Center, Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| |
Collapse
|
189
|
Li AJ, Suzuki S, Suzuki M, Mizukoshi E, Imamura T. Fibroblast growth factor-2 increases functional excitatory synapses on hippocampal neurons. Eur J Neurosci 2002; 16:1313-24. [PMID: 12405992 DOI: 10.1046/j.1460-9568.2002.02193.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effect of fibroblast growth factor-2 (FGF-2) on synapse formation was investigated using rat cultured hippocampal neurons. Treatment with FGF-2 (0.4-10 ng/mL) for 6 days enhanced synaptogenesis on these neurons by approximately 50%, as determined by counting puncta immunostained for presynaptic- or postsynaptic-specific proteins. This enhancement was statistically significant, and was abolished by a specific inhibitor of mitogen-activated protein kinase (MAPK). The majority of neurons expressed FGF receptors (types 1-3) abundantly on the membrane of somata, dendrites, and growth cones, and in these regions phosphorylation of MAPK was enhanced after FGF-2 application. Furthermore, our experiments showed that the majority of synapses formed in cultures containing FGF-2 were positive both for presynaptic proteins and postsynaptic excitatory synapse-specific proteins, and that these synapses had a similar capacity to recycle the fluorescent styryl dye FM4-64 as those in the control culture. These results indicate that: (i) FGF-2 increases excitatory synapses on hippocampal neurons by activating MAPK activity through FGF receptors; and (ii) synapses formed in FGF-2-treated culture are capable of cycling vesicles.
Collapse
Affiliation(s)
- Ai-Jun Li
- Age Dimension Research Centre, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | | | | | | | | |
Collapse
|
190
|
Segal M. Changing views of Cajal's neuron: the case of the dendritic spine. PROGRESS IN BRAIN RESEARCH 2002; 136:101-7. [PMID: 12143374 DOI: 10.1016/s0079-6123(02)36011-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Ever since dendritic spines were first described in detail by Santiago Ramón y Cajal, they were assumed to underlie the physical substrate of long term memory in the brain. Recent time-lapse imaging of dendritic spines in live tissue, using confocal microscopy, have revealed an amazingly plastic structure, which undergoes continuous changes in shape and size, not intuitively related to its assumed role in long term memory. Functionally, the spine is shown to be an independent cellular compartment, able to regulate calcium concentration independently of its parent dendrite. The shape of the spine is instrumental in regulating the link between the synapse and the parent dendrite such that longer spines have less impact on the dendrite than shorter ones. The spine can be formed, change its shape and disappear in response to afferent stimulation, in a dynamic fashion, indicating that spine morphology is an important vehicle for structuring synaptic interactions. While this role is crucial in the developing nervous system, large variations in spine densities in the adult brain indicate that tuning of synaptic impact may be a role of spines throughout the life of a neuron.
Collapse
Affiliation(s)
- Menahem Segal
- Department of Neurobiology, Weizmann Institute, Rehovot 76100, Israel.
| |
Collapse
|
191
|
Yamada MK, Nakanishi K, Ohba S, Nakamura T, Ikegaya Y, Nishiyama N, Matsuki N. Brain-derived neurotrophic factor promotes the maturation of GABAergic mechanisms in cultured hippocampal neurons. J Neurosci 2002; 22:7580-5. [PMID: 12196581 PMCID: PMC6757965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) has been implicated in activity-dependent plasticity of neuronal function and network arrangement. To clarify how BDNF exerts its action, we evaluated the physiological, histological, and biochemical characteristics of cultured hippocampal neurons after long-term treatment with BDNF. Here we show that BDNF facilitates high K(+)-elicited release of GABA but not of glutamate and induces an increase in immunoreactive signals of glutamic acid decarboxylase, a GABA-synthesizing enzyme. The soma size of GABAergic neurons was enlarged in BDNF-treated cultures, whereas the average soma size of all neurons was virtually unchanged. BDNF also upregulated protein levels of GABA(A) receptors but not of glutamate receptors. These data imply that BDNF selectively advances the maturation of GABAergic synapses. However, immunocytochemical analyses revealed that a significant expression of TrkB, a high-affinity receptor for BDNF, was detected in non-GABAergic as well as GABAergic neurons. BDNF also increased to total amount of synaptic vesicle-associated proteins without affecting the number of presynaptic vesicles that can be labeled with FM1-43 after K(+) depolarization. Together, our findings indicate that BDNF principally promotes GABAergic maturation but may also potentially contribute to excitatory synapse development via increasing resting synaptic vesicles.
Collapse
Affiliation(s)
- Maki K Yamada
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | | | | | | | | | | | | |
Collapse
|
192
|
Abstract
In the mature brain, GABA (gamma-aminobutyric acid) functions primarily as an inhibitory neurotransmitter. But it can also act as a trophic factor during nervous system development to influence events such as proliferation, migration, differentiation, synapse maturation and cell death. GABA mediates these processes by the activation of traditional ionotropic and metabotropic receptors, and probably by both synaptic and non-synaptic mechanisms. However, the functional properties of GABA receptor signalling in the immature brain are significantly different from, and in some ways opposite to, those found in the adult brain. The unique features of the early-appearing GABA signalling systems might help to explain how GABA acts as a developmental signal.
Collapse
Affiliation(s)
- David F Owens
- Laboratory of Molecular Biology, National Institute of Neurological Disorders and Stroke, Building 36, Room 3C09, 36 Convent Drive, Bethesda, Maryland 20892-4092, USA
| | | |
Collapse
|
193
|
Henneberger C, Jüttner R, Rothe T, Grantyn R. Postsynaptic action of BDNF on GABAergic synaptic transmission in the superficial layers of the mouse superior colliculus. J Neurophysiol 2002; 88:595-603. [PMID: 12163512 DOI: 10.1152/jn.2002.88.2.595] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The neurotrophin brain-derived neurotrophic factor (BDNF) is involved in numerous aspects of synapse development and plasticity. The present study was aimed at clarifying the significance of endogenous BDNF for the synaptically driven spontaneous network activity and GABAergic inhibition in the superficial layers of the mouse superior colliculus. In this structure neuron survival is unaffected by the absence of BDNF. Two experimental approaches were used: comparison of BDNF-deficient (-/-) and wild-type (+/+) mice and blockade of BDNF receptor signaling by the tyrosine kinase inhibitor K-252a. Patch-clamp recordings were performed on horizontal slices during postnatal days 15 and 16. The lack of BDNF in -/- mice caused a significant reduction of the spontaneous action potential frequency and an increase in the pharmacologically induced disinhibition of spike discharge. This change was accompanied by an increase in the amplitudes of GABAergic evoked, spontaneous, and miniature inhibitory postsynaptic currents (IPSCs). BDNF gene inactivation had no effect on the degree of paired-pulse facilitation or the frequency of miniature IPSCs. The increase of IPSC amplitudes by chronic BDNF deprivation was completely mimicked by acute exposure to K-252a in +/+ animals. The enhancement of GABAergic IPSCs in -/- animals was reversed by acute application of 100 ng/ml BDNF, but this rescue was completely prevented by blocking postsynaptic protein kinase C (PKC) activation with the PKC inhibitor peptide 19-31. From these results we conclude that BDNF increases spontaneous network activity by suppressing GABAergic inhibition, the site of action of BDNF is predominantly postsynaptic, BDNF-induced suppression of GABAergic synaptic transmission is caused by acute downregulation of GABA(A) receptors, and BDNF effects are mediated by its TrkB receptor and require PKC activation in the postsynaptic cell.
Collapse
Affiliation(s)
- Christian Henneberger
- Developmental Physiology, Johannes Müller Institute of Physiology, Charité, D-10117 Berlin, Germany
| | | | | | | |
Collapse
|
194
|
Abstract
Recent preclinical and clinical studies have shown that mechanisms underlying neuronal plasticity and survival are involved in both the outcome of stressful experiences and the action of antidepressants. Whereas most antidepressants predominantly affect the brain levels of monoamine neurotransmitters, it is increasingly appreciated that they also modulate neurotransmission at synapses using the neurotransmitter glutamate (the most abundant in the brain). In the hippocampus, a main area of the limbic system involved in cognitive functions as well as attention and affect, specific molecules enriched at glutamatergic synapses mediate major changes in synaptic plasticity induced by stress paradigms or antidepressant treatments. We analyze here the modifications induced by stress or antidepressants in the strength of synaptic transmission in hippocampus, and the molecular modifications induced by antidepressants in two main mediators of synaptic plasticity: the N-methyl-D-aspartate (NMDA) receptor complex for glutamate and the Ca2+/calmodulin-dependent protein kinase II (CaM kinase II). Both stress and antidepressants induce alterations in long-term potentiation of hippocampal glutamatergic synapses, which may be partly accounted for by the influence of environmental or drug-induced stimulation of monoaminergic pathways projecting to the hippocampus. In the course of antidepressant treatments significant changes have been described in both the NMDA receptor and CaM kinase II, which may account for the physiological changes observed. A central role in these synaptic changes is exerted by brain-derived neurotrophic factor (BDNF), which modulates both synaptic plasticity and its molecular mediators, as well as inducing morphological synaptic changes. The role of these molecular effectors in synaptic plasticity is discussed in relation to the action of antidepressants and the search for new molecular targets of drug action in the therapy of mood disorders.
Collapse
Affiliation(s)
- Maurizio Popoli
- Center of Neuropharmacology, Department of Pharmacological Sciences, Center of Excellence on Neurodegenerative Diseases, University of Milano, Italy.
| | | | | |
Collapse
|
195
|
Illing RB, Michler SA, Kraus KS, Laszig R. Transcription factor modulation and expression in the rat auditory brainstem following electrical intracochlear stimulation. Exp Neurol 2002; 175:226-44. [PMID: 12009775 DOI: 10.1006/exnr.2002.7895] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Neuronal activity in sensory organs elicited by adequate or electrical stimulation not only invokes fast electrical responses but may also trigger complex molecular changes inside central neurons. Following electrical intracochlear stimulation with a cochlear implant under urethane anesthesia, we observed changes in the phosphorylation state of the cAMP response element binding protein (CREB) and the expression of the immediate-early genes c-fos and egr-1, molecules known to act as transcription factors, in a tonotopically precise pattern in central auditory neurons. These neurons resided in the posteroventral and anteroventral cochlear nucleus, the dorsal cochlear nucleus, the lateral superior olive, the medial nucleus of the trapezoid body, the dorsal and ventral nucleus of the lateral lemniscus, and the central nucleus of the inferior colliculus. Moreover, effects of electrical stimulation were identified in the medial vestibular nucleus and the lateral parabrachial nucleus. Regionally, CREB was dephosphorylated wherever immediate-early gene expression went up. These massive stimulation-dependent modulations of transcription factors in the ascending auditory system are indicative of ongoing changes that modify the chemistry and structure of the affected cells and, consequently, their response characteristics to subsequent stimulation of the inner ear.
Collapse
Affiliation(s)
- Robert-Benjamin Illing
- Neurobiological Research Laboratory, Department of Otorhinolaryngology, University of Freiburg, Killianstrasse 5, Freiburg, D-79106, Germany.
| | | | | | | |
Collapse
|
196
|
Shi L, Poe BH, Constance Linville M, Sonntag WE, Brunso-Bechtold JK. Caloric restricted male rats demonstrate fewer synapses in layer 2 of sensorimotor cortex. Brain Res 2002; 931:32-40. [PMID: 11897086 DOI: 10.1016/s0006-8993(02)02249-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Previous studies have demonstrated an age-related decline in the density of presumptive inhibitory synapses in layer 2 of rat sensorimotor cortex [J. Comp. Neurol. 439(1) (2001) 65]. Caloric restriction has been shown to ameliorate age-related deterioration in a variety of systems and to extend life span. The present study tested the hypothesis that caloric restriction would prevent the previously reported age-related synaptic decline. Accordingly, synaptic density in layer 2 of sensorimotor cortex was compared between 29-month-old male rats fed ad libitum and 29-month-old male rats that were caloric restricted (60% of ad libitum calories) from 4 months of age. In serial electron micrographs, the physical disector was used to determine the numerical density of presumptive excitatory and inhibitory synapses (those containing round or nonround vesicles, respectively) as well as that of neurons. Not only was the previously reported age-related decline in numerical density of presumptive inhibitory synapses not ameliorated by caloric restriction, the numerical density was significantly lower in caloric restricted than in ad libitum fed rats for total as well as for presumptive excitatory and inhibitory synapses. Analysis further revealed no difference in the numerical density of neurons in this region. Relating synapse density to neuron density as the ratio of synapses to neuron also demonstrated significantly fewer synapses per neuron in caloric restricted than in ad libitum fed old rats. Finally, synapse length was significantly less in caloric restricted rats. These results suggest that not only does caloric restriction fail to prevent the age-related decline in presumptive inhibitory synapses, it results in fewer presumptive excitatory synapses as well.
Collapse
Affiliation(s)
- Lei Shi
- Department of Neurobiology and Anatomy, Medical Center Boulevard, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1010, USA.
| | | | | | | | | |
Collapse
|
197
|
Rico B, Xu B, Reichardt LF. TrkB receptor signaling is required for establishment of GABAergic synapses in the cerebellum. Nat Neurosci 2002; 5:225-33. [PMID: 11836532 PMCID: PMC2758226 DOI: 10.1038/nn808] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Neurotrophins are essential to the normal development and maintenance of the nervous system. Neurotrophin signaling is mediated by Trk family tyrosine kinases such as TrkA, TrkB and TrkC, as well as by the pan-neurotrophin receptor p75NTR. Here we have deleted the trkB gene in cerebellar precursors by Wnt1-driven Cre--mediated recombination to study the function of the TrkB in the cerebellum. Despite the absence of TrkB, the mature cerebellum of mutant mice appears similar to that of wild type, with all types of cell present in normal numbers and positions. Granule and Purkinje cell dendrites appear normal and the former have typical numbers of excitatory synapses. By contrast, inhibitory interneurons are strongly affected: although present in normal numbers, they express reduced amounts of GABAergic markers and develop reduced numbers of GABAergic boutons and synaptic specializations. Thus, TrkB is essential to the development of GABAergic neurons and regulates synapse formation in addition to its role in the development of axon terminals.
Collapse
Affiliation(s)
- Beatriz Rico
- Howard Hughes Medical Institute and Department of Physiology, University of California, San Francisco, California 94143, USA
| | | | | |
Collapse
|
198
|
Mistry SK, Keefer EW, Cunningham BA, Edelman GM, Crossin KL. Cultured rat hippocampal neural progenitors generate spontaneously active neural networks. Proc Natl Acad Sci U S A 2002; 99:1621-6. [PMID: 11818538 PMCID: PMC122240 DOI: 10.1073/pnas.022646599] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We previously demonstrated that the neural cell adhesion molecule (N-CAM) inhibited the proliferation of cultured rat hippocampal progenitor cells and increased the number of neurons generated. We demonstrate here that the continued presence of fibroblast growth factor 2 along with N-CAM or brain-derived neurotrophic factor over 12 days of culture greatly increased the number of both progenitors and neurons. These progenitor-derived neurons expressed neurotransmitters, neurotransmitter receptors, and synaptic proteins in vitro consistent with those expressed in the mature hippocampus. Progenitor cells cultured on microelectrode plates formed elaborate neural networks that exhibited spontaneously generated action potentials after 21 days. This activity was observed only in cultures grown in the presence of fibroblast growth factor 2 and either N-CAM or brain-derived neurotrophic factor. Analysis of neuronal activity after various pharmacological treatments indicated that the networks formed functional GABAergic and glutamatergic synapses. We conclude that mitogenic growth factors can synergize with N-CAM or neurotrophins to generate spontaneously active neural networks from neural progenitors.
Collapse
Affiliation(s)
- Sanjay K Mistry
- Department of Neurobiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | | | | | | | |
Collapse
|
199
|
Frost DO. BDNF/trkB signaling in the developmental sculpting of visual connections. PROGRESS IN BRAIN RESEARCH 2002; 134:35-49. [PMID: 11702553 DOI: 10.1016/s0079-6123(01)34004-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Neurotrophins are a family of secreted molecules that have multiple, profound actions on the structure and function of both developing and mature neurons. Neurotrophins exert their influences by signaling through the trk family of receptor tyrosine kinases and the p75 low affinity neurotrophin receptor. Here we review the contributions of neurotrophins to the development of neural circuitry in the mammalian visual system. We emphasize: (1) the role of neurotrophins as components of the cellular mechanisms by which neuroelectric activity sculpts pattern of brain connectivity; and (2) the results of recent experiments suggesting that the trafficking of neurotrophin proteins may be activity dependent.
Collapse
Affiliation(s)
- D O Frost
- Department of Pharmacology and Experimental Therapeutics, Department of Anesthesiology and Neuroscience Program, University of Maryland School of Medicine, 655 West Baltimore St., Baltimore, MD 21201, USA.
| |
Collapse
|
200
|
Boukhaddaoui H, Sieso V, Scamps F, Valmier J. An activity-dependent neurotrophin-3 autocrine loop regulates the phenotype of developing hippocampal pyramidal neurons before target contact. J Neurosci 2001; 21:8789-97. [PMID: 11698591 PMCID: PMC6762280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023] Open
Abstract
Neurotrophin-3 (NT-3), its cognate receptor trkC, and voltage-gated calcium channels are coexpressed by embryonic pyramidal neurons before target contact, but their functions at this stage of development are still unclear. We show here that, in vitro, anti-NT-3 and anti-trkC antibodies blocked the increase, and NT-3 reversed the decrease in the number of calbindin-D(28k)-positive pyramidal neurons induced by, respectively, calcium channel activations and blockades. Similar results were obtained with single-neuron microcultures. In addition, voltage-gated calcium channel inhibition downregulates the extracellular levels of NT-3 in high-density cultures. Moreover, electrophysiological experiments in single-cell cultures reveal a tetrodotoxin-sensitive spontaneous electrical activity allowing voltage-gated calcium channel activation. The mouse NT-3 (-/-) mutation decreases by 40% the number of developing calbindin-D(28k)-positive pyramidal neurons, without affecting neuronal survival, both in vitro and in vivo. Thus, present results strongly support that an activity-dependent autocrine NT-3 loop provides a local, intrinsic mechanism by which, before target contact, hippocampal pyramidal-like neurons may regulate their own differentiation, a role that may be important during early CNS differentiation or after adult target disruption.
Collapse
Affiliation(s)
- H Boukhaddaoui
- Institut National de la Santé et de la Recherche Médicale U-432, Universite Montpellier II, 34095 Montpellier, Cedex 5, France
| | | | | | | |
Collapse
|