Neurotrophins (NTs), a family of proteins essential for the survival and differentiation of developing neurons, have been shown to participate in activity-dependent synaptic plasticity. In this project, we propose to test the hypothesis that secretion of NTs at developing synapses is triggered by synaptic activity in a spike pattern-dependent manner and localized synaptic actions of secreted NTs in turn produce long-term functional and structural modification of developing synaptic connections. We will focus our attention on brain-derived neurotrophic factor (BDNF), a NT widely expressed in the developing nervous system, using a combination of physiological, molecular biological, and optical imaging methods. The proposed research consists of three parts. In PART I, we will use cultures of rat or mouse hippocampal neurons to examine the acute pre- and postsynaptic effects of exogenously-applied BDNF on the function and plasticity of glutamatergic and GABAergic synapses and on axon/dendrite morphology and synaptogenesis. The synapse-specific local actions of BDNF and underlying signaling mechanisms will also be investigated. In PART II, we will study the role of endogenously-secreted BDNF in activity-induced modifications of synaptic function and morphology in hippocampal cultures, activity-dependent BDNF secretion, and intra- and interneuronal trafficking of BDNF. In PART Ill, using developing Xenopus tadpoles, we will examine the in vivo effect of BDNF on the function and plasticity of retinotectal synapses, axon/dendrite dynamics and synaptogenesis in the tectum, and the trafficking and secretion of endogenous BDNF. Finally, we will investigate the role of BDNF in the development of retinotopic map and direction-selective receptive field of tectal neurons. Taken together, these in vitro and in vivo studies provide unique opportunities to address several fundamental cell biological issues concerning the modulatory function of neurotrophins in activity-dependent refinement of developing neural connections, and are likely to yield new information relevant to our basic understanding of physiology and pathology of the developing nervous system.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS037831-07
Application #
6640238
Study Section
Molecular, Cellular and Developmental Neurosciences 2 (MDCN)
Program Officer
Mamounas, Laura
Project Start
1998-07-24
Project End
2007-06-30
Budget Start
2003-07-01
Budget End
2004-06-30
Support Year
7
Fiscal Year
2003
Total Cost
$346,065
Indirect Cost
Name
University of California Berkeley
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
124726725
City
Berkeley
State
CA
Country
United States
Zip Code
94704
Liu, Qing-song; Pu, Lu; Poo, Mu-ming (2005) Repeated cocaine exposure in vivo facilitates LTP induction in midbrain dopamine neurons. Nature 437:1027-31
Zhou, Qiang; Homma, Koichi J; Poo, Mu-ming (2004) Shrinkage of dendritic spines associated with long-term depression of hippocampal synapses. Neuron 44:749-57
Wardle, Rinda A; Poo, Mu-ming (2003) Brain-derived neurotrophic factor modulation of GABAergic synapses by postsynaptic regulation of chloride transport. J Neurosci 23:8722-32
Zhang, Xiao hui; Poo, Mu-ming (2002) Localized synaptic potentiation by BDNF requires local protein synthesis in the developing axon. Neuron 36:675-88
Kao, Hung-Teh; Song, Hong-jun; Porton, Barbara et al. (2002) A protein kinase A-dependent molecular switch in synapsins regulates neurite outgrowth. Nat Neurosci 5:431-7
Ganguly, K; Schinder, A F; Wong, S T et al. (2001) GABA itself promotes the developmental switch of neuronal GABAergic responses from excitation to inhibition. Cell 105:521-32
Ming, G; Henley, J; Tessier-Lavigne, M et al. (2001) Electrical activity modulates growth cone guidance by diffusible factors. Neuron 29:441-52
Schinder, A F; Berninger, B; Poo, M (2000) Postsynaptic target specificity of neurotrophin-induced presynaptic potentiation. Neuron 25:151-63
Schinder, A F; Poo, M (2000) The neurotrophin hypothesis for synaptic plasticity. Trends Neurosci 23:639-45
Boulanger, L; Poo, M (1999) Gating of BDNF-induced synaptic potentiation by cAMP. Science 284:1982-4

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