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Delibaş B, Kaplan AA, Marangoz AH, Eltahir MI, Altun G, Kaplan S. The effect of dietary sesame oil and ginger oil as antioxidants in the adult rat dorsal root ganglia after peripheral nerve crush injury. Int J Neurosci 2024; 134:714-724. [PMID: 36342428 DOI: 10.1080/00207454.2022.2145475] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022]
Abstract
AIM The purpose of this study was to investigate the effect of dietary sesame oil and ginger oil supplements on the dorsal root ganglia following a sciatic nerve crush model in male Wistar albino rats. MATERIALS AND METHODS Crush injury models have been done by means of graded forceps (50 Newton). The animals were given a daily sesame oil (4 ml/kg/day) and ginger oil (400 mg/kg/day) via oral gavage for a period of 28 days. Dorsal root ganglia from the L5 levels were harvested. Processing of tissues was done for electron microscopy and light microscopy. Immunohistochemical staining with active caspase-3 antibody and qualitative ultrastructural analyses of tissues were made by a light and a transmission electron microscope, respectively. RESULTS The results showed that crush injury leads to remarkable ultrastructural changes in sensory neurons, such as swollen mitochondria, disruption of cristae structure, glial cell proliferation and, consequently, phagocytosis of the damaged neuron. These ultrastructural changes were less evident in the treated groups, and both natural compounds reduced the expression of activated caspase-3, which may also affect ultrastructural changes. CONCLUSION The application of the natural products sesame oil and ginger oil may represent a supportive approach to the protection of sensory neurons against the destructive effects of peripheral nerve crush injury.
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Affiliation(s)
- Burcu Delibaş
- Departments of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Arife Ahsen Kaplan
- Department of Histology and Embryology, Faculty of Medicine, İstanbul Medipol University, İstanbul, Turkey
| | | | - Mohammed Issa Eltahir
- Departments of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
- Faculty of Medicine, National University, Khartoum, Sudan
| | - Gamze Altun
- Departments of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Suleyman Kaplan
- Departments of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
- Nelson Mandela African Institute of Science and Technology, Arusha, Tanzania
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Scott H, Novikov B, Ugur B, Allen B, Mertsalov I, Monagas-Valentin P, Koff M, Baas Robinson S, Aoki K, Veizaj R, Lefeber DJ, Tiemeyer M, Bellen H, Panin V. Glia-neuron coupling via a bipartite sialylation pathway promotes neural transmission and stress tolerance in Drosophila. eLife 2023; 12:e78280. [PMID: 36946697 PMCID: PMC10110239 DOI: 10.7554/elife.78280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 03/16/2023] [Indexed: 03/23/2023] Open
Abstract
Modification by sialylated glycans can affect protein functions, underlying mechanisms that control animal development and physiology. Sialylation relies on a dedicated pathway involving evolutionarily conserved enzymes, including CMP-sialic acid synthetase (CSAS) and sialyltransferase (SiaT) that mediate the activation of sialic acid and its transfer onto glycan termini, respectively. In Drosophila, CSAS and DSiaT genes function in the nervous system, affecting neural transmission and excitability. We found that these genes function in different cells: the function of CSAS is restricted to glia, while DSiaT functions in neurons. This partition of the sialylation pathway allows for regulation of neural functions via a glia-mediated control of neural sialylation. The sialylation genes were shown to be required for tolerance to heat and oxidative stress and for maintenance of the normal level of voltage-gated sodium channels. Our results uncovered a unique bipartite sialylation pathway that mediates glia-neuron coupling and regulates neural excitability and stress tolerance.
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Affiliation(s)
- Hilary Scott
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Boris Novikov
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Berrak Ugur
- Departments of Molecular and Human Genetics and Neuroscience, Baylor College of Medicine, and Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
| | - Brooke Allen
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Ilya Mertsalov
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Pedro Monagas-Valentin
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Melissa Koff
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Sarah Baas Robinson
- Complex Carbohydrate Research Center, University of GeorgiaAthensUnited States
| | - Kazuhiro Aoki
- Complex Carbohydrate Research Center, University of GeorgiaAthensUnited States
| | - Raisa Veizaj
- Translational Metabolic Laboratory, Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical CenterNijmegenNetherlands
| | - Dirk J Lefeber
- Translational Metabolic Laboratory, Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical CenterNijmegenNetherlands
| | - Michael Tiemeyer
- Complex Carbohydrate Research Center, University of GeorgiaAthensUnited States
| | - Hugo Bellen
- Departments of Molecular and Human Genetics and Neuroscience, Baylor College of Medicine, and Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
| | - Vladislav Panin
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
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Zhang H, Li P, Wu B, Hou J, Ren J, Zhu Y, Xu J, Si F, Sun Z, Liu X. Transcriptomic analysis reveals the genes involved in tetrodotoxin (TTX) accumulation, translocation, and detoxification in the pufferfish Takifugu rubripes. CHEMOSPHERE 2022; 303:134962. [PMID: 35580645 DOI: 10.1016/j.chemosphere.2022.134962] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/04/2022] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
Tetrodotoxin (TTX) is a potent marine neurotoxin that exists in a variety of aquatic and terrestrial organisms. Pufferfish in different habitats show great variation in their TTX contents. Exploring the genes involved in TTX metabolism could contribute to our understanding of the molecular mechanisms underlying TTX accumulation, translocation, and detoxification in pufferfish. In this study, transcriptomic analysis was used to identify the functional genes related to TTX metabolism in the blood, liver, and muscle of the toxic and non-toxic tiger puffer (Takifugu rubripes). A total of 6101 differentially expressed genes (DEGs) were obtained after transcriptomic analysis; of these, 2401 were identified in the blood, 2262 in the liver, and 1438 in the muscle. After enrichment analysis, fourteen genes encoding glutathione S-transferases (GSTs), glutathione peroxidase (GPx), thioredoxins (TXNs), superoxide dismutase (SOD), ATP-binding cassettes (ABCs), apolipoproteins (APOs), inhibitors of apoptosis protein (IAP), and solute carrier (SLC), which are mainly antioxidant enzymes, membrane transporters, or anti-apoptotic factors, were revealed in the blood. Thirty-six genes encoding SLCs, ABCs, long-chain-fatty-acid-CoA ligases (ACSLs), interleukin 6 cytokine family signal transducer (IL6ST), endoplasmic reticulum (ER), and heat shock protein family A (Hsp70) were involved in transmembrane transporter activity and innate immune response. Notably, a large number of slc genes were found to play critical and diverse roles in TTX accumulation and translocation in the liver of T. rubripes. Nine genes from the slc, hsp70, complement C5 (c5), acsl, er, and serpin peptidase inhibitor (serpin) gene families were found to participate in the regulation of protein processing and anti-apoptosis. These results reflect the diverse functions of genes closely related to TTX accumulation, translocation, and detoxification in T. rubripes.
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Affiliation(s)
- Hanyuan Zhang
- Key Laboratory of Aquatic Genomics, Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory of Fishery Biotechnology, Chinese Academy of Fishery Sciences, Beijing, 100141, China.
| | - Peizhen Li
- Key Laboratory of Aquatic Genomics, Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory of Fishery Biotechnology, Chinese Academy of Fishery Sciences, Beijing, 100141, China
| | - Biyin Wu
- Key Laboratory of Aquatic Genomics, Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory of Fishery Biotechnology, Chinese Academy of Fishery Sciences, Beijing, 100141, China
| | - Jilun Hou
- Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao, Hebei, 066100, China
| | - Jiangong Ren
- Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao, Hebei, 066100, China
| | - Youxiu Zhu
- Key Laboratory of Aquatic Genomics, Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory of Fishery Biotechnology, Chinese Academy of Fishery Sciences, Beijing, 100141, China
| | - Jian Xu
- Key Laboratory of Aquatic Genomics, Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory of Fishery Biotechnology, Chinese Academy of Fishery Sciences, Beijing, 100141, China
| | - Fei Si
- Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao, Hebei, 066100, China
| | - Zhaohui Sun
- Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao, Hebei, 066100, China
| | - Xia Liu
- Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao, Hebei, 066100, China
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Lipopolysaccharide Modifies Sodium Current Kinetics through ROS and PKC Signalling in Induced Pluripotent Stem-Derived Cardiomyocytes from Brugada Syndrome Patient. J Cardiovasc Dev Dis 2022; 9:jcdd9040119. [PMID: 35448095 PMCID: PMC9025958 DOI: 10.3390/jcdd9040119] [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: 01/24/2022] [Revised: 03/17/2022] [Accepted: 04/11/2022] [Indexed: 02/01/2023] Open
Abstract
Studies have suggested a connection between inflammation and arrhythmogenesis of Brugada syndrome (BrS). However, experimental studies regarding the roles of inflammation in the arrhythmogenesis of BrS and its underlying mechanism are still lacking. This study aimed to investigate the influence of inflammation on BrS-phenotype features using human-induced stem cell-derived cardiomyocytes (hiPSC-CMs) from a BrS-patient carrying an SCN10A variant (c.3749G > A). After LPS treatment, the peak sodium current decreased significantly in SCN10A-hiPSC-CMs, but not in healthy donor-hiPSC-CMs. LPS also changed sodium channel gating kinetics, including activation, inactivation, and recovery from inactivation. NAC (N-acetyl-l-cysteine), a blocker of ROS (reactive oxygen species), failed to affect the sodium current, but prevented the LPS-induced reduction of sodium channel currents and changes in gating kinetics, suggesting a contribution of ROS to the LPS effects. Hydrogen peroxide (H2O2), a main form of ROS in cells, mimicked the LPS effects on sodium channel currents and gating kinetics, implying that ROS might mediate LPS-effects on sodium channels. The effects of H2O2 could be attenuated by a PKC blocker chelerythrine, indicating that PKC is a downstream factor of ROS. This study demonstrated that LPS can exacerbate the loss-of-function of sodium channels in BrS cells. Inflammation may play an important role in the pathogenesis of BrS.
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Hong J, Fu S, Gao L, Cai Y, Lazartigues E, Wang HJ. Voltage-gated potassium channel dysfunction in dorsal root ganglia contributes to the exaggerated exercise pressor reflex in rats with chronic heart failure. Am J Physiol Heart Circ Physiol 2021; 321:H461-H474. [PMID: 34270374 DOI: 10.1152/ajpheart.00256.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An exaggerated exercise pressor reflex (EPR) causes excessive sympathoexcitation and exercise intolerance during physical activity in the chronic heart failure (CHF) state. Muscle afferent sensitization contributes to the genesis of the exaggerated EPR in CHF. However, the cellular mechanisms underlying muscle afferent sensitization in CHF remain unclear. Considering that voltage-gated potassium (Kv) channels critically regulate afferent neuronal excitability, we examined the potential role of Kv channels in mediating the sensitized EPR in male rats with CHF. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting experiments demonstrate that both mRNA and protein expressions of multiple Kv channel isoforms (Kv1.4, Kv3.4, Kv4.2, and Kv4.3) were downregulated in lumbar dorsal root ganglions (DRGs) of CHF rats compared with sham rats. Immunofluorescence data demonstrate significant decreased Kv channel staining in both NF200-positive and IB4-positive lumbar DRG neurons in CHF rats compared with sham rats. Data from patch-clamp experiments demonstrate that the total Kv current, especially IA, was dramatically decreased in medium-sized IB4-negative muscle afferent neurons (a subpopulation containing mostly Aδ neurons) from CHF rats compared with sham rats, indicating a potential functional loss of Kv channels in muscle afferent Aδ neurons. In in vivo experiments, adenoviral overexpression of Kv4.3 in lumbar DRGs for 1 wk attenuated the exaggerated EPR induced by muscle static contraction and the mechanoreflex by passive stretch without affecting the blunted cardiovascular response to hindlimb arterial injection of capsaicin in CHF rats. These data suggest that Kv channel dysfunction in DRGs plays a critical role in mediating the exaggerated EPR and muscle afferent sensitization in CHF.NEW & NOTEWORTHY The primary finding of this manuscript is that voltage-gated potassium (Kv) channel dysfunction in DRGs plays a critical role in mediating the exaggerated EPR and muscle afferent sensitization in chronic heart failure (CHF). We propose that manipulation of Kv channels in DRG neurons could be considered as a potential new approach to reduce the exaggerated sympathoexcitation and to improve exercise intolerance in CHF, which can ultimately facilitate an improved quality of life and reduce mortality.
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Affiliation(s)
- Juan Hong
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Shubin Fu
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska.,College of Animal Science and Technology, Southwest University, Chongqing, People's Republic of China
| | - Lie Gao
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Yanhui Cai
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Eric Lazartigues
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Han-Jun Wang
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska
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Pérez-Hernández M, Leo-Macias A, Keegan S, Jouni M, Kim JC, Agullo-Pascual E, Vermij S, Zhang M, Liang FX, Burridge P, Fenyö D, Rothenberg E, Delmar M. Structural and Functional Characterization of a Na v1.5-Mitochondrial Couplon. Circ Res 2021; 128:419-432. [PMID: 33342222 PMCID: PMC7864872 DOI: 10.1161/circresaha.120.318239] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
RATIONALE The cardiac sodium channel NaV1.5 has a fundamental role in excitability and conduction. Previous studies have shown that sodium channels cluster together in specific cellular subdomains. Their association with intracellular organelles in defined regions of the myocytes, and the functional consequences of that association, remain to be defined. OBJECTIVE To characterize a subcellular domain formed by sodium channel clusters in the crest region of the myocytes and the subjacent subsarcolemmal mitochondria. METHODS AND RESULTS Through a combination of imaging approaches including super-resolution microscopy and electron microscopy we identified, in adult cardiac myocytes, a NaV1.5 subpopulation in close proximity to subjacent subsarcolemmal mitochondria; we further found that subjacent subsarcolemmal mitochondria preferentially host the mitochondrial NCLX (Na+/Ca2+ exchanger). This anatomic proximity led us to investigate functional changes in mitochondria resulting from sodium channel activity. Upon TTX (tetrodotoxin) exposure, mitochondria near NaV1.5 channels accumulated more Ca2+ and showed increased reactive oxygen species production when compared with interfibrillar mitochondria. Finally, crosstalk between NaV1.5 channels and mitochondria was analyzed at a transcriptional level. We found that SCN5A (encoding NaV1.5) and SLC8B1 (which encode NaV1.5 and NCLX, respectively) are negatively correlated both in a human transcriptome data set (Genotype-Tissue Expression) and in human-induced pluripotent stem cell-derived cardiac myocytes deficient in SCN5A. CONCLUSIONS We describe an anatomic hub (a couplon) formed by sodium channel clusters and subjacent subsarcolemmal mitochondria. Preferential localization of NCLX to this domain allows for functional coupling where the extrusion of Ca2+ from the mitochondria is powered, at least in part, by the entry of sodium through NaV1.5 channels. These results provide a novel entry-point into a mechanistic understanding of the intersection between electrical and structural functions of the heart.
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Affiliation(s)
| | - Alejandra Leo-Macias
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
| | - Sarah Keegan
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology. NYU Grossman School of Medicine. New York, NY
| | - Mariam Jouni
- Department of Pharmacology, Northwestern University Feinberg School of Medicine. Chicago, IL
| | - Joon-Chul Kim
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
| | | | - Sarah Vermij
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
| | - Mingliang Zhang
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
| | - Feng-Xia Liang
- Microscopy laboratory, Division of Advanced Research Technologies. NYU Grossman School of Medicine. New York, NY
| | - Paul Burridge
- Department of Pharmacology, Northwestern University Feinberg School of Medicine. Chicago, IL
| | - David Fenyö
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology. NYU Grossman School of Medicine. New York, NY
| | - Eli Rothenberg
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology. NYU Grossman School of Medicine. New York, NY
| | - Mario Delmar
- Leon H Charney Division of Cardiology NYU Grossman School of Medicine. New York, NY
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Sex Difference in Trigeminal Neuropathic Pain Response to Exercise: Role of Oxidative Stress. Pain Res Manag 2020; 2020:3939757. [PMID: 32676135 PMCID: PMC7341438 DOI: 10.1155/2020/3939757] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/17/2020] [Accepted: 06/08/2020] [Indexed: 11/17/2022]
Abstract
Aim Orofacial chronic neuropathic pain commonly occurs following trigeminal nerve injuries. We investigated whether swimming exercise can reduce trigeminal neuropathic pain through improving antioxidant capacity. Materials and Methods Twenty-eight Wistar rats of either sex and 180–220 grams were divided into 4 groups as sham, neuropathy, neuropathy + single bout exercise, and neuropathy + 2 weeks of exercise. Trigeminal neuropathy was carried out through chronic constriction injury (CCI) of infraorbital nerve. Protocols of exercise were included a single bout session (45 minutes) and a 2-week (45 minutes/day/6 days a week) swimming exercise. Mechanical allodynia was detected using Von Frey filaments. The activity of the serum antioxidant enzymes glutathione peroxidase and superoxides dismutase was assayed using ELISA kits. Results We found that CCI significantly reduced facial pain threshold in both sexes (P < 0.05). Both swimming exercise protocols significantly reduced mechanical allodynia in female rats compared to the sham group; however, only 2 weeks of exercise were significantly effective in male rats. The activity of antioxidant enzyme glutathione peroxidase significantly (P < 0.05) decreased following CCI in female rats against that in the sham group and 2-week exercise significantly (P < 0.05) increased it toward the control level. The levels of glutathione peroxidase in male rats and superoxidase dismutase in both sexes were not significantly different compared to their sham groups. Conclusion Swimming exercise alleviates trigeminal neuropathic pain in both sexes. Oxidative stress as a possible mechanism was involved in the effect of exercise on female rat trigeminal neuropathy.
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Raven PB, Young BE, Fadel PJ. Arterial Baroreflex Resetting During Exercise in Humans: Underlying Signaling Mechanisms. Exerc Sport Sci Rev 2020; 47:129-141. [PMID: 30921029 DOI: 10.1249/jes.0000000000000190] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The arterial baroreflex (ABR) resets during exercise in an intensity-dependent manner to operate around a higher blood pressure with maintained sensitivity. This review provides a historical perspective of ABR resetting and the involvement of other neural reflexes in mediating exercise resetting. Furthermore, we discuss potential underlying signaling mechanisms that may contribute to exercise ABR resetting in physiological and pathophysiological conditions.
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Affiliation(s)
- Peter B Raven
- Department of Integrative Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth
| | - Benjamin E Young
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX
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Lian S, Zhao L, Xun X, Lou J, Li M, Li X, Wang S, Zhang L, Hu X, Bao Z. Genome-Wide Identification and Characterization of SODs in Zhikong Scallop Reveals Gene Expansion and Regulation Divergence after Toxic Dinoflagellate Exposure. Mar Drugs 2019; 17:md17120700. [PMID: 31842317 PMCID: PMC6949909 DOI: 10.3390/md17120700] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 11/29/2019] [Accepted: 12/05/2019] [Indexed: 12/12/2022] Open
Abstract
As filter-feeding animals mainly ingesting microalgae, bivalves could accumulate paralytic shellfish toxins (PSTs) produced by harmful algae through diet. To protect themselves from the toxic effects of PSTs, especially the concomitant oxidative damage, the production of superoxide dismutase (SOD), which is the only eukaryotic metalloenzyme capable of detoxifying superoxide, may assist with toxin tolerance in bivalves. To better understand this process, in the present study, we performed the first systematic analysis of SOD genes in bivalve Chlamys farreri, an important aquaculture species in China. A total of six Cu/Zn-SODs (SOD1-6) and two Mn-SODs (SOD7, SOD8) were identified in C. farreri, with gene expansion being revealed in Cu/Zn-SODs. In scallops exposed to two different PSTs-producing dinoflagellates, Alexandrium minutum and A. catenella, expression regulation of SOD genes was analyzed in the top ranked toxin-rich organs, the hepatopancreas and the kidney. In hepatopancreas, which mainly accumulates the incoming PSTs, all of the six Cu/Zn-SODs showed significant alterations after A. minutum exposure, with SOD1, 2, 3, 5, and 6 being up-regulated, and SOD4 being down-regulated, while no significant change was detected in Mn-SODs. After A. catenella exposure, up-regulation was observed in SOD2, 4, 6, and 8, and SOD7 was down-regulated. In the kidney, where PSTs transformation occurs, SOD4, 5, 6, and 8 were up-regulated, and SOD7 was down-regulated in response to A. minutum feeding. After A. catenella exposure, all the Cu/Zn-SODs except SOD1 were up-regulated, and SOD7 was down-regulated in kidney. Overall, in scallops after ingesting different toxic algae, SOD up-regulation mainly occurred in the expanded Cu/Zn-SOD group, and SOD6 was the only member being up-regulated in both toxic organs, which also showed the highest fold change among all the SODs, implying the importance of SOD6 in protecting scallops from the stress of PSTs. Our results suggest the diverse function of scallop SODs in response to the PST-producing algae challenge, and the expansion of Cu/Zn-SODs might be implicated in the adaptive evolution of scallops or bivalves with respect to antioxidant defense against the ingested toxic algae.
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Affiliation(s)
- Shanshan Lian
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Liang Zhao
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Xiaogang Xun
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
| | - Jiarun Lou
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
| | - Moli Li
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
| | - Xu Li
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
| | - Shi Wang
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Lingling Zhang
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Xiaoli Hu
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
- Correspondence: ; Tel.: +86-0532-8203-1970; Fax: +86-0532-8203-1802
| | - Zhenmin Bao
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao 266003, China; (S.L.); (L.Z.); (X.X.); (J.L.); (M.L.); (X.L.); (S.W.); (L.Z.); (Z.B.)
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
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Mueller PJ, Clifford PS, Crandall CG, Smith SA, Fadel PJ. Integration of Central and Peripheral Regulation of the Circulation during Exercise: Acute and Chronic Adaptations. Compr Physiol 2017; 8:103-151. [DOI: 10.1002/cphy.c160040] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Cooper MA, Kluding PM, Wright DE. Emerging Relationships between Exercise, Sensory Nerves, and Neuropathic Pain. Front Neurosci 2016; 10:372. [PMID: 27601974 PMCID: PMC4993768 DOI: 10.3389/fnins.2016.00372] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/02/2016] [Indexed: 01/09/2023] Open
Abstract
The utilization of physical activity as a therapeutic tool is rapidly growing in the medical community and the role exercise may offer in the alleviation of painful disease states is an emerging research area. The development of neuropathic pain is a complex mechanism, which clinicians and researchers are continually working to better understand. The limited therapies available for alleviation of these pain states are still focused on pain abatement and as opposed to treating underlying mechanisms. The continued research into exercise and pain may address these underlying mechanisms, but the mechanisms which exercise acts through are still poorly understood. The objective of this review is to provide an overview of how the peripheral nervous system responds to exercise, the relationship of inflammation and exercise, and experimental and clinical use of exercise to treat pain. Although pain is associated with many conditions, this review highlights pain associated with diabetes as well as experimental studies on nerve damages-associated pain. Because of the global effects of exercise across multiple organ systems, exercise intervention can address multiple problems across the entire nervous system through a single intervention. This is a double-edged sword however, as the global interactions of exercise also require in depth investigations to include and identify the many changes that can occur after physical activity. A continued investment into research is necessary to advance the adoption of physical activity as a beneficial remedy for neuropathic pain. The following highlights our current understanding of how exercise alters pain, the varied pain models used to explore exercise intervention, and the molecular pathways leading to the physiological and pathological changes following exercise intervention.
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Affiliation(s)
- Michael A Cooper
- Department of Anatomy and Cell Biology, University of Kansas Medical Center Kansas City, KS, USA
| | - Patricia M Kluding
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center Kansas City, KS, USA
| | - Douglas E Wright
- Department of Anatomy and Cell Biology, University of Kansas Medical Center Kansas City, KS, USA
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Ramachandra R, Elmslie KS. EXPRESS: Voltage-dependent sodium (NaV) channels in group IV sensory afferents. Mol Pain 2016; 12:12/0/1744806916660721. [PMID: 27385723 PMCID: PMC4956173 DOI: 10.1177/1744806916660721] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Patients with intermittent claudication suffer from both muscle pain and an exacerbated exercise pressor reflex. Excitability of the group III and group IV afferent fibers mediating these functions is controlled in part by voltage-dependent sodium (NaV) channels. We previously found tetrodotoxin-resistant NaV1.8 channels to be the primary type in muscle afferent somata. However, action potentials in group III and IV afferent axons are blocked by TTX, supporting a minimal role of NaV1.8 channels. To address these apparent differences in NaV channel expression between axon and soma, we used immunohistochemistry to identify the NaV channels expressed in group IV axons within the gastrocnemius muscle and the dorsal root ganglia sections. Positive labeling by an antibody against the neurofilament protein peripherin was used to identify group IV neurons and axons. We show that >67% of group IV fibers express NaV1.8, NaV1.6, or NaV1.7. Interestingly, expression of NaV1.8 channels in group IV somata was significantly higher than in the fibers, whereas there were no significant differences for either NaV1.6 or NaV1.7. When combined with previous work, our results suggest that NaV1.8 channels are expressed in most group IV axons, but that, under normal conditions, NaV1.6 and/or NaV1.7 play a more important role in action potential generation to signal muscle pain and the exercise pressor reflex.
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Affiliation(s)
- Renuka Ramachandra
- The Baker Laboratory of Pharmacology, Department of Pharmacology, AT Still University of Health Sciences, Kirksville, MO, USA
- Renuka Ramachandra, The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, AT Still University of Health Sciences, Kirksville, MO 63501, USA.
| | - Keith S Elmslie
- The Baker Laboratory of Pharmacology, Department of Pharmacology, AT Still University of Health Sciences, Kirksville, MO, USA
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Caioli S, Candelotti E, Pedersen JZ, Saba L, Antonini A, Incerpi S, Zona C. Baicalein reverts L-valine-induced persistent sodium current up-modulation in primary cortical neurons. Biochim Biophys Acta Mol Basis Dis 2016; 1862:566-575. [DOI: 10.1016/j.bbadis.2015.12.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 11/18/2015] [Accepted: 12/19/2015] [Indexed: 01/24/2023]
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Laux-Biehlmann A, d’Hooghe T, Zollner TM. Menstruation pulls the trigger for inflammation and pain in endometriosis. Trends Pharmacol Sci 2015; 36:270-6. [DOI: 10.1016/j.tips.2015.03.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/10/2015] [Accepted: 03/12/2015] [Indexed: 01/02/2023]
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15
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Gamper N, Ooi L. Redox and nitric oxide-mediated regulation of sensory neuron ion channel function. Antioxid Redox Signal 2015; 22:486-504. [PMID: 24735331 PMCID: PMC4323017 DOI: 10.1089/ars.2014.5884] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
SIGNIFICANCE Reactive oxygen and nitrogen species (ROS and RNS, respectively) can intimately control neuronal excitability and synaptic strength by regulating the function of many ion channels. In peripheral sensory neurons, such regulation contributes towards the control of somatosensory processing; therefore, understanding the mechanisms of such regulation is necessary for the development of new therapeutic strategies and for the treatment of sensory dysfunctions, such as chronic pain. RECENT ADVANCES Tremendous progress in deciphering nitric oxide (NO) and ROS signaling in the nervous system has been made in recent decades. This includes the recognition of these molecules as important second messengers and the elucidation of their metabolic pathways and cellular targets. Mounting evidence suggests that these targets include many ion channels which can be directly or indirectly modulated by ROS and NO. However, the mechanisms specific to sensory neurons are still poorly understood. This review will therefore summarize recent findings that highlight the complex nature of the signaling pathways involved in redox/NO regulation of sensory neuron ion channels and excitability; references to redox mechanisms described in other neuron types will be made where necessary. CRITICAL ISSUES The complexity and interplay within the redox, NO, and other gasotransmitter modulation of protein function are still largely unresolved. Issues of specificity and intracellular localization of these signaling cascades will also be addressed. FUTURE DIRECTIONS Since our understanding of ROS and RNS signaling in sensory neurons is limited, there is a multitude of future directions; one of the most important issues for further study is the establishment of the exact roles that these signaling pathways play in pain processing and the translation of this understanding into new therapeutics.
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Affiliation(s)
- Nikita Gamper
- 1 Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds , Leeds, United Kingdom
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16
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Curcumin abolishes mutant TDP-43 induced excitability in a motoneuron-like cellular model of ALS. Neuroscience 2014; 272:141-53. [DOI: 10.1016/j.neuroscience.2014.04.032] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Revised: 03/31/2014] [Accepted: 04/19/2014] [Indexed: 12/12/2022]
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17
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Thakurta IG, Banerjee P, Bagh MB, Ghosh A, Sahoo A, Chattopadhyay S, Chakrabarti S. Combination of N-acetylcysteine, α-lipoic acid and α-tocopherol substantially prevents the brain synaptosomal alterations and memory and learning deficits of aged rats. Exp Gerontol 2014; 50:19-25. [DOI: 10.1016/j.exger.2013.11.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Revised: 11/16/2013] [Accepted: 11/19/2013] [Indexed: 11/25/2022]
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18
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Ramachandra R, McGrew S, Elmslie K. Identification of specific sensory neuron populations for study of expressed ion channels. J Vis Exp 2013:50782. [PMID: 24430510 DOI: 10.3791/50782] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Sensory neurons transmit signals from various parts of the body to the central nervous system. The soma for these neurons are located in the dorsal root ganglia that line the spinal column. Understanding the receptors and channels expressed by these sensory afferent neurons could lead to novel therapies for disease. The initial step is to identify the specific subset of sensory neurons of interest. Here we describe a method to identify afferent neurons innervating the muscles by retrograde labeling using a fluorescent dye DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate). Understanding the contribution of ion channels to excitation of muscle afferents could help to better control excessive excitability induced by certain disease states such as peripheral vascular disease or heart failure. We used two approaches to identify the voltage dependent ion channels expressed by these neurons, patch clamp electrophysiology and immunocytochemistry. While electrophysiology plus pharmacological blockers can identify functional ion channel types, we used immunocytochemistry to identify channels for which specific blockers were unavailable and to better understand the ion channel distribution pattern in the cell population. These techniques can be applied to other areas of the nervous system to study specific neuronal groups.
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Affiliation(s)
- Renuka Ramachandra
- Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, AT Still University of Health Sciences
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Gueret G, Guillouet M, Vermeersch V, Guillard E, Talarmin H, Nguyen BV, Rannou F, Giroux-Metges MA, Pennec JP, Ozier Y. [ICU acquired neuromyopathy]. ACTA ACUST UNITED AC 2013; 32:580-91. [PMID: 23958176 DOI: 10.1016/j.annfar.2013.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Accepted: 05/08/2013] [Indexed: 12/19/2022]
Abstract
ICU acquired neuromyopathy (IANM) is the most frequent neurological pathology observed in ICU. Nerve and muscle defects are merged with neuromuscular junction abnormalities. Its physiopathology is complex. The aim is probably the redistribution of nutriments and metabolism towards defense against sepsis. The main risk factors are sepsis, its severity and its duration of evolution. IANM is usually diagnosed in view of difficulties in weaning from mechanical ventilation, but electrophysiology may allow an earlier diagnosis. There is no curative therapy, but early treatment of sepsis, glycemic control as well as early physiotherapy may decrease its incidence. The outcomes of IANM are an increase in morbi-mortality and possibly long-lasting neuromuscular abnormalities as far as tetraplegia.
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Affiliation(s)
- G Gueret
- Pôle anesthésie réanimations soins intensifs blocs opératoires urgences (ARSIBOU), CHRU de Brest, boulevard Tanguy-Prigent, 29200 Brest, France; Laboratoire de physiologie, faculté de médecine et des sciences de la santé, EA 1274 (mouvement, sport santé), université de Bretagne-Occidentale, 22, avenue Camille-Desmoulins, 29200 Brest, France; Université européenne de Bretagne, 5, boulevard Laennec, 35000 Rennes, France.
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Singh JN, Jain G, Sharma SS. In vitro hyperglycemia enhances sodium currents in dorsal root ganglion neurons: an effect attenuated by carbamazepine. Neuroscience 2012; 232:64-73. [PMID: 23262239 DOI: 10.1016/j.neuroscience.2012.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 12/06/2012] [Accepted: 12/07/2012] [Indexed: 12/13/2022]
Abstract
Neuropathy is often seen in uncontrolled diabetes and the mechanisms involved for neuropathic pain are poorly understood. Hyperglycemia is a consequence of chronic uncontrolled diabetes and it is postulated to produce neuropathic pain. Therefore, in this study, we have investigated the effects of hyperglycemia on Na(+) channel kinetics in cultured dorsal root ganglion (DRG) neurons from neonatal rats using whole-cell patch-clamp technique. Hyperglycemia-induced increase in density of tetrodotoxin resistant (TTXr) Na(+) currents was increased in time- and concentration-dependent manner. The increase was maximal with 60 mM and 24 h. There was no change Na(+) current density in time-matched control neurons. The conductance curve of TTXr Na(+) current shifted leftward after 24 h exposure to 45 mM glucose. Carbamazepine (CBZ, 100 μM) depressed TTXr Na(+) current in neurons incubated with control (17.26), 45 and 60 mM of glucose. The depression observed with CBZ in the presence of high glucose, i.e., 45 mM (86.5±4.9%) was significantly greater than control (61.6±1.8%). Hyperglycemia also increased reactive oxygen species (ROS) activity and was attenuated by CBZ. These results suggest that short-term exposure of DRG neurons to high glucose concentrations enhance the Na(+) channel activity, and were attenuated by CBZ via ROS-dependent mechanisms.
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Affiliation(s)
- J N Singh
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)(1), S. A. S. Nagar (Mohali) 160 062, Punjab, India.
| | - G Jain
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)(1), S. A. S. Nagar (Mohali) 160 062, Punjab, India
| | - S S Sharma
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)(1), S. A. S. Nagar (Mohali) 160 062, Punjab, India
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Koba S, Watanabe R, Kano N, Watanabe T. Oxidative stress exaggerates skeletal muscle contraction-evoked reflex sympathoexcitation in rats with hypertension induced by angiotensin II. Am J Physiol Heart Circ Physiol 2012; 304:H142-53. [PMID: 23086992 DOI: 10.1152/ajpheart.00423.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Muscle contraction stimulates thin fiber muscle afferents and evokes reflex sympathoexcitation. In hypertension, this reflex is exaggerated. ANG II, which is elevated in hypertension, has been reported to trigger the production of superoxide and other reactive oxygen species. In the present study, we tested the hypothesis that increased ANG II in hypertension exaggerates skeletal muscle contraction-evoked reflex sympathoexcitation by inducing oxidative stress in the muscle. In rats, subcutaneous infusion of ANG II at 450 ng·kg(-1)·min(-1) for 14 days significantly (P < 0.05) elevated blood pressure compared with sham-operated (sham) rats. Electrically induced 30-s hindlimb muscle contraction in decerebrate rats with hypertension evoked larger renal sympathoexcitatory and pressor responses [+1,173 ± 212 arbitrary units (AU) and +35 ± 5 mmHg, n = 10] compared with sham normotensive rats (+419 ± 103 AU and +13 ± 2 mmHg, n = 11). Tempol, a SOD mimetic, injected intra-arterially into the hindlimb circulation significantly reduced responses in hypertensive rats, whereas this compound had no effect on responses in sham rats. Tiron, another SOD mimetic, also significantly reduced reflex renal sympathetic and pressor responses in a subset of hypertensive rats (n = 10). Generation of muscle superoxide, as evaluated by dihydroethidium staining, was increased in hypertensive rats. RT-PCR and immunoblot experiments showed that mRNA and protein for gp91(phox), a NADPH oxidase subunit, in skeletal muscle tissue were upregulated in hypertensive rats. Taken together, hese results suggest that increased ANG II in hypertension induces oxidative stress in skeletal muscle, thereby exaggerating the muscle reflex.
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Affiliation(s)
- Satoshi Koba
- Division of Integrative Physiology, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori, Japan.
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Wang HJ, Zucker IH, Wang W. Muscle reflex in heart failure: the role of exercise training. Front Physiol 2012; 3:398. [PMID: 23060821 PMCID: PMC3464681 DOI: 10.3389/fphys.2012.00398] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 09/20/2012] [Indexed: 12/25/2022] Open
Abstract
Exercise evokes sympathetic activation and increases blood pressure and heart rate (HR). Two neural mechanisms that cause the exercise-induced increase in sympathetic discharge are central command and the exercise pressor reflex (EPR). The former suggests that a volitional signal emanating from central motor areas leads to increased sympathetic activation during exercise. The latter is a reflex originating in skeletal muscle which contributes significantly to the regulation of the cardiovascular and respiratory systems during exercise. The afferent arm of this reflex is composed of metabolically sensitive (predominantly group IV, C-fibers) and mechanically sensitive (predominately group III, A-delta fibers) afferent fibers. Activation of these receptors and their associated afferent fibers reflexively adjusts sympathetic and parasympathetic nerve activity during exercise. In heart failure, the sympathetic activation during exercise is exaggerated, which potentially increases cardiovascular risk and contributes to exercise intolerance during physical activity in chronic heart failure (CHF) patients. A therapeutic strategy for preventing or slowing the progression of the exaggerated EPR may be of benefit in CHF patients. Long-term exercise training (ExT), as a non-pharmacological treatment for CHF increases exercise capacity, reduces sympatho-excitation and improves cardiovascular function in CHF animals and patients. In this review, we will discuss the effects of ExT and the mechanisms that contribute to the exaggerated EPR in the CHF state.
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Affiliation(s)
- Han-Jun Wang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center Omaha, NE, USA
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Ramachandra R, McGrew SY, Baxter JC, Kiveric E, Elmslie KS. Tetrodotoxin-resistant voltage-dependent sodium channels in identified muscle afferent neurons. J Neurophysiol 2012; 108:2230-41. [PMID: 22855776 DOI: 10.1152/jn.00219.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Muscle afferents are critical regulators of motor function (Group I and II) and cardiovascular responses to exercise (Group III and IV). However, little is known regarding the expressed voltage-dependent ion channels. We identified muscle afferent neurons in dorsal root ganglia (DRGs), using retrograde labeling to examine voltage-dependent sodium (Na(V)) channels. In patch-clamp recordings, we found that the dominant Na(V) current in the majority of identified neurons was insensitive to tetrodotoxin (TTX-R), with Na(V) current in only a few (14%) neurons showing substantial (>50%) TTX sensitivity (TTX-S). The TTX-R current was sensitive to a Na(V)1.8 channel blocker, A803467. Immunocytochemistry demonstrated labeling of muscle afferent neurons by a Na(V)1.8 antibody, which further supported expression of these channels. A portion of the TTX-R Na(V) current appeared to be noninactivating during our 25-ms voltage steps, which suggested activity of Na(V)1.9 channels. The majority of the noninactivating current was insensitive to A803467 but sensitive to extracellular sodium. Immunocytochemistry showed labeling of muscle afferent neurons by a Na(V)1.9 channel antibody, which supports expression of these channels. Further examination of the muscle afferent neurons showed that functional TTX-S channels were expressed, but were largely inactivated at physiological membrane potentials. Immunocytochemistry showed expression of the TTX-S channels Na(V)1.6 and Na(V)1.7 but not Na(V)1.1. Na(V)1.8 and Na(V)1.9 appear to be the dominant functional sodium channels in small- to medium-diameter muscle afferent neurons. The expression of these channels is consistent with the identification of these neurons as Group III and IV, which mediate the exercise pressor reflex.
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Affiliation(s)
- Renuka Ramachandra
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, AT Still University of Health Sciences, Kirksville, MO 63501, USA
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Heterogeneous responses to antioxidants in noradrenergic neurons of the Locus coeruleus indicate differing susceptibility to free radical content. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:820285. [PMID: 22577493 PMCID: PMC3345253 DOI: 10.1155/2012/820285] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 01/24/2012] [Accepted: 02/08/2012] [Indexed: 11/17/2022]
Abstract
The present study investigated the effects of the antioxidants trolox and dithiothreitol (DTT) on mouse Locus coeruleus (LC) neurons. Electrophysiological measurement of action potential discharge and whole cell current responses in the presence of each antioxidant suggested that there are three neuronal subpopulations within the LC. In current clamp experiments, most neurons (55%; 6/11) did not respond to the antioxidants. The remaining neurons exhibited either hyperpolarization and decreased firing rate (27%; 3/11) or depolarization and increased firing rate (18%; 2/11). Calcium and JC-1 imaging demonstrated that these effects did not change intracellular Ca2+ concentration but may influence mitochondrial function as both antioxidant treatments modulated mitochondrial membrane potential. These suggest that the antioxidant-sensitive subpopulations of LC neurons may be more susceptible to oxidative stress (e.g., due to ATP depletion and/or overactivation of Ca2+-dependent pathways). Indeed it may be that this subpopulation of LC neurons is preferentially destroyed in neurological pathologies such as Parkinson's disease. If this is the case, there may be a protective role for antioxidant therapies.
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Wang HJ, Li YL, Zucker IH, Wang W. Exercise training prevents skeletal muscle afferent sensitization in rats with chronic heart failure. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1260-70. [PMID: 22496362 DOI: 10.1152/ajpregu.00054.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
An exaggerated exercise pressor reflex (EPR) contributes to exercise intolerance and excessive sympathoexcitation in the chronic heart failure (CHF) state, which is prevented by exercise training (ExT) at an early stage in the development of CHF. We hypothesized that ExT has a beneficial effect on the exaggerated EPR by improving the dysfunction of muscle afferents in CHF. We recorded the discharge of mechanically sensitive (group III) and metabolically sensitive (group IV) afferents in response to static contraction, passive stretch, and hindlimb intra-arterial injection of capsaicin in sham+sedentary (Sed), sham+ExT, CHF+Sed, and CHF+ExT rats. Compared with sham+Sed rats, CHF+Sed rats exhibited greater responses of group III afferents to contraction and stretch, whereas the responses of group IV afferents to contraction and capsaicin were blunted. ExT prevented the sensitization of group III responses to contraction or stretch and partially prevented the blunted group IV responses to contraction or capsaicin in CHF rats. Furthermore, we investigated whether purinergic 2X (P2X) and transient receptor potential vanilloid 1 (TRPV1) receptors mediate the altered sensitivity of muscle afferents by ExT in CHF. We found that the upregulated P2X and downregulated TRPV1 receptors in L4/5 dorsal root ganglia of CHF rats were normalized by ExT. Hindlimb intra-arterial infusion of a P2X antagonist attenuated the group III response to contraction or stretch in CHF rats to a greater extent than in sham rats, which was normalized by ExT. These findings suggest that ExT improves the abnormal sensitization of muscle afferents in CHF at least, in part, via restoring the dysfunction of P2X and TRPV1 receptors.
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Affiliation(s)
- Han-Jun Wang
- Dept. of Cellular and Integrative Physiology, Univ. of Nebraska Medical Center, Omaha, NE 68198, USA
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