text: an industrial partnership grant from the BBSRC and AstraZeneca. 
  The remaining authors have no conflicts of interest to declare. 
  [7] Boucher TJ, Okuse K, Bennett DLH, Munson JB, Wood JN, McMahon 
  SB. Potent analgesic effects of GDNF in neuropathic pain states. Science 
  2000;290:124–7. 
  
  to lead contact G.- 
  A.W.—gregory.weir@glasgow.ac.uk. Further 
  information and 
  requests for reagents and/or reagents used in this study should 
  also be directed to G.A.W., and we will endeavour to fulfil these. 
  
  Data are available on request 
  
  [8] Bradbury EJ, Burnstock G, McMahon SB. The expression of P2X3 
  purinoreceptors in sensory neurons: effects of axotomy and glial-derived 
  neurotrophic factor. Mol Cell Neurosci 1998;12:256–68. 
  
  [9] Br ´az JM, Basbaum AI. Triggering genetically-expressed transneuronal 
  tracers by peripheral axotomy reveals convergent and segregated 
  sensory neuron-spinal cord connectivity. Neuroscience 2009;163: 
  1220–32. 