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Neale JH, Yamamoto T. N-acetylaspartylglutamate (NAAG) and glutamate carboxypeptidase II: An abundant peptide neurotransmitter-enzyme system with multiple clinical applications. Prog Neurobiol 2019; 184:101722. [PMID: 31730793 DOI: 10.1016/j.pneurobio.2019.101722] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/24/2019] [Accepted: 11/11/2019] [Indexed: 12/13/2022]
Abstract
N-Acetylaspartylglutamate (NAAG) is the third most prevalent neurotransmitter in the mammalian nervous system, yet its therapeutic potential is only now being fully recognized. Drugs that inhibit the inactivation of NAAG by glutamate carboxypeptidase II (GCPII) increase its extracellular concentration and its activation of its receptor, mGluR3. These drugs warrant attention, as they are effective in animal models of several clinical disorders including stroke, traumatic brain injury and schizophrenia. In inflammatory and neuropathic pain studies, GCPII inhibitors moderated both the primary and secondary pain responses when given systemically, locally or in brain regions associated with the pain perception pathway. The finding that GCPII inhibition also moderated the motor and cognitive effects of ethanol intoxication led to the discovery of their procognitive efficacy in long-term memory tests in control mice and in short-term memory in a mouse model of Alzheimer's disease. NAAG and GCPII inhibitors respectively reduce cocaine self-administration and the rewarding effects of a synthetic stimulant. Most recently, GCPII inhibition also has been reported to be efficacious in a model of inflammatory bowel disease. GCPII was first discovered as a protein expressed by and released from metastatic prostate cells where it is known as prostate specific membrane antigen (PSMA). GCPII inhibitors with high affinity for this protein have been developed as prostate imaging and radiochemical therapies for prostate cancer. Taken together, these data militate in favor of the development and application of GCPII inhibitors in more advanced preclinical research as a prelude to clinical trials.
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Affiliation(s)
- Joseph H Neale
- Department of Biology, Georgetown University, 37(th) and O Sts., NW, Washington, DC, 20057, USA.
| | - Tatsuo Yamamoto
- Dept. of Anesthesiology, Kumamoto University., Kumamoto, Japan
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Dai WL, Yan B, Jiang N, Wu JJ, Liu XF, Liu JH, Yu BY. Simultaneous inhibition of NMDA and mGlu1/5 receptors bylevo-corydalmine in rat spinal cord attenuates bone cancer pain. Int J Cancer 2017; 141:805-815. [DOI: 10.1002/ijc.30780] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 04/10/2017] [Accepted: 04/27/2017] [Indexed: 01/30/2023]
Affiliation(s)
- Wen-Ling Dai
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research; Department of Traditional Chinese Medicine, China Pharmaceutical University; Nanjing Jiangsu China
| | - Bing Yan
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research; Department of Traditional Chinese Medicine, China Pharmaceutical University; Nanjing Jiangsu China
| | - Nan Jiang
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research; Department of Traditional Chinese Medicine, China Pharmaceutical University; Nanjing Jiangsu China
| | - Juan-Juan Wu
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research; Department of Traditional Chinese Medicine, China Pharmaceutical University; Nanjing Jiangsu China
| | - Xiu-Feng Liu
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research; Department of Traditional Chinese Medicine, China Pharmaceutical University; Nanjing Jiangsu China
| | - Ji-Hua Liu
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research; Department of Traditional Chinese Medicine, China Pharmaceutical University; Nanjing Jiangsu China
- State Key Laboratory of Natural Medicines; Department of Traditional Chinese Medicine, China Pharmaceutical University; Nanjing Jiangsu China
| | - Bo-Yang Yu
- State Key Laboratory of Natural Medicines; Department of Traditional Chinese Medicine, China Pharmaceutical University; Nanjing Jiangsu China
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Palazzo E, Marabese I, Luongo L, Guida F, de Novellis V, Maione S. Nociception modulation by supraspinal group III metabotropic glutamate receptors. J Neurochem 2017; 141:507-519. [DOI: 10.1111/jnc.13725] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 06/15/2016] [Accepted: 06/20/2016] [Indexed: 02/02/2023]
Affiliation(s)
- Enza Palazzo
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Ida Marabese
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Livio Luongo
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Francesca Guida
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Vito de Novellis
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
| | - Sabatino Maione
- Department of Experimental Medicine; The Second University of Naples; Naples Italy
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Nonaka T, Yamada T, Ishimura T, Zuo D, Moffett JR, Neale JH, Yamamoto T. A role for the locus coeruleus in the analgesic efficacy of N-acetylaspartylglutamate peptidase (GCPII) inhibitors ZJ43 and 2-PMPA. Mol Pain 2017; 13:1744806917697008. [PMID: 28326936 PMCID: PMC5407666 DOI: 10.1177/1744806917697008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 01/24/2017] [Accepted: 01/31/2017] [Indexed: 11/16/2022] Open
Abstract
N-acetylaspartylglutamate (NAAG) is the third most prevalent and widely distributed neurotransmitter in the mammalian nervous system. NAAG activates a group II metabotropic glutamate receptor (mGluR3) and is inactivated by an extracellular enzyme, glutamate carboxypeptidase II (GCPII) in vivo. Inhibitors of this enzyme are analgesic in animal models of inflammatory, neuropathic and bone cancer pain. NAAG and GCPII are present in the locus coeruleus, a center for the descending noradrenergic inhibitory pain system. In the formalin footpad model, systemic treatment with GCPII inhibitors reduces both phases of the inflammatory pain response and increases release of spinal noradrenaline. This analgesic efficacy is blocked by systemic injection of a group II mGluR antagonist, by intrathecal (spinal) injection of an alpha 2 adrenergic receptor antagonist and by microinjection of an α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor antagonist directly into the contralateral locus coeruleus. Footpad inflammation increases release of glutamate in the contralateral locus coeruleus and systemic treatment with a GCPII inhibitor blocks this increase. Direct injection of GCPII inhibitors into the contralateral or ipsilateral locus coeruleus reduces both phases of the inflammatory pain response in a dose-dependent manner and the contralateral effect also is blocked by intrathecal injection of an alpha 2 adrenergic receptor antagonist. These data support the hypothesis that the analgesic efficacy of systemically administered GCPII inhibitors is mediated, at least in part, by the contralateral locus coeruleus via group II mGluR, AMPA and alpha 2 adrenergic receptors.
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Affiliation(s)
- Takahiro Nonaka
- Department of Anesthesiology, School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Toshihiko Yamada
- Department of Anesthesiology, School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Tatsuhiro Ishimura
- Department of Anesthesiology, School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Daiying Zuo
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, China
| | - John R Moffett
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Joseph H Neale
- Department of Biology, Georgetown University, Washington, DC, USA
| | - Tatsuo Yamamoto
- Department of Anesthesiology, School of Medical Science, Kumamoto University, Kumamoto, Japan
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Rais R, Wozniak K, Wu Y, Niwa M, Stathis M, Alt J, Giroux M, Sawa A, Rojas C, Slusher BS. Selective CNS Uptake of the GCP-II Inhibitor 2-PMPA following Intranasal Administration. PLoS One 2015; 10:e0131861. [PMID: 26151906 PMCID: PMC4494705 DOI: 10.1371/journal.pone.0131861] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 06/09/2015] [Indexed: 11/19/2022] Open
Abstract
Glutamate carboxypeptidase II (GCP-II) is a brain metallopeptidase that hydrolyzes the abundant neuropeptide N-acetyl-aspartyl-glutamate (NAAG) to NAA and glutamate. Small molecule GCP-II inhibitors increase brain NAAG, which activates mGluR3, decreases glutamate, and provide therapeutic utility in a variety of preclinical models of neurodegenerative diseases wherein excess glutamate is presumed pathogenic. Unfortunately no GCP-II inhibitor has advanced clinically, largely due to their highly polar nature resulting in insufficient oral bioavailability and limited brain penetration. Herein we report a non-invasive route for delivery of GCP-II inhibitors to the brain via intranasal (i.n.) administration. Three structurally distinct classes of GCP-II inhibitors were evaluated including DCMC (urea-based), 2-MPPA (thiol-based) and 2-PMPA (phosphonate-based). While all showed some brain penetration following i.n. administration, 2-PMPA exhibited the highest levels and was chosen for further evaluation. Compared to intraperitoneal (i.p.) administration, equivalent doses of i.n. administered 2-PMPA resulted in similar plasma exposures (AUC0-t, i.n./AUC0-t, i.p. = 1.0) but dramatically enhanced brain exposures in the olfactory bulb (AUC0-t, i.n./AUC0-t, i.p. = 67), cortex (AUC0-t, i.n./AUC0-t, i.p. = 46) and cerebellum (AUC0-t, i.n./AUC0-t, i.p. = 6.3). Following i.n. administration, the brain tissue to plasma ratio based on AUC0-t in the olfactory bulb, cortex, and cerebellum were 1.49, 0.71 and 0.10, respectively, compared to an i.p. brain tissue to plasma ratio of less than 0.02 in all areas. Furthermore, i.n. administration of 2-PMPA resulted in complete inhibition of brain GCP-II enzymatic activity ex-vivo confirming target engagement. Lastly, because the rodent nasal system is not similar to humans, we evaluated i.n. 2-PMPA also in a non-human primate. We report that i.n. 2-PMPA provides selective brain delivery with micromolar concentrations. These studies support intranasal delivery of 2-PMPA to deliver therapeutic concentrations in the brain and may facilitate its clinical development.
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Affiliation(s)
- Rana Rais
- Brain Science Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Krystyna Wozniak
- Brain Science Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Ying Wu
- Brain Science Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Minae Niwa
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Marigo Stathis
- Brain Science Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Jesse Alt
- Brain Science Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Marc Giroux
- Kurve Technology, Inc., Bothell, Washington, United States of America
| | - Akira Sawa
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Camilo Rojas
- Brain Science Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
- Department of Molecular and Comparative Pathobiology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Barbara S. Slusher
- Brain Science Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
- Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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Liu Y, Cui X, Sun YE, Yang X, Ni K, Zhou Y, Ma Z, Gu X. Intrathecal injection of the peptide myr-NR2B9c attenuates bone cancer pain via perturbing N-methyl-D-aspartate receptor-PSD-95 protein interactions in mice. Anesth Analg 2014; 118:1345-54. [PMID: 24842180 DOI: 10.1213/ane.0000000000000202] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND N-methyl-D-aspartate receptor (NMDARs)-dependent central sensitization plays an important role in cancer pain. Binding of NMDAR subunit 2B (NR2B) by postsynaptic density protein-95 (PSD-95) can couple NMDAR activity to intracellular enzymes, such as neuronal nitric oxide synthase (nNOS), facilitate downstream signaling pathways, and modulate NMDAR stability, contributing to synaptic plasticity. In this study, we investigated whether perturbing the specific interaction between spinal NR2B-containing NMDAR and PSD-95, using a peptide-mimetic strategy, could attenuate bone cancer-related pain behaviors. METHODS Osteosarcoma cells were implanted into the intramedullary space of the right femurs of C3H/HeJ mice to induce progressive bone cancer-related pain behaviors. Western blotting was applied to examine the expression of spinal phospho-Tyr1472 NR2B, nNOS, and PSD-95. We further investigated the effects of intrathecal injection of the mimetic peptide Myr-NR2B9c, which competitively disrupts the interaction between PSD-95 and NR2B, on nociceptive behaviors and on the upregulation of phospho-Tyr1472 NR2B, nNOS, and PSD-95 associated with bone cancer pain in the spinal cord. RESULTS Inoculation of osteosarcoma cells induced progressive bone cancer pain and resulted in a significant upregulation of phospho-Tyr1472 NR2B, nNOS, and PSD-95. Intrathecal administration of Myr-NR2B9c attenuated bone cancer-evoked mechanical allodynia, thermal hyperalgesia, and reduced spinal phospho-Tyr1472 NR2B, nNOS, and PSD-95 expression. CONCLUSIONS Intrathecal administration of Myr-NR2B9c reduced bone cancer pain. Internalization of spinal NR2B and dissociation NR2B-containing NMDARs activation from downstream nNOS signaling may contribute to the analgesic effects of Myr-NR2B9c. This approach may circumvent the negative consequences associated with blocking NMDARs, and may be a novel strategy for the treatment of bone cancer pain.
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Affiliation(s)
- Yue Liu
- From the Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing, China
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Yamada T, Zuo D, Yamamoto T, Olszewski RT, Bzdega T, Moffett JR, Neale JH. NAAG peptidase inhibition in the periaqueductal gray and rostral ventromedial medulla reduces flinching in the formalin model of inflammation. Mol Pain 2012; 8:67. [PMID: 22971334 PMCID: PMC3539905 DOI: 10.1186/1744-8069-8-67] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 05/21/2012] [Indexed: 11/28/2022] Open
Abstract
Background Metabotropic glutamate receptors (mGluRs) have been identified as significant analgesic targets. Systemic treatments with inhibitors of the enzymes that inactivate the peptide transmitter N-acetylaspartylglutamate (NAAG), an mGluR3 agonist, have an analgesia-like effect in rat models of inflammatory and neuropathic pain. The goal of this study was to begin defining locations within the central pain pathway at which NAAG activation of its receptor mediates this effect. Results NAAG immunoreactivity was found in neurons in two brain regions that mediate nociceptive processing, the periaqueductal gray (PAG) and the rostral ventromedial medulla (RVM). Microinjection of the NAAG peptidase inhibitor ZJ43 into the PAG contralateral, but not ipsilateral, to the formalin injected footpad reduced the rapid and slow phases of the nociceptive response in a dose-dependent manner. ZJ43 injected into the RVM also reduced the rapid and slow phase of the response. The group II mGluR antagonist LY341495 blocked these effects of ZJ43 on the PAG and RVM. NAAG peptidase inhibition in the PAG and RVM did not affect the thermal withdrawal response in the hot plate test. Footpad inflammation also induced a significant increase in glutamate release in the PAG. Systemic injection of ZJ43 increased NAAG levels in the PAG and RVM and blocked the inflammation-induced increase in glutamate release in the PAG. Conclusion These data demonstrate a behavioral and neurochemical role for NAAG in the PAG and RVM in regulating the spinal motor response to inflammation and that NAAG peptidase inhibition has potential as an approach to treating inflammatory pain via either the ascending (PAG) and/or the descending pain pathways (PAG and RVM) that warrants further study.
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Affiliation(s)
- Toshihiko Yamada
- Department of Biology, Georgetown University, Washington, DC, USA
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Bařinka C, Rojas C, Slusher B, Pomper M. Glutamate carboxypeptidase II in diagnosis and treatment of neurologic disorders and prostate cancer. Curr Med Chem 2012; 19:856-70. [PMID: 22214450 DOI: 10.2174/092986712799034888] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 11/10/2011] [Accepted: 11/14/2011] [Indexed: 12/14/2022]
Abstract
Glutamate carboxypeptidase II (GCPII) is a membrane-bound binuclear zinc metallopeptidase with the highest expression levels found in the nervous and prostatic tissue. Throughout the nervous system, glia-bound GCPII is intimately involved in the neuron-neuron and neuron-glia signaling via the hydrolysis of N-acetylaspartylglutamate (NAAG), the most abundant mammalian peptidic neurotransmitter. The inhibition of the GCPII-controlled NAAG catabolism has been shown to attenuate neurotoxicity associated with enhanced glutamate transmission and GCPII-specific inhibitors demonstrate efficacy in multiple preclinical models including traumatic brain injury, stroke, neuropathic and inflammatory pain, amyotrophic lateral sclerosis, and schizophrenia. The second major area of pharmacological interventions targeting GCPII focuses on prostate carcinoma; GCPII expression levels are highly increased in androgen-independent and metastatic disease. Consequently, the enzyme serves as a potential target for imaging and therapy. This review offers a summary of GCPII structure, physiological functions in healthy tissues, and its association with various pathologies. The review also outlines the development of GCPII-specific small-molecule compounds and their use in preclinical and clinical settings.
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Affiliation(s)
- C Bařinka
- Institute of Biotechnology, Academy of Sciences of the Czech Republic, Videnska 1083, 14200 Praha 4, Czech Republic.
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Shih MH, Kao SC, Wang W, Yaster M, Tao YX. Spinal cord NMDA receptor-mediated activation of mammalian target of rapamycin is required for the development and maintenance of bone cancer-induced pain hypersensitivities in rats. THE JOURNAL OF PAIN 2012; 13:338-49. [PMID: 22341316 DOI: 10.1016/j.jpain.2011.12.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Revised: 12/08/2011] [Accepted: 12/19/2011] [Indexed: 10/28/2022]
Abstract
UNLABELLED Mammalian target of rapamycin (mTOR) controls mRNA translation and is critical for neuronal plasticity. However, how it participates in central sensitization underlying chronic pain is unclear. Here, we show that NMDA receptors are required for the functional role of spinal cord mTOR in bone cancer pain induced by injecting prostate cancer cells (PCCs) into the tibia. Intrathecal rapamycin, a specific mTOR inhibitor, dose dependently attenuated the development and maintenance of PCC-induced mechanical allodynia and thermal hyperalgesia. Rapamycin alone did not affect locomotor activity and acute responses to thermal or mechanical stimuli. Phosphorylation of mTOR and p70S6K (a downstream effector) was increased time dependently in L(4-5) dorsal horn and transiently in L(4-5) dorsal root ganglions on the ipsilateral side after PCC injection, although total expression of mTOR or p70S6K was not changed in these regions. The increases in dorsal horn were abolished by intrathecal infusion of DL-AP5, an NMDA receptor antagonist. Moreover, NMDA receptor subunit NR1 colocalized with mTOR and p70S6K in dorsal horn neurons. These findings suggest that PCC-induced dorsal horn activation of the mTOR pathway participates in NMDA receptor-triggered dorsal central sensitization under cancer pain conditions. PERSPECTIVE The present study shows that inhibition of spinal mTOR blocks cancer-related pain without affecting acute pain and locomotor function. Given that mTOR inhibitors are FDA-approved drugs, mTOR in spinal cord may represent a potential new target for preventing and/or treating cancer-related pain.
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Affiliation(s)
- Ming-Hung Shih
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Neale JH, Olszewski RT, Zuo D, Janczura KJ, Profaci CP, Lavin KM, Madore JC, Bzdega T. Advances in understanding the peptide neurotransmitter NAAG and appearance of a new member of the NAAG neuropeptide family. J Neurochem 2011; 118:490-8. [PMID: 21644997 DOI: 10.1111/j.1471-4159.2011.07338.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A substantial body of data was reported between 1984 and 2000 demonstrating that the neuropeptide N-acetylaspartylglutamate (NAAG) not only functions as a neurotransmitter but also is the third most prevalent transmitter in the mammalian nervous system behind glutamate and GABA. By 2005, this conclusion was validated further through a series of studies in vivo and in vitro. The primary enzyme responsible for the inactivation of NAAG following its synaptic release had been cloned, characterized and knocked out. Potent inhibitors of this enzyme were developed and their efficacy has been extensively studied in a series of animal models of clinical conditions, including stroke, peripheral neuropathy, traumatic brain injury, inflammatory and neuropathic pain, cocaine addiction, and schizophrenia. Considerable progress also has been made in defining further the mechanism of action of these peptidase inhibitors in elevating synaptic levels of NAAG with the consequent inhibition of transmitter release via the activation of pre-synaptic metabotropic glutamate receptor 3 by this peptide. Very recent discoveries include identification of two different nervous system enzymes that mediate the synthesis of NAAG from N-acetylaspartate and glutamate and the finding that one of these enzymes also mediates the synthesis of a second member of the NAAG family of neuropeptides, N-acetylaspartylglutamylglutamate.
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Affiliation(s)
- Joseph H Neale
- Department of Biology, Georgetown University, Washington, District of Columbia 20057, USA.
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Seidlitz EP, Sharma MK, Singh G. A by-product of glutathione production in cancer cells may cause disruption in bone metabolic processes. Can J Physiol Pharmacol 2011; 88:197-203. [PMID: 20393585 DOI: 10.1139/y09-129] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bone is a frequent site for metastasis of breast and prostate cancers, often resulting in pathologic changes in bone metabolism and severe pain. The mechanisms involved are not well understood, but tumour cells may release factors that interfere with bone homeostasis. Several observations have led us to hypothesize that the functional disruptions in bone metastasis are the result of a biological process common to many cell types. The high metabolic activity characteristic of cancer cells often upregulates oxidative stress protection mechanisms such as the antioxidant molecule glutathione. In maintaining redox balance, this normal metabolic response may result in unintended pathologic effects in certain sensitive organ sites. Malignant glioma cells kill surrounding neurons in the brain specifically by secreting the amino acid glutamate, an obligatory waste product of glutathione synthesis. We suggest that glutamate release is a plausible mechanism that may account for the pathologic changes in bone metastasis, since bone, like brain, is also highly sensitive to glutamatergic disruption. This report reviews the available evidence to draw a mechanistic connection between tumour cell oxidative stress and the pathology seen in patients with bone metastasis.
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Affiliation(s)
- Eric P Seidlitz
- Department of Pathology and Molecular Medicine, McMaster University, 699 Concession Street, Hamilton, ON L8V 5C2, Canada
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Adedoyin MO, Vicini S, Neale JH. Endogenous N-acetylaspartylglutamate (NAAG) inhibits synaptic plasticity/transmission in the amygdala in a mouse inflammatory pain model. Mol Pain 2010; 6:60. [PMID: 20860833 PMCID: PMC3152775 DOI: 10.1186/1744-8069-6-60] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Accepted: 09/22/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The peptide neurotransmitter N-acetylaspartylglutamate (NAAG) is widely expressed throughout the vertebrate nervous system, including the pain processing neuraxis. Inhibitors of NAAG peptidases are analgesic in animal models of pain. However, the brain regions involved in NAAG's analgesic action have not been rigorously defined. Group II metabotropic glutamate receptors (mGluR2/3) play a role in pain processing in the laterocapsular part of the central nucleus of the amygdala (CeLC). Given the high concentration of NAAG in the amygdala and its activation of group II mGluRs (mGluR3 > mGluR2), this study was undertaken using the mouse formalin model of inflammatory pain to test the hypothesis that NAAG influences pain processing in the amygdala. Evoked excitatory postsynaptic currents (eEPSCs) were studied in neurons in the CeLC of mouse brain slices following stimulation of the spinoparabrachial amygdaloid afferents. RESULTS Application of a NAAG peptidase inhibitor, ZJ43, dose dependently inhibited the amplitude of the eEPSCs by up to 50% in control CeLC demonstrating the role of NAAG in regulation of excitatory transmission at this synapse. A group II mGluR agonist (SLx-3095-1) similarly inhibited eEPSC amplitude by about 30%. Both effects were blocked by the group II mGluR antagonist LY341495. ZJ43 was much less effective than SLx in reducing eEPSCs 24 hours post inflammation suggesting an inflammation induced reduction in NAAG release or an increase in the ratio of mGluR2 to mGluR3 expression. Systemic injection of ZJ43 proximal to the time of inflammation blocked peripheral inflammation-induced increases in synaptic transmission of this pathway 24 hrs later and blocked the induction of mechanical allodynia that developed by this time point. CONCLUSIONS The main finding of this study is that NAAG and NAAG peptidase inhibition reduce excitatory neurotransmission and inflammation-induced plasticity at the spinoparabrachial synapse within the pain processing pathway of the central amygdaloid nucleus.
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Affiliation(s)
- Mary O Adedoyin
- Department of Biology, Georgetown University, Biology Reiss Building 37th and O St. NW, Washington, D.C. 20057, USA
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Gu X, Zhang J, Ma Z, Wang J, Zhou X, Jin Y, Xia X, Gao Q, Mei F. The role of N-methyl-D-aspartate receptor subunit NR2B in spinal cord in cancer pain. Eur J Pain 2009; 14:496-502. [PMID: 19815434 DOI: 10.1016/j.ejpain.2009.09.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 08/24/2009] [Accepted: 09/04/2009] [Indexed: 10/20/2022]
Abstract
Cancer pain is one kind of the most common and severe kinds of chronic pain. No breakthrough regarding the mechanisms and therapeutics of cancer pains has yet been achieved. Based on the well established involvement of the NMDA (N-methyl-D-aspartate) receptor containing NR2B in inflammatory pain and neuropathic pain and the effective pain relief obtained with ketamine in cancer patients with intractable pain, we supposed that NR2B in the spinal cord was an important factor for cancer pain. In this study, we investigated the possible role of NR2B in the spinal cord using a murine model of bone cancer pain. C3H/HeJ mice were inoculated into the intramedullary space of the right femur with Osteosarcoma NCTC 2472 cells to induce ongoing bone cancer-related pain behaviors. At day 14 after operation, the expression of NR2B mRNA and NR2B protein in the spinal cord were higher in tumor-bearing mice compared to the sham mice. Intrathecal administration of 5 and 10 microg of NR2B subunit-specific NMDA receptor antagonist ifenprodil attenuated cancer-evoked spontaneous pain, thermal hyperalgesia and mechanical allodynia. These results suggest that NR2B in the spinal cord may participate in bone cancer pain in mice, and ifenprodil may be a useful alternative or adjunct therapy for bone cancer pain. The findings may lead to novel strategies for the treatment of bone cancer pain.
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Affiliation(s)
- XiaoPing Gu
- Department of Anesthesiology, Affiliated Drum-Tower Hospital of Medical College of Nanjing University, Nanjing, 210008 Jiangsu Province, China
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Opioid Switching and Burst Ketamine to Improve the Opioid Response in Patients With Movement-related Pain Due to Bone Metastases. Clin J Pain 2009; 25:648-9. [DOI: 10.1097/ajp.0b013e3181a68a85] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Grande LA, O’Donnell BR, Fitzgibbon DR, Terman GW. Ultra-Low Dose Ketamine and Memantine Treatment for Pain in an Opioid-Tolerant Oncology Patient. Anesth Analg 2008; 107:1380-3. [DOI: 10.1213/ane.0b013e3181733ddd] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Yamamoto T, Kozikowski A, Zhou J, Neale JH. Intracerebroventricular administration of N-acetylaspartylglutamate (NAAG) peptidase inhibitors is analgesic in inflammatory pain. Mol Pain 2008; 4:31. [PMID: 18673570 PMCID: PMC2517065 DOI: 10.1186/1744-8069-4-31] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Accepted: 08/01/2008] [Indexed: 11/16/2022] Open
Abstract
Background The peptide neurotransmitter N-Acetylaspartylglutamate (NAAG) is the third most prevalent transmitter in the mammalian central nervous system. Local, intrathecal and systemic administration of inhibitors of enzymes that inactivate NAAG decrease responses to inflammatory pain in rat models. Consistent with NAAG's activation of group II metabotropic glutamate receptors, this analgesia is blocked by a group II antagonist. Results This research aimed at determining if analgesia obtained following systemic administration of NAAG peptidase inhibitors is due to NAAG activation of group II mGluRs in brain circuits that mediate perception of inflammatory pain. NAAG and NAAG peptidase inhibitors, ZJ43 and 2-PMPA, were microinjected into a lateral ventricle prior to injection of formalin in the rat footpad. Each treatment reduced the early and late phases of the formalin-induced inflammatory pain response in a dose-dependent manner. The group II mGluR antagonist reversed these analgesic effects consistent with the conclusion that analgesia was mediated by increasing NAAG levels and the peptide's activation of group II receptors. Conclusion These data contribute to proof of the concept that NAAG peptidase inhibition is a novel therapeutic approach to inflammatory pain and that these inhibitors achieve analgesia by elevating synaptic levels of NAAG within pain processing circuits in brain.
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Affiliation(s)
- Tatsuo Yamamoto
- Department of Biology, Georgetown University, Washington, DC 20057, USA.
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Andoh T, Sugiyama K, Fujita M, Iida Y, Nojima H, Saiki I, Kuraishi Y. Pharmacological evaluation of morphine and non-opioid analgesic adjuvants in a mouse model of skin cancer pain. Biol Pharm Bull 2008; 31:520-2. [PMID: 18310922 DOI: 10.1248/bpb.31.520] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using a mouse model of advanced skin cancer which has mixed nociceptive-neuropathic pain, we evaluated the analgesic effects of morphine and analgesic adjuvants. Morphine hydrochloride (10--30 mg/kg, oral) and mexiletine hydrochloride (10--30 mg/kg, intraperitoneal) dose-dependently inhibited thermal hyperalgesia. Baclofen (10 mg/kg, subcutaneous) suppressed thermal hyperalgesia, without effects at lower doses of 1 and 5 mg/kg. Ketamine hydrochloride (50 mg/kg, oral) was without effect. Analgesic tolerance was observed after 6th administration of morphine, and it was not developed until at least 7th administration of mexiletine and baclofen. This mouse model of skin cancer may be useful for the pharmacological evaluation of the effects of opioids and analgesic adjuvants on mixed nociceptive-neuropathic pain of advanced cancer.
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Affiliation(s)
- Tsugunobu Andoh
- Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
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Yamamoto T, Saito O, Aoe T, Bartolozzi A, Sarva J, Zhou J, Kozikowski A, Wroblewska B, Bzdega T, Neale JH. Local administration of N-acetylaspartylglutamate (NAAG) peptidase inhibitors is analgesic in peripheral pain in rats. Eur J Neurosci 2007; 25:147-58. [PMID: 17241276 DOI: 10.1111/j.1460-9568.2006.05272.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The peptide neurotransmitter N-acetylaspartylglutamate (NAAG) selectively activates group II metabotropic glutamate receptors (mGluRs). Systemic administration of inhibitors of the enzymes that inactivate NAAG results in decreased pain responses in rat models of inflammatory and neuropathic pain. These effects are blocked by a group II mGluR antagonist. This research tested the hypothesis that some analgesic effects of NAAG peptidase inhibition are mediated by NAAG acting on sensory neurite mGluRs at the site of inflammation. Group II mGluR agonists, SLx-3095-1, NAAG and APDC, or NAAG peptidase inhibitors, ZJ-43 and 2-PMPA, injected into the rat footpad reduced pain responses in carrageenan or formalin models. The analgesic effects of SLx-3095-1, APDC, ZJ-43, 2-PMPA and NAAG were blocked by co-injection of LY341495, a selective group II mGluR antagonist. Injection of group II mGluR agonists, NAAG or the peptidase inhibitors into the contralateral rat footpad had no effect on pain perception in the injected paw. At 10-100 microm ZJ-43 and 2-PMPA demonstrated no consistent agonist activity at mGluR2 or mGluR3. Consistent with the conclusion that peripherally administered NAAG peptidase inhibitors increase the activation of mGluR3 by NAAG that is released from peripheral sensory neurites, we found that the tissue average concentration of NAAG in the unstimulated rat hind paw was about 6 microm. These data extend our understanding of the role of this peptide in sensory neurons and reveal the potential for treatment of inflammatory pain via local application of NAAG peptidase inhibitors at doses that may have little or no central nervous system effects.
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Affiliation(s)
- Tatsuo Yamamoto
- Department of Anaesthesiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba-shi, Chiba 260-8670, Japan
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