Nerve growth factor collaborates with myocyte-derived factors to promote development of presynaptic sites in cultured sympathetic neurons.
Nerve growth factor (NGF) acutely modulates synaptic transmission between sympathetic neurons and their cardiac myocyte targets. NGF also has developmental effects in establishing the level of synaptic transmission between sympathetic neurons and myocytes in culture, although little is known about the mechanisms by which NGF influences this synaptic connectivity. Here we report that NGF acts in conjunction with factors produced by cardiac myocytes to promote neuronal contact with the target and the extension of synaptic vesicle-containing growth cones. In conjunction with previously published results showing that NGF has long-term effects on synaptic transmission between sympathetic neurons and myocytes, this work suggests that NGF acts to promote sympathetic neurotransmission by increasing the number of sympathetic fibers establishing target contact. Further, we found that developmental changes in cardiac myocytes led to an increase in the density of synaptic vesicle-containing variocosities along sympathetic fibers, a process regulated by NGF. Thus, as myocytes mature they produce factors that promote the formation of sympathetic presynaptic structures. These results argue that multiple target interactions regulate the extent of synapse formation between sympathetic neurons and cardiac cells and suggest that NGF promotes presynaptic development by increasing neuronal contact with myocyte-derived cell surface or matrix-associated factors.
Lockhart
S T
ST
Department of Biology and Volen National Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02454, USA.
Mead
J N
JN
Pisano
J M
JM
Slonimsky
J D
JD
Birren
S J
SJ
D000185:Actinin / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D020439:Growth Cones / Q000187:drug effects / Q000378:metabolism; D007150:Immunohistochemistry; D007365:Intercellular Junctions / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000378:metabolism; D016900:Neurofilament Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D064531:Peripherins; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D020800:Receptor, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism; D020917:Receptor, trkA / Q000235:genetics / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D017077:Culture Media, Conditioned; D007381:Intermediate Filament Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D016900:Neurofilament Proteins; D064531:Peripherins; D012333:RNA, Messenger; D020800:Receptor, Nerve Growth Factor; C489618:Sv2a protein, rat; C489617:Sv2b protein, rat; D000185:Actinin; D020932:Nerve Growth Factor; D020917:Receptor, trkA