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P2X7 receptors in the central nervous system. Biochem Pharmacol 2021; 187:114472. [PMID: 33587917 DOI: 10.1016/j.bcp.2021.114472] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 02/07/2023]
Abstract
For the past three decades, our laboratory has conducted pioneering research to elucidate the complexity of purinergic signaling in the CNS, alone and in collaboration with other groups, inspired by the ground-breaking efforts of Geoffrey Burnstock. This review summarizes our contribution to understand the nucleotide receptor signaling in the CNS with a special focus on the P2X7 receptor.
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Martínez-Cuesta MÁ, Blanch-Ruiz MA, Ortega-Luna R, Sánchez-López A, Álvarez Á. Structural and Functional Basis for Understanding the Biological Significance of P2X7 Receptor. Int J Mol Sci 2020; 21:ijms21228454. [PMID: 33182829 PMCID: PMC7696479 DOI: 10.3390/ijms21228454] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/04/2020] [Accepted: 11/06/2020] [Indexed: 12/11/2022] Open
Abstract
The P2X7 receptor (P2X7R) possesses a unique structure associated to an as yet not fully understood mechanism of action that facilitates cell permeability to large ionic molecules through the receptor itself and/or nearby membrane proteins. High extracellular adenosine triphosphate (ATP) levels—inexistent in physiological conditions—are required for the receptor to be triggered and contribute to its role in cell damage signaling. The inconsistent data on its activation pathways and the few studies performed in natively expressed human P2X7R have led us to review the structure, activation pathways, and specific cellular location of P2X7R in order to analyze its biological relevance. The ATP-gated P2X7R is a homo-trimeric receptor channel that is occasionally hetero-trimeric and highly polymorphic, with at least nine human splice variants. It is localized predominantly in the cellular membrane and has a characteristic plasticity due to an extended C-termini, which confers it the capacity of interacting with membrane structural compounds and/or intracellular signaling messengers to mediate flexible transduction pathways. Diverse drugs and a few endogenous molecules have been highlighted as extracellular allosteric modulators of P2X7R. Therefore, studies in human cells that constitutively express P2X7R need to investigate the precise endogenous mediator located nearby the activation/modulation domains of the receptor. Such research could help us understand the possible physiological ATP-mediated P2X7R homeostasis signaling.
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Affiliation(s)
- María Ángeles Martínez-Cuesta
- Departamento de Farmacología, Facultad de Medicina y Odontología, Universidad de Valencia, 46010 Valencia, Spain; (M.A.B.-R.); (R.O.-L.); (A.S.-L.)
- CIBERehd, Valencia, Spain
- Correspondence: (M.Á.M.-C.); (Á.Á.); Tel.: +34-963983716 (M.Á.M.-C.); +34-963864898 (Á.Á.)
| | - María Amparo Blanch-Ruiz
- Departamento de Farmacología, Facultad de Medicina y Odontología, Universidad de Valencia, 46010 Valencia, Spain; (M.A.B.-R.); (R.O.-L.); (A.S.-L.)
| | - Raquel Ortega-Luna
- Departamento de Farmacología, Facultad de Medicina y Odontología, Universidad de Valencia, 46010 Valencia, Spain; (M.A.B.-R.); (R.O.-L.); (A.S.-L.)
| | - Ainhoa Sánchez-López
- Departamento de Farmacología, Facultad de Medicina y Odontología, Universidad de Valencia, 46010 Valencia, Spain; (M.A.B.-R.); (R.O.-L.); (A.S.-L.)
| | - Ángeles Álvarez
- Departamento de Farmacología, Facultad de Medicina y Odontología, Universidad de Valencia, 46010 Valencia, Spain; (M.A.B.-R.); (R.O.-L.); (A.S.-L.)
- CIBERehd, Valencia, Spain
- Correspondence: (M.Á.M.-C.); (Á.Á.); Tel.: +34-963983716 (M.Á.M.-C.); +34-963864898 (Á.Á.)
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Miteva A, Gaydukov A, Balezina O. Interaction between Calcium Chelators and the Activity of P2X7 Receptors in Mouse Motor Synapses. Int J Mol Sci 2020; 21:ijms21062034. [PMID: 32188153 PMCID: PMC7139400 DOI: 10.3390/ijms21062034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/12/2020] [Accepted: 03/15/2020] [Indexed: 11/19/2022] Open
Abstract
The ability of P2X7 receptors to potentiate rhythmically evoked acetylcholine (ACh) release through Ca2+ entry via P2X7 receptors and via L-type voltage-dependent Ca2+ channels (VDCCs) was compared by loading Ca2+ chelators into motor nerve terminals. Neuromuscular preparations of the diaphragms of wild-type (WT) mice and pannexin-1 knockout (Panx1−/−) mice, in which ACh release is potentiated by the disinhibition of the L-type VDCCs upon the activation of P2X7 receptors, were used. Miniature end-plate potentials (MEPPs) and evoked end-plate potentials (EPPs) were recorded when the motor terminals were loaded with slow or fast Ca2+ chelators (EGTA-AM or BAPTA-AM, respectively, 50 μM). In WT and Panx1−/− mice, EGTA-AM did not change either spontaneous or evoked ACh release, while BAPTA-AM inhibited synaptic transmission by suppressing the quantal content of EPPs throughout the course of the short rhythmic train (50 Hz, 1 s). In the motor synapses of either WT or Panx1−/− mice in the presence of BAPTA-AM, the activation of P2X7 receptors by BzATP (30 μM) returned the EPP quantal content to the control level. In the neuromuscular junctions (NMJs) of Panx1−/− mice, EGTA-AM completely prevented the BzATP-induced increase in EPP quantal content. After Panx1−/− NMJs were treated with BAPTA-AM, BzATP lost its ability to enhance the EPP quantal content to above the control level. Nitrendipine (1 μM), an inhibitor of L-type VDCCs, was unable to prevent this BzATP-induced enhancement of EPP quantal content to the control level. We propose that the activation of P2X7 receptors may provide additional Ca2+ entry into motor nerve terminals, which, independent of the modulation of L-type VDCC activity, can partially reduce the buffering capacity of Ca2+ chelators, thereby providing sufficient Ca2+ signals for ACh secretion at the control level. However, the activity of both Ca2+ chelators was sufficient to eliminate Ca2+ entry via L-type VDCCs activated by P2X7 receptors and increase the EPP quantal content in the NMJs of Panx1−/− mice to above the control level.
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Ni CM, Sun HP, Xu X, Ling BY, Jin H, Zhang YQ, Zhao ZQ, Cao H, Xu L. Spinal P2X7R contributes to streptozotocin-induced mechanical allodynia in mice. J Zhejiang Univ Sci B 2020; 21:155-165. [PMID: 32115912 DOI: 10.1631/jzus.b1900456] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Painful diabetic neuropathy (PDN) is a diabetes mellitus complication. Unfortunately, the mechanisms underlying PDN are still poorly understood. Adenosine triphosphate (ATP)-gated P2X7 receptor (P2X7R) plays a pivotal role in non-diabetic neuropathic pain, but little is known about its effects on streptozotocin (STZ)-induced peripheral neuropathy. Here, we explored whether spinal cord P2X7R was correlated with the generation of mechanical allodynia (MA) in STZ-induced type 1 diabetic neuropathy in mice. MA was assessed by measuring paw withdrawal thresholds and western blotting. Immunohistochemistry was applied to analyze the protein expression levels and localization of P2X7R. STZ-induced mice expressed increased P2X7R in the dorsal horn of the lumbar spinal cord during MA. Mice injected intrathecally with a selective antagonist of P2X7R and P2X7R knockout (KO) mice both presented attenuated progression of MA. Double-immunofluorescent labeling demonstrated that P2X7R-positive cells were mostly co-expressed with Iba1 (a microglia marker). Our results suggest that P2X7R plays an important role in the development of MA and could be used as a cellular target for treating PDN.
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Affiliation(s)
- Cheng-Ming Ni
- Department of Endocrinology, the Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi 214023, China
| | - He-Ping Sun
- Department of Endocrinology, the Affiliated Kunshan First People's Hospital of Jiangsu University, Kunshan 215300, China
| | - Xiang Xu
- Department of Endocrinology, the Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi 214023, China
| | - Bing-Yu Ling
- Department of Emergency, Northern Jiangsu People's Hospital, Yangzhou University, Yangzhou 225001, China
| | - Hui Jin
- Department of Endocrinology, the Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi 214023, China
| | - Yu-Qiu Zhang
- Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Zhi-Qi Zhao
- Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Hong Cao
- Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Lan Xu
- Department of Endocrinology, the Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi 214023, China
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Zhu G, Dai B, Chen Z, He L, Guo J, Dan Y, Liang S, Li G. Effects of chronic lead exposure on the sympathoexcitatory response associated with the P2X7 receptor in rat superior cervical ganglia. Auton Neurosci 2019; 219:33-41. [DOI: 10.1016/j.autneu.2019.03.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 02/01/2019] [Accepted: 03/20/2019] [Indexed: 12/23/2022]
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Mechanism of P2X7 receptor-dependent enhancement of neuromuscular transmission in pannexin 1 knockout mice. Purinergic Signal 2018; 14:459-469. [PMID: 30362043 DOI: 10.1007/s11302-018-9630-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 10/02/2018] [Indexed: 01/15/2023] Open
Abstract
P2X7 receptors are present in presynaptic membranes of motor synapses, but their regulatory role in modulation of neurotransmitter release remains poorly understood. P2X7 receptors may interact with pannexin 1 channels to form a purinergic signaling unit. The potential mechanism of P2X7 receptor-dependent modulation of acetylcholine (ACh) release was investigated by recording miniature endplate potentials (MEPPs) and evoked endplate potentials (EPPs) in neuromuscular junctions of wild-type (WT) and pannexin 1 knockout (Panx1-/-) mice. Modulation of P2X7 receptors with the selective inhibitor A740003 or the selective agonist BzATP did not alter the parameters of either spontaneous or evoked ACh release in WT mice. In Panx1-/- mice, BzATP-induced activation of P2X7 receptors resulted in a uniformly increased quantal content of EPPs during a short stimulation train. This effect was accompanied by an increase in the size of the readily releasable pool, while the release probability did not change. Inhibition of calmodulin by W-7 or of calcium/calmodulin-dependent kinase II (CaMKII) by KN-93 completely prevented the potentiating effect of BzATP on the EPP quantal content. The blockade of L-type calcium channels also prevented BzATP action on evoked synaptic activity. Thus, the activation of presynaptic P2X7 receptors in mice lacking pannexin 1 resulted in enhanced evoked ACh release. Such enhanced release was provoked by triggering the calmodulin- and CaMKII-dependent signaling pathway, followed by activation of presynaptic L-type calcium channels. We suggest that in WT mice, this pathway is downregulated due to pannexin 1-dependent tonic activation of inhibitory presynaptic purinergic receptors, which overcomes P2X7-mediated effects.
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Menéndez-Méndez A, Díaz-Hernández JI, Ortega F, Gualix J, Gómez-Villafuertes R, Miras-Portugal MT. Specific Temporal Distribution and Subcellular Localization of a Functional Vesicular Nucleotide Transporter (VNUT) in Cerebellar Granule Neurons. Front Pharmacol 2017; 8:951. [PMID: 29311945 PMCID: PMC5744399 DOI: 10.3389/fphar.2017.00951] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 12/15/2017] [Indexed: 12/14/2022] Open
Abstract
Adenosine triphosphate (ATP) is an important extracellular neurotransmitter that participates in several critical processes like cell differentiation, neuroprotection or axon guidance. Prior to its exocytosis, ATP must be stored in secretory vesicles, a process that is mediated by the Vesicular Nucleotide Transporter (VNUT). This transporter has been identified as the product of the SLC17A9 gene and it is prominently expressed in discrete brain areas, including the cerebellum. The main population of cerebellar neurons, the glutamatergic granule neurons, depends on purinergic signaling to trigger neuroprotective responses. However, while nucleotide receptors like P2X7 and P2Y13 are known to be involved in neuroprotection, the mechanisms that regulate ATP release in relation to such events are less clearly understood. In this work, we demonstrate that cerebellar granule cells express a functional VNUT that is involved in the regulation of ATP exocytosis. Numerous vesicles loaded with this nucleotide can be detected in these granule cells and are staining by the fluorescent ATP-marker, quinacrine. High potassium stimulation reduces quinacrine fluorescence in granule cells, indicating they release ATP via calcium dependent exocytosis. Specific subcellular markers were used to assess the localization of VNUT in granule cells, and the transporter was detected in both the axonal and somatodendritic compartments, most predominantly in the latter. However, co-localization with the specific lysosomal marker LAMP-1 indicated that VNUT can also be found in non-synaptic vesicles, such as lysosomes. Interestingly, the weak co-localization between VNUT and VGLUT1 suggests that the ATP and glutamate vesicle pools are segregated, as also observed in the cerebellar cortex. During post-natal cerebellar development, VNUT is found in granule cell precursors, co-localizing with markers of immature cells like doublecortin, suggesting that this transporter may be implicated in the initial stages of granule cell development.
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Affiliation(s)
- Aida Menéndez-Méndez
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain.,University Institute of Neurochemistry Research (IUIN), Complutense University of Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
| | - Juan I Díaz-Hernández
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain.,University Institute of Neurochemistry Research (IUIN), Complutense University of Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
| | - Felipe Ortega
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain.,University Institute of Neurochemistry Research (IUIN), Complutense University of Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
| | - Javier Gualix
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain.,University Institute of Neurochemistry Research (IUIN), Complutense University of Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
| | - Rosa Gómez-Villafuertes
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain.,University Institute of Neurochemistry Research (IUIN), Complutense University of Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
| | - María T Miras-Portugal
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain.,University Institute of Neurochemistry Research (IUIN), Complutense University of Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
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Neuronal P2X7 Receptor: Involvement in Neuronal Physiology and Pathology. J Neurosci 2017; 37:7063-7072. [PMID: 28747389 DOI: 10.1523/jneurosci.3104-16.2017] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 05/12/2017] [Accepted: 05/16/2017] [Indexed: 12/28/2022] Open
Abstract
The proposed presence of P2X7 receptor (P2X7R) in neurons has been the source of some contention. Initial studies suggested an absence of P2X7R mRNA in neurons, and the apparent nonspecificity of the antibodies used to identify P2X7R raised further doubts. However, subsequent studies using new pharmacological and biomolecular tools provided conclusive evidence supporting the existence of functional P2X7Rs in neurons. The P2X7 receptor has since been shown to play a leading role in multiple aspects of neuronal physiology, including axonal elongation and branching and neurotransmitter release. P2X7R has also been implicated in neuronal pathologies, in which it may influence neuronal survival. Together, this body of research suggests that P2X7R may constitute an important therapeutic target for a variety of neurological disorders.
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Abstract
The P2X7 receptor is a trimeric ion channel gated by extracellular adenosine 5'-triphosphate. The receptor is present on an increasing number of different cells types including stem, blood, glial, neural, ocular, bone, dental, exocrine, endothelial, muscle, renal and skin cells. The P2X7 receptor induces various downstream events in a cell-specific manner, including inflammatory molecule release, cell proliferation and death, metabolic events, and phagocytosis. As such this receptor plays important roles in heath and disease. Increasing knowledge about the P2X7 receptor has been gained from studies of, but not limited to, protein chemistry including cloning, site-directed mutagenesis, crystal structures and atomic modeling, as well as from studies of primary tissues and transgenic mice. This chapter focuses on the P2X7 receptor itself. This includes the P2RX7 gene and its products including splice and polymorphic variants. This chapter also reviews modulators of P2X7 receptor activation and inhibition, as well as the transcriptional regulation of the P2RX7 gene via its promoter and enhancer regions, and by microRNA and long-coding RNA. Furthermore, this chapter discusses the post-translational modification of the P2X7 receptor by N-linked glycosylation, adenosine 5'-diphosphate ribosylation and palmitoylation. Finally, this chapter reviews interaction partners of the P2X7 receptor, and its cellular localisation and trafficking within cells.
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Affiliation(s)
- Ronald Sluyter
- School of Biological Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
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Signaling pathways underlying the antidepressant-like effect of inosine in mice. Purinergic Signal 2016; 13:203-214. [PMID: 27966087 DOI: 10.1007/s11302-016-9551-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/01/2016] [Indexed: 12/15/2022] Open
Abstract
Inosine is a purine nucleoside formed by the breakdown of adenosine that elicits an antidepressant-like effect in mice through activation of adenosine A1 and A2A receptors. However, the signaling pathways underlying this effect are largely unknown. To address this issue, the present study investigated the influence of extracellular-regulated protein kinase (ERK)1/2, Ca2+/calmoduline-dependent protein kinase (CaMKII), protein kinase A (PKA), phosphoinositide 3-kinase (PI3K)/Akt, and glycogen synthase kinase 3beta (GSK-3β) modulation in the antiimmobility effect of inosine in the tail suspension test (TST) in mice. In addition, we attempted to verify if inosine treatment was capable of altering the immunocontent and phosphorylation of the transcription factor cyclic adenosine monophosphatate (cAMP) response-binding element protein (CREB) in mouse prefrontal cortex and hippocampus. Intracerebroventricular administration of U0126 (5 μg/mouse, MEK1/2 inhibitor), KN-62 (1 μg/mouse, CaMKII inhibitor), H-89 (1 μg/mouse, PKA inhibitor), and wortmannin (0.1 μg/mouse, PI3K inhibitor) prevented the antiimmobility effect of inosine (10 mg/kg, intraperitoneal (i.p.)) in the TST. Also, administration of a sub-effective dose of inosine (0.1 mg/kg, i.p.) in combination with a sub-effective dose of AR-A014418 (0.001 μg/mouse, GSK-3β inhibitor) induced a synergic antidepressant-like effect. None of the treatments altered locomotor activity of mice. Moreover, 24 h after a single administration of inosine (10 mg/kg, i.p.), CREB phosphorylation was increased in the hippocampus. Our findings provided new evidence that the antidepressant-like effect of inosine in the TST involves the activation of PKA, PI3K/Akt, ERK1/2, and CaMKII and the inhibition of GSK-3β. These results contribute to the comprehension of the mechanisms underlying the purinergic system modulation and indicate the intracellular signaling pathways involved in the antidepressant-like effect of inosine in a preclinical test of depression.
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Cao S, Xiao Z, Sun M, Li Y. D-serine in the midbrain periaqueductal gray contributes to morphine tolerance in rats. Mol Pain 2016; 12:12/0/1744806916646786. [PMID: 27175014 PMCID: PMC4956000 DOI: 10.1177/1744806916646786] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Accepted: 04/04/2016] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The N-methyl-D-aspartate subtype of glutamate receptor plays a critical role in morphine tolerance. D-serine, a co-agonist of N-methyl-D-aspartate receptor, participates in many physiological and pathophysiological processes via regulating N-methyl-D-aspartate receptor activation. The purinergic P2X7 receptor activation can induce the D-serine release in the central nervous system. This study aimed to investigate the role of the ventrolateral midbrain periaqueductal gray D-serine in the mechanism of morphine tolerance in rats. The development of morphine tolerance was induced in normal adult male Sprague-Dawley rats through subcutaneous injection of morphine (10 mg/kg). The analgesic effect of morphine (5 mg/kg, i.p.) was assessed by measuring mechanical withdrawal thresholds in rats with an electronic von Frey anesthesiometer. The D-serine concentration and serine racemase expression levels in the ventrolateral midbrain periaqueductal gray were evaluated through enzyme-linked immunosorbent assay and Western blot analysis, respectively. The effects of intra-ventrolateral midbrain periaqueductal gray injections of the D-serine degrading enzyme D-amino acid oxidase and antisense oligodeoxynucleotide targeting the P2X7 receptor on chronic morphine-treated rats were also explored. RESULTS We found that repeated morphine administrations decreased the antinociceptive potency of morphine evidenced by the percent changes in mechanical pain threshold in rats. By contrast, the D-serine contents and the expression levels of the serine racemase protein were upregulated in the ventrolateral midbrain periaqueductal gray in morphine-tolerant rats. The development of morphine tolerance was markedly alleviated by intra-ventrolateral midbrain periaqueductal gray injections of D-amino acid oxidase or antisense oligodeoxynucleotide targeting the P2X7 receptor. CONCLUSIONS Our data indicate that the development of antinociceptive tolerance to morphine is partially mediated by ventrolateral midbrain periaqueductal gray D-serine content, and the activation of the ventrolateral midbrain periaqueductal gray P2X7 receptor is an essential prelude to D-serine release. These results suggest that a cascade involving P2X7 receptor-D-serine-N-methyl-D-aspartate receptor mediated signaling pathway in the supraspinal mechanism of morphine tolerance.
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Affiliation(s)
- Song Cao
- Department of Pain Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Zunyi, Guizhou, China
| | - Zhi Xiao
- Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Mengjie Sun
- Graduate School, Zunyi Medical University, Zunyi, Guizhou, China
| | - Youyan Li
- Graduate School, Zunyi Medical University, Zunyi, Guizhou, China
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12
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Mittal R, Chan B, Grati M, Mittal J, Patel K, Debs LH, Patel AP, Yan D, Chapagain P, Liu XZ. Molecular Structure and Regulation of P2X Receptors With a Special Emphasis on the Role of P2X2 in the Auditory System. J Cell Physiol 2015; 231:1656-70. [PMID: 26627116 DOI: 10.1002/jcp.25274] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 12/01/2015] [Indexed: 12/23/2022]
Abstract
The P2X purinergic receptors are cation-selective channels gated by extracellular adenosine 5'-triphosphate (ATP). These purinergic receptors are found in virtually all mammalian cell types and facilitate a number of important physiological processes. Within the past few years, the characterization of crystal structures of the zebrafish P2X4 receptor in its closed and open states has provided critical insights into the mechanisms of ligand binding and channel activation. Understanding of this gating mechanism has facilitated to design and interpret new modeling and structure-function experiments to better elucidate how different agonists and antagonists can affect the receptor with differing levels of potency. This review summarizes the current knowledge on the structure, activation, allosteric modulators, function, and location of the different P2X receptors. Moreover, an emphasis on the P2X2 receptors has been placed in respect to its role in the auditory system. In particular, the discovery of three missense mutations in P2X2 receptors could become important areas of study in the field of gene therapy to treat progressive and noise-induced hearing loss. J. Cell. Physiol. 231: 1656-1670, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Rahul Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Brandon Chan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - M'hamed Grati
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Jeenu Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Kunal Patel
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Luca H Debs
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Amit P Patel
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Prem Chapagain
- Department of Physics, Florida International University, Miami, Florida.,Biomolecular Science Institute, Florida International University, Miami, Florida
| | - Xue Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida.,Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida.,Department of Biochemistry, University of Miami Miller School of Medicine, Miami, Florida
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13
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Miras-Portugal MT, Gomez-Villafuertes R, Gualix J, Diaz-Hernandez JI, Artalejo AR, Ortega F, Delicado EG, Perez-Sen R. Nucleotides in neuroregeneration and neuroprotection. Neuropharmacology 2015; 104:243-54. [PMID: 26359530 DOI: 10.1016/j.neuropharm.2015.09.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/01/2015] [Accepted: 09/02/2015] [Indexed: 02/03/2023]
Abstract
Brain injury generates the release of a multitude of factors including extracellular nucleotides, which exhibit bi-functional properties and contribute to both detrimental actions in the acute phase and also protective and reparative actions in the later recovery phase to allow neuroregeneration. A promising strategy toward restoration of neuronal function is based on activation of endogenous adult neural stem/progenitor cells. The implication of purinergic signaling in stem cell biology, including regulation of proliferation, differentiation, and cell death has become evident in the last decade. In this regard, current strategies of acute transplantation of ependymal stem/progenitor cells after spinal cord injury restore altered expression of P2X4 and P2X7 receptors and improve functional locomotor recovery. The expression of both receptors is transcriptionally regulated by Sp1 factor, which plays a key role in the startup of the transcription machinery to induce regeneration-associated genes expression. Finally, general signaling pathways triggered by nucleotide receptors in neuronal populations converge on several intracellular kinases, such as PI3K/Akt, GSK3 and ERK1,2, as well as the Nrf-2/heme oxigenase-1 axis, which specifically link them to neuroprotection. In this regard, regulation of dual specificity protein phosphatases can become novel mechanism of actions for nucleotide receptors that associate them to cell homeostasis regulation. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Affiliation(s)
- M Teresa Miras-Portugal
- Department of Biochemistry and Molecular Biology IV, Veterinary School, Universidad Complutense of Madrid, 28040 Madrid, Spain
| | - Rosa Gomez-Villafuertes
- Department of Biochemistry and Molecular Biology IV, Veterinary School, Universidad Complutense of Madrid, 28040 Madrid, Spain.
| | - Javier Gualix
- Department of Biochemistry and Molecular Biology IV, Veterinary School, Universidad Complutense of Madrid, 28040 Madrid, Spain
| | - Juan Ignacio Diaz-Hernandez
- Department of Biochemistry and Molecular Biology IV, Veterinary School, Universidad Complutense of Madrid, 28040 Madrid, Spain
| | - Antonio R Artalejo
- Department of Toxicology and Pharmacology, Veterinary School, Universidad Complutense of Madrid, 28040 Madrid, Spain
| | - Felipe Ortega
- Department of Biochemistry and Molecular Biology IV, Veterinary School, Universidad Complutense of Madrid, 28040 Madrid, Spain
| | - Esmerilda G Delicado
- Department of Biochemistry and Molecular Biology IV, Veterinary School, Universidad Complutense of Madrid, 28040 Madrid, Spain
| | - Raquel Perez-Sen
- Department of Biochemistry and Molecular Biology IV, Veterinary School, Universidad Complutense of Madrid, 28040 Madrid, Spain
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14
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Masuch A, Shieh CH, van Rooijen N, van Calker D, Biber K. Mechanism of microglia neuroprotection: Involvement of P2X7, TNFα, and valproic acid. Glia 2015; 64:76-89. [PMID: 26295445 DOI: 10.1002/glia.22904] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 08/03/2015] [Accepted: 08/05/2015] [Indexed: 11/05/2022]
Abstract
Recently, we have demonstrated that ramified microglia are neuroprotective in N-methyl-D-aspartate (NMDA)-induced excitotoxicity in organotypic hippocampal slice cultures (OHSCs). The present study aimed to elucidate the underlying neuron-glia communication mechanism. It is shown here that pretreatment of OHSC with high concentrations of adenosine 5'-triphosphate (ATP) reduced NMDA-induced neuronal death only in presence of microglia. Specific agonists and antagonists identified the P2X7 receptor as neuroprotective receptor which was confirmed by absence of ATP-dependent neuroprotection in P2X7-deficient OHSC. Microglia replenished chimeric OHSC consisting of wild-type tissue replenished with P2X7-deficient microglia confirmed the involvement of microglial P2X7 receptor in neuroprotection. Stimulation of P2X7 in primary microglia induced tumor necrosis factor α (TNFα) release and blocking TNFα by a neutralizing antibody in OHSC abolished neuroprotection by ATP. OHSC from TNFα-deficient mice show increased exicitoxicity and activation of P2X7 did not rescue neuronal survival in the absence of TNFα. The neuroprotective effect of valproic acid (VPA) was strictly dependent on the presence of microglia and was mediated by upregulation of P2X7 in the cells. The present study demonstrates that microglia-mediated neuroprotection depends on ATP-activated purine receptor P2X7 and induction of TNFα release. This neuroprotective pathway was strengthened by VPA elucidating a novel mechanism for the neuroprotective function of VPA.
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Affiliation(s)
- Annette Masuch
- Department of Psychiatry and Psychotherapy, University Hospital Freiburg, Freiburg, Germany
| | - Chu-Hsin Shieh
- Department of Psychiatry and Psychotherapy, University Hospital Freiburg, Freiburg, Germany
| | - Nico van Rooijen
- Department of Molecular Cell Biology, Free University Medical Center (VUMC), Amsterdam, the Netherlands
| | - Dietrich van Calker
- Department of Psychiatry and Psychotherapy, University Hospital Freiburg, Freiburg, Germany
| | - Knut Biber
- Department of Psychiatry and Psychotherapy, University Hospital Freiburg, Freiburg, Germany.,Department of Neuroscience, University Medical Center Groningen (UMCG), University of Groningen, the Netherlands
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15
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Xiao Z, Li YY, Sun MJ. Activation of P2X7 receptors in the midbrain periaqueductal gray of rats facilitates morphine tolerance. Pharmacol Biochem Behav 2015; 135:145-53. [PMID: 26054441 DOI: 10.1016/j.pbb.2015.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 05/27/2015] [Accepted: 06/04/2015] [Indexed: 02/01/2023]
Abstract
Opiates such as morphine exhibit analgesic effect in various pain models, but repeated and chronic morphine administration may develop resistance to antinociception. The purinergic signaling system is involved in the mechanisms of pain modulation and morphine tolerance. This study aimed to determine whether the P2X7 receptor in the ventrolateral midbrain periaqueductal gray (vlPAG) is involved in morphine tolerance. Development of tolerance to the antinociceptive effect of morphine was induced in normal adult male Sprague-Dawley (SD) rats through subcutaneous injection of morphine (10mg/kg). The analgesic effect of morphine (5mg/kg, i.p.) was assessed by measuring mechanical withdrawal thresholds (MWTs) in rats with an electronic von Frey anesthesiometer. The expression levels and distribution of the P2X7 receptor in the vlPAG was evaluated through Western blot analysis and immunohistochemistry. The acute effects of intra-vlPAG injection of the selective P2X7 receptor agonist Bz-ATP, the selective P2X7 receptor antagonist A-740003, or antisense oligodeoxynucleotide (AS ODN) targeting the P2X7 receptor on morphine-treated rats were also observed. Results demonstrated that repeated morphine administration decreased the mechanical pain thresholds. By contrast, the expression of the P2X7 receptor protein was up-regulated in the vlPAG in morphine tolerant rats. The percent changes in MWT were markedly but only transiently attenuated by intra-vlPAG injection of Bz-ATP (9nmol/0.3μL) but elevated by A-740003 at doses of 10 and 100nmol/0.3μL. AS ODN (15nmol/0.3μL) against the P2X7 receptor reduced the development of chronic morphine tolerance in rats. These results suggest that the development of antinociceptive tolerance to morphine is partially mediated by activating the vlPAG P2X7 receptors. The present data also suggest that the P2X7 receptors may be a therapeutic target for improving the analgesic effect of morphine in treatments of pain when morphine tolerance occurs.
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Affiliation(s)
- Zhi Xiao
- Research Center for Medicine & Biology, Zunyi Medical University, Zunyi, Guizhou 563003, PR China.
| | - You-Yan Li
- Graduate School, Zunyi Medical University, Zunyi, Guizhou 563003, PR China
| | - Meng-Jie Sun
- Graduate School, Zunyi Medical University, Zunyi, Guizhou 563003, PR China
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