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Yao X, Hu J, Wang G, Lin X, Sun J, Dong G, Kang J, Feng W, Xie B, Huang Y, Tian X, Chen E. Deposition of Gadolinium in the Central and Peripheral Nervous Systems and Its Effects on Sensory, Cognitive, and Athletic Implications after Multiple Injections of Gadolinium-Based Contrast Agents in Rats. AJNR Am J Neuroradiol 2024; 45:1153-1161. [PMID: 38991773 PMCID: PMC11383410 DOI: 10.3174/ajnr.a8295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 03/17/2024] [Indexed: 07/13/2024]
Abstract
BACKGROUND AND PURPOSE After repeat administration of gadolinium-based contrast agents (GBCAs), the association between gadolinium retention in the central and peripheral nervous systems and the main manifestations of myelopathy and progressive neurologic symptoms remains unclear. We investigated the effects of the repeat administration of GBCAs on gadolinium retention in the central and peripheral nervous systems and the sensory, cognitive, and athletic implications. MATERIALS AND METHODS Forty-eight male Wistar rats (6 weeks of age) were randomly divided into 4 experimental groups (12 rats in each group): the gadodiamide group (linear and nonionic GBCAs), the gadopentetate dimeglumine group (linear and ionic GBCAs), the gadoterate meglumine group (macrocyclic and ionic GBCAs), and the control group (0.9% saline solution). The brains of the rats were scanned using 9.4T MRI. Sensory behavioral tests were performed to assess the effect of GBCAs on pain sensitivity function. Gadolinium deposition in the brain, spinal cord, and peripheral nerves was determined by inductively coupled plasma mass-spectrometry. Transmission electron microscopy was used to observe the microscopic distribution of gadolinium after deposition in the spinal cord. The histopathologic features in the spinal cord were analyzed by H&E staining, Nissl staining, glial fibrillary acidic protein staining, and neuron-specific enolase staining after administration of GBCAs. RESULTS All GBCAs resulted in gadolinium deposition in the central and peripheral nerve tissues, with the highest deposition in the sciatic nerve tissue (mean, 62.86 [SD, 12.56] nmol/g). Decreased muscle power, impairment of spatial cognitive function power, and pain hypersensitivity to thermal and mechanical stimuli were observed after exposure to gadodiamide. At the spinal cord, transmission electron microscopy found that the region of gadolinium depositions had a spheric structure similar to "sea urchins" and was mainly located near the vascular basement membrane. CONCLUSIONS Multiple injections of GBCAs caused gadolinium deposition in the brain, spinal cord, and peripheral nerves, especially in the spinal cords of the gadodiamide group. Gadodiamide led to pain hypersensitivity and decreased muscle power and cognitive ability. For the patients who are hypersensitive to pain and need multiple MRI examinations, we recommend using macrocyclic GBCAs and the lowest dose possible.
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Affiliation(s)
- Xiang Yao
- From the Department of Neurosurgery (X.Y., X.L., J.S, G.D., J.K., W.F., Y.H., X.T., E.C.), Zhongshan Hospital of Xiamen University, School of Medcine, Xiamen University, XiaMen, China
| | - Jingyi Hu
- The Basic Medicine College of Lanzhou University (J.H.), Lanzhou, China
| | - Guangsong Wang
- Department of Radiology (G.W.), Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xia Men, China
| | - Xiaoning Lin
- From the Department of Neurosurgery (X.Y., X.L., J.S, G.D., J.K., W.F., Y.H., X.T., E.C.), Zhongshan Hospital of Xiamen University, School of Medcine, Xiamen University, XiaMen, China
| | - Jin Sun
- From the Department of Neurosurgery (X.Y., X.L., J.S, G.D., J.K., W.F., Y.H., X.T., E.C.), Zhongshan Hospital of Xiamen University, School of Medcine, Xiamen University, XiaMen, China
| | - Guijiang Dong
- From the Department of Neurosurgery (X.Y., X.L., J.S, G.D., J.K., W.F., Y.H., X.T., E.C.), Zhongshan Hospital of Xiamen University, School of Medcine, Xiamen University, XiaMen, China
| | - Junlong Kang
- From the Department of Neurosurgery (X.Y., X.L., J.S, G.D., J.K., W.F., Y.H., X.T., E.C.), Zhongshan Hospital of Xiamen University, School of Medcine, Xiamen University, XiaMen, China
| | - Wei Feng
- From the Department of Neurosurgery (X.Y., X.L., J.S, G.D., J.K., W.F., Y.H., X.T., E.C.), Zhongshan Hospital of Xiamen University, School of Medcine, Xiamen University, XiaMen, China
| | - Bowen Xie
- Suining Jinghua Senior High School (B.X.), Xuzhou, China
| | - Yanlin Huang
- From the Department of Neurosurgery (X.Y., X.L., J.S, G.D., J.K., W.F., Y.H., X.T., E.C.), Zhongshan Hospital of Xiamen University, School of Medcine, Xiamen University, XiaMen, China
| | - Xinhua Tian
- From the Department of Neurosurgery (X.Y., X.L., J.S, G.D., J.K., W.F., Y.H., X.T., E.C.), Zhongshan Hospital of Xiamen University, School of Medcine, Xiamen University, XiaMen, China
| | - E Chen
- From the Department of Neurosurgery (X.Y., X.L., J.S, G.D., J.K., W.F., Y.H., X.T., E.C.), Zhongshan Hospital of Xiamen University, School of Medcine, Xiamen University, XiaMen, China
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Dynamic MRI of the Mesenchymal Stem Cells Distribution during Intravenous Transplantation in a Rat Model of Ischemic Stroke. Life (Basel) 2023; 13:life13020288. [PMID: 36836645 PMCID: PMC9962901 DOI: 10.3390/life13020288] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/29/2022] [Accepted: 01/17/2023] [Indexed: 01/22/2023] Open
Abstract
Systemic transplantation of mesenchymal stem cells (MSCs) is a promising approach for the treatment of ischemia-associated disorders, including stroke. However, exact mechanisms underlying its beneficial effects are still debated. In this respect, studies of the transplanted cells distribution and homing are indispensable. We proposed an MRI protocol which allowed us to estimate the dynamic distribution of single superparamagnetic iron oxide labeled MSCs in live ischemic rat brain during intravenous transplantation after the transient middle cerebral artery occlusion. Additionally, we evaluated therapeutic efficacy of cell therapy in this rat stroke model. According to the dynamic MRI data, limited numbers of MSCs accumulated diffusely in the brain vessels starting at the 7th minute from the onset of infusion, reached its maximum by 29 min, and gradually eliminated from cerebral circulation during 24 h. Despite low numbers of cells entering brain blood flow and their short-term engraftment, MSCs transplantation induced long lasting improvement of the neurological deficit, but without acceleration of the stroke volume reduction compared to the control animals during 14 post-transplantation days. Taken together, these findings indicate that MSCs convey their positive action by triggering certain paracrine mechanisms or cell-cell interactions or invoking direct long-lasting effects on brain vessels.
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Abstract
Spinal projection neurons convey nociceptive signals to multiple brain regions including the parabrachial (PB) nucleus, which contributes to the emotional valence of pain perception. Despite the clear importance of projection neurons to pain processing, our understanding of the factors that shape their intrinsic membrane excitability remains limited. Here, we investigate a potential role for the Na leak channel NALCN in regulating the activity of spino-PB neurons in the developing rodent. Pharmacological reduction of NALCN current (INALCN), or the genetic deletion of NALCN channels, significantly reduced the intrinsic excitability of lamina I spino-PB neurons. In addition, substance P (SP) activated INALCN in ascending projection neurons through downstream Src kinase signaling, and the knockout of NALCN prevented SP-evoked action potential discharge in this neuronal population. These results identify, for the first time, NALCN as a strong regulator of neuronal activity within central pain circuits and also elucidate an additional ionic mechanism by which SP can modulate spinal nociceptive processing. Collectively, these findings indicate that the level of NALCN conductance within spino-PB neurons tightly governs ascending nociceptive transmission to the brain and thereby potentially influences pain perception.
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El Hachmane MF, Olofsson CS. A mechanically activated TRPC1-like current in white adipocytes. Biochem Biophys Res Commun 2018. [PMID: 29524421 DOI: 10.1016/j.bbrc.2018.03.050] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ca2+ impacts a large array of cellular processes in every known cell type. In the white adipocyte, Ca2+ is involved in regulation of metabolic processes such as lipolysis, glucose uptake and hormone secretion. Although the importance of Ca2+ in control of white adipocyte function is clear, knowledge is still lacking regarding the control of dynamic Ca2+ alterations within adipocytes and mechanisms inducing intracellular Ca2+ changes remain elusive. Own work has recently demonstrated the existence of store-operated Ca2+ entry (SOCE) in lipid filled adipocytes. We defined stromal interaction molecule 1 (STIM1) and the calcium release-activated calcium channel protein 1 (ORAI1) as the key players involved in this process and we showed that the transient receptor potential (TRP) channel TRPC1 contributed to SOCE. Here we have aimed to further characterised SOCE in the white adipocyte by use of single cell whole-cell patch clamp recordings. The electrophysiological measurements show the existence of a seemingly constitutively active current that is inhibited by known store-operated Ca2+ channel (SOCC) blockers. We demonstrate that the mechanical force applied to the plasma membrane upon patching leads to an elevation of the cytoplasmic Ca2+ concentration and that this elevation can be reversed by SOCC antagonists. We conclude that a mechanically activated current with properties similar to TRPC1 is present in white adipocytes. Activation of TRPC1 by membrane tension/stretch may be specifically important for the function of this cell type, since adipocytes can rapidly increase or decrease in size.
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Affiliation(s)
- Mickaël F El Hachmane
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 11, SE-405 30, Göteborg, Sweden
| | - Charlotta S Olofsson
- Department of Physiology/Metabolic Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Medicinaregatan 11, SE-405 30, Göteborg, Sweden.
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Song Z, Ye Y, Zhang Z, Shen J, Hu Z, Wang Z, Zheng J. Noninvasive, targeted gene therapy for acute spinal cord injury using LIFU-mediated BDNF-loaded cationic nanobubble destruction. Biochem Biophys Res Commun 2018; 496:911-920. [PMID: 29360450 DOI: 10.1016/j.bbrc.2018.01.123] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 01/19/2018] [Indexed: 12/21/2022]
Abstract
Various gene delivery systems have been widely studied for the acute spinal cord injury (SCI) treatment. In the present study, a novel type of brain-derived neurotrophic factor (BDNF)-loaded cationic nanobubbles (CNBs) conjugated with MAP-2 antibody (mAbMAP-2/BDNF/CNBs) was prepared to provide low-intensity focused ultrasound (LIFU)-targeted gene therapy. In vitro experiments, the ultrasound-targeted tranfection to BDNF overexpressioin in neurons and efficiently inhibition neuronal apoptosis have been demonstrated, and the elaborately designed mAbMAP-2/BDNF/CNBs can specifically target to the neurons. Furthermore, in a acute SCI rat model, LIFU-mediated mAbMAP-2/BDNF/CNBs transfection significantly increased BDNF expression, attenuated histological injury, decreased neurons loss, inhibited neuronal apoptosis in injured spinal cords, and increased BBB scores in SCI rats. LIFU-mediated mAbMAP-2/BDNF/CNBs destruction significantly increase transfection efficiency of BDNF gene both in vitro and in vivo, and has a significant neuroprotective effect on the injured spinal cord. Therefore, the combination of LIFU irradiation and gene therapy through mAbMAP-2/BDNF/CNBs can be considered as a novel non-invasive and targeted treatment for gene therapy of SCI.
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Affiliation(s)
- Zhaojun Song
- Department of Orthopaedics, Suining Central Hospital, Sichuan, People's Republic of China
| | - Yongjie Ye
- Department of Orthopaedics, Suining Central Hospital, Sichuan, People's Republic of China
| | - Zhi Zhang
- Department of Orthopaedics, Suining Central Hospital, Sichuan, People's Republic of China.
| | - Jieliang Shen
- Department of Orthopaedics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Zhenming Hu
- Department of Orthopaedics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Zhigang Wang
- Institution of Ultrasound Imaging, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, People's Republic of China
| | - Jiazhuang Zheng
- Department of Orthopaedics, Suining Central Hospital, Sichuan, People's Republic of China
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Andrzejewska A, Nowakowski A, Janowski M, Bulte JWM, Gilad AA, Walczak P, Lukomska B. Pre- and postmortem imaging of transplanted cells. Int J Nanomedicine 2015; 10:5543-59. [PMID: 26366076 PMCID: PMC4562754 DOI: 10.2147/ijn.s83557] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Therapeutic interventions based on the transplantation of stem and progenitor cells have garnered increasing interest. This interest is fueled by successful preclinical studies for indications in many diseases, including the cardiovascular, central nervous, and musculoskeletal system. Further progress in this field is contingent upon access to techniques that facilitate an unambiguous identification and characterization of grafted cells. Such methods are invaluable for optimization of cell delivery, improvement of cell survival, and assessment of the functional integration of grafted cells. Following is a focused overview of the currently available cell detection and tracking methodologies that covers the entire spectrum from pre- to postmortem cell identification.
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Affiliation(s)
- Anna Andrzejewska
- NeuroRepair Department, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Adam Nowakowski
- NeuroRepair Department, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Miroslaw Janowski
- NeuroRepair Department, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
- Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
- RusselI H Morgan Department of Radiology and Radiological Science, Division of Magnetic Resonance Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jeff WM Bulte
- RusselI H Morgan Department of Radiology and Radiological Science, Division of Magnetic Resonance Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Chemical & Biomolecular Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Assaf A Gilad
- RusselI H Morgan Department of Radiology and Radiological Science, Division of Magnetic Resonance Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Piotr Walczak
- RusselI H Morgan Department of Radiology and Radiological Science, Division of Magnetic Resonance Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Radiology, Faculty of Medical Sciences, University of Warmia and Mazury, Olsztyn, Poland
| | - Barbara Lukomska
- NeuroRepair Department, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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Ishibashi H, Yamaguchi J, Nakahata Y, Nabekura J. Dynamic regulation of glycine-GABA co-transmission at spinal inhibitory synapses by neuronal glutamate transporter. J Physiol 2013; 591:3821-32. [PMID: 23690564 DOI: 10.1113/jphysiol.2012.250647] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Fast inhibitory neurotransmission in the central nervous system is mediated by γ-aminobutyric acid (GABA) and glycine, which are accumulated into synaptic vesicles by a common vesicular inhibitory amino acid transporter (VIAAT) and are then co-released. However, the mechanisms that control the packaging of GABA + glycine into synaptic vesicles are not fully understood. In this study, we demonstrate the dynamic control of the GABA-glycine co-transmission by the neuronal glutamate transporter, using paired whole-cell patch recording from monosynaptically coupled cultured spinal cord neurons derived from VIAAT-Venus transgenic rats. Short step depolarization of presynaptic neurons evoked unitary (cell-to-cell) inhibitory postsynaptic currents (IPSCs). Under normal conditions, the fractional contribution of postsynaptic GABA or glycine receptors to the unitary IPSCs did not change during a 1 h recording. Intracellular loading of GABA or glycine via a patch pipette enhanced the respective components of inhibitory transmission, indicating the importance of the cytoplasmic concentration of inhibitory transmitters. Raised extracellular glutamate levels increased the amplitude of GABAergic IPSCs but reduced glycine release by enhancing glutamate uptake. Similar effects were observed when presynaptic neurons were intracellularly perfused with glutamate. Interestingly, high-frequency trains of stimulation decreased glycinergic IPSCs more than GABAergic IPSCs, and repetitive stimulation occasionally failed to evoke glycinergic but not GABAergic IPSCs. The present results suggest that the enhancement of GABA release by glutamate uptake may be advantageous for rapid vesicular refilling of the inhibitory transmitter at mixed GABA/glycinergic synapses and thus may help prevent hyperexcitability.
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Affiliation(s)
- Hitoshi Ishibashi
- Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, 444-8585, Japan
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Xu C, Mu L, Roes I, Miranda-Nieves D, Nahrendorf M, Ankrum JA, Zhao W, Karp JM. Nanoparticle-based monitoring of cell therapy. NANOTECHNOLOGY 2011; 22:494001. [PMID: 22101191 PMCID: PMC3334527 DOI: 10.1088/0957-4484/22/49/494001] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Exogenous cell therapy aims to replace/repair diseased or dysfunctional cells and promises to revolutionize medicine by restoring tissue and organ function. To develop effective cell therapy, the location, distribution and long-term persistence of transplanted cells must be evaluated. Nanoparticle (NP) based imaging technologies have the potential to track transplanted cells non-invasively. Here we summarize the most recent advances in NP-based cell tracking with emphasis on (1) the design criteria for cell tracking NPs, (2) protocols for cell labeling, (3) a comparison of available imaging modalities and their corresponding contrast agents, (4) a summary of preclinical studies on NP-based cell tracking and finally (5) perspectives and future directions.
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Affiliation(s)
- Chenjie Xu
- Center for Regenerative Therapeutics and Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard Stem Cell Institute, Harvard-MIT, Division of Health Sciences and Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA
| | - Luye Mu
- Center for Regenerative Therapeutics and Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard Stem Cell Institute, Harvard-MIT, Division of Health Sciences and Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA
| | - Isaac Roes
- Center for Regenerative Therapeutics and Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard Stem Cell Institute, Harvard-MIT, Division of Health Sciences and Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA
| | - David Miranda-Nieves
- Center for Regenerative Therapeutics and Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard Stem Cell Institute, Harvard-MIT, Division of Health Sciences and Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA
| | - Matthias Nahrendorf
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA 02114, USA
| | - James A Ankrum
- Center for Regenerative Therapeutics and Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard Stem Cell Institute, Harvard-MIT, Division of Health Sciences and Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA
| | - Weian Zhao
- Center for Regenerative Therapeutics and Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard Stem Cell Institute, Harvard-MIT, Division of Health Sciences and Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA
| | - Jeffrey M Karp
- Center for Regenerative Therapeutics and Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard Stem Cell Institute, Harvard-MIT, Division of Health Sciences and Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA
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Nakahata Y, Miyamoto A, Watanabe M, Moorhouse AJ, Nabekura J, Ishibashi H. Depolarizing shift in the GABA-induced current reversal potential by lidocaine hydrochloride. Brain Res 2010; 1345:19-27. [PMID: 20580693 DOI: 10.1016/j.brainres.2010.05.052] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 05/06/2010] [Accepted: 05/16/2010] [Indexed: 11/23/2022]
Abstract
Lidocaine hydrochloride (LC-HCl) is widely used as a local anesthetic, while various adverse effects of LC-HCl, such as seizures have also been reported. Lidocaine is reported to inhibit various channels and receptors including GABA(A) receptors. Although the GABA(A) receptor-mediated response depends on Cl(-) equilibrium potential (E(Cl)), little is known about the effect of LC-HCl on E(Cl). In the present study, we investigated the effect of LC-HCl on GABA-induced currents in cultured rat hippocampal neurons with gramicidin-perforated patch-clamp recording which is known to keep the intracellular Cl(-) concentration intact. LC-HCl inhibited outward GABA-induced currents with depolarizing shift of the GABA reversal potential (E(GABA)). The LC-HCl-induced positive E(GABA) shift was not observed with conventional whole-cell patch-clamp method which cannot retain intact intracellular Cl(-) concentration. The LC-HCl action on E(GABA) was inhibited by either furosemide, a blocker of both Na(+)-K(+)-Cl(-) cotransporter (NKCC) and K(+)-Cl(-) cotransporter (KCC), or an increase in extracellular K(+) concentrations. Neither bumetanide, a specific inhibitor of NKCC, nor Na(+)-free external solution had any effect on the LC-HCl-induced E(GABA) shift. QX-314, a membrane impermeable lidocaine derivative, failed to shift E(GABA) to positive potential. Furthermore, LC-HCl caused a depolarizing shift of E(GABA) in cultured GT1-7 cells expressing KCC2 but failed to change E(GABA) in GT1-7 cells without expression of KCC2. These results suggest that the LC-HCl-induced positive E(GABA) shift is due to a blockade of KCC2. Together with the direct LC-HCl action to GABA(A) receptors, the positive E(GABA) shift induced by LC-HCl reduces the GABAergic inhibition in the central nervous system.
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Affiliation(s)
- Yoshihisa Nakahata
- Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Japan
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