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Stanojević M, Djuricic N, Parezanovic M, Biorac M, Pathak D, Spasic S, Lopicic S, Kovacevic S, Nesovic Ostojic J. The Impact of Chronic Magnesium Deficiency on Excitable Tissues-Translational Aspects. Biol Trace Elem Res 2024:10.1007/s12011-024-04216-2. [PMID: 38709369 DOI: 10.1007/s12011-024-04216-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Accepted: 04/28/2024] [Indexed: 05/07/2024]
Abstract
Neuromuscular excitability is a vital body function, and Mg2+ is an essential regulatory cation for the function of excitable membranes. Loss of Mg2+ homeostasis disturbs fluxes of other cations across cell membranes, leading to pathophysiological electrogenesis, which can eventually cause vital threat to the patient. Chronic subclinical Mg2+ deficiency is an increasingly prevalent condition in the general population. It is associated with an elevated risk of cardiovascular, respiratory and neurological conditions and an increased mortality. Magnesium favours bronchodilation (by antagonizing Ca2+ channels on airway smooth muscle and inhibiting the release of endogenous bronchoconstrictors). Magnesium exerts antihypertensive effects by reducing peripheral vascular resistance (increasing endothelial NO and PgI2 release and inhibiting Ca2+ influx into vascular smooth muscle). Magnesium deficiency disturbs heart impulse generation and propagation by prolonging cell depolarization (due to Na+/K+ pump and Kir channel dysfunction) and dysregulating cardiac gap junctions, causing arrhythmias, while prolonged diastolic Ca2+ release (through leaky RyRs) disturbs cardiac excitation-contraction coupling, compromising diastolic relaxation and systolic contraction. In the brain, Mg2+ regulates the function of ion channels and neurotransmitters (blocks voltage-gated Ca2+ channel-mediated transmitter release, antagonizes NMDARs, activates GABAARs, suppresses nAChR ion current and modulates gap junction channels) and blocks ACh release at neuromuscular junctions. Magnesium exerts multiple therapeutic neuroactive effects (antiepileptic, antimigraine, analgesic, neuroprotective, antidepressant, anxiolytic, etc.). This review focuses on the effects of Mg2+ on excitable tissues in health and disease. As a natural membrane stabilizer, Mg2+ opposes the development of many conditions of hyperexcitability. Its beneficial recompensation and supplementation help treat hyperexcitability and should therefore be considered wherever needed.
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Affiliation(s)
- Marija Stanojević
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia.
| | - Nadezda Djuricic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Miro Parezanovic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
- Institute for Mother and Child Healthcare of Serbia "Dr Vukan Čupić", Belgrade, Serbia
| | - Marko Biorac
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Dhruba Pathak
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Svetolik Spasic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Srdjan Lopicic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Sanjin Kovacevic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Jelena Nesovic Ostojic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
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Hanafy MS, Cui Z. Connexin-Containing Vesicles for Drug Delivery. AAPS J 2024; 26:20. [PMID: 38267725 DOI: 10.1208/s12248-024-00889-8] [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: 09/30/2023] [Accepted: 12/20/2023] [Indexed: 01/26/2024] Open
Abstract
Connexin is a transmembrane protein present on the cell membrane of most cell types. Connexins assemble into a hexameric hemichannel known as connexon that pairs with another hemichannel present on a neighboring cell to form gap junction that acts as a channel or pore for the transport of ions and small molecules between the cytoplasm of the two cells. Extracellular vesicles released from connexin-expressing cells could carry connexin hemichannels on their surface and couple with another connexin hemichannel on a distant recipient cell to allow the transfer of the intravesicular content directly into the cytoplasm. Connexin-containing vesicles can be potentially utilized for intracellular drug delivery. In this review, we introduced cell-derived, connexin-containing extracellular vesicles and cell-free connexin-containing liposomes, methods of preparing them, procedures to load cargos in them, factors regulating the connexin hemichannel activity, (potential) applications of connexin-containing vesicles in drug delivery, and finally the challenges and future directions in realizing the promises of this platform delivery system for (intracellular) drug delivery.
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Affiliation(s)
- Mahmoud S Hanafy
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, The University of Texas at Austin, Austin, Texas, USA
| | - Zhengrong Cui
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, The University of Texas at Austin, Austin, Texas, USA.
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Gutiérrez R. Gap Junctions in the Brain: Hardwired but Functionally Versatile. Neuroscientist 2023; 29:554-568. [PMID: 36125001 DOI: 10.1177/10738584221120804] [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] [Indexed: 11/15/2022]
Abstract
Gap junctions between neurons of the brain are thought to be present in only certain cell types, and they mostly connect dendrites, somata, and axons. Synapses with gap junctions serve bidirectional metabolic and electrical coupling between connected neuronal compartments. Although plasticity of electrical synapses has been described, recent evidence of the presence of silent, but activatable, gap junctions suggests that electrical nodes in a neuronal circuit can be added or suppressed by changes in the synaptic microenvironment. This opens the possibility of reconfiguration of neuronal ensembles in response to activity. Moreover, the coexistence of gap junctions in a glutamatergic synapse may add electric and metabolic coupling to a neuronal aggregate and may serve to constitute primed ensembles within a higher-order neural network. The interaction of chemical with electrical synapses should be further explored to find, especially, emerging properties of neuronal ensembles. It will be worth to reexamine in a new light the "functional" implications of the "anatomic" concepts: "continuity" and "contiguity," which were championed by Golgi and Ramón y Cajal, respectively. In any case, exploring the versatility of the gap junctions will likely enrich the heuristic aspects of the neural and network postulates.
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Affiliation(s)
- Rafael Gutiérrez
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
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Viegas MPC, Santos LEC, Aarão MC, Cecilio SG, Medrado JM, Pires AC, Rodrigues AM, Scorza CA, Moret MA, Finsterer J, Scorza FA, Almeida ACG. The nonsynaptic plasticity in Parkinson's disease: Insights from an animal model. Clinics (Sao Paulo) 2023; 78:100242. [PMID: 37480642 PMCID: PMC10387572 DOI: 10.1016/j.clinsp.2023.100242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 06/01/2023] [Accepted: 06/19/2023] [Indexed: 07/24/2023] Open
Abstract
BACKGROUND The 6-OHDA nigro-striatal lesion model has already been related to disorders in the excitability and synchronicity of neural networks and variation in the expression of transmembrane proteins that control intra and extracellular ionic concentrations, such as cation-chloride cotransporters (NKCC1 and KCC2) and Na+/K+-ATPase and, also, to the glial proliferation after injury. All these non-synaptic mechanisms have already been related to neuronal injury and hyper-synchronism processes. OBJECTIVE The main objective of this study is to verify whether mechanisms not directly related to synaptic neurotransmission could be involved in the modulation of nigrostriatal pathways. METHODS Male Wistar rats, 3 months old, were submitted to a unilateral injection of 24 µg of 6-OHDA, in the striatum (n = 8). The animals in the Control group (n = 8) were submitted to the same protocol, with the replacement of 6-OHDA by 0.9% saline. The analysis by optical densitometry was performed to quantify the immunoreactivity intensity of GFAP, NKCC1, KCC2, Na+/K+-ATPase, TH and Cx36. RESULTS The 6-OHDA induced lesions in the striatum, were not followed by changes in the expression cation-chloride cotransporters and Na+/K+-ATPase, but with astrocytic reactivity in the lesioned and adjacent regions of the nigrostriatal. Moreover, the dopaminergic degeneration caused by 6-OHDA is followed by changes in the expression of connexin-36. CONCLUSIONS The use of the GJ blockers directly along the nigrostriatal pathways to control PD motor symptoms is conjectured. Electrophysiology of the striatum and the substantia nigra, to verify changes in neuronal synchronism, comparing brain slices of control animals and experimental models of PD, is needed.
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Affiliation(s)
- Mônica P C Viegas
- Laboratory of Experimental and Computational Neuroscience, Department of Biosystems Engineering, Universidade Federal de São João del-Rei (UFSJ), São João del-Rei, MG, Brazil
| | - Luiz E C Santos
- Laboratory of Experimental and Computational Neuroscience, Department of Biosystems Engineering, Universidade Federal de São João del-Rei (UFSJ), São João del-Rei, MG, Brazil
| | - Mayra C Aarão
- Laboratory of Experimental and Computational Neuroscience, Department of Biosystems Engineering, Universidade Federal de São João del-Rei (UFSJ), São João del-Rei, MG, Brazil
| | - Samyra G Cecilio
- Laboratory of Experimental and Computational Neuroscience, Department of Biosystems Engineering, Universidade Federal de São João del-Rei (UFSJ), São João del-Rei, MG, Brazil
| | - Joana M Medrado
- Laboratory of Experimental and Computational Neuroscience, Department of Biosystems Engineering, Universidade Federal de São João del-Rei (UFSJ), São João del-Rei, MG, Brazil
| | - Arthur C Pires
- Laboratory of Experimental and Computational Neuroscience, Department of Biosystems Engineering, Universidade Federal de São João del-Rei (UFSJ), São João del-Rei, MG, Brazil
| | - Antônio M Rodrigues
- Laboratory of Experimental and Computational Neuroscience, Department of Biosystems Engineering, Universidade Federal de São João del-Rei (UFSJ), São João del-Rei, MG, Brazil
| | - Carla A Scorza
- Neuroscience Discipline, Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, SP, Brazil; Centro de Neurociências e Saúde da Mulher "Professor Geraldo Rodrigues de Lima", Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, SP, Brazil
| | - Marcelo A Moret
- SENAI ‒ Departamento Regional da Bahia, Centro Integrado de Manufatura e Tecnologia, Bahia, BA, Brazil
| | | | - Fulvio A Scorza
- Neuroscience Discipline, Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, SP, Brazil; Centro de Neurociências e Saúde da Mulher "Professor Geraldo Rodrigues de Lima", Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, SP, Brazil.
| | - Antônio-Carlos G Almeida
- Laboratory of Experimental and Computational Neuroscience, Department of Biosystems Engineering, Universidade Federal de São João del-Rei (UFSJ), São João del-Rei, MG, Brazil; Centro de Neurociências e Saúde da Mulher "Professor Geraldo Rodrigues de Lima", Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, SP, Brazil
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Lee SN, Cho HJ, Jeong H, Ryu B, Lee HJ, Kim M, Yoo J, Woo JS, Lee HH. Cryo-EM structures of human Cx36/GJD2 neuronal gap junction channel. Nat Commun 2023; 14:1347. [PMID: 36906653 PMCID: PMC10008584 DOI: 10.1038/s41467-023-37040-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 02/28/2023] [Indexed: 03/13/2023] Open
Abstract
Connexin 36 (Cx36) is responsible for signal transmission in electrical synapses by forming interneuronal gap junctions. Despite the critical role of Cx36 in normal brain function, the molecular architecture of the Cx36 gap junction channel (GJC) is unknown. Here, we determine cryo-electron microscopy structures of Cx36 GJC at 2.2-3.6 Å resolutions, revealing a dynamic equilibrium between its closed and open states. In the closed state, channel pores are obstructed by lipids, while N-terminal helices (NTHs) are excluded from the pore. In the open state with pore-lining NTHs, the pore is more acidic than those in Cx26 and Cx46/50 GJCs, explaining its strong cation selectivity. The conformational change during channel opening also includes the α-to-π-helix transition of the first transmembrane helix, which weakens the protomer-protomer interaction. Our structural analyses provide high resolution information on the conformational flexibility of Cx36 GJC and suggest a potential role of lipids in the channel gating.
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Affiliation(s)
- Seu-Na Lee
- Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Hwa-Jin Cho
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea
| | - Hyeongseop Jeong
- Center for Research Equipment, Korea Basic Science Institute, Chungcheongbuk-do, 28119, Korea
| | - Bumhan Ryu
- Research Solution Center, Institute for Basic Science, Daejeon, 34126, Republic of Korea
| | - Hyuk-Joon Lee
- Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Minsoo Kim
- Department of Physics, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Jejoong Yoo
- Department of Physics, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Jae-Sung Woo
- Department of Life Sciences, Korea University, Seoul, 02841, Republic of Korea.
| | - Hyung Ho Lee
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea.
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Altered neural cell junctions and ion-channels leading to disrupted neuron communication in Parkinson's disease. NPJ Parkinsons Dis 2022; 8:66. [PMID: 35650269 PMCID: PMC9160246 DOI: 10.1038/s41531-022-00324-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 05/05/2022] [Indexed: 12/16/2022] Open
Abstract
Parkinson’s disease (PD) is a neurological disorder that affects the movement of the human body. It is primarily characterized by reduced dopamine levels in the brain. The causative agent of PD is still unclear but it is generally accepted that α-synuclein has a central role to play. It is also known that gap-junctions and associated connexins are complicated structures that play critical roles in nervous system signaling and associated misfunctioning. Thus, our current article emphasizes how, alongside α-synuclein, ion-channels, gap-junctions, and related connexins, all play vital roles in influencing multiple metabolic activities of the brain during PD. It also highlights that ion-channel and gap-junction disruptions, which are primarily mediated by their structural-functional changes and alterations, have a role in PD. Furthermore, we discussed available drugs and advanced therapeutic interventions that target Parkinson’s pathogenesis. In conclusion, it warrants creating better treatments for PD patients. Although, dopaminergic replenishment therapy is useful in treating neurological problems, such therapies are, however, unable to control the degeneration that underpins the disease, thereby declining their overall efficacy. This creates an additional challenge and an untapped scope for neurologists to adopt treatments for PD by targeting the ion-channels and gap-junctions, which is well-reviewed in the present article.
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Kraujalis T, Gudaitis L, Kraujaliene L, Snipas M, Palacios-Prado N, Verselis VK. The Amino Terminal Domain and Modulation of Connexin36 Gap Junction Channels by Intracellular Magnesium Ions. Front Physiol 2022; 13:839223. [PMID: 35264979 PMCID: PMC8899287 DOI: 10.3389/fphys.2022.839223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 01/28/2022] [Indexed: 11/13/2022] Open
Abstract
Electrical synapses between neurons in the mammalian CNS are predominantly formed of the connexin36 (Cx36) gap junction (GJ) channel protein. Unique among GJs formed of a number of other members of the Cx gene family, Cx36 GJs possess a high sensitivity to intracellular Mg2+ that can robustly act to modulate the strength of electrical synaptic transmission. Although a putative Mg2+ binding site was previously identified to reside in the aqueous pore in the first extracellular (E1) loop domain, the involvement of the N-terminal (NT) domain in the atypical response of Cx36 GJs to pH was shown to depend on intracellular levels of Mg2+. In this study, we examined the impact of amino acid substitutions in the NT domain on Mg2+ modulation of Cx36 GJs, focusing on positions predicted to line the pore funnel, which constitutes the cytoplasmic entrance of the channel pore. We find that charge substitutions at the 8th, 13th, and 18th positions had pronounced effects on Mg2+ sensitivity, particularly at position 13 at which an A13K substitution completely abolished sensitivity to Mg2+. To assess potential mechanisms of Mg2+ action, we constructed and tested a series of mathematical models that took into account gating of the component hemichannels in a Cx36 GJ channel as well as Mg2+ binding to each hemichannel in open and/or closed states. Simultaneous model fitting of measurements of junctional conductance, gj, and transjunctional Mg2+ fluxes using a fluorescent Mg2+ indicator suggested that the most viable mechanism for Cx36 regulation by Mg2+ entails the binding of Mg2+ to and subsequent stabilization of the closed state in each hemichannel. Reduced permeability to Mg2+ was also evident, particularly for the A13K substitution, but homology modeling of all charge-substituted NT variants showed only a moderate correlation between a reduction in the negative electrostatic potential and a reduction in the permeability to Mg2+ ions. Given the reported role of the E1 domain in Mg2+ binding together with the impact of NT substitutions on gating and the apparent state-dependence of Mg2+ binding, this study suggests that the NT domain can be an integral part of Mg2+ modulation of Cx36 GJs likely through the coupling of conformational changes between NT and E1 domains.
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Affiliation(s)
- Tadas Kraujalis
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
- Department of Applied Informatics, Kaunas University of Technology, Kaunas, Lithuania
- *Correspondence: Tadas Kraujalis,
| | - Lukas Gudaitis
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Lina Kraujaliene
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Mindaugas Snipas
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
- Department of Mathematical Modelling, Kaunas University of Technology, Kaunas, Lithuania
| | - Nicolás Palacios-Prado
- Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaiso, Valparaíso, Chile
| | - Vytas K. Verselis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
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Postić S, Gosak M, Tsai WH, Pfabe J, Sarikas S, Stožer A, Korošak D, Yang SB, Slak Rupnik M. pH-Dependence of Glucose-Dependent Activity of Beta Cell Networks in Acute Mouse Pancreatic Tissue Slice. Front Endocrinol (Lausanne) 2022; 13:916688. [PMID: 35837307 PMCID: PMC9273738 DOI: 10.3389/fendo.2022.916688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 05/24/2022] [Indexed: 12/01/2022] Open
Abstract
Extracellular pH has the potential to affect various aspects of the pancreatic beta cell function. To explain this effect, a number of mechanisms was proposed involving both extracellular and intracellular targets and pathways. Here, we focus on reassessing the influence of extracellular pH on glucose-dependent beta cell activation and collective activity in physiological conditions. To this end we employed mouse pancreatic tissue slices to perform high-temporally resolved functional imaging of cytosolic Ca2+ oscillations. We investigated the effect of either physiological H+ excess or depletion on the activation properties as well as on the collective activity of beta cell in an islet. Our results indicate that lowered pH invokes activation of a subset of beta cells in substimulatory glucose concentrations, enhances the average activity of beta cells, and alters the beta cell network properties in an islet. The enhanced average activity of beta cells was determined indirectly utilizing cytosolic Ca2+ imaging, while direct measuring of insulin secretion confirmed that this enhanced activity is accompanied by a higher insulin release. Furthermore, reduced functional connectivity and higher functional segregation at lower pH, both signs of a reduced intercellular communication, do not necessary result in an impaired insulin release.
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Affiliation(s)
- Sandra Postić
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- *Correspondence: Sandra Postić,
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Wen-Hao Tsai
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Johannes Pfabe
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Srdjan Sarikas
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Dean Korošak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Shi-Bing Yang
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Marjan Slak Rupnik
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea – European Center Maribor, Maribor, Slovenia
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Chronic Stress and Gonadectomy Affect the Expression of Cx37, Cx40 and Cx43 in the Spinal Cord. Life (Basel) 2021; 11:life11121330. [PMID: 34947861 PMCID: PMC8706389 DOI: 10.3390/life11121330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/22/2021] [Accepted: 11/29/2021] [Indexed: 11/20/2022] Open
Abstract
The study aimed to determine whether the exposure to chronic stress and/or performance of gonadectomy might lead to disturbance in the expression of connexin (Cx) 37, 40 and 43 in the spinal cord (SC), as a potential explanation for sex differences in stress-related chronic pain conditions. After the rats were sham-operated or gonadectomized, three 10-day sessions of sham or chronic stress were applied. Immunohistochemistry and transmission electron microscopy (TEM) were used to examine Cx localization and expression in the SC. The gonadectomy resulted in an increase of Cx37 expression in the dorsal horn (DH) of the female rats, but chronic stress suppressed the effects of castration. In male rats, only the combined effects of castration and chronic stress increased Cx37 expression. The influence of chronic stress on the DH Cx40 expression was inversely evident after the castration: increased in the ovariectomized female rats, while decreased in the orchidectomized male rats. We did not find any effect of chronic stress and castration, alone or together, on Cx43 expression in the DH, but the percentage of Cx43 overlapping the astrocyte marker glial fibrillary acidic protein (gfap) increased in the male stressed group after the castration. In conclusion, the association of the chronic stress with sex hormone depletion results in disturbances of the SC Cx expression and might be a possible mechanism of disturbed pain perception after chronic stress exposure.
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Šket R, Deutsch L, Prevoršek Z, Mekjavić IB, Plavec J, Rittweger J, Debevec T, Eiken O, Stres B. Systems View of Deconditioning During Spaceflight Simulation in the PlanHab Project: The Departure of Urine 1 H-NMR Metabolomes From Healthy State in Young Males Subjected to Bedrest Inactivity and Hypoxia. Front Physiol 2020; 11:532271. [PMID: 33364971 PMCID: PMC7750454 DOI: 10.3389/fphys.2020.532271] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 11/04/2020] [Indexed: 12/27/2022] Open
Abstract
We explored the metabolic makeup of urine in prescreened healthy male participants within the PlanHab experiment. The run-in (5 day) and the following three 21-day interventions [normoxic bedrest (NBR), hypoxic bedrest (HBR), and hypoxic ambulation (HAmb)] were executed in a crossover manner within a controlled laboratory setup (medical oversight, fluid and dietary intakes, microbial bioburden, circadian rhythm, and oxygen level). The inspired O2 (FiO2) fraction next to inspired O2 (PiO2) partial pressure were 0.209 and 133.1 ± 0.3 mmHg for the NBR variant in contrast to 0.141 ± 0.004 and 90.0 ± 0.4 mmHg (approx. 4,000 m of simulated altitude) for HBR and HAmb interventions, respectively. 1H-NMR metabolomes were processed using standard quantitative approaches. A consensus of ensemble of multivariate analyses showed that the metabolic makeup at the start of the experiment and at HAmb endpoint differed significantly from the NBR and HBR endpoints. Inactivity alone or combined with hypoxia resulted in a significant reduction of metabolic diversity and increasing number of affected metabolic pathways. Sliding window analysis (3 + 1) unraveled that metabolic changes in the NBR lagged behind those observed in the HBR. These results show that the negative effects of cessation of activity on systemic metabolism are further aggravated by additional hypoxia. The PlanHab HAmb variant that enabled ambulation, maintained vertical posture, and controlled but limited activity levels apparently prevented the development of negative physiological symptoms such as insulin resistance, low-level systemic inflammation, constipation, and depression. This indicates that exercise apparently prevented the negative spiral between the host's metabolism, intestinal environment, microbiome physiology, and proinflammatory immune activities in the host.
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Affiliation(s)
- Robert Šket
- Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Leon Deutsch
- Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Zala Prevoršek
- Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Igor B. Mekjavić
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Janez Plavec
- National Institute of Chemistry, NMR Center, Ljubljana, Slovenia
| | - Joern Rittweger
- German Aerospace Center, Institute of Aerospace Medicine, Muscle and Bone Metabolism, Köln, Germany
| | - Tadej Debevec
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
- Faculty of Sports, University of Ljubljana, Ljubljana, Slovenia
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Blaz Stres
- Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
- Faculty of Civil and Geodetic Engineering, Institute of Sanitary Engineering, University of Ljubljana, Ljubljana, Slovenia
- Laboratory for Clinical Toxicology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Department of Microbiology, University of Innsbruck, Innsbruck, Austria
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11
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Osaghae BE, Arrowsmith S, Wray S. Gestational and Hormonal Effects on Magnesium Sulfate's Ability to Inhibit Mouse Uterine Contractility. Reprod Sci 2020; 27:1570-1579. [PMID: 32430707 DOI: 10.1007/s43032-020-00185-8] [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] [Indexed: 11/25/2022]
Abstract
Magnesium sulfate is used as a tocolytic, but clinical efficacy has been seriously questioned. Our objective was to use controlled ex vivo conditions and known pregnancy stages, to investigate how 2 key factors, hormones and gestation, affect magnesium's tocolytic ability. We hypothesized that these factors could underlie the varying clinical findings around magnesium's efficacy. Myometrial strips were obtained from nonpregnant (n = 10), mid-pregnant (n = 12), and term-pregnant (n = 11) mouse uterus. The strips were mounted in organ baths superfused with oxygenated physiological saline at pH 7.4 and 37 °C. The effect of different concentrations of MgSO4 (2-20 mM) was examined on spontaneous and oxytocin-induced (0.5-1 nM) contractions. Contractile properties (amplitude, frequency, and area under the curve) were measured before and after application of magnesium. Magnesium sulfate had a dose-dependent inhibitory effect on both spontaneous and oxytocin-induced contractions but was less effective in the presence of oxytocin. In spontaneous contractions, magnesium was more potent as gestation progressed (P < .0001). In the presence of oxytocin, however, there were no significant gestational differences in its effects on contraction. The rapid onset and reversal of magnesium's effects suggest an extracellular action on calcium entry. Taken together, we conclude that magnesium's actions are influenced by both gestational state and hormones, such that, at least in mice, it is least effective in early gestation with oxytocin present and most effective at term in the absence of oxytocin. That magnesium is least effective preterm and oxytocin decreases its effectiveness throughout gestation, may explain its disappointing clinical effects as a tocolytic.
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Affiliation(s)
- Blessing E Osaghae
- Department of Molecular and Cellular Physiology, University Department, Harris-Wellbeing Preterm Birth Research Centre, Institute of Translational Medicine, University of Liverpool, First floor Liverpool Women's Hospital, Crown Street, Liverpool, L8 7SS, UK
| | - Sarah Arrowsmith
- Department of Molecular and Cellular Physiology, University Department, Harris-Wellbeing Preterm Birth Research Centre, Institute of Translational Medicine, University of Liverpool, First floor Liverpool Women's Hospital, Crown Street, Liverpool, L8 7SS, UK
| | - Susan Wray
- Department of Molecular and Cellular Physiology, University Department, Harris-Wellbeing Preterm Birth Research Centre, Institute of Translational Medicine, University of Liverpool, First floor Liverpool Women's Hospital, Crown Street, Liverpool, L8 7SS, UK.
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12
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Sánchez OF, Rodríguez AV, Velasco-España JM, Murillo LC, Sutachan JJ, Albarracin SL. Role of Connexins 30, 36, and 43 in Brain Tumors, Neurodegenerative Diseases, and Neuroprotection. Cells 2020; 9:E846. [PMID: 32244528 PMCID: PMC7226843 DOI: 10.3390/cells9040846] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 02/15/2020] [Accepted: 02/24/2020] [Indexed: 02/07/2023] Open
Abstract
Gap junction (GJ) channels and their connexins (Cxs) are complex proteins that have essential functions in cell communication processes in the central nervous system (CNS). Neurons, astrocytes, oligodendrocytes, and microglial cells express an extraordinary repertory of Cxs that are important for cell to cell communication and diffusion of metabolites, ions, neurotransmitters, and gliotransmitters. GJs and Cxs not only contribute to the normal function of the CNS but also the pathological progress of several diseases, such as cancer and neurodegenerative diseases. Besides, they have important roles in mediating neuroprotection by internal or external molecules. However, regulation of Cx expression by epigenetic mechanisms has not been fully elucidated. In this review, we provide an overview of the known mechanisms that regulate the expression of the most abundant Cxs in the central nervous system, Cx30, Cx36, and Cx43, and their role in brain cancer, CNS disorders, and neuroprotection. Initially, we focus on describing the Cx gene structure and how this is regulated by epigenetic mechanisms. Then, the posttranslational modifications that mediate the activity and stability of Cxs are reviewed. Finally, the role of GJs and Cxs in glioblastoma, Alzheimer's, Parkinson's, and Huntington's diseases, and neuroprotection are analyzed with the aim of shedding light in the possibility of using Cx regulators as potential therapeutic molecules.
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Affiliation(s)
- Oscar F. Sánchez
- Department of Nutrition and Biochemistry, Pontificia Universidad Javeriana, 110911 Bogota, Colombia; (A.V.R.); (J.M.V.-E.); (L.C.M.); (J.-J.S.)
| | | | | | | | | | - Sonia-Luz Albarracin
- Department of Nutrition and Biochemistry, Pontificia Universidad Javeriana, 110911 Bogota, Colombia; (A.V.R.); (J.M.V.-E.); (L.C.M.); (J.-J.S.)
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13
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Connexins-Based Hemichannels/Channels and Their Relationship with Inflammation, Seizures and Epilepsy. Int J Mol Sci 2019; 20:ijms20235976. [PMID: 31783599 PMCID: PMC6929063 DOI: 10.3390/ijms20235976] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/13/2019] [Accepted: 11/20/2019] [Indexed: 12/11/2022] Open
Abstract
Connexins (Cxs) are a family of 21 protein isoforms, eleven of which are expressed in the central nervous system, and they are found in neurons and glia. Cxs form hemichannels (connexons) and channels (gap junctions/electric synapses) that permit functional and metabolic coupling between neurons and astrocytes. Altered Cx expression and function is involved in inflammation and neurological diseases. Cxs-based hemichannels and channels have a relevance to seizures and epilepsy in two ways: First, this pathological condition increases the opening probability of hemichannels in glial cells to enable gliotransmitter release, sustaining the inflammatory process and exacerbating seizure generation and epileptogenesis, and second, the opening of channels favors excitability and synchronization through coupled neurons. These biological events highlight the global pathological mechanism of epilepsy, and the therapeutic potential of Cxs-based hemichannels and channels. Therefore, this review describes the role of Cxs in neuroinflammation and epilepsy and examines how the blocking of channels and hemichannels may be therapeutic targets of anti-convulsive and anti-epileptic treatments.
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Osaghae BE, Arrowsmith S, Wray S. Gestational and Hormonal Effects on Magnesium Sulfate's Ability to Inhibit Mouse Uterine Contractility. Reprod Sci 2019:1933719119828089. [PMID: 30773125 DOI: 10.1177/1933719119828089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Magnesium sulfate is used as a tocolytic, but clinical efficacy has been seriously questioned. Our objective was to use controlled ex vivo conditions and known pregnancy stages, to investigate how 2 key factors, hormones and gestation, affect magnesium's tocolytic ability. We hypothesized that these factors could underlie the varying clinical findings around magnesium's efficacy. Myometrial strips were obtained from nonpregnant (n = 10), mid-pregnant (n = 12), and term-pregnant (n = 11) mouse uterus. The strips were mounted in organ baths superfused with oxygenated physiological saline at pH 7.4 and 37°C. The effect of different concentrations of MgSO4 (2-20 mM) was examined on spontaneous and oxytocin-induced (0.5-1 nM) contractions. Contractile properties (amplitude, frequency, and area under the curve) were measured before and after application of magnesium. Magnesium sulfate had a dose-dependent inhibitory effect on both spontaneous and oxytocin-induced contractions but was less effective in the presence of oxytocin. In spontaneous contractions, magnesium was more potent as gestation progressed ( P < .0001). In the presence of oxytocin, however, there were no significant gestational differences in its effects on contraction. The rapid onset and reversal of magnesium's effects suggest an extracellular action on calcium entry. Taken together, we conclude that magnesium's actions are influenced by both gestational state and hormones, such that, at least in mice, it is least effective in early gestation with oxytocin present and most effective at term in the absence of oxytocin. That magnesium is least effective preterm and oxytocin decreases its effectiveness throughout gestation, may explain its disappointing clinical effects as a tocolytic.
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Affiliation(s)
- Blessing E Osaghae
- 1 Department of Cellular and Molecular Physiology, University Department, Harris-Wellbeing Preterm Birth Research Centre, The Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Sarah Arrowsmith
- 1 Department of Cellular and Molecular Physiology, University Department, Harris-Wellbeing Preterm Birth Research Centre, The Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Susan Wray
- 1 Department of Cellular and Molecular Physiology, University Department, Harris-Wellbeing Preterm Birth Research Centre, The Institute of Translational Medicine, University of Liverpool, Liverpool, UK
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