The development of appropriate neuronal circuitry is critical for normal function of the nervous system. Defects in the formation or modulation of synaptic connections may contribute to the etiology of a number of developmental and nervous system disorders. Yet little is known about the molecules that regulate synapse formation and function. In the peripheral nervous system, nerve growth factor (NGF) has been implicated in the innervation of target tissues by sympathetic neurons. Recent studies in this laboratory have indicated that NGF also influences the formation and strength of synapses between sympathetic neurons and cardiac myocytes in vitro. This system provides a novel opportunity to investigate both developmental and modulatory roles of neurotrophins in the establishment of neuronal circuitry. The goals of this proposal are to define the cellular and molecular mechanisms underlying NGF-mediated enhancements in synapse formation and function. Synaptic connections that form between sympathetic neurons and cardiac myocytes can be assayed physiologically by measuring evoked postsynaptic currents in myocytes, or functionally as an increase in myocyte beat rate upon stimulation of a connected neuron. The neurotransmitter dependence, neurotrophin NGF-dependent synaptic modulation will be determined in neuron/myocyte co-cultures. We will determine whether NGF acts presynaptically to alter neurotransmitter release or postsynaptically to alter the myocyte response to neurotransmitter. We will test the hypothesis that NGF acutely potentiates synaptic transmission by enhancing the release of norepinephrine from presynaptic terminals and will investigate a role for additional co-transmitters in the system. Preliminary results indicate that NGF-dependent modulation of sympathetic synapses may involve two different receptors for NGF, TrkA and p75. We will investigate whether the level of NGF-dependent synaptic modulation is regulated through two interacting signal transduction systems. Finally, we have demonstrated long-term effects of NGF on the development of sympathetic synapses. We will investigate whether NGF determines the number or strength of synapses that develop between sympathetic neurons and cardiac myocytes. These experiments will, for the first time, define the developmental and modulatory roles of NGF at the synaptic level.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS040168-03
Application #
6477180
Study Section
Special Emphasis Panel (ZRG1-MDCN-7 (01))
Program Officer
Mamounas, Laura
Project Start
1999-12-17
Project End
2004-11-30
Budget Start
2001-12-01
Budget End
2002-11-30
Support Year
3
Fiscal Year
2002
Total Cost
$269,359
Indirect Cost
Name
Brandeis University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
616845814
City
Waltham
State
MA
Country
United States
Zip Code
02454
Luther, Jason A; Birren, Susan J (2009) Neurotrophins and target interactions in the development and regulation of sympathetic neuron electrical and synaptic properties. Auton Neurosci 151:46-60
Habecker, Beth A; Bilimoria, Parizad; Linick, Camille et al. (2008) Regulation of cardiac innervation and function via the p75 neurotrophin receptor. Auton Neurosci 140:40-8
Moon, Jung-Il; Birren, Susan J (2008) Target-dependent inhibition of sympathetic neuron growth via modulation of a BMP signaling pathway. Dev Biol 315:404-17
Luther, Jason A; Birren, Susan J (2006) Nerve growth factor decreases potassium currents and alters repetitive firing in rat sympathetic neurons. J Neurophysiol 96:946-58
Slonimsky, John D; Mattaliano, Mark D; Moon, Jung-Il et al. (2006) Role for calcium/calmodulin-dependent protein kinase II in the p75-mediated regulation of sympathetic cholinergic transmission. Proc Natl Acad Sci U S A 103:2915-9
Dore, Justin J; Crotty, Kate L; Birren, Susan J (2005) Inhibition of glial maturation by bone morphogenetic protein 2 in a neural crest-derived cell line. Dev Neurosci 27:37-48
Slonimsky, John D; Yang, Bo; Hinterneder, Jeanine M et al. (2003) BDNF and CNTF regulate cholinergic properties of sympathetic neurons through independent mechanisms. Mol Cell Neurosci 23:648-60
Yang, Bo; Slonimsky, John D; Birren, Susan J (2002) A rapid switch in sympathetic neurotransmitter release properties mediated by the p75 receptor. Nat Neurosci 5:539-45
Bharmal, S; Slonimsky, J D; Mead, J N et al. (2001) Target cells promote the development and functional maturation of neurons derived from a sympathetic precursor cell line. Dev Neurosci 23:153-64
Pisano, J M; Colon-Hastings, F; Birren, S J (2000) Postmigratory enteric and sympathetic neural precursors share common, developmentally regulated, responses to BMP2. Dev Biol 227:11-Jan

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