Signals Inducing Axonal Regeneration

Neurotrophins can prime neurons for regeneration. They elevate cAMP in neurons in the absence of inhibitory signals, and this elevation sufficiently over-rides any subsequent inhibitory signals. In vivo, crushed DRG axons have been shown to regenerate into spinal cord by apphcation of neurotrophins (Ramer et al., 2000). Interestingly, effects of neurotrophins, in most cases, occur through Trk receptor, while inhibitory Summary effects are mediated through pVS.  

Events downstream of cAMP elevation occur in two phases - transcription-independent and transcription-dependent. In the first phase, PKA is activated which is believed to levy a direct effect on the cytoskeleton via Rho GTPase. The second phase 

Although not every dimension of CNS cellular signahng is covered in entirety due to restriction of publisher s space and reader s patience, yet sincere attempt has been made to introduce every known major signal transduction pathway 

Neurotrophins are employed for regulation and/or maintenance of axonal growth, dentritic pruning and synaptic refinements. List receptors for neurotrophins and mechanisms by which neurotrophin-receptor complexes become internalized. 

Three Trk receptor tyrosine kinases and four neurotrophins have been identified in the brain. How is affinity and specificity of neurotropins for Trk receptors regulated  

Ca + regulates a wide array of neuronal functions. How can tliis single ion regulate such a diverse functions as neuronal functions, ranging frem neuiite outgrowth, synaptic plasticity, transmitter release, etc.  

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Qiu, J., Cafferty, W. B., McMahon, S. B., and Thompson, S. W. (2005). Conditioning injury-induced spinal axon regeneration requires signal transducer and activator of transcription 3 activation. J. Neurosci. 25, 1645—1653. 

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