Journal of Pain Research (Jul 2022)
Post-Inhibitory Rebound Firing of Dorsal Root Ganglia Neurons
Abstract
Tong Zhu,1,2 Siqi Wei,1 Yuying Wang1,3,4 1Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China; 2Clinical Experimental Center, Xi’an International Medical Center Hospital, Xi’an, Shaanxi, 710100, People’s Republic of China; 3Institute of Neuroscience, Translational Medicine Institute, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, 710061, People’s Republic of China; 4Key Laboratory of Environment and Genes Related to Diseases (Xi’an Jiaotong University), Ministry of Education, Xi’an, People’s Republic of ChinaCorrespondence: Yuying Wang, Email [email protected]: In the central nervous system, post-inhibitory rebound firing (RF) may mediate overactivity of neurons under pathophysiological condition. RF is also observed in dorsal root ganglion (IRA) neurons. However, the functional significance of RF in primary sensory neurons has remained unknown. After peripheral sensory nerve/neuron injury, DRG neurons exhibit hyperexcitability. Therefore, RF may play a role in neuropathic pain.Methods: Chronic compression of DRG (CCD) is used as a neuropathic pain model. Rats were divided into 2 groups: Sham and CCD groups. Patch clamp was performed on the whole DRG and cultured DRG neurons to record RF and T-type Ca2+ currents. The blocker of T-type Ca2+ channels, NiCl2, was applied to DRG neurons.Results: Rebound neurons were more excitable than non-rebound neurons. And they discharged RF with prominent after depolarizing potentials, which were blocked by NiCl2. After DRG injury, the proportion of rebound neurons augmented, and rebound neurons’ excitability increased. Meanwhile, the steady-state activation curve of T-type Ca2+ channels was shifted toward the left.Conclusion: RF may be related to highly excitable neurons and sensitive to both depolarization and hyperpolarization. T-type Ca2+ channels were critical to RF, potentially enhancing the spontaneous firing of rebound neurons in response to resting membrane potential fluctuations.Keywords: post-inhibitory rebound firing, dorsal root ganglia, chronic compression, T-type Ca2+ currents
