Our studies show that different cell adhesion molecules (CAM) are regulated by different patterns of neural impulses, and that this has functional effects on key developmental processes in the nervous system. Expression of both calcium-dependent and calcium-independent classes of CAMs is regulated by neural impulse activity in DRG neurons, but different CAMs respond differently to different patterns of stimulation. Low-frequency stimulation down-regulates L1 mRNA and protein levels, but NCAM is not affected. Expression of N-cadherin is down-regulated by higher frequencies of stimulation than those affecting L1 expression. Studies in vivo show that levels of L1 mRNA decrease abruptly in DRG neurons at the embryonic period when spontaneous impulse activity begins, which is consistent with decreased expression of L1 following low-frequency stimulation in cultured DRG neurons. Activity-dependent regulation of L1 induces defasciculation of axon terminals, reduces adhesion and the mitotic rate of Schwann cells on axons stimulated at frequencies that lower L1 expression. Exposure to specific neurotrophins and appropriate target neurons from the spinal cord prevents the activity-dependent down-regulation of L1 in cultured DRG neurons. Studies of how intracellular signaling pathways in neurons integrate and transmit information coded in the temporal pattern of neural impulses support a mechanism in which the differing kinetics of parallel intracellular signaling reactions confers sensitivity to different temporal patterns of activation and thereby activates distinct intracellular pathways controlling gene expression and other neuronal and synaptic functions. These results are based on studies of the signaling pathways (second messengers, protein kinases, and transcription factors) that activate the immediate early gene c-fos in response to different patterns of action potential stimulation in vitro.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Intramural Research (Z01)
Project #
1Z01HD000713-02
Application #
2575648
Study Section
Special Emphasis Panel (LDN)
Project Start
Project End
Budget Start
Budget End
Support Year
2
Fiscal Year
1996
Total Cost
Indirect Cost
City
State
Country
United States
Zip Code
Bukalo, Olena; Lee, Philip R; Fields, R Douglas (2016) BDNF mRNA abundance regulated by antidromic action potentials and AP-LTD in hippocampus. Neurosci Lett 635:97-102
Lee, Philip R; Fields, R Douglas (2009) Regulation of myelin genes implicated in psychiatric disorders by functional activity in axons. Front Neuroanat 3:4
Fields, R Douglas (2008) Oligodendrocytes changing the rules: action potentials in glia and oligodendrocytes controlling action potentials. Neuroscientist 14:540-3
Fields, R Douglas (2008) White matter in learning, cognition and psychiatric disorders. Trends Neurosci 31:361-70
Fields, R Douglas (2008) White matter matters. Sci Am 298:42-9
Jia, Min; Li, Min-Xu; Fields, R Douglas et al. (2007) Extracellular ATP in activity-dependent remodeling of the neuromuscular junction. Dev Neurobiol 67:924-32
Fields, R Douglas; Fields, Kyle D; Fields, Melanie C (2007) Semiconductor gel in shark sense organs? Neurosci Lett 426:166-70
Lee, Philip R; Cohen, Jonathan E; Fields, R Douglas (2006) Immune system evasion by peripheral nerve sheath tumor. Neurosci Lett 397:126-9
Fields, R Douglas (2006) Nerve impulses regulate myelination through purinergic signalling. Novartis Found Symp 276:148-58; discussion 158-61, 233-
Cohen, Jonathan E; Fields, R Douglas (2006) CaMKII inactivation by extracellular Ca(2+) depletion in dorsal root ganglion neurons. Cell Calcium 39:445-54

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