1. Academic Validation
  2. Orexin enhances firing activities in the gigantocellular reticular nucleus through the activation of non-selective cationic conductance

Orexin enhances firing activities in the gigantocellular reticular nucleus through the activation of non-selective cationic conductance

  • Neurosci Lett. 2020 Aug 10;733:135088. doi: 10.1016/j.neulet.2020.135088.
Yu-Jie Pang 1 Hui Feng 1 Si-Yi Wen 1 Qi-Cheng Qiao 1 Jun Zhang 2 Nian Yang 3
Affiliations

Affiliations

  • 1 Department of Physiology, Army Medical University, Chongqing 400038, PR China.
  • 2 Department of Physiology, Army Medical University, Chongqing 400038, PR China. Electronic address: [email protected].
  • 3 Department of Physiology, Army Medical University, Chongqing 400038, PR China. Electronic address: [email protected].
Abstract

Orexin/hypocretin has been implicated in central motor control. The gigantocellular reticular nucleus (Gi), a key element of the brainstem motor inhibitory system, also receives orexinergic innervations. However, the modulations of orexin on the neuronal activities and the underlying cellular mechanisms in Gi neurons remain unknown. Here, through whole-cell patch-clamp recordings, we first observed that orexin increased the firing frequency in Gi neurons. Interestingly, a postsynaptic depolarization elicited by orexin was observed in the presence of tetrodotoxin, without altering the input resistance of Gi neurons at around -60 mV. Moreover, through comparing the current-frequency curves constructed by identical current injections from equal membrane potentials, we found that orexin also increased the repetitive firing ability of Gi neurons. This action appeared to be caused by the shortening of inter-spike intervals, without altering the waveform of individual action potentials. We finally revealed that activation of the non-selective cationic conductance contributed to the orexin-elicited excitation in Gi neurons. Together, these results suggest that orexin may facilitate Gi-mediated motor functions through enhancing the neuronal activities of Gi neurons.

Keywords

Firing activities; Gigantocellular reticular nucleus; Motor control; Non-selective cationic conductance; Orexin.

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