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Oxidative Stress as a Potential Mechanism Underlying Membrane Hyperexcitability in Neurodegenerative Diseases. Antioxidants (Basel) 2022; 11:antiox11081511. [PMID: 36009230 PMCID: PMC9405356 DOI: 10.3390/antiox11081511] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 02/01/2023] Open
Abstract
Neurodegenerative diseases are characterized by gradually progressive, selective loss of anatomically or physiologically related neuronal systems that produce brain damage from which there is no recovery. Despite the differences in clinical manifestations and neuronal vulnerability, the pathological processes appear to be similar, suggesting common neurodegenerative pathways. It is well known that oxidative stress and the production of reactive oxygen radicals plays a key role in neuronal cell damage. It has been proposed that this stress, among other mechanisms, could contribute to neuronal degeneration and might be one of the factors triggering the development of these pathologies. Another common feature in most neurodegenerative diseases is neuron hyperexcitability, an aberrant electrical activity. This review, focusing mainly on primary motor cortex pyramidal neurons, critically evaluates the idea that oxidative stress and inflammation may be involved in neurodegeneration via their capacity to increase membrane excitability.
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Acute Colon Inflammation Triggers Primary Motor Cortex Glial Activation, Neuroinflammation, Neuronal Hyperexcitability, and Motor Coordination Deficits. Int J Mol Sci 2022; 23:ijms23105347. [PMID: 35628158 PMCID: PMC9141031 DOI: 10.3390/ijms23105347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/28/2022] [Accepted: 05/07/2022] [Indexed: 02/05/2023] Open
Abstract
Neuroinflammation underlies neurodegenerative diseases. Herein, we test whether acute colon inflammation activates microglia and astrocytes, induces neuroinflammation, disturbs neuron intrinsic electrical properties in the primary motor cortex, and alters motor behaviors. We used a rat model of acute colon inflammation induced by dextran sulfate sodium. Inflammatory mediators and microglial activation were assessed in the primary motor cortex by PCR and immunofluorescence assays. Electrophysiological properties of the motor cortex neurons were determined by whole-cell patch-clamp recordings. Motor behaviors were examined using open-field and rotarod tests. We show that the primary motor cortex of rats with acute colon inflammation exhibited microglial and astrocyte activation and increased mRNA abundance of interleukin-6, tumor necrosis factor-alpha, and both inducible and neuronal nitric oxide synthases. These changes were accompanied by a reduction in resting membrane potential and rheobase and increased input resistance and action potential frequency, indicating motor neuron hyperexcitability. In addition, locomotion and motor coordination were impaired. In conclusion, acute colon inflammation induces motor cortex microglial and astrocyte activation and inflammation, which led to neurons’ hyperexcitability and reduced motor coordination performance. The described disturbances resembled some of the early features found in amyotrophic lateral sclerosis patients and animal models, suggesting that colon inflammation might be a risk factor for developing this disease.
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Rijal S, Jang SH, Cho DH, Han SK. Hydrogen peroxide suppresses excitability of gonadotropin-releasing hormone neurons in adult mouse. Front Endocrinol (Lausanne) 2022; 13:939699. [PMID: 36387844 PMCID: PMC9650413 DOI: 10.3389/fendo.2022.939699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/14/2022] [Indexed: 11/13/2022] Open
Abstract
It has been reported that reactive oxygen species (ROS) derived from oxygen molecule reduction can interfere with the cross-talk between the hypothalamic-pituitary-gonadal (HPG) axis and other endocrine axes, thus affecting fertility. Furthermore, ROS have been linked to GnRH receptor signaling in gonadotropes involved in gonadotropin release. There has been evidence that ROS can interfere with the HPG axis and gonadotropin release at various levels. However, the direct effect of ROS on gonadotropin-releasing hormone (GnRH) neuron remains unclear. Thus, the objective of this study was to determine the effect of hydrogen peroxide (H2O2), an ROS source, on GnRH neuronal excitabilities in transgenic GnRH-green fluorescent protein-tagged mice using the whole-cell patch-clamp electrophysiology. In adults, H2O2 at high concentrations (mM level) hyperpolarized most GnRH neurons tested, whereas low concentrations (pM to μM) caused slight depolarization. In immature GnRH neurons, H2O2 exposure induced excitation. The sensitivity of GnRH neurons to H2O2 was increased with postnatal development. The effect of H2O2 on adult female GnRH neurons was found to be estrous cycle-dependent. Hyperpolarization mediated by H2O2 persisted in the presence of tetrodotoxin, a voltage-gated Na+ channel blocker, and amino-acids receptor blocking cocktail containing blockers for the ionotropic glutamate receptors, glycine receptors, and GABAA receptors, indicating that H2O2 could act on GnRH neurons directly. Furthermore, glibenclamide, an ATP-sensitive K+ (KATP) channel blocker, completely blocked H2O2-mediated hyperpolarization. Increasing endogenous H2O2 by inhibiting glutathione peroxidase decreased spontaneous activities of most GnRH neurons. We conclude that ROS can act as signaling molecules for regulating GnRH neuron's excitability and that adult GnRH neurons are sensitive to increased ROS concentration. Results of this study demonstrate that ROS have direct modulatory effects on the HPG axis at the hypothalamic level to regulate GnRH neuron's excitabilities.
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Affiliation(s)
- Santosh Rijal
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, South Korea
| | - Seon Hui Jang
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, South Korea
| | - Dong Hyu Cho
- Department of Obstetrics and Gynecology, Jeonbuk National University Medical School, Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute for Medical Sciences, Jeonbuk National University Hospital, Jeonju, South Korea
- *Correspondence: Dong Hyu Cho, ; Seong Kyu Han,
| | - Seong Kyu Han
- Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju, South Korea
- *Correspondence: Dong Hyu Cho, ; Seong Kyu Han,
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Perez-García P, Pardillo-Díaz R, Geribaldi-Doldán N, Gómez-Oliva R, Domínguez-García S, Castro C, Nunez-Abades P, Carrascal L. Refinement of Active and Passive Membrane Properties of Layer V Pyramidal Neurons in Rat Primary Motor Cortex During Postnatal Development. Front Mol Neurosci 2021; 14:754393. [PMID: 34924951 PMCID: PMC8671142 DOI: 10.3389/fnmol.2021.754393] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/19/2021] [Indexed: 11/13/2022] Open
Abstract
Achieving the distinctive complex behaviors of adult mammals requires the development of a great variety of specialized neural circuits. Although the development of these circuits begins during the embryonic stage, they remain immature at birth, requiring a postnatal maturation process to achieve these complex tasks. Understanding how the neuronal membrane properties and circuits change during development is the first step to understand their transition into efficient ones. Thus, using whole cell patch clamp recordings, we have studied the changes in the electrophysiological properties of layer V pyramidal neurons of the rat primary motor cortex during postnatal development. Among all the parameters studied, only the voltage threshold was established at birth and, although some of the changes occurred mainly during the second postnatal week, other properties such as membrane potential, capacitance, duration of the post-hyperpolarization phase or the maximum firing rate were not defined until the beginning of adulthood. Those modifications lead to a decrease in neuronal excitability and to an increase in the working range in young adult neurons, allowing more sensitive and accurate responses. This maturation process, that involves an increase in neuronal size and changes in ionic conductances, seems to be influenced by the neuronal type and by the task that neurons perform as inferred from the comparison with other pyramidal and motor neuron populations.
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Affiliation(s)
- Patricia Perez-García
- Department of Physiology, School of Pharmacy, University of Seville, Seville, Spain.,Division of Physiology, School of Medicine, University of Cádiz, Cádiz, Spain
| | - Ricardo Pardillo-Díaz
- Division of Physiology, School of Medicine, University of Cádiz, Cádiz, Spain.,Biomedical Research and Innovation Institute of Cádiz (INiBICA), Cádiz, Spain
| | - Noelia Geribaldi-Doldán
- Biomedical Research and Innovation Institute of Cádiz (INiBICA), Cádiz, Spain.,Department of Human Anatomy and Embriology, University of Cádiz, Cádiz, Spain
| | - Ricardo Gómez-Oliva
- Division of Physiology, School of Medicine, University of Cádiz, Cádiz, Spain.,Biomedical Research and Innovation Institute of Cádiz (INiBICA), Cádiz, Spain
| | - Samuel Domínguez-García
- Division of Physiology, School of Medicine, University of Cádiz, Cádiz, Spain.,Biomedical Research and Innovation Institute of Cádiz (INiBICA), Cádiz, Spain
| | - Carmen Castro
- Division of Physiology, School of Medicine, University of Cádiz, Cádiz, Spain.,Biomedical Research and Innovation Institute of Cádiz (INiBICA), Cádiz, Spain
| | - Pedro Nunez-Abades
- Department of Physiology, School of Pharmacy, University of Seville, Seville, Spain.,Biomedical Research and Innovation Institute of Cádiz (INiBICA), Cádiz, Spain
| | - Livia Carrascal
- Department of Physiology, School of Pharmacy, University of Seville, Seville, Spain.,Biomedical Research and Innovation Institute of Cádiz (INiBICA), Cádiz, Spain
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