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Jiang B, Kitamura A, Yasuda H, Sohya K, Maruyama A, Yanagawa Y, Obata K, Tsumoto T. Brain-derived neurotrophic factor acutely depresses excitatory synaptic transmission to GABAergic neurons in visual cortical slices. Eur J Neurosci 2004; 20:709-18. [PMID: 15255981 DOI: 10.1111/j.1460-9568.2004.03523.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) acutely modulates synaptic transmission to excitatory neurons in hippocampus and neocortex. The question of whether BDNF acts similarly on excitatory synaptic transmission to GABAergic neurons was eluded in previous studies using cortical slices. To address this question, we used transgenic mice in which expression of green fluorescence protein (GFP) is regulated by glutamic acid decarboxylase 67 (GAD67) promoter. In cortical slices prepared from these GAD67-GFP knock-in mice, we could detect GABAergic neurons under a fluorescent microscope. An application of BDNF rapidly depressed excitatory postsynaptic currents (EPSCs) evoked by layer IV stimulation in most GFP-positive neurons in layer II/III of the cortex. This effect was seen at synapses activated during the BDNF application and blocked by anti-TrkB IgG, indicating that the acute inhibitory action of BDNF is activity-dependent and mediated through TrkB. Paired-pulse ratios of the amplitude of EPSCs to paired stimulation at intervals of 10-100 ms were not significantly changed after BDNF application, suggesting that the site of depression may be postsynaptic. Responses to directly applied glutamate were also depressed by BDNF in most of neurons, being consistent with the interpretation of postsynaptic action of BDNF. The depressive action of BDNF was blocked by an intracellular injection of a Ca(2+) chelator, suggesting that a rise in Ca(2+) is involved in the acute depression of EPSCs. This action of BDNF was seen in 67% of parvalbumin (PV)-positive neurons, but in only 19% of PV-negative neurons, indicating that the depressive action is biased to PV-positive GABAergic neurons.
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Affiliation(s)
- Bin Jiang
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Kawaguchi 332-0012 Japan
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102
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Kramár EA, Lin B, Lin CY, Arai AC, Gall CM, Lynch G. A novel mechanism for the facilitation of theta-induced long-term potentiation by brain-derived neurotrophic factor. J Neurosci 2004; 24:5151-61. [PMID: 15175384 PMCID: PMC6729196 DOI: 10.1523/jneurosci.0800-04.2004] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) contributes to the induction of long-term potentiation (LTP) by theta-pattern stimulation, but the specific processes underlying this effect are not known. Experiments described here, using BDNF concentrations that have minor effects on baseline responses, show that the neurotrophin both reduces the threshold for LTP induction and elevates the ceiling on maximal potentiation. The enhanced LTP proved to be as stable and resistant to reversal as that recorded under control conditions. BDNF markedly increased the facilitation of burst responses that occurs within a theta train. This suggests that the neurotrophin acts on long-lasting events that (1) are set in motion by the first burst in a train and (2) regulate the amplitude of subsequent bursts. Whole-cell recordings established that BDNF causes a rapid reduction in the size of the long-lasting afterhyperpolarization (AHP) that follows individual theta bursts. Apamin, an antagonist of type 2 small-conductance Ca2+-activated potassium (SK2) channels, also reduced hippocampal AHPs and closely reproduced the effects of BDNF on theta-burst responses and LTP. The latter results were replicated with a newly introduced, highly selective inhibitor of SK2 channels. Immunoblot analyses indicated that BDNF increases SK2 serine phosphorylation in hippocampal slices. These findings point to the conclusion that BDNF-driven protein kinase cascades serve to depress the SK2 component, and possibly other constituents, of the AHP. It is likely that this mechanism, acting with other factors, promotes the formation and increases the magnitude of LTP.
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Affiliation(s)
- Enikö A Kramár
- Department of Psychiatry and Human Behavior, University of California, Irvine, California 92612-1695, USA.
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103
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Canas N, Pereira IT, Ribeiro JA, Sebastião AM. Brain-derived neurotrophic factor facilitates glutamate and inhibits GABA release from hippocampal synaptosomes through different mechanisms. Brain Res 2004; 1016:72-8. [PMID: 15234254 DOI: 10.1016/j.brainres.2004.04.070] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2004] [Indexed: 10/26/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) has an acute excitatory effect on rat hippocampal synaptic transmission. To compare the action of BDNF upon the release of excitatory and inhibitory neurotransmitters in the hippocampus, we studied the effect of acutely applied BDNF on the K+-evoked glutamate and on the K+-evoked gamma-aminobutyric acid (GABA) release from rat hippocampal nerve terminals (synaptosomes). The acute application of BDNF (30-100 ng/ml) enhanced the K+-evoked [3H]glutamate release. This effect involved tyrosine-kinase B (TrkB) receptor phosphorylation and Ca2+ entry into synaptosomes through voltage-sensitive calcium channels, since it was abolished by K252a (200 nM), which prevents TrkB-mediated phosphorylation, and by CdCl2 (0.2 mM), a blocker of voltage-sensitive calcium channels. In contrast, BDNF (3-100 ng/ml) inhibited K+-evoked [3H]GABA release from hippocampal synaptosomes. This action was also mediated by phosphorylation of the TrkB receptor, but was independent of Ca2+ entry into synaptosomes through voltage-sensitive calcium channels. Blockade of transport of GABA with SKF 89976a (20 microM) prevented the inhibitory action of BDNF upon GABA release, indicating that BDNF influences the activity of GABA transporters. It is concluded that BDNF influences in an opposite way, through distinct mechanisms, the release of glutamate and the release of GABA from hippocampal synaptosomes.
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Affiliation(s)
- Nuno Canas
- Laboratory of Neurosciences, Faculty of Medicine, University of Lisbon, Av. Prof. Egas Moniz, Lisbon 1649-028, Portugal
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104
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Kato A, Fukazawa Y, Ozawa F, Inokuchi K, Sugiyama H. Activation of ERK cascade promotes accumulation of Vesl-1S/Homer-1a immunoreactivity at synapses. ACTA ACUST UNITED AC 2004; 118:33-44. [PMID: 14559352 DOI: 10.1016/j.molbrainres.2003.07.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The Vesl-1S/Homer-1a protein is induced during long-term potentiation (LTP), and contains a motif that binds postsynaptic proteins. We have previously reported that synaptic accumulation of Vesl-1S/Homer-1a immunoreactivity (IR) at synapses on the contour of neuronal somata is promoted by stimulation of cells with phorbol esters, 90 mM KCl or proteasome inhibitors. In the present study, we investigated the intracellular mechanism that results in the synaptic accumulation of this protein at synapses. MEK inhibitors completely blocked the effects of phorbol esters and KCl on the accumulation of Vesl-1S/Homer-1a and partially blocked the effect of proteasome inhibitors. Conversely, brain-derived neurotrophic factor (BDNF) and NT3 promoted the accumulation of Vesl-1S/Homer-1a IR at synapses. The extent of this accumulation is correlated with the level of activation of extracellular signal-regulated kinases, ERK following treatment with BDNF. BDNF also caused an increase in the amount of Vesl-1S/Homer-1a protein, but this occurred after Vesl-1S/Homer-1a had accumulated at the synapses. In addition, inhibition of de novo protein synthesis did not affect the phorbol ester-mediated accumulation of Vesl-1S/Homer-1a IR at synapses. These results indicate that activation of the ERK cascade plays a crucial role in the synaptic accumulation of Vesl-1S/Homer-1a IR, and suggest that this accumulation occurs mainly by re-localization of Vesl-1S/Homer-1a protein, and not through an increase in the level of Vesl-1S/Homer-1a. Activity-dependent release of neurotrophins or depolarization may cause local activation of the ERK cascade to produce the synapse-specific localization of Vesl-1S/Homer-1a.
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Affiliation(s)
- Akihiko Kato
- Department of Biology, Faculty of Science, Graduate School of Science, Kyushu University, Higashi, Fukuoka 812-8581, Japan
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105
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Jovanovic JN, Thomas P, Kittler JT, Smart TG, Moss SJ. Brain-derived neurotrophic factor modulates fast synaptic inhibition by regulating GABA(A) receptor phosphorylation, activity, and cell-surface stability. J Neurosci 2004; 24:522-30. [PMID: 14724252 PMCID: PMC6729993 DOI: 10.1523/jneurosci.3606-03.2004] [Citation(s) in RCA: 221] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The efficacy of GABAergic synaptic inhibition is a principal factor in controlling neuronal activity. We demonstrate here that brain-derived neurotrophic factor modulates the activity of GABA(A) receptors, the main sites of fast synaptic inhibition in the brain, within minutes of application. Temporally, this comprised an early enhancement in the miniature IPSC amplitude, followed by a prolonged depression. This modulation was concurrent with enhanced PKC-mediated phosphorylation, followed by protein phosphatase 2A (PP2A)-mediated dephosphorylation of the GABA(A) receptor. Mechanistically, these events were facilitated by differential recruitment of PKC, receptor for activated C-kinase, and PP2A to GABA(A) receptors, depending on the phosphorylation state of the receptor beta3-subunit. Thus, transient formation of GABA(A) receptor signaling complexes has the potential to provide a basis for acute changes in receptor function underlying GABAergic synaptic plasticity.
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Affiliation(s)
- Jasmina N Jovanovic
- Department of Pharmacology, University College, London, WC1E 6BT, United Kingdom
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106
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Garza AA, Ha TG, Garcia C, Chen MJ, Russo-Neustadt AA. Exercise, antidepressant treatment, and BDNF mRNA expression in the aging brain. Pharmacol Biochem Behav 2004; 77:209-20. [PMID: 14751447 DOI: 10.1016/j.pbb.2003.10.020] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Principal mental disorders affecting the geriatric population include dementia and depression. A lack of trophic support is thought to contribute to the pathology of these disorders. Physical activity and antidepressant treatment increase the expression of brain-derived neurotrophic factor (BDNF) in the young rat hippocampus. Herein, we investigated the responsiveness of the aging rat hippocampus to antidepressant treatment and voluntary exercise. In situ hybridization revealed that, in young animals, exercise, antidepressant treatment, or their combination elevated BDNF mRNA levels in several hippocampal regions, most notably in the CA3, CA4, and dentate gyrus (DG). This effect was rapid (detectable at 2 days) and sustainable to 20 days. In aged (22-month-old) rats, hippocampal responsiveness to antidepressant treatment and exercise was also rapid and sustainable, but evident mostly in the CA1 and CA2. Daily swimming also revealed that small amounts of activity led to marked elevations in hippocampal BDNF mRNA. The differences in regional patterns of BDNF mRNA elevations between young and aged animals observed with running were maintained with this different exercise modality. Our results indicate that the aged brain is responsive to exercise and antidepressant treatment, and changes in regional response patterns may reflect shifts in hippocampal physiology during the lifespan.
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Affiliation(s)
- Antonio A Garza
- Department of Biological Sciences, California State University-Los Angeles, 5151 State University Drive, Los Angeles, CA 90032, USA
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107
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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.
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Affiliation(s)
- M R Palizvan
- Division of Neurophysiology, Osaka University Graduate School of Medicine (D-14), Suita, Japan
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108
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Binder DK. The Role of BDNF in Epilepsy and Other Diseases of the Mature Nervous System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 548:34-56. [PMID: 15250584 DOI: 10.1007/978-1-4757-6376-8_3] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The neurotrophin brain-derived neurotrophic factor (BDNF) is ubiquitous in the central nervous system (CNS) throughout life. In addition to trophic effects on target neurons, BDNF appears to be part of a general mechanism for activity-dependent modification of synapses in the developing and adult nervous system. Thus, diseases of abnormal trophic support (such as neurodegenerative diseases) and diseases of abnormal excitability (such as epilepsy and central pain sensitization) can be related in some cases to abnormal BDNF signaling. For example, various studies have shown that BDNF is upregulated in areas implicated in epileptogenesis, and interference with BDNF signal transduction inhibits the development of the epileptic state. Further study of the cellular and molecular mechanisms by which BDNF influences cell survival and excitability will likely provide novel concepts and targets for the treatment of diverse CNS diseases.
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Affiliation(s)
- Devin K Binder
- Department of Neurological Surgery, University of California at San Francisco, Moffitt Hospital, USA
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109
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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.
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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.
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110
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Purcell AL, Carew TJ. Tyrosine kinases, synaptic plasticity and memory: insights from vertebrates and invertebrates. Trends Neurosci 2003; 26:625-30. [PMID: 14585603 DOI: 10.1016/j.tins.2003.09.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Tyrosine kinases were first characterized in terms of their function during development. Over the past decade, it has become clear that tyrosine phosphorylation also plays an important role in the adult mammalian nervous system. This article reviews three different families of tyrosine kinase signaling cascades: the Trk receptor tyrosine kinases, the Src family of non-receptor tyrosine kinases and the Eph receptor tyrosine kinases. Each of these cascades has been implicated in both adult synaptic plasticity and memory formation. Evidence from invertebrate systems also demonstrates a role for tyrosine kinase signaling in the induction of long-term memory, suggesting that molecular mechanisms of memory formation are conserved across species.
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Affiliation(s)
- Angela L Purcell
- Department of Neurobiology and Behavior and Center for Learning and Memory, University of California at Irvine, Irvine, CA 92697, USA
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111
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Brain-derived neurotrophic factor modulation of GABAergic synapses by postsynaptic regulation of chloride transport. J Neurosci 2003. [PMID: 14507972 DOI: 10.1523/jneurosci.23-25-08722.2003] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) potentiates excitatory synapses in a variety of systems by promoting presynaptic transmitter release. The existing evidence indicates that BDNF attenuates inhibitory transmission, but reports differ considerably in their characterization of the effect and proposed mechanisms. We examined the effects of exogenously applied BDNF on EPSCs and IPSCs recorded from functionally identified neurons in dissociated rat hippocampal cultures. When recording from glutamatergic neurons, we found that BDNF exerted differential effects at excitatory versus inhibitory synapses: increasing amplitude of EPSCs but slightly decreasing that of IPSCs. Furthermore, when recording from GABAergic neurons, we found that BDNF increased the IPSC amplitude. That these differential BDNF effects reflect distinct presynaptic and postsynaptic mechanisms was suggested by the BDNF-induced changes in miniature EPSCs and IPSCs. An increased mini-frequency was found at all synapses, indicating elevated presynaptic transmitter secretion; a change in the amplitude of mini-IPSCs was found at GABAergic cells, suggesting postsynaptic modulation of GABA responses. Selective postsynaptic mechanisms were further examined by comparing the effect of BDNF on GABA-induced currents recorded from glutamatergic versus GABAergic cells. For GABAergic but not glutamatergic postsynaptic cells, BDNF induced a shift in the reversal potential (EIPSC) toward more positive levels, hence reducing the inhibitory action of IPSCs. This BDNF-induced effect correlates with the existing level of furosemide-sensitive K+-Cl- transport activity in the postsynaptic cell. Thus, BDNF may decrease the efficacy of inhibitory transmission by acute postsynaptic downregulation of Cl- transport, in addition to its well known presynaptic effect.
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112
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Blits B, Oudega M, Boer GJ, Bartlett Bunge M, Verhaagen J. Adeno-associated viral vector-mediated neurotrophin gene transfer in the injured adult rat spinal cord improves hind-limb function. Neuroscience 2003; 118:271-81. [PMID: 12676157 DOI: 10.1016/s0306-4522(02)00970-3] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To foster axonal growth from a Schwann cell bridge into the caudal spinal cord, spinal cells caudal to the implant were transduced with adeno-associated viral (AAV) vectors encoding for brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (AAV-NT-3). Control rats received AAV vectors encoding for green fluorescent protein or saline. AAV-BDNF- and AAV-NT-3-transduced 293 human kidney cells produced and secreted BDNF or NT-3, respectively, in vitro. The secreted neurotrophins were biologically active; they both promoted outgrowth of sensory neurites in vitro. In vivo, transgene expression was observed predominantly in neurons for at least 16 weeks after injection. Compared with controls, a modest though significant improvement in hind-limb function was found in rats that received AAV-BDNF and AAV-NT-3. Retrograde tracing demonstrated that twice as many neurons with processes extending toward the Schwann cell graft were present in the second lumbar cord segment of AAV-BDNF- and AAV-NT-3-injected animals compared with controls. We found no evidence, however, for growth of regenerated axons from the Schwann cell implant into the caudal cord. Our results suggest that AAV vector-mediated overexpression of BDNF and NT-3 in the cord caudal to a Schwann cell bridge modified the local lumbar axonal circuitry, which was beneficial for locomotor function.
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Affiliation(s)
- B Blits
- Graduate School for Neurosciences Amsterdam, Netherlands Institute for Brain Research, Amsterdam, The Netherlands
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113
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Inhibitory but not excitatory cortical neurons require presynaptic brain-derived neurotrophic factor for dendritic development, as revealed by chimera cell culture. J Neurosci 2003. [PMID: 12853431 DOI: 10.1523/jneurosci.23-14-06123.2003] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] 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.
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114
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Sato E, Takano Y, Kuno Y, Takano M, Sato I. Involvement of spinal tyrosine kinase in inflammatory and N-methyl-D-aspartate-induced hyperalgesia in rats. Eur J Pharmacol 2003; 468:191-8. [PMID: 12754057 DOI: 10.1016/s0014-2999(03)01718-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Phosphorylation of a subunit of N-methyl-D-aspartate (NMDA) receptor by protein tyrosine kinase (PTK) Src or Trk is known to enhance its channel activity. We examined whether a spinally administered selective PTK inhibitor, lavendustin A, which has high affinity for Src and Trk tyrosine kinases, could influence the development and maintenance of inflammatory hyperalgesia or NMDA-induced hyperalgesia. Inflammation was induced by injection of a mixture of carrageenan and kaolin into the tail base of rats. In another group of rats, hyperalgesia was induced by intrathecal administration of NMDA. Intrathecal administration of lavendustin A (1.0 microg) or NMDA receptor antagonist, (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cycloheptane-5,10-iminemaleate, MK-801 (3.0 microg) before injection of a mixture of carrageenan and kaolin or after the development of inflammation inhibited carrageenan-kaolin-induced mechanical hyperalgesia. Intrathecal injection of 1.0 microg NMDA produced thermal and mechanical hyperalgesia. Co-administration of 1.0 microg lavendustin A with NMDA significantly reduced the duration of spontaneous pain behaviour and inhibited NMDA-induced hyperalgesia. Lavendustin A itself did not cause any sedation, motor impairment or analgesia. Our results suggest that inhibition of PTK could be therapeutically effective as an analgesic in some NMDA receptor-mediated hyperalgesic states.
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Affiliation(s)
- Eiru Sato
- Department of Anesthesiology, Koshigaya Hospital, Dokkyo University, School of Medicine, 2-1-50 Minami-Koshigaya, Saitama 343-8555, Koshigaya City, Japan.
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115
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Cheng Q, Yeh HH. Brain-derived neurotrophic factor attenuates mouse cerebellar granule cell GABA(A) receptor-mediated responses via postsynaptic mechanisms. J Physiol 2003; 548:711-21. [PMID: 12640011 PMCID: PMC2342883 DOI: 10.1113/jphysiol.2002.037846] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
In addition to exerting long-term neurotrophic influences on developmental process such as neuronal survival and neuritic outgrowth, brain-derived neurotrophic factor (BDNF) has been reported to modulate synaptic transmission in the short-term. Considerable evidence indicates that BDNF acutely modulates NMDA receptor-mediated synaptic activity. However, whether BDNF modulates inhibitory synaptic transmission remains to be firmly established. In the present study, we examined the effect of acute BDNF exposure on GABA-evoked whole-cell responses as well as GABAergic synaptic activity in cultured mouse cerebellar granule cells. GABA-evoked responses were reduced by 39.5 +/- 4.7 % upon acute and focal application of BDNF (100 ng ml-1). The reduction of the GABA response recovered only partially even minutes after removal of BDNF. TrkB-IgG and K252a, but not K252b, prevented the BDNF-induced attenuation of the GABA response. BDNF exposure shifted the cumulative peak amplitude distribution leftward for both spontaneous IPSCs (sIPSCs) and miniature IPSCs (mIPSCs) without affecting the rise time and decay time constants. Acute exposure to BDNF also resulted in internalization of GABAA receptors in cultured cerebellar granule cells, as reflected by diminished immunostaining with an antibody against the GABAA receptor beta2/3 subunit. Although the BDNF-induced GABAA receptor internalization was sensitive to K252a, it did not become manifest until 5 min after exposure to BDNF. Therefore, receptor internalization alone cannot account for the prompt BDNF-induced attenuation of GABA-mediated activity. We conclude that BDNF modulates GABAA receptor-mediated activity through TrkB receptor signalling that triggers a kinase-dependent short latency effect and a delayed longer latency effect hallmarked by receptor internalization.
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Affiliation(s)
- Qing Cheng
- Center for Aging and Developmental Biology, Department of Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA
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116
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Ivanova SY, Storozhuk MV, Melnick IV, Kostyuk PG. Chronic treatment with ionotropic glutamate receptor antagonist kynurenate affects GABAergic synaptic transmission in rat hippocampal cell cultures. Neurosci Lett 2003; 341:61-4. [PMID: 12676344 DOI: 10.1016/s0304-3940(03)00154-x] [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] [Indexed: 10/27/2022]
Abstract
It is well documented that prolonged treatment with antagonists of ionotropic glutamate receptors activates a number of homeostatic mechanisms including alteration of glutamatergic transmission. We studied whether this treatment can also affect GABAergic transmission. Using whole-cell voltage clamp recording and local extracellular stimulation we investigated evoked inhibitory postsynaptic currents (IPSCs) in cultured rat hippocampal neurons grown in the presence of ionotropic glutamate receptor antagonist kynurenate (1 mM) and in control conditions. Chronic kynurenate treatment did not significantly affect the amplitude of evoked IPSCs and IPSC reversal potentials. In contrast we found that the paired-pulse depression was increased by 67% in cultures treated with kynurenic acid. We conclude that additional mechanism(s), alteration of GABAergic synaptic transmission, may contribute to homeostatic plasticity induced by chronic block of ionotropic glutamate receptors.
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Affiliation(s)
- Svetlana Y Ivanova
- Department of General Physiology of the Nervous System, Bogomoletz Institute of Physiology, National Academy of Sciences, Bogomoletz str 4, 252024 Kiev 24, Ukraine
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117
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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.
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Affiliation(s)
- A Kimberley McAllister
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, California 95616, USA
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118
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Malcangio M, Lessmann V. A common thread for pain and memory synapses? Brain-derived neurotrophic factor and trkB receptors. Trends Pharmacol Sci 2003; 24:116-21. [PMID: 12628355 DOI: 10.1016/s0165-6147(03)00025-7] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Recent evidence indicates that trophic factors can exert fast effects on neurones and so alter synaptic plasticity. Here, we focus on brain-derived neurotrophic factor (BDNF), which exerts a modulatory action at hippocampal synapses that are involved in learning and memory, and at the first pain synapse between primary sensory neurones and dorsal horn neurones. Hippocampal and sensory neurones share some properties for the release of endogenous BDNF. In the Schaffer collateral pathway of the hippocampus, binding of BDNF to high-affinity trkB receptors is essential for the induction of long-term potentiation, a specific type of synaptic plasticity. However, the consequences of BDNF binding to trkB receptors in the dorsal horn in relation to pain mechanisms are less well established and are considered in detail.
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Affiliation(s)
- Marzia Malcangio
- Sensory Function, Centre for Neuroscience, King's College London, London SE1 1UL, UK.
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119
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120
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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.
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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
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Affiliation(s)
- Maria A Carmona
- Department of Cell Biology and Barcelona Science Park, University of Barcelona, 08028, Barcelona, Spain
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121
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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
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122
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Rivera C, Li H, Thomas-Crusells J, Lahtinen H, Viitanen T, Nanobashvili A, Kokaia Z, Airaksinen MS, Voipio J, Kaila K, Saarma M. BDNF-induced TrkB activation down-regulates the K+-Cl- cotransporter KCC2 and impairs neuronal Cl- extrusion. J Cell Biol 2002; 159:747-52. [PMID: 12473684 PMCID: PMC2173387 DOI: 10.1083/jcb.200209011] [Citation(s) in RCA: 384] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2002] [Revised: 10/31/2002] [Accepted: 11/01/2002] [Indexed: 01/19/2023] Open
Abstract
Pathophysiological activity and various kinds of traumatic insults are known to have deleterious long-term effects on neuronal Cl- regulation, which can lead to a suppression of fast postsynaptic GABAergic responses. Brain-derived neurotrophic factor (BDNF) increases neuronal excitability through a conjunction of mechanisms that include regulation of the efficacy of GABAergic transmission. Here, we show that exposure of rat hippocampal slice cultures and acute slices to exogenous BDNF or neurotrophin-4 produces a TrkB-mediated fall in the neuron-specific K+-Cl- cotransporter KCC2 mRNA and protein, as well as a consequent impairment in neuronal Cl- extrusion capacity. After kindling-induced seizures in vivo, the expression of KCC2 is down-regulated in the mouse hippocampus with a spatiotemporal profile complementary to the up-regulation of TrkB and BDNF. The present data demonstrate a novel mechanism whereby BDNF/TrkB signaling suppresses chloride-dependent fast GABAergic inhibition, which most likely contributes to the well-known role of TrkB-activated signaling cascades in the induction and establishment of epileptic activity.
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Affiliation(s)
- Claudio Rivera
- Department of Biosciences, Division of Animal Physiology, Institute of Biotechnology, University of Helsinki, Finland.
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123
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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.
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124
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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.
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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
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Affiliation(s)
- P Baldelli
- INFM Research Unit, University of Turin, I-10125 Turin, Italy
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125
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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.
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Affiliation(s)
- Lucia Schwyzer
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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126
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Abstract
This review covers recent developments in the cellular neurophysiology of retrograde signaling in the mammalian central nervous system. Normally at a chemical synapse a neurotransmitter is released from the presynaptic element and diffuses to the postsynaptic element, where it binds to and activates receptors. In retrograde signaling a diffusible messenger is liberated from the postsynaptic element, and travels "backwards" across the synaptic cleft, where it activates receptors on the presynaptic cell. Receptors for retrograde messengers are usually located on or near the presynaptic nerve terminals, and their activation causes an alteration in synaptic transmitter release. Although often considered in the context of long-term synaptic plasticity, retrograde messengers have numerous roles on the short-term regulation of synaptic transmission. The focus of this review will be on a group of molecules from different chemical classes that appear to act as retrograde messengers. The evidence supporting their candidacy as retrograde messengers is considered and evaluated. Endocannabinoids have recently emerged as one of the most thoroughly investigated, and widely accepted, classes of retrograde messenger in the brain. The study of the endocannabinoids can therefore serve as a model for the investigation of other putative messengers, and most attention is devoted to a discussion of systems that use these new messenger molecules.
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Affiliation(s)
- Bradley E Alger
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201, USA.
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127
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Brain-derived neurotrophic factor triggers transcription-dependent, late phase long-term potentiation in vivo. J Neurosci 2002. [PMID: 12196567 DOI: 10.1523/jneurosci.22-17-07453.2002] [Citation(s) in RCA: 215] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Acute intrahippocampal infusion of brain-derived neurotrophic factor (BDNF) leads to long-term potentiation (BDNF-LTP) of synaptic transmission at medial perforant path-->granule cell synapses in the rat dentate gyrus. Endogenous BDNF is implicated in the maintenance of high-frequency stimulation-induced LTP (HFS-LTP). However, the relationship between exogenous BDNF-LTP and HFS-LTP is unclear. First, we found that BDNF-LTP, like HFS-LTP, is associated with enhancement in both synaptic strength and granule cell excitability (EPSP-spike coupling). Second, treatment with a competitive NMDA receptor (NMDAR) antagonist blocked HFS-LTP but had no effect on the development or magnitude of BDNF-LTP. Thus, NMDAR activation is not required for the induction or expression of BDNF-LTP. Formation of stable, late phase HFS-LTP requires mRNA synthesis and is coupled to upregulation of the immediate early gene activity-regulated cytoskeleton-associated protein (Arc). Local infusion of the transcription inhibitor actinomycin D (ACD) 1 hr before or immediately before BDNF infusion inhibited BDNF-LTP and upregulation of Arc protein expression. ACD applied 2 hr after BDNF infusion had no effect, defining a critical time window of transcription-dependent synaptic strengthening. Finally, the functional role of BDNF-LTP was assessed in occlusion experiments with HFS-LTP. HFS-LTP was induced, and BDNF was infused at time points corresponding to early phase (1 hr) or late phase (4 hr) HFS-LTP. BDNF applied during the early phase led to normal BDNF-LTP. In contrast, BDNF-LTP was completely occluded during the late phase. The results strongly support a role for BDNF in triggering transcription-dependent, late phase LTP in the intact adult brain.
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128
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Wang H, Zhou XF. Injection of brain-derived neurotrophic factor in the rostral ventrolateral medulla increases arterial blood pressure in anaesthetized rats. Neuroscience 2002; 112:967-75. [PMID: 12088754 DOI: 10.1016/s0306-4522(02)00085-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is a unique neurotrophin which not only supports the development of neurons but also modulates the synaptic activity in a number of neuronal systems. BDNF is synthesized in neurons, anterogradely transported and released from nerve terminals and exerts acute effects on synaptic transmission in both peripheral and central nervous systems. Previous studies have shown that BDNF is distributed in several groups of neurons in the brain stem which regulate cardiovascular functions. Here we showed that injection of BDNF (40-400 ng/100 nl) into the rostral ventrolateral medulla resulted in a significant increase in arterial blood pressure (Delta35.5+/-3.5 mmHg) in rats. The duration of change in blood pressure was 145+/-40 s with a latency of 3-5 s. There was no significant effect on the heart rate. The injection of glutamate as a positive control also triggered an increase in blood pressure. Injection of phosphate-buffered saline as a control or the same amount of nerve growth factor did not cause significant changes in blood pressure in different preparations. Immunohistochemistry showed that the nerve terminals immunoreactive for BDNF were localized in several brain stem regions and terminate around spinal projection neurons in the rostral ventrolateral medulla. Neurons in the rostral ventrolateral medulla can uptake exogenous BDNF and express the high affinity receptor trkB. From these results we suggest that BNDF in the medulla may play a role in the regulation of blood pressure.
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Affiliation(s)
- H Wang
- Department of Human Physiology and Centre for Neuroscience, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
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129
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Pezet S, Cunningham J, Patel J, Grist J, Gavazzi I, Lever IJ, Malcangio M. BDNF modulates sensory neuron synaptic activity by a facilitation of GABA transmission in the dorsal horn. Mol Cell Neurosci 2002; 21:51-62. [PMID: 12359151 DOI: 10.1006/mcne.2002.1166] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Topical application of brain-derived neurotrophic factor (BDNF) to the adult rat isolated dorsal horn with dorsal root attached preparation inhibited the electrically evoked release of substance P (SP) from sensory neurons. This effect of BDNF was dose dependent (EC(50) 250 pM) and reversed by the tyrosine kinase inhibitor, K-252a. BDNF-induced inhibition of SP release was blocked by the GABA(B) receptor antagonist CGP 55485 but not by naloxone. Acute application of BDNF significantly increased potassium-stimulated release of GABA in the dorsal horn isolated in vitro and this effect was blocked by K-252a. Intrathecal injection of BDNF into the rat lumbar spinal cord induced a short-lasting increase in hindpaw threshold to noxious thermal stimulation that was blocked by CGP 55485 and was associated with activation of ERK in dorsal horn. These data suggest that exogenous BDNF can indirectly modulate primary sensory neuron synaptic efficacy via facilitation of the release of GABA from dorsal horn interneurons.
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Affiliation(s)
- Sophie Pezet
- Neuroscience Research Centre, Guy's, King's and St Thomas' School of Biomedical Sciences, King's College London, London SE1 1UL, United Kingdom
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130
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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.
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Affiliation(s)
- Christian Henneberger
- Developmental Physiology, Johannes Müller Institute of Physiology, Charité, D-10117 Berlin, Germany
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131
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Ikegaya Y, Ishizaka Y, Matsuki N. BDNF attenuates hippocampal LTD via activation of phospholipase C: implications for a vertical shift in the frequency-response curve of synaptic plasticity. Eur J Neurosci 2002; 16:145-8. [PMID: 12153539 DOI: 10.1046/j.1460-9568.2002.02051.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recent evidence shows that neurotrophins are not only involved in neuronal survival and differentiation during development but also in modulating synaptic strength in the mature brain. To understand how neurotrophins alter this synaptic modification, we have investigated the effect of brain-derived neurotrophic factor (BDNF) on long-term depression (LTD) at Schaffer collateral-CA1 synapses in rat hippocampal slices. The slices treated with BDNF for 5 min showed significantly less LTD in response to a 1-Hz tetanus compared with controls but displayed normal LTD when the afferents were tetanized at 10 Hz. Because BDNF enhanced long-term potentiation (LTP) induced by a 30-Hz tetanus, the synaptic modification threshold (theta(m)) as defined in the 'BCM' theory of Bienenstock Cooper & Monroe [Bienenstock et al. (1982), J. Neurosci., 2, 32-48] was not shifted. BNDF is likely to alter the capability of the plastic changes in synaptic efficacy, i.e. to produce an upward shift in the BCM curve. The suppressive effect of BDNF on LTD was prevented by either the tyrosine kinase (Trk) receptor inhibitor K252a or the phospholipase C inhibitor U73122. Thus, TrkB activation may attenuate LTD through phospholipase C signalling pathway.
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Affiliation(s)
- Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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133
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Abstract
Tremendous achievements in neuroscience over the past three decades have provided a solid foundation for basic and clinical research in neurotransplantation. Restorative neurosurgical procedures will develop from different directions, and it is likely that a combination of approaches will be necessary to maximise patient outcomes. We believe that cerebral infarction and selected neurodegenerative disorders are appropriate initial candidates for this research.
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Affiliation(s)
- Douglas Kondziolka
- Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
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134
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Scharfman H. Does BDNF Contribute to Temporal Lobe Epilepsy? Epilepsy Curr 2002; 2:92-94. [PMID: 15309154 PMCID: PMC321024 DOI: 10.1111/j.1535-7597.2002.t01-1-00033.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Brain-Derived Neurotrophic Factor Enhances Fast Excitatory Synaptic Transmission in Human Epileptic Dentate Gyrus Zhu WJ, Roper SN Ann Neurol 2001;50:188–194 Purpose Brain-derived neurotrophic factor (BDNF) has trophic effects and modulates synaptic transmission in the hippocampal formation in animal studies. It also is upregulated in acute and chronic epilepsy models and in human temporal lobe epilepsy. This study was undertaken to examine the effects of BDNF on fast synaptic transmission in the human epileptic dentate gyrus. Methods Hippocampal specimens were acquired from patients with temporal lobe epilepsy during surgical removal of the anterior temporal lobe, intended to treat the epileptic condition. Whole-cell patch-clamp recordings were obtained from dentate granule cells in transverse hippocampal slices in vitro. Results Application of BDNF increased the amplitude and frequency of spontaneous excitatory postsynaptic currents and increased the amplitude of evoked excitatory postsynaptic currents. BDNF had no effect on spontaneous inhibitory postsynaptic currents but produced a decrease in amplitude of evoked inhibitory postsynaptic currents. The effects of BDNF were abolished by coapplication of the tyrosine kinase inhibitor K252a; therefore, BDNF enhances fast excitatory transmission in the epileptic human dentate gyrus and may play an important role in epileptogenesis in temporal lobe epilepsy. Conclusions This raises the possibility of designing therapies for this disorder that may be both anticonvulsant and antiepileptogenic.
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135
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Scharfman HE, Goodman JH, Sollas AL, Croll SD. Spontaneous limbic seizures after intrahippocampal infusion of brain-derived neurotrophic factor. Exp Neurol 2002; 174:201-14. [PMID: 11922662 DOI: 10.1006/exnr.2002.7869] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The results of several studies have contributed to the hypothesis that BDNF promotes seizure activity, particularly in adult hippocampus. To test this hypothesis, BDNF, vehicle (phosphate-buffered saline, PBS), or albumin was infused directly into the hippocampus for 2 weeks using osmotic minipumps. Rats were examined behaviorally, electrophysiologically, and anatomically. An additional group was tested for sensitivity to the convulsant pilocarpine. Spontaneous behavioral seizures were observed in BDNF-infused rats (8/32; 25%) but not in controls (0/20; 0%). In a subset of six animals (three BDNF, three albumin), blind electrophysiological analysis of scalp recordings contralateral to the infused hippocampus demonstrated abnormalities in all BDNF rats; but not controls. Neuronal loss in BDNF-treated rats was not detected relative to PBS- or albumin-treated animals, but immunocytochemical markers showed a pattern of expression in BDNF-treated rats that was similar to rats with experimentally induced seizures. Thus, BDNF-infused rats had increased expression of NPY in hilar neurons of the dentate gyrus relative to control rats. NPY and BDNF expression was increased in the mossy fiber axons of dentate gyrus granule cells relative to controls. The increase in NPY and BDNF expression in BDNF-treated rats was bilateral and occurred throughout the septotemporal axis of the hippocampus. Mossy fiber sprouting occurred in five BDNF-treated rats but no controls. In another group of infused rats that was tested for seizure sensitivity to the convulsant pilocarpine, BDNF-infused rats had a shorter latency to status epilepticus than PBS-infused rats. In addition, the progression from normal behavior to severe seizures was faster in BDNF-treated rats. These data support the hypothesis that intrahippocampal BDNF infusion can facilitate, and potentially initiate, seizure activity in adult hippocampus.
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Affiliation(s)
- Helen E Scharfman
- Center for Neural Recovery and Rehabilitation Research, Helen Hayes Hospital, West Haverstraw, New York, 10993-1195, USA
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136
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Brain-derived neurotrophic factor induces long-term potentiation in intact adult hippocampus: requirement for ERK activation coupled to CREB and upregulation of Arc synthesis. J Neurosci 2002. [PMID: 11880483 DOI: 10.1523/jneurosci.22-05-01532.2002] [Citation(s) in RCA: 553] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is implicated in long-term synaptic plasticity in the adult hippocampus, but the cellular mechanisms are little understood. Here we used intrahippocampal microinfusion of BDNF to trigger long-term potentiation (BDNF-LTP) at medial perforant path--granule cell synapses in vivo. BDNF infusion led to rapid phosphorylation of the mitogen-activated protein (MAP) kinases ERK (extracellular signal-regulated protein kinase) and p38 but not JNK (c-Jun N-terminal protein kinase). These effects were restricted to the infused dentate gyrus; no changes were observed in microdissected CA3 and CA1 regions. Local infusion of MEK (MAP kinase kinase) inhibitors (PD98059 and U0126) during BDNF delivery abolished BDNF-LTP and the associated ERK activation. Application of MEK inhibitor during established BDNF-LTP had no effect. Activation of MEK-ERK is therefore required for the induction, but not the maintenance, of BDNF-LTP. BDNF-LTP was further coupled to ERK-dependent phosphorylation of the transcription factor cAMP response element-binding protein. Finally, we investigated the expression of two immediate early genes, activity-regulated cytoskeleton-associated protein (Arc) and Zif268, both of which are required for generation of late, mRNA synthesis-dependent LTP. BDNF infusion resulted in selective upregulation of mRNA and protein for Arc. In situ hybridization showed that Arc transcripts are rapidly and extensively delivered to granule cell dendrites. U0126 blocked Arc upregulation in parallel with BDNF-LTP. The results support a model in which BDNF triggers long-lasting synaptic strengthening through MEK-ERK and selective induction of the dendritic mRNA species Arc.
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137
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Kovalchuk Y, Hanse E, Kafitz KW, Konnerth A. Postsynaptic Induction of BDNF-Mediated Long-Term Potentiation. Science 2002; 295:1729-34. [PMID: 11872844 DOI: 10.1126/science.1067766] [Citation(s) in RCA: 351] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) and other neurotrophins are critically involved in long-term potentiation (LTP). Previous reports point to a presynaptic site of neurotrophin action. By imaging dentate granule cells in mouse hippocampal slices, we identified BDNF-evoked Ca2+ transients in dendrites and spines, but not at presynaptic sites. Pairing a weak burst of synaptic stimulation with a brief dendritic BDNF application caused an immediate and robust induction of LTP. LTP induction required activation of postsynaptic Ca2+ channels and N-methyl-d-aspartate receptors and was prevented by the blockage of postsynaptic Ca2+ transients. Thus, our results suggest that BDNF-mediated LTP is induced postsynaptically. Our finding that dendritic spines are the exclusive synaptic sites for rapid BDNF-evoked Ca2+ signaling supports this conclusion.
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Affiliation(s)
- Yury Kovalchuk
- Institut für Physiologie, Ludwig-Maximilians Universität München, 80336 München, Germany
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138
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Trophic factor-induced excitatory synaptogenesis involves postsynaptic modulation of nicotinic acetylcholine receptors. J Neurosci 2002. [PMID: 11784796 DOI: 10.1523/jneurosci.22-02-00505.2002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurotrophic factors have well established roles in neuronal development, although their precise involvement in synapse formation and plasticity is yet to be fully determined. Using soma-soma synapses between identified Lymnaea neurons, we have shown recently that trophic factors are required for excitatory but not inhibitory synapse formation. However, neither the precise site (presynaptic versus postsynaptic cell) nor the underlying mechanisms have yet been defined. In the present study, synapse formation between the presynaptic cell visceral dorsal 4 (VD4) and its postsynaptic partner right pedal dorsal 1 (RPeD1) was examined to define the cellular mechanisms mediating trophic factor-induced excitatory synaptogenesis in cell culture. When paired in a soma-soma configuration in the presence of defined media (DM, nonproteinacious), mutually inhibitory synapses were appropriately reconstructed between VD4 and RPeD1. However, when cells were paired in the presence of increasing concentrations of Lymnaea brain-conditioned medium (CM), a biphasic synapse (initial excitatory synaptic component followed by inhibition) developed. The CM-induced excitatory synapse formation required trophic factor-mediated activation of receptor tyrosine kinases in the postsynaptic cell, RPeD1, and a concomitant modulation of existing postsynaptic nicotinic acetylcholine receptors (nAChRs). Specifically, when RPeD1 was isolated in DM, exogenously applied ACh induced a hyperpolarizing response that was sensitive to the AChR antagonist methyllycaconitine (MLA). In contrast, a single RPeD1 isolated in CM exhibited a biphasic response to exogenously applied ACh. The initial depolarizing phase of the biphasic response was sensitive to both mecamylamine and hexamethonium chloride, whereas the hyperpolarizing phase was blocked by MLA. In soma-soma-paired neurons, the VD4-induced synaptic responses in RPeD1 were sensitive to the cholinergic antagonists in a concentration range similar to that used to block cholinergic responses in single RPeD1 cells. Therefore, the modulation of postsynaptic nAChRs was sufficient to account for the trophic factor-induced excitatory synaptogenesis. This study thus provides the first direct evidence that trophic factors act postsynaptically to promote excitatory synapse formation.
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139
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Jiang B, Akaneya Y, Ohshima M, Ichisaka S, Hata Y, Tsumoto T. Brain-derived neurotrophic factor induces long-lasting potentiation of synaptic transmission in visual cortex in vivo in young rats, but not in the adult. Eur J Neurosci 2001; 14:1219-28. [PMID: 11703451 DOI: 10.1046/j.0953-816x.2001.01751.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) rapidly enhances excitatory synaptic transmission in cortical slices. To date, however, a question of how long such an action persists remains unanswered as it is hard to record synaptic responses longer than several hours in slice preparations. To address this question and to investigate possible age-dependency of the action, we analysed effects of a brief application of BDNF and nerve growth factor (NGF) on field potentials of visual cortex in rats of postnatal days 13-17 and 19-24 and in the adulthood for 10-24 h. Evoked potentials to stimulation of the lateral geniculate nucleus were recorded simultaneously from two cortical sites into which the neurotrophin and control solution were injected. An application of BDNF induced a slowly developing increase in the field potential amplitude in young rats. The amplitude attained a plateau level 3-4 h after the infusion; 139 +/- 26% (mean +/- SD) and 132 +/- 21% of the baseline in the rats at P13-17 and P19-24, respectively. This potentiation remained stable from 4 to 8 h, then gradually decreased to the baseline 15-16 h after the infusion. NGF applied in the same way did not induce potentiation. An inhibitor of BDNF receptors blocked the potentiation when it was applied immediately after the BDNF application, but was not effective about 2 h later. In the adults, BDNF did not potentiate field potentials. These results indicate that BDNF induces synaptic potentiation lasting for several hours only in the developing cortex through processes downstream of receptor activation.
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Affiliation(s)
- B Jiang
- Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012 Japan
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140
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Zhu WJ, Roper SN. Brain-derived neurotrophic factor enhances fast excitatory synaptic transmission in human epileptic dentate gyrus. Ann Neurol 2001; 50:188-94. [PMID: 11506401 DOI: 10.1002/ana.1074] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) has trophic effects and modulates synaptic transmission in the hippocampal formation in animal studies. It is also upregulated in acute and chronic epilepsy models and in human temporal lobe epilepsy. This study was undertaken to examine the effects of BDNF on fast synaptic transmission in the human epileptic dentate gyrus. Hippocampal specimens were acquired from patients with temporal lobe epilepsy during surgical removal of the anterior temporal lobe intended to treat the epileptic condition. Whole-cell patch-clamp recordings were obtained from dentate granule cells in transverse hippocampal slices in vitro. Application of BDNF increased the amplitude and frequency of spontaneous excitatory postsynaptic currents and increased the amplitude of evoked excitatory postsynaptic currents. BDNF had no effect on spontaneous inhibitory postsynaptic currents but produced a decrease in amplitude of evoked inhibitory postsynaptic currents. BDNF's effects were abolished by coapplication of the tyrosine kinase inhibitor K252a. Therefore, BDNF enhances fast excitatory transmission in the epileptic human dentate gyrus and may play an important role in epileptogenesis in temporal lobe epilepsy. This raises the possibility of designing therapies for this disorder that may be both anticonvulsant and antiepileptogenic.
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Affiliation(s)
- W J Zhu
- Department of Neurological Surgery and Evelyn F. and William L. McKnight Brain Institute, University of Florida, Gainesville 32610-0265, USA
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141
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Ankeny DP, McTigue DM, Guan Z, Yan Q, Kinstler O, Stokes BT, Jakeman LB. Pegylated brain-derived neurotrophic factor shows improved distribution into the spinal cord and stimulates locomotor activity and morphological changes after injury. Exp Neurol 2001; 170:85-100. [PMID: 11421586 DOI: 10.1006/exnr.2001.7699] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The neurotrophin brain-derived neurotrophic factor (BDNF) shows promise for the treatment of central nervous system (CNS) trauma and disease. Effective delivery methods are required, however, for BDNF to be useful as a therapeutic agent. To this end, we examined the penetration of intrathecally infused N-terminal pegylated BDNF (peg-BDNF) compared to similar infusion of native BDNF after spinal cord injury (SCI). Pegylation dramatically improved delivery of BDNF to the spinal cord and induced the expression of Fos in spinal cord neurons. To test whether enhanced delivery would improve the modest effects on behavioral recovery and axonal outgrowth observed with native BDNF infusion, we assessed the efficacy of 2-week 25 microg/day peg-BDNF treatment, beginning 12-24 h (early) or 15 days (delayed) after midthoracic spinal contusion. Similar to native BDNF, early treatment with peg-BDNF accelerated the recovery of stepping in the open-field and acutely stimulated locomotor central pattern generator activity, as seen by the activation of hindlimb airstepping during either period of administration. The infusion of peg-BDNF, regardless of the timing of delivery, was related to enhanced sprouting of putative cholinergic fibers, like that observed after high dose native BDNF treatment. Despite improved delivery, however, neither axonal responses nor the extent of locomotor recovery were enhanced compared to native BDNF treatment. This suggests that alternative strategies, such as neurotrophin treatment in conjunction with cell transplantation techniques, or treatment nearer the cell bodies of target neurons might be employed in an attempt to effect significant repair after SCI.
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Affiliation(s)
- D P Ankeny
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA
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142
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Brünig I, Penschuck S, Berninger B, Benson J, Fritschy JM. BDNF reduces miniature inhibitory postsynaptic currents by rapid downregulation of GABA(A) receptor surface expression. Eur J Neurosci 2001; 13:1320-8. [PMID: 11298792 DOI: 10.1046/j.0953-816x.2001.01506.x] [Citation(s) in RCA: 205] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Changes in neurotransmitter receptor density at the synapse have been proposed as a mechanism underlying synaptic plasticity. Neurotrophic factors are known to influence synaptic strength rapidly. In the present study, we found that brain-derived neurotrophic factor (BDNF) acts postsynaptically to reduce gamma-aminobutyric acid (GABA)-ergic function. Using primary cultures of rat hippocampal neurons, we investigated the effects of BDNF on GABAergic miniature inhibitory postsynaptic currents (mIPSCs) and on the localization of GABAA receptors. Application of BDNF (100 ng/mL) led within minutes to a marked reduction (33.5%) of mIPSC amplitudes in 50% of neurons, recorded in the whole-cell patch-clamp mode, leaving frequency and decay kinetics unaffected. This effect was blocked by the protein kinase inhibitor K252a, which binds with high affinity to trkB receptors. Immunofluorescence staining with an antibody against trkB revealed that about 70% of cultured hippocampal pyramidal cells express trkB. In dual labelling experiments, use of neurobiotin injections to label the recorded cells revealed that all cells responsive to BDNF were immunopositive for trkB. Treatment of cultures with BDNF reduced the immunoreactivity for the GABAA receptor subunits-alpha2, -beta2,3 and -gamma2 in the majority of neurons. This effect was detectable after 15 min and lasted at least 12 h. Neurotrophin-4 (NT-4), but not neurotrophin-3 (NT-3), also reduced GABAA receptor immunoreactivity, supporting the proposal that this effect is mediated by trkB. Altogether the results suggest that exposure to BDNF induces a rapid reduction in postsynaptic GABAA receptor number that is responsible for the decline in GABAergic mIPSC amplitudes.
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Affiliation(s)
- I Brünig
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland
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143
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Olofsdotter K, Lindvall O, Asztély F. Increased synaptic inhibition in dentate gyrus of mice with reduced levels of endogenous brain-derived neurotrophic factor. Neuroscience 2001; 101:531-9. [PMID: 11113302 DOI: 10.1016/s0306-4522(00)00428-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aim of this study was to explore the role of endogenous neurotrophins for inhibitory synaptic transmission in the dentate gyrus of adult mice. Heterozygous knockout (+/-) mice or neurotrophin scavenging proteins were used to reduce the levels of endogenous brain-derived neurotrophic factor and neurotrophin-3. Patch-clamp recordings from dentate granule cells in brain slices showed that the frequency, but not the kinetics or amplitude, of miniature inhibitory postsynaptic currents was modulated in brain-derived neurotrophic factor +/- compared to wild-type (+/+) mice. Furthermore, paired-pulse depression of evoked inhibitory synaptic responses was increased in brain-derived neurotrophic factor +/- mice. Similar results were obtained in brain slices from brain-derived neurotrophic factor +/+ mice incubated with tyrosine receptor kinase B-immunoglobulin G, which scavenges endogenous brain-derived neurotrophic factor. The increased inhibitory synaptic activity in brain-derived neurotrophic factor +/- mice was accompanied by decreased excitability of the granule cells. No differences in the frequency, amplitude or kinetics of miniature inhibitory postsynaptic currents were seen between neurotrophin-3 +/- and +/+ mice. From these results we suggest that endogenous brain-derived neurotrophic factor, but not neurotrophin-3, has acute modulatory effects on synaptic inhibition onto dentate granule cells. The site of action seems to be located presynaptically, i.e. brain-derived neurotrophic factor regulates the properties of inhibitory interneurons, leading to increased excitability of dentate granule cells. We propose that through this mechanism, brain-derived neurotrophic factor can change the gating/filtering properties of the dentate gyrus for incoming information from the entorhinal cortex to hippocampus. This will have consequences for the recruitment of hippocampal neural circuitries both under physiological and pathological conditions, such as epileptogenesis.
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Affiliation(s)
- K Olofsdotter
- Section of Restorative Neurology, Wallenberg Neuroscience Center, University Hospital, S-221 85, Lund, Sweden.
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144
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Kempermann G, van Praag H, Gage FH. Activity-dependent regulation of neuronal plasticity and self repair. PROGRESS IN BRAIN RESEARCH 2001; 127:35-48. [PMID: 11142036 DOI: 10.1016/s0079-6123(00)27004-0] [Citation(s) in RCA: 154] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Plasticity is an essential characteristic of the brain: it is part of how the brain functions and is continuous while the brain interacts with the outer world. The state of activation and the level of activity of the entire organism affect the brain's plastic response. Brain plasticity has many substrates, ranging from synapses to neurites and entire cells. The production of new neurons is part of plasticity even in the adult and old brain, but under normal conditions neurogenesis only occurs in two privileged regions of the adult brain: hippocampus and olfactory system. At least in the hippocampus, physical activity stimulates neurogenesis by acting on the proliferation of neuronal stem cells. More specific functions such as learning may be able to recruit new neurons from the pool of cells with neurogenic potential. In a broader context neuronal stem cells can likely be found throughout the brain. Therefore, novel approaches to neuroregeneration will, when most effective, make use of the activity-related effects on neuronal stem cells in the adult brain to activate these stem cells in a targeted manner to enhance brain function.
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Affiliation(s)
- G Kempermann
- Salk Institute for Biological Studies, Laboratory of Genetics, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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145
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Bolton MM, Lo DC, Sherwood NT. Long-term regulation of excitatory and inhibitory synaptic transmission in hippocampal cultures by brain-derived neurotrophic factor. PROGRESS IN BRAIN RESEARCH 2001; 128:203-18. [PMID: 11105680 DOI: 10.1016/s0079-6123(00)28018-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- M M Bolton
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
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146
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Lu B, Gottschalk W. Modulation of hippocampal synaptic transmission and plasticity by neurotrophins. PROGRESS IN BRAIN RESEARCH 2001; 128:231-41. [PMID: 11105682 DOI: 10.1016/s0079-6123(00)28020-5] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- B Lu
- Unit on Synapse Development and Plasticity, NICHD, NIH, Bethesda, MD 20892-4480, USA.
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147
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Reibel S, Larmet Y, Lê BT, Carnahan J, Marescaux C, Depaulis A. Brain-derived neurotrophic factor delays hippocampal kindling in the rat. Neuroscience 2001; 100:777-88. [PMID: 11036211 DOI: 10.1016/s0306-4522(00)00351-1] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Epileptic seizures increase the expression of brain-derived neurotrophic factor in the hippocampus. Since this neurotrophin exerts modulatory effects on neuronal excitability in this structure, it may play an important role in hippocampal epileptogenesis. This question was addressed by studying the effects of chronic infusions of recombinant brain-derived neurotrophic factor and brain-derived neurotrophic factor antisense in the hippocampus during the first seven days of hippocampal kindling. Infusion with brain-derived neurotrophic factor (6-24 microg/day) significantly delayed the progression of standard hippocampal kindling and strongly suppressed seizures induced by rapid hippocampal kindling. These suppressive effects were dose dependent, long lasting, not secondary to neuronal toxicity and specific to this neurotrophin, as nerve growth factor accelerated hippocampal kindling progression. They also appeared to be specific to the hippocampus, as infusion of brain-derived neurotrophic factor (48 microg/day) in the amygdala only resulted in a slight and transient delay of amygdala kindling. Conversely to the protective effects of exogenous brain-derived neurotrophic factor, chronic hippocampal infusion of antisense oligodeoxynucleotides (12 nmol/day), resulting in reduced expression of endogenous brain-derived neurotrophic factor in the hippocampus, aggravated seizures during hippocampal kindling. Taken together, our results lead us to suggest that the seizure-induced increase in brain-derived neurotrophic factor expression in the hippocampus may constitute an endogenous regulatory mechanism able to restrain hippocampal epileptogenesis.
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Affiliation(s)
- S Reibel
- INSERM U398, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67085 Cedex, Strasbourg, France
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148
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Abstract
The role of neurotrophins as regulatory factors that mediate the differentiation and survival of neurons has been well described. More recent evidence indicates that neurotrophins may also act as synaptic modulators. Here, I review the evidence that synaptic activity regulates the synthesis, secretion and action of neurotrophins, which can in turn induce immediate changes in synaptic efficacy and morphology. By this account, neurotrophins may participate in activity-dependent synaptic plasticity, linking synaptic activity with long-term functional and structural modification of synaptic connections.
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Affiliation(s)
- M M Poo
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3200, USA.
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149
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Murer MG, Yan Q, Raisman-Vozari R. Brain-derived neurotrophic factor in the control human brain, and in Alzheimer's disease and Parkinson's disease. Prog Neurobiol 2001; 63:71-124. [PMID: 11040419 DOI: 10.1016/s0301-0082(00)00014-9] [Citation(s) in RCA: 633] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is a small dimeric protein, structurally related to nerve growth factor, which is abundantly and widely expressed in the adult mammalian brain. BDNF has been found to promote survival of all major neuronal types affected in Alzheimer's disease and Parkinson's disease, like hippocampal and neocortical neurons, cholinergic septal and basal forebrain neurons, and nigral dopaminergic neurons. In this article, we summarize recent work on the molecular and cellular biology of BDNF, including current ideas about its intracellular trafficking, regulated synthesis and release, and actions at the synaptic level, which have considerably expanded our conception of BDNF actions in the central nervous system. But our primary aim is to review the literature regarding BDNF distribution in the human brain, and the modifications of BDNF expression which occur in the brain of individuals with Alzheimer's disease and Parkinson's disease. Our knowledge concerning BDNF actions on the neuronal populations affected in these pathological states is also reviewed, with an aim at understanding its pathogenic and pathophysiological relevance.
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Affiliation(s)
- M G Murer
- Departamento de Fisiologia, Facultad de Medicina, Universidad de Buenos Aires, Paraguay.
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150
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Abstract
Neurotrophins regulate development, maintenance, and function of vertebrate nervous systems. Neurotrophins activate two different classes of receptors, the Trk family of receptor tyrosine kinases and p75NTR, a member of the TNF receptor superfamily. Through these, neurotrophins activate many signaling pathways, including those mediated by ras and members of the cdc-42/ras/rho G protein families, and the MAP kinase, PI-3 kinase, and Jun kinase cascades. During development, limiting amounts of neurotrophins function as survival factors to ensure a match between the number of surviving neurons and the requirement for appropriate target innervation. They also regulate cell fate decisions, axon growth, dendrite pruning, the patterning of innervation and the expression of proteins crucial for normal neuronal function, such as neurotransmitters and ion channels. These proteins also regulate many aspects of neural function. In the mature nervous system, they control synaptic function and synaptic plasticity, while continuing to modulate neuronal survival.
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Affiliation(s)
- Eric J Huang
- Department of Pathology, University of California, San Francisco, California 94143; e-mail:
| | - Louis F Reichardt
- Department of Physiology, University of California, San Francisco, California 94143, and Howard Hughes Medical Institute, San Francisco, California 94143; e-mail:
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