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Beckers P, Lara O, Belo do Nascimento I, Desmet N, Massie A, Hermans E. Validation of a System xc– Functional Assay in Cultured Astrocytes and Nervous Tissue Samples. Front Cell Neurosci 2022; 15:815771. [PMID: 35095428 PMCID: PMC8793334 DOI: 10.3389/fncel.2021.815771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/24/2021] [Indexed: 11/13/2022] Open
Abstract
Disruption of the glutamatergic homeostasis is commonly observed in neurological diseases and has been frequently correlated with the altered expression and/or function of astrocytic high-affinity glutamate transporters. There is, however, a growing interest for the role of the cystine-glutamate exchanger system xc– in controlling glutamate transmission. This exchanger is predominantly expressed in glial cells, especially in microglia and astrocytes, and its dysregulation has been documented in diverse neurological conditions. While most studies have focused on measuring the expression of its specific subunit xCT by RT-qPCR or by Western blotting, the activity of this exchanger in tissue samples remains poorly examined. Indeed, the reported use of sulfur- and carbon-radiolabeled cystine in uptake assays shows several drawbacks related to its short radioactive half-life and its relatively high cost. We here report on the elaborate validation of a method using tritiated glutamate as a substrate for the reversed transport mediated by system xc–. The uptake assay was validated in primary cultured astrocytes, in transfected cells as well as in crude synaptosomes obtained from fresh nervous tissue samples. Working in buffers containing defined concentrations of Na+, allowed us to differentiate the glutamate uptake supported by system xc– or by high-affinity glutamate transporters, as confirmed by using selective pharmacological inhibitors. The specificity was further demonstrated in primary astrocyte cultures from transgenic mice lacking xCT or in cell lines where xCT expression was genetically induced or reduced. As such, this assay appears to be a robust and cost-efficient solution to investigate the activity of this exchanger in physiological and pathological conditions. It also provides a reliable tool for the screening and characterization of new system xc– inhibitors which have been frequently cited as valuable drugs for nervous disorders and cancer.
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Affiliation(s)
- Pauline Beckers
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Olaya Lara
- Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Ines Belo do Nascimento
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Nathalie Desmet
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Ann Massie
- Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Emmanuel Hermans
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
- *Correspondence: Emmanuel Hermans,
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Solymar M, Ivic I, Balasko M, Fulop BD, Toth G, Tamas A, Reman G, Koller A, Reglodi D. Pituitary adenylate cyclase-activating polypeptide ameliorates vascular dysfunction induced by hyperglycaemia. Diab Vasc Dis Res 2018; 15:277-285. [PMID: 29466879 DOI: 10.1177/1479164118757922] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Short-lasting hyperglycaemia occurs frequently in prediabetes and poorly controlled diabetes mellitus leading to vascular damage. Pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to play a protective role in vascular complications of diabetes; moreover, antioxidant effects of PACAP were also described. Therefore, we hypothesized that PACAP exerts protective effects in short-term hyperglycaemia-induced vascular dysfunctions. METHODS After short-term hyperglycaemia, acetylcholine-induced and sodium nitroprusside-induced vascular relaxation of mouse carotid arteries were tested with a myograph with or without the presence of PACAP or superoxide dismutase. Potential direct antioxidant superoxide-scavenging action of pituitary adenylate cyclase-activating peptide was tested with pyrogallol autoxidation assay; furthermore, the effect of pituitary adenylate cyclase-activating peptide or superoxide dismutase was investigated on hyperglycaemia-associated vascular markers. RESULTS PACAP administration resulted in reduced endothelial dysfunction after a 1-h hyperglycaemic episode. PACAP was able to restore acetylcholine-induced relaxation of the vessels and improved sodium nitroprusside-induced relaxation. This effect was comparable to the protective effect of superoxide dismutase, but PACAP was unable to directly scavenge superoxide produced by autoxidation of pyrogallol. Endothelial dysfunction was associated with elevated levels of fibroblast growth factor basic, matrix metalloproteinase 9 and nephroblastoma overexpressed gene proteins. Their release was reduced by PACAP administration. CONCLUSION These results suggest a strong protective role of PACAP in the vascular complications of diabetes.
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Affiliation(s)
- Margit Solymar
- 1 Institute for Translational Medicine, Medical School, University of Pécs, Pécs, Hungary
| | - Ivan Ivic
- 2 Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, Medical School, University of Pécs, Pécs, Hungary
| | - Marta Balasko
- 1 Institute for Translational Medicine, Medical School, University of Pécs, Pécs, Hungary
| | - Balazs D Fulop
- 2 Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, Medical School, University of Pécs, Pécs, Hungary
| | - Gabor Toth
- 3 Department of Medical Chemistry, University of Szeged, Szeged, Hungary
| | - Andrea Tamas
- 2 Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, Medical School, University of Pécs, Pécs, Hungary
| | - Gyongyver Reman
- 2 Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, Medical School, University of Pécs, Pécs, Hungary
| | - Akos Koller
- 4 Department of Physiology, New York Medical College, Valhalla, NY, USA
- 5 Department of Neurosurgery, Medical School, University of Pécs, Pécs, Hungary
- 6 Institute of Natural Sciences, University of Physical Education, Budapest, Hungary
| | - Dora Reglodi
- 2 Department of Anatomy, MTA-PTE PACAP Research Team, Centre for Neuroscience, Medical School, University of Pécs, Pécs, Hungary
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3
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Hurley MM, Maunze B, Block ME, Frenkel MM, Reilly MJ, Kim E, Chen Y, Li Y, Baker DA, Liu QS, Choi S. Pituitary Adenylate-Cyclase Activating Polypeptide Regulates Hunger- and Palatability-Induced Binge Eating. Front Neurosci 2016; 10:383. [PMID: 27597817 PMCID: PMC4993128 DOI: 10.3389/fnins.2016.00383] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 08/05/2016] [Indexed: 11/13/2022] Open
Abstract
While pituitary adenylate cyclase activating polypeptide (PACAP) signaling in the hypothalamic ventromedial nuclei (VMN) has been shown to regulate feeding, a challenge in unmasking a role for this peptide in obesity is that excess feeding can involve numerous mechanisms including homeostatic (hunger) and hedonic-related (palatability) drives. In these studies, we first isolated distinct feeding drives by developing a novel model of binge behavior in which homeostatic-driven feeding was temporally separated from feeding driven by food palatability. We found that stimulation of the VMN, achieved by local microinjections of AMPA, decreased standard chow consumption in food-restricted rats (e.g., homeostatic feeding); surprisingly, this manipulation failed to alter palatable food consumption in satiated rats (e.g., hedonic feeding). In contrast, inhibition of the nucleus accumbens (NAc), through local microinjections of GABA receptor agonists baclofen and muscimol, decreased hedonic feeding without altering homeostatic feeding. PACAP microinjections produced the site-specific changes in synaptic transmission needed to decrease feeding via VMN or NAc circuitry. PACAP into the NAc mimicked the actions of GABA agonists by reducing hedonic feeding without altering homeostatic feeding. In contrast, PACAP into the VMN mimicked the actions of AMPA by decreasing homeostatic feeding without affecting hedonic feeding. Slice electrophysiology recordings verified PACAP excitation of VMN neurons and inhibition of NAc neurons. These data suggest that the VMN and NAc regulate distinct circuits giving rise to unique feeding drives, but that both can be regulated by the neuropeptide PACAP to potentially curb excessive eating stemming from either drive.
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Affiliation(s)
- Matthew M Hurley
- Department of Biomedical Sciences, Marquette University Milwaukee, WI, USA
| | - Brian Maunze
- Department of Biomedical Sciences, Marquette University Milwaukee, WI, USA
| | - Megan E Block
- Department of Biomedical Sciences, Marquette University Milwaukee, WI, USA
| | - Mogen M Frenkel
- Department of Biomedical Sciences, Marquette University Milwaukee, WI, USA
| | - Michael J Reilly
- Department of Biomedical Sciences, Marquette University Milwaukee, WI, USA
| | - Eugene Kim
- Department of Biomedical Sciences, Marquette University Milwaukee, WI, USA
| | - Yao Chen
- Department of Pharmacology and Toxicology, Medical College of Wisconsin Milwaukee, WI, USA
| | - Yan Li
- Department of Pharmacology and Toxicology, Medical College of Wisconsin Milwaukee, WI, USA
| | - David A Baker
- Department of Biomedical Sciences, Marquette University Milwaukee, WI, USA
| | - Qing-Song Liu
- Department of Pharmacology and Toxicology, Medical College of Wisconsin Milwaukee, WI, USA
| | - SuJean Choi
- Department of Biomedical Sciences, Marquette University Milwaukee, WI, USA
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Douiri S, Bahdoudi S, Hamdi Y, Cubì R, Basille M, Fournier A, Vaudry H, Tonon MC, Amri M, Vaudry D, Masmoudi-Kouki O. Involvement of endogenous antioxidant systems in the protective activity of pituitary adenylate cyclase-activating polypeptide against hydrogen peroxide-induced oxidative damages in cultured rat astrocytes. J Neurochem 2016; 137:913-30. [DOI: 10.1111/jnc.13614] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 02/09/2016] [Accepted: 02/24/2016] [Indexed: 02/04/2023]
Affiliation(s)
- Salma Douiri
- Laboratory of Functional Neurophysiology and Pathology; Research Unit UR/11ES09; Department of Biological Sciences; Faculty of Science of Tunis; University Tunis El Manar; Tunis Tunisia
| | - Seyma Bahdoudi
- Laboratory of Functional Neurophysiology and Pathology; Research Unit UR/11ES09; Department of Biological Sciences; Faculty of Science of Tunis; University Tunis El Manar; Tunis Tunisia
- Inserm U982; Laboratory of Neuronal and Neuroendocrine Communication and Differentiation; University of Rouen; Mont-Saint-Aignan France
| | - Yosra Hamdi
- Laboratory of Functional Neurophysiology and Pathology; Research Unit UR/11ES09; Department of Biological Sciences; Faculty of Science of Tunis; University Tunis El Manar; Tunis Tunisia
| | - Roger Cubì
- Inserm U982; Laboratory of Neuronal and Neuroendocrine Communication and Differentiation; University of Rouen; Mont-Saint-Aignan France
| | - Magali Basille
- Inserm U982; Laboratory of Neuronal and Neuroendocrine Communication and Differentiation; University of Rouen; Mont-Saint-Aignan France
- Regional Platform for Cell Imaging of Normandie (PRIMACEN); Institute for Biomedical Research and Innovation; University of Rouen; Mont-Saint-Aignan France
| | - Alain Fournier
- INRS - Institut Armand-Frappier; Laval Quebec Canada
- Laboratoire International Associé Samuel de Champlain; Institut Armand-Frappier; Laval Quebec Canada
- International Associated Laboratory Samuel de Champlain; University of Rouen; Mont-Saint-Aignan France
| | - Hubert Vaudry
- Inserm U982; Laboratory of Neuronal and Neuroendocrine Communication and Differentiation; University of Rouen; Mont-Saint-Aignan France
- Regional Platform for Cell Imaging of Normandie (PRIMACEN); Institute for Biomedical Research and Innovation; University of Rouen; Mont-Saint-Aignan France
- International Associated Laboratory Samuel de Champlain; University of Rouen; Mont-Saint-Aignan France
| | - Marie-Christine Tonon
- Inserm U982; Laboratory of Neuronal and Neuroendocrine Communication and Differentiation; University of Rouen; Mont-Saint-Aignan France
- Regional Platform for Cell Imaging of Normandie (PRIMACEN); Institute for Biomedical Research and Innovation; University of Rouen; Mont-Saint-Aignan France
| | - Mohamed Amri
- Laboratory of Functional Neurophysiology and Pathology; Research Unit UR/11ES09; Department of Biological Sciences; Faculty of Science of Tunis; University Tunis El Manar; Tunis Tunisia
| | - David Vaudry
- Inserm U982; Laboratory of Neuronal and Neuroendocrine Communication and Differentiation; University of Rouen; Mont-Saint-Aignan France
- Regional Platform for Cell Imaging of Normandie (PRIMACEN); Institute for Biomedical Research and Innovation; University of Rouen; Mont-Saint-Aignan France
- International Associated Laboratory Samuel de Champlain; University of Rouen; Mont-Saint-Aignan France
| | - Olfa Masmoudi-Kouki
- Laboratory of Functional Neurophysiology and Pathology; Research Unit UR/11ES09; Department of Biological Sciences; Faculty of Science of Tunis; University Tunis El Manar; Tunis Tunisia
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Kong L, Albano R, Madayag A, Raddatz N, Mantsch JR, Choi S, Lobner D, Baker DA. Pituitary Adenylate cyclase-activating polypeptide orchestrates neuronal regulation of the astrocytic glutamate-releasing mechanism system xc (.). J Neurochem 2016; 137:384-93. [PMID: 26851652 DOI: 10.1111/jnc.13566] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 01/28/2016] [Accepted: 02/01/2016] [Indexed: 12/26/2022]
Abstract
Glutamate signaling is achieved by an elaborate network involving neurons and astrocytes. Hence, it is critical to better understand how neurons and astrocytes interact to coordinate the cellular regulation of glutamate signaling. In these studies, we used rat cortical cell cultures to examine whether neurons or releasable neuronal factors were capable of regulating system xc (-) (Sxc), a glutamate-releasing mechanism that is expressed primarily by astrocytes and has been shown to regulate synaptic transmission. We found that astrocytes cultured with neurons or exposed to neuronal-conditioned media displayed significantly higher levels of Sxc activity. Next, we demonstrated that the pituitary adenylate cyclase-activating polypeptide (PACAP) may be a neuronal factor capable of regulating astrocytes. In support, we found that PACAP expression was restricted to neurons, and that PACAP receptors were expressed in astrocytes. Interestingly, blockade of PACAP receptors in cultures comprised of astrocytes and neurons significantly decreased Sxc activity to the level observed in purified astrocytes, whereas application of PACAP to purified astrocytes increased Sxc activity to the level observed in cultures comprised of neurons and astrocytes. Collectively, these data reveal that neurons coordinate the actions of glutamate-related mechanisms expressed by astrocytes, such as Sxc, a process that likely involves PACAP. A critical gap in modeling excitatory signaling is how distinct components of the glutamate system expressed by neurons and astrocytes are coordinated. In these studies, we found that system xc (-) (Sxc), a glutamate release mechanism expressed by astrocytes, is regulated by releasable neuronal factors including PACAP. This represents a novel form of neuron-astrocyte communication, and highlights the possibility that pathological changes involving astrocytic Sxc may stem from altered neuronal activity.
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Affiliation(s)
- Linghai Kong
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Rebecca Albano
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Aric Madayag
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Nicholas Raddatz
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - John R Mantsch
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - SuJean Choi
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Doug Lobner
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - David A Baker
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
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6
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Massie A, Boillée S, Hewett S, Knackstedt L, Lewerenz J. Main path and byways: non-vesicular glutamate release by system xc(-) as an important modifier of glutamatergic neurotransmission. J Neurochem 2015; 135:1062-79. [PMID: 26336934 DOI: 10.1111/jnc.13348] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 08/24/2015] [Accepted: 08/25/2015] [Indexed: 12/14/2022]
Abstract
System xc(-) is a cystine/glutamate antiporter that exchanges extracellular cystine for intracellular glutamate. Cystine is intracellularly reduced to cysteine, a building block of GSH. As such, system xc(-) can regulate the antioxidant capacity of cells. Moreover, in several brain regions, system xc(-) is the major source of extracellular glutamate. As such this antiporter is able to fulfill key physiological functions in the CNS, while evidence indicates it also plays a role in certain brain pathologies. Since the transcription of xCT, the specific subunit of system xc(-), is enhanced by the presence of reactive oxygen species and inflammatory cytokines, system xc(-) could be involved in toxic extracellular glutamate release in neurological disorders that are associated with increased oxidative stress and neuroinflammation. System xc(-) has also been reported to contribute to the invasiveness of brain tumors and, as a source of extracellular glutamate, could participate in the induction of peritumoral seizures. Two independent reviews (Pharmacol. Rev. 64, 2012, 780; Antioxid. Redox Signal. 18, 2013, 522), approached from a different perspective, have recently been published on the functions of system xc(-) in the CNS. In this review, we highlight novel achievements and insights covering the regulation of system xc(-) as well as its involvement in emotional behavior, cognition, addiction, neurological disorders and glioblastomas, acquired in the past few years. System xc(-) constitutes an important source of extrasynaptic glutamate in the brain. By modulating the tone of extrasynaptic metabotropic or ionotropic glutamate receptors, it affects excitatory neurotransmission, the threshold for overexcitation and excitotoxicity and, as a consequence, behavior. This review describes the current knowledge of how system xc(-) is regulated and involved in physiological as well as pathophysiological brain functioning.
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Affiliation(s)
- Ann Massie
- Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Séverine Boillée
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - Sandra Hewett
- Department of Biology, Program in Neuroscience, Syracuse University, Syracuse, New York, USA
| | - Lori Knackstedt
- Psychology Department, University of Florida, Gainesville, Florida, USA
| | - Jan Lewerenz
- Department of Neurology, Ulm University, Oberer Eselsberg 45, Ulm, Germany
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Schmidt S, Myskiw J, Furini C, Schmidt B, Cavalcante L, Izquierdo I. PACAP modulates the consolidation and extinction of the contextual fear conditioning through NMDA receptors. Neurobiol Learn Mem 2015; 118:120-4. [DOI: 10.1016/j.nlm.2014.11.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 11/24/2014] [Accepted: 11/27/2014] [Indexed: 01/07/2023]
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