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Qiao QC, Wen SY, Jiang YB, Feng H, Xu R, Huang YJ, Chen BY, Chen WH, Niu JH, Hu R, Yang N, Zhang J. Orexin recruits non-selective cationic conductance and endocannabinoid to dynamically modulate firing of caudal pontine reticular nuclear neurones. J Physiol 2023; 601:3585-3604. [PMID: 37421377 DOI: 10.1113/jp284602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 06/19/2023] [Indexed: 07/10/2023] Open
Abstract
The neuropeptide orexin is involved in motor circuit function. However, its modulation on neuronal activities of motor structures, integrating orexin's diverse downstream molecular cascades, remains elusive. By combining whole-cell patch-clamp recordings and neuropharmacological methods, we revealed that both non-selective cationic conductance (NSCC) and endocannabinoids (eCBs) are recruited by orexin signalling on reticulospinal neurones in the caudal pontine reticular nucleus (PnC). The orexin-NSCC cascade provides a depolarizing force that proportionally enhances the firing-responsive gain of these neurones. Meanwhile, the orexin-eCB cascade selectively attenuates excitatory synaptic strength in these neurones by activating presynaptic cannabinoid receptor type 1. This cascade restrains the firing response of the PnC reticulospinal neurones to excitatory inputs. Intriguingly, non-linear or linear interactions between orexin postsynaptic excitation and presynaptic inhibition can influence the firing responses of PnC reticulospinal neurones in different directions. When presynaptic inhibition is in the lead, non-linear interactions can prominently downregulate or even gate the firing response. Conversely, linear interactions occur to promote the firing response, and these linear interactions can be considered a proportional reduction in the contribution of depolarization to firing by presynaptic inhibition. Through the dynamic employment of these interactions, adaptive modulation may be achieved by orexin to restrain or even gate the firing output of the PnC to weak/irrelevant input signals and facilitate those to salient signals. KEY POINTS: This study investigated the effects of orexin on the firing activity of PnC reticulospinal neurones, a key element of central motor control. We found that orexin recruited both the non-selective cationic conductances (NSCCs) and endocannabinoid (eCB)-cannabinoid receptor type 1 (CB1R) system to pontine reticular nucleus (PnC) reticulospinal neurones. The orexin-NSCC cascade exerts a postsynaptic excitation that enhances the firing response, whereas the orexin-eCB-CB1R cascade selectively attenuates excitatory synaptic strength that restrains the firing response. The postsynaptic and presynaptic actions of orexins occur in an overlapping time window and interact to dynamically modulate firings in PnC reticulospinal neurones. Non-linear interactions occur when presynaptic inhibition of orexin is in the lead, and these interactions can prominently downregulate or even gate firing responses in PnC reticulospinal neurones. Linear interactions occur when postsynaptic excitation of orexin is in the lead, and these interactions can promote the firing response. These linear interactions can be considered a proportional reduction of the contribution of depolarization to firing by presynaptic inhibition.
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Affiliation(s)
- Qi-Cheng Qiao
- Department of Physiology, Army Medical University, Chongqing, China
| | - Si-Yi Wen
- Department of Physiology, Army Medical University, Chongqing, China
| | - Yi-Bin Jiang
- Department of Neurosurgery and Key Laboratory of Neurotrauma, Southwest Hospital, Army Medical University, Chongqing, China
| | - Hui Feng
- Department of Neurosurgery and Key Laboratory of Neurotrauma, Southwest Hospital, Army Medical University, Chongqing, China
| | - Rui Xu
- Department of Physiology, Army Medical University, Chongqing, China
| | - Yan-Jia Huang
- Department of Physiology, Army Medical University, Chongqing, China
| | - Bang-Yun Chen
- Department of Physiology, Army Medical University, Chongqing, China
| | - Wen-Hao Chen
- Department of Physiology, Army Medical University, Chongqing, China
| | - Jia-Hui Niu
- Department of Physiology, Army Medical University, Chongqing, China
| | - Rong Hu
- Department of Neurosurgery and Key Laboratory of Neurotrauma, Southwest Hospital, Army Medical University, Chongqing, China
| | - Nian Yang
- Department of Physiology, Army Medical University, Chongqing, China
| | - Jun Zhang
- Department of Physiology, Army Medical University, Chongqing, China
- Department of Neurobiology, Army Medical University, Chongqing, China
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Ahmadirad N, Fathollahi Y, Janahmadi M, Ghasemi Z, Shojaei A, Rezaei M, Barkley V, Mirnajafi-Zadeh J. The role of α adrenergic receptors in mediating the inhibitory effect of electrical brain stimulation on epileptiform activity in rat hippocampal slices. Brain Res 2021; 1765:147492. [PMID: 33887250 DOI: 10.1016/j.brainres.2021.147492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/06/2021] [Accepted: 04/14/2021] [Indexed: 10/21/2022]
Abstract
The Inhibitory effect of electrical low-frequency stimulation (LFS) on neuronal excitability and seizure occurrence has been indicated in experimental models, but the precise mechanism has not established. This investigation was intended to figure out the role of α1 and α2 adrenergic receptors in LFS' inhibitory effect on neuronal excitability. Epileptiform activity induced in an in vitro rat hippocampal slice preparation by high K+ ACSF and LFS (900 square wave pulses at 1 Hz) was administered at the beginning of epileptiform activity to the Schaffer collaterals. In CA1 pyramidal neurons, the electrophysiological properties were measured at the baseline, before high K+ ACSF washout, and at 15 min after high K+ ACSF washout using whole-cell, patch-clamp recording. Results indicated that after high K+ ACSF washout, prazosine (10 µM; α1 adrenergic receptor antagonist) and yohimbine (5 µM; α2 adrenergic receptor antagonist) suppressed the LFS' effect of reducing rheobase current and utilization time following depolarizing ramp current, the latency to the first spike following a depolarizing current and latency to the first rebound action potential following hyperpolarizing current pulses. Thus, it may be proposed that LFS' inhibitory action on the neuronal hyperexcitability, in some way, is mediated by α1 and α2 adrenergic receptors.
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Affiliation(s)
- Nooshin Ahmadirad
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Yaghoub Fathollahi
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mahyar Janahmadi
- Department of Physiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Zahra Ghasemi
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Amir Shojaei
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mahmoud Rezaei
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Victoria Barkley
- Krembil Research Institute, University Health Network, Toronto, Canada
| | - Javad Mirnajafi-Zadeh
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran; Institute for Brain Sciences and Cognition, Tarbiat Modares University, Tehran, Iran.
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