AUTHOR=Zhu Mengye , Yan Yi , Cao Xuezhong , Zeng Fei , Xu Gang , Shen Wei , Li Fan , Luo Lingyun , Wang Zhijian , Zhang Yong , Zhang Xuexue , Zhang Daying , Liu Tao TITLE=Electrophysiological and Morphological Features of Rebound Depolarization Characterized Interneurons in Rat Superficial Spinal Dorsal Horn JOURNAL=Frontiers in Cellular Neuroscience VOLUME=15 YEAR=2021 URL=https://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2021.736879 DOI=10.3389/fncel.2021.736879 ISSN=1662-5102 ABSTRACT=
Substantia gelatinosa (SG) neurons, which are located in the spinal dorsal horn (lamina II), have been identified as the “central gate” for the transmission and modulation of nociceptive information. Rebound depolarization (RD), a biophysical property mediated by membrane hyperpolarization that is frequently recorded in the central nervous system, contributes to shaping neuronal intrinsic excitability and, in turn, contributes to neuronal output and network function. However, the electrophysiological and morphological properties of SG neurons exhibiting RD remain unclarified. In this study, whole-cell patch-clamp recordings were performed on SG neurons from parasagittal spinal cord slices. RD was detected in 44.44% (84 out of 189) of the SG neurons recorded. We found that RD-expressing neurons had more depolarized resting membrane potentials, more hyperpolarized action potential (AP) thresholds, higher AP amplitudes, shorter AP durations, and higher spike frequencies in response to depolarizing current injection than neurons without RD. Based on their firing patterns and morphological characteristics, we propose that most of the SG neurons with RD mainly displayed tonic firing (69.05%) and corresponded to islet cell morphology (58.82%). Meanwhile, subthreshold currents, including the hyperpolarization-activated cation current (I