It is hypothesised that when galanin expression rises to high levels within the peripheral nervous system, such as after peripheral nerve injury, and is released into the dorsal horn [46, 62], GalR2 activation switches from a Gq- (low galanin concentration) to a Gi/o- dependent pathway (high galanin concentration), that is from a pro- to antinociceptive signalling pathway [59]. This evidence concerns the gene GALR2 and peripheral nerve injury.