Prolonged hindlimb unloading leads to changes in electrophysiological properties of L5 dorsal root ganglion neurons in rats after 14 days

Introduction: The purpose of this study was to evaluate the electrophysiological changes observed in dorsal root ganglion (DRG) neurons in a simulated weightlessness rat model and to assess the mechanisms involved in these changes. Methods: The simulated weightlessness model was created by hindlimb unloading (HU). Whole‐cell patch‐clamp recordings, conduction velocity measurement, and ultrastructural observation were performed. Results: In the HU rats, the action potentials had a longer duration and slower falling rate, but there was no significant effect on amplitude or rate of rise. HU also induced lowering of rheobase and of the threshold potential, making the cells more excitable. The conduction velocities in the proximal branches of ganglion cells were also decreased, and some degenerative changes in the myelin sheath were noted. Conclusions: This study provides evidence of plasticity of DRG neurons induced by HU. The changes observed might contribute to impaired motor performance in rats submitted to HU. Muscle Nerve 45: 65–69, 2012