A dual role for peripheral GDNF signaling in nociception and cardiovascular reflexes

Abstract Group III/IV muscle afferents transduce nociceptive signals and modulate exercise pressor reflexes (EPR). However, the mechanisms governing afferent responsiveness to dually modulate these processes are not well characterized. We and others have shown that ischemic injury can induce both nociception-related behaviors and exacerbated EPRs in the same mice. This correlated with primary muscle afferent sensitization and increased expression of glial cell line-derived neurotrophic factor (GDNF) in injured muscle and increased expression of GDNF family receptor α1 (GFRα1) in DRGs. Here we report that increased GDNF/GFRα1 signaling to sensory neurons from ischemia/reperfusion affected muscle modulated nociceptive-like behaviors, increased EPRs, and group III/IV muscle afferent sensitization. This appeared to have taken effect through increased CREB/CREB-binding protein mediated expression of the purinergic receptor P2X5 in the DRGs. Muscle GDNF signaling to neurons may play an important dual role in nociception and sympathetic reflexes and could provide a novel therapeutic target for treating complications from ischemic injuries.