Canto-Bustos Martha, Loeza-Alcocer Emanuel, González-Ramírez Ricardo, Gandini María A, Delgado-Lezama Rodolfo, Felix Ricardo
Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico.
Department of Molecular Biology and Histocompatibility, "Dr. Manuel Gea González" General Hospital, Mexico City, Mexico.
PLoS One. 2014 Sep 25;9(9):e108187. doi: 10.1371/journal.pone.0108187. eCollection 2014.
Voltage-gated Ca2+ (CaV) channels are transmembrane proteins comprising three subfamilies named CaV1, CaV2 and CaV3. The CaV3 channel subfamily groups the low-voltage activated Ca2+ channels (LVA or T-type) a significant role in regulating neuronal excitability. CaV3 channel activity may lead to the generation of complex patterns of action potential firing such as the postinhibitory rebound (PIR). In the adult spinal cord, these channels have been found in dorsal horn interneurons where they control physiological events near the resting potential and participate in determining excitability. In motoneurons, CaV3 channels have been found during development, but their functional expression has not yet been reported in adult animals. Here, we show evidence for the presence of CaV3 channel-mediated PIR in motoneurons of the adult turtle spinal cord. Our results indicate that Ni2+ and NNC55-0396, two antagonists of CaV3 channel activity, inhibited PIR in the adult turtle spinal cord. Molecular biology and biochemical assays revealed the expression of the CaV3.1 channel isotype and its localization in motoneurons. Together, these results provide evidence for the expression of CaV3.1 channels in the spinal cord of adult animals and show also that these channels may contribute to determine the excitability of motoneurons.
电压门控性Ca2+（CaV）通道是跨膜蛋白，由CaV1、CaV2和CaV3三个亚家族组成。CaV3通道亚家族包含低电压激活的Ca2+通道（LVA或T型），在调节神经元兴奋性方面发挥重要作用。CaV3通道活性可能导致复杂的动作电位发放模式的产生，如抑制后反弹（PIR）。在成年脊髓中，已在背角中间神经元中发现这些通道，它们在静息电位附近控制生理事件，并参与确定兴奋性。在运动神经元中，发育期间已发现CaV3通道，但在成年动物中尚未报道其功能表达。在此，我们展示了成年海龟脊髓运动神经元中存在CaV3通道介导的PIR的证据。我们的结果表明，CaV3通道活性的两种拮抗剂Ni2+和NNC55 - 0396抑制了成年海龟脊髓中的PIR。分子生物学和生化分析揭示了CaV3.1通道亚型的表达及其在运动神经元中的定位。总之，这些结果为成年动物脊髓中CaV3.1通道的表达提供了证据，也表明这些通道可能有助于确定运动神经元的兴奋性。
