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Morland C, Nordengen K. N-Acetyl-Aspartyl-Glutamate in Brain Health and Disease. Int J Mol Sci 2022; 23:ijms23031268. [PMID: 35163193 PMCID: PMC8836185 DOI: 10.3390/ijms23031268] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 02/04/2023] Open
Abstract
N-acetyl-aspartyl-glutamate (NAAG) is the most abundant dipeptide in the brain, where it acts as a neuromodulator of glutamatergic synapses by activating presynaptic metabotropic glutamate receptor 3 (mGluR3). Recent data suggest that NAAG is selectively localized to postsynaptic dendrites in glutamatergic synapses and that it works as a retrograde neurotransmitter. NAAG is released in response to glutamate and provides the postsynaptic neuron with a feedback mechanisms to inhibit excessive glutamate signaling. A key regulator of synaptically available NAAG is rapid degradation by the extracellular enzyme glutamate carboxypeptidase II (GCPII). Increasing endogenous NAAG—for instance by inhibiting GCPII—is a promising treatment option for many brain disorders where glutamatergic excitotoxicity plays a role. The main effect of NAAG occurs through increased mGluR3 activation and thereby reduced glutamate release. In the present review, we summarize the transmitter role of NAAG and discuss the involvement of NAAG in normal brain physiology. We further present the suggested roles of NAAG in various neurological and psychiatric diseases and discuss the therapeutic potential of strategies aiming to enhance NAAG levels.
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Affiliation(s)
- Cecilie Morland
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, The Faculty of Mathematics and Natural Sciences, University of Oslo, 1068 Oslo, Norway
- Correspondence: (C.M.); (K.N.); Tel.: +47-22844937; (C.M.); +47-23073580 (K.N.)
| | - Kaja Nordengen
- Department of Neurology, Oslo University Hospital, 0424 Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, 0318 Oslo, Norway
- Correspondence: (C.M.); (K.N.); Tel.: +47-22844937; (C.M.); +47-23073580 (K.N.)
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2
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Krečmerová M, Majer P, Rais R, Slusher BS. Phosphonates and Phosphonate Prodrugs in Medicinal Chemistry: Past Successes and Future Prospects. Front Chem 2022; 10:889737. [PMID: 35668826 PMCID: PMC9163707 DOI: 10.3389/fchem.2022.889737] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/26/2022] [Indexed: 12/25/2022] Open
Abstract
Compounds with a phosphonate group, i.e., -P(O)(OH)2 group attached directly to the molecule via a P-C bond serve as suitable non-hydrolyzable phosphate mimics in various biomedical applications. In principle, they often inhibit enzymes utilizing various phosphates as substrates. In this review we focus mainly on biologically active phosphonates that originated from our institute (Institute of Organic Chemistry and Biochemistry in Prague); i.e., acyclic nucleoside phosphonates (ANPs, e.g., adefovir, tenofovir, and cidofovir) and derivatives of non-nucleoside phosphonates such as 2-(phosphonomethyl) pentanedioic acid (2-PMPA). Principal strategies of their syntheses and modifications to prodrugs is reported. Besides clinically used ANP antivirals, a special attention is paid to new biologically active molecules with respect to emerging infections and arising resistance of many pathogens against standard treatments. These new structures include 2,4-diamino-6-[2-(phosphonomethoxy)ethoxy]pyrimidines or so-called "open-ring" derivatives, acyclic nucleoside phosphonates with 5-azacytosine as a base moiety, side-chain fluorinated ANPs, aza/deazapurine ANPs. When transformed into an appropriate prodrug by derivatizing their charged functionalities, all these compounds show promising potential to become drug candidates for the treatment of viral infections. ANP prodrugs with suitable pharmacokinetics include amino acid phosphoramidates, pivaloyloxymethyl (POM) and isopropoxycarbonyloxymethyl (POC) esters, alkyl and alkoxyalkyl esters, salicylic esters, (methyl-2-oxo-1,3-dioxol-4-yl) methyl (ODOL) esters and peptidomimetic prodrugs. We also focus on the story of cytostatics related to 9-[2-(phosphonomethoxy)ethyl]guanine and its prodrugs which eventually led to development of the veterinary drug rabacfosadine. Various new ANP structures are also currently investigated as antiparasitics, especially antimalarial agents e.g., guanine and hypoxanthine derivatives with 2-(phosphonoethoxy)ethyl moiety, their thia-analogues and N-branched derivatives. In addition to ANPs and their analogs, we also describe prodrugs of 2-(phosphonomethyl)pentanedioic acid (2-PMPA), a potent inhibitor of the enzyme glutamate carboxypeptidase II (GCPII), also known as prostate-specific membrane antigen (PSMA). Glutamate carboxypeptidase II inhibitors, including 2-PMPA have been found efficacious in various preclinical models of neurological disorders which are caused by glutamatergic excitotoxicity. Unfortunately its highly polar character and hence low bioavailability severely limits its potential for clinical use. To overcome this problem, various prodrug strategies have been used to mask carboxylates and/or phosphonate functionalities with pivaloyloxymethyl, POC, ODOL and alkyl esters. Chemistry and biological characterization led to identification of prodrugs with 44-80 fold greater oral bioavailability (tetra-ODOL-2-PMPA).
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Affiliation(s)
- Marcela Krečmerová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic (ASCR), Prague, Czechia
- *Correspondence: Marcela Krečmerová,
| | - Pavel Majer
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic (ASCR), Prague, Czechia
| | - Rana Rais
- Departments of Neurology, Pharmacology and Molecular Sciences, Johns Hopkins Drug Discovery, Baltimore, MD, United States
| | - Barbara S. Slusher
- Departments of Neurology, Pharmacology and Molecular Sciences, Psychiatry and Behavioral Sciences, Neuroscience, Medicine, Oncology, Johns Hopkins Drug Discovery, Baltimore, MD, United States
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3
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Abdul-Wahab R, Long MT, Ordaz R, Lyeth BG, Pfister BJ. Outcome measures from experimental traumatic brain injury in male rats vary with the complete temporal biomechanical profile of the injury event. J Neurosci Res 2020; 98:2027-2044. [PMID: 32741029 DOI: 10.1002/jnr.24670] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 05/12/2020] [Accepted: 05/19/2020] [Indexed: 11/05/2022]
Abstract
Millions suffer a traumatic brain injury (TBI) each year wherein the outcomes associated with injury can vary greatly between individuals. This study postulates that variations in each biomechanical parameter of a head trauma lead to differences in histological and behavioral outcome measures that should be considered collectively in assessing injury. While trauma severity typically scales with the magnitude of injury, much less is known about the effects of rate and duration of the mechanical insult. In this study, a newly developed voice-coil fluid percussion injury system was used to investigate the effects of injury rate and fluid percussion impulse on a collection of post-injury outcomes in male rats. Collectively the data suggest a potential shift in the specificity and progression of neuronal injury and function rather than a general scaling of injury severity. While a faster, shorter fluid percussion first presents as a mild TBI, neuronal loss and some behavioral tasks were similar among the slower and faster fluid percussion injuries. This study concludes that the sequelae of neuronal degeneration and behavioral outcomes are related to the complete temporal profile of the fluid percussion and do not scale only with peak pressure.
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Affiliation(s)
- Radia Abdul-Wahab
- Center for Injury Biomechanics, Materials and Medicine, Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA.,Department of Neurological Surgery, University of California, Davis, CA, USA
| | - Mathew T Long
- Center for Injury Biomechanics, Materials and Medicine, Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA
| | - Rafael Ordaz
- Department of Neurological Surgery, University of California, Davis, CA, USA
| | - Bruce G Lyeth
- Department of Neurological Surgery, University of California, Davis, CA, USA
| | - Bryan J Pfister
- Center for Injury Biomechanics, Materials and Medicine, Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA
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4
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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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Kim S, Mortera M, Hu X, Krishnan S, Hoffecker L, Herrold A, Terhorst L, King L, Machtinger J, Zumsteg JM, Negm A, Heyn P. Overview of pharmacological interventions after traumatic brain injuries: impact on selected outcomes. Brain Inj 2019; 33:442-455. [DOI: 10.1080/02699052.2019.1565896] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Sonya Kim
- Department of Neurology and Department of Rehabilitation Medicine, NYU School of Medicine, New York, USA
| | - Marianne Mortera
- NYU Steinhardt, Department of Occupational Therapy, New York University, New York, USA
| | - Xiaolei Hu
- Department of Community Medicine and Rehabilitation, Umeå University, Sweden
| | - Shilpa Krishnan
- Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, Georgia, USA
| | - Lilian Hoffecker
- Health Sciences Library, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Amy Herrold
- Center of Innovation for Complex Chronic Healthcare, Edward Hines Jr., VA Hospital, Hines, Illinois, USA
| | - Lauren Terhorst
- Department of Occupational Therapy, School of Health and Rehabilitation Services, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Laurie King
- Neurology, Oregon Health & Science University, Portland, Oregon, USA
| | - Joseph Machtinger
- Department of Neurology, Division of Multiple Sclerosis, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Jennifer M. Zumsteg
- Department of Rehabilitation Medicine, University of Washington, Seattle, Washington, USA
| | - Ahmed Negm
- School of Rehabilitation Sciences, McMaster University, Hamilton, Ontario, USA
| | - Patricia Heyn
- Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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6
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Barinka C, Novakova Z, Hin N, Bím D, Ferraris DV, Duvall B, Kabarriti G, Tsukamoto R, Budesinsky M, Motlova L, Rojas C, Slusher BS, Rokob TA, Rulíšek L, Tsukamoto T. Structural and computational basis for potent inhibition of glutamate carboxypeptidase II by carbamate-based inhibitors. Bioorg Med Chem 2018; 27:255-264. [PMID: 30552009 DOI: 10.1016/j.bmc.2018.11.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/07/2018] [Accepted: 11/14/2018] [Indexed: 02/04/2023]
Abstract
A series of carbamate-based inhibitors of glutamate carboxypeptidase II (GCPII) were designed and synthesized using ZJ-43, N-[[[(1S)-1-carboxy-3-methylbutyl]amino]carbonyl]-l-glutamic acid, as a molecular template in order to better understand the impact of replacing one of the two nitrogen atoms in the urea-based GCPII inhibitor with an oxygen atom. Compound 7 containing a C-terminal 2-oxypentanedioic acid was more potent than compound 5 containing a C-terminal glutamic acid (2-aminopentanedioic acid) despite GCPII's preference for peptides containing an N-terminal glutamate as substrates. Subsequent crystallographic analysis revealed that ZJ-43 and its two carbamate analogs 5 and 7 with the same (S,S)-stereochemical configuration adopt a nearly identical binding mode while (R,S)-carbamate analog 8 containing a d-leucine forms a less extensive hydrogen bonding network. QM and QM/MM calculations have identified no specific interactions in the GCPII active site that would distinguish ZJ-43 from compounds 5 and 7 and attributed the higher potency of ZJ-43 and compound 7 to the free energy changes associated with the transfer of the ligand from bulk solvent to the protein active site as a result of the lower ligand strain energy and solvation/desolvation energy. Our findings underscore a broader range of factors that need to be taken into account in predicting ligand-protein binding affinity. These insights should be of particular importance in future efforts to design and develop GCPII inhibitors for optimal inhibitory potency.
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Affiliation(s)
- Cyril Barinka
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic.
| | - Zora Novakova
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Niyada Hin
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, United States
| | - Daniel Bím
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, Prague 6 166 10, Czech Republic
| | - Dana V Ferraris
- McDaniel College, 2 College Hill, Westminster MD 21157, United States
| | - Bridget Duvall
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, United States
| | - Gabriel Kabarriti
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, United States
| | - Reiji Tsukamoto
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, United States
| | - Milos Budesinsky
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, Prague 6 166 10, Czech Republic
| | - Lucia Motlova
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Camilo Rojas
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, United States; Department of Molecular and Comparative Pathobiology, Johns Hopkins University, Baltimore, MD 21205, United States
| | - Barbara S Slusher
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, United States; Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, United States
| | - Tibor András Rokob
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1117 Budapest, Magyar Tudósok körútja 2, Hungary
| | - Lubomír Rulíšek
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, Prague 6 166 10, Czech Republic.
| | - Takashi Tsukamoto
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21205, United States; Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, United States.
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7
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Evans JC, Malhotra M, Cryan JF, O'Driscoll CM. The therapeutic and diagnostic potential of the prostate specific membrane antigen/glutamate carboxypeptidase II (PSMA/GCPII) in cancer and neurological disease. Br J Pharmacol 2016; 173:3041-3079. [PMID: 27526115 PMCID: PMC5056232 DOI: 10.1111/bph.13576] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 07/08/2016] [Accepted: 07/25/2016] [Indexed: 12/11/2022] Open
Abstract
Prostate specific membrane antigen (PSMA) otherwise known as glutamate carboxypeptidase II (GCPII) is a membrane bound protein that is highly expressed in prostate cancer and in the neovasculature of a wide variety of tumours including glioblastomas, breast and bladder cancers. This protein is also involved in a variety of neurological diseases including schizophrenia and ALS. In recent years, there has been a surge in the development of both diagnostics and therapeutics that take advantage of the expression and activity of PSMA/GCPII. These include gene therapy, immunotherapy, chemotherapy and radiotherapy. In this review, we discuss the biological roles that PSMA/GCPII plays, both in normal and diseased tissues, and the current therapies exploiting its activity that are at the preclinical stage. We conclude by giving an expert opinion on the future direction of PSMA/GCPII based therapies and diagnostics and hurdles that need to be overcome to make them effective and viable.
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Affiliation(s)
- James C Evans
- Pharmacodelivery Group, School of Pharmacy, University College Cork, Cork, Ireland
| | - Meenakshi Malhotra
- Pharmacodelivery Group, School of Pharmacy, University College Cork, Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
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8
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Majer P, Jančařík A, Krečmerová M, Tichý T, Tenora L, Wozniak K, Wu Y, Pommier E, Ferraris D, Rais R, Slusher BS. Discovery of Orally Available Prodrugs of the Glutamate Carboxypeptidase II (GCPII) Inhibitor 2-Phosphonomethylpentanedioic Acid (2-PMPA). J Med Chem 2016; 59:2810-9. [PMID: 26930119 DOI: 10.1021/acs.jmedchem.6b00062] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
2-Phosphonomethylpentanedioic acid (1, 2-PMPA) is a potent inhibitor of glutamate carboxypeptidase II which has demonstrated robust neuroprotective efficacy in many neurological disease models. However, 1 is highly polar containing a phosphonate and two carboxylates, severely limiting its oral bioavailability. We strategized to mask the polar groups via a prodrug approach, increasing the likelihood of passive oral absorption. Our initial strategy was to cover the phosphonate with hydrophobic moieties such as pivaloyloxymethyl (POM) and isopropyloxycarbonyloxymethyl (POC) while keeping the α- and γ-carboxylates unsubstituted. This attempt was unsuccessful due to the chemical instability of the bis-POC/POM derivatives. Addition of α,γ-diesters and α-monoesters enhanced chemical stability and provided excellent oral exposure in mice, but these mixed esters were too stable in vivo, resulting in minimal release of 1. By introducing POC groups on both the phosphonate and α-carboxylate, we synthesized Tris-POC-2-PMPA (21b), which afforded excellent release of 1 following oral administration in both mice and dog.
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Affiliation(s)
- Pavel Majer
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague, Czech Republic
| | - Andrej Jančařík
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague, Czech Republic
| | - Marcela Krečmerová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague, Czech Republic
| | - Tomáš Tichý
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague, Czech Republic
| | - Lukáš Tenora
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague, Czech Republic
| | - Krystyna Wozniak
- Johns Hopkins Drug Discovery, Johns Hopkins University , Baltimore, Maryland 21205, United States
| | - Ying Wu
- Johns Hopkins Drug Discovery, Johns Hopkins University , Baltimore, Maryland 21205, United States
| | - Elie Pommier
- Johns Hopkins Drug Discovery, Johns Hopkins University , Baltimore, Maryland 21205, United States
| | - Dana Ferraris
- Department of Chemistry, McDaniel College , Westminster, Maryland 21157, United States
| | - Rana Rais
- Johns Hopkins Drug Discovery, Johns Hopkins University , Baltimore, Maryland 21205, United States.,Johns Hopkins Department of Neurology, Johns Hopkins University , Baltimore, Maryland 21205, United States
| | - Barbara S Slusher
- Johns Hopkins Drug Discovery, Johns Hopkins University , Baltimore, Maryland 21205, United States.,Johns Hopkins Department of Neurology, Johns Hopkins University , Baltimore, Maryland 21205, United States
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9
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Hollinger KR, Alt J, Riehm AM, Slusher BS, Kaplin AI. Dose-dependent inhibition of GCPII to prevent and treat cognitive impairment in the EAE model of multiple sclerosis. Brain Res 2016; 1635:105-12. [PMID: 26826008 DOI: 10.1016/j.brainres.2016.01.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 01/13/2016] [Accepted: 01/20/2016] [Indexed: 11/19/2022]
Abstract
There are no treatments for cognitive impairment in multiple sclerosis (MS). Novel treatments can be evaluated in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS that displays both physical and cognitive impairments. Inhibition of the neuropeptidase glutamate carboxypeptidase II (GCPII) has previously been shown to ameliorate cognitive impairment in EAE, but dosing has not yet been optimized and only a prevention treatment paradigm has been explored. In the study described herein, the dose response of the GCPII inhibitor 2-(phosphonomethyl)pentanedioic acid (2-PMPA) was evaluated for preventing cognitive impairment in EAE mice. Mice were immunized and received daily injections of vehicle or 2-PMPA (10, 30, 100, or 300 mg/kg) from the time of immunization (i.e. day 0). Although no doses of the drug altered physical disease severity, the 100mg/kg dose was most efficacious at preventing cognitive impairments in Barnes maze performance. Dose-related increases in brain NAAG levels were observed in post-mortem analysis, confirming target engagement. Using the 100mg/kg dose, we subsequently evaluated 2-PMPA׳s ability to treat EAE-induced symptoms by commencing treatment after the onset of physical signs of EAE (i.e. day 14). Mice were immunized for EAE and received daily injections of vehicle or 100mg/kg 2-PMPA starting two weeks post-immunization. Significant improvements in both cognitive performance and increases in brain NAAG levels were observed. GCPII inhibition is a promising treatment for cognitive impairment in MS, and doses providing equivalent exposures to 100mg/kg 2-PMPA in mice should be evaluated in clinical studies for the prevention and/or treatment of MS-related cognitive impairment.
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Affiliation(s)
- Kristen R Hollinger
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD 21287, USA; Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Jesse Alt
- Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Alison M Riehm
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Barbara S Slusher
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD 21287, USA; Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA; Johns Hopkins Drug Discovery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Adam I Kaplin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD 21287, USA; Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA.
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10
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Still NAAG’ing After All These Years. NEUROPSYCHOPHARMACOLOGY: A TRIBUTE TO JOSEPH T. COYLE 2016; 76:215-55. [DOI: 10.1016/bs.apha.2016.01.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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11
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N -acetyl-aspartyl-glutamate and inhibition of glutamate carboxypeptidases protects against soman-induced neuropathology. Neurotoxicology 2015; 48:180-91. [DOI: 10.1016/j.neuro.2015.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/26/2015] [Accepted: 03/13/2015] [Indexed: 12/31/2022]
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12
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Gao Y, Xu S, Cui Z, Zhang M, Lin Y, Cai L, Wang Z, Luo X, Zheng Y, Wang Y, Luo Q, Jiang J, Neale JH, Zhong C. Mice lacking glutamate carboxypeptidase II develop normally, but are less susceptible to traumatic brain injury. J Neurochem 2015; 134:340-53. [PMID: 25872793 DOI: 10.1111/jnc.13123] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 04/04/2015] [Accepted: 04/08/2015] [Indexed: 11/26/2022]
Affiliation(s)
- Yang Gao
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
| | - Siyi Xu
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
| | - Zhenwen Cui
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
| | - Mingkun Zhang
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
| | - Yingying Lin
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
| | - Lei Cai
- Shanghai Research Center for Model Organisms; Shanghai China
| | - Zhugang Wang
- Shanghai Research Center for Model Organisms; Shanghai China
| | - Xingguang Luo
- Department of Psychiatry; Yale University School of Medicine; West Haven Connecticut USA
| | - Yan Zheng
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
| | - Yong Wang
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
| | - Qizhong Luo
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
| | - Jiyao Jiang
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
| | - Joseph H. Neale
- Department of Biology; Georgetown University; Washington DC USA
| | - Chunlong Zhong
- Department of Neurosurgery; Ren Ji Hospital; School of Medicine; Shanghai Jiao Tong University; Shanghai China
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13
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Jia F, Yin YH, Gao GY, Wang Y, Cen L, Jiang JY. MMP-9 inhibitor SB-3CT attenuates behavioral impairments and hippocampal loss after traumatic brain injury in rat. J Neurotrauma 2014; 31:1225-34. [PMID: 24661104 DOI: 10.1089/neu.2013.3230] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The aim of this study was to evaluate the potential efficacy of SB-3CT, a matrix metallopeptidase 9 inhibitor, on behavioral and histological outcomes after traumatic brain injury (TBI) in rats. Adult male Sprague-Dawley rats were randomly divided into three groups (n=15/group): TBI with SB-3CT treatment, TBI with saline, and sham injury. The TBI model was induced by a fluid percussion TBI device. SB-3CT (50 mg/kg in 10% dimethyl sulfoxide) was administered intraperitoneally at 30 min, 6 h, and 12 h after the TBI. Motor function (beam-balance/beam-walk tests) and spatial learning/memory (Morris water maze) were assessed on post-operative Days 1-5 and 11-15, respectively. Fluoro-Jade staining, immunofluorescence, and cresyl violet-staining were carried out for histopathological evaluation at 24 h, 72 h, and 15 days after TBI, respectively. It was shown that TBI can result in significant behavioral deficit induced by acute neurodegeneration, increased expression of cleaved caspase-3, and long-term neuronal loss. SB-3CT intervention via the current regime provides robust behavioral protection and hippocampal neurons preservation from the deleterious effects of TBI. Hence, the efficacy of SB-3CT on TBI prognosis could be ascertained. It is believed that the current study adds to the growing literature in identifying SB-3CT as a potential therapy for human brain injury.
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Affiliation(s)
- Feng Jia
- 1 Department of Neurosurgery, Shanghai JiaoTong University , Shanghai, China
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14
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Pavlicek J, Ptacek J, Cerny J, Byun Y, Skultetyova L, Pomper MG, Lubkowski J, Barinka C. Structural characterization of P1'-diversified urea-based inhibitors of glutamate carboxypeptidase II. Bioorg Med Chem Lett 2014; 24:2340-5. [PMID: 24731280 DOI: 10.1016/j.bmcl.2014.03.066] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 03/19/2014] [Accepted: 03/20/2014] [Indexed: 11/26/2022]
Abstract
Urea-based inhibitors of human glutamate carboxypeptidase II (GCPII) have advanced into clinical trials for imaging metastatic prostate cancer. In parallel efforts, agents with increased lipophilicity have been designed and evaluated for targeting GCPII residing within the neuraxis. Here we report the structural and computational characterization of six complexes between GCPII and P1'-diversified urea-based inhibitors that have the C-terminal glutamate replaced by more hydrophobic moieties. The X-ray structures are complemented by quantum mechanics calculations that provide a quantitative insight into the GCPII/inhibitor interactions. These data can be used for the rational design of novel glutamate-free GCPII inhibitors with tailored physicochemical properties.
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Affiliation(s)
- Jiri Pavlicek
- Institute of Biotechnology, Academy of Sciences of the Czech Republic, v.v.i., Laboratory of Structural Biology, Vídeňská 1083, 14220 Prague 4, Czech Republic
| | - Jakub Ptacek
- Institute of Biotechnology, Academy of Sciences of the Czech Republic, v.v.i., Laboratory of Structural Biology, Vídeňská 1083, 14220 Prague 4, Czech Republic
| | - Jiri Cerny
- Institute of Biotechnology, Academy of Sciences of the Czech Republic, v.v.i., Laboratory of Structural Biology, Vídeňská 1083, 14220 Prague 4, Czech Republic
| | - Youngjoo Byun
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, 1550 Orleans Street, Baltimore, MD 21231, USA; College of Pharmacy, Korea University, 2511 Sejong-ro, Sejong 339-700, South Korea
| | - Lubica Skultetyova
- Institute of Biotechnology, Academy of Sciences of the Czech Republic, v.v.i., Laboratory of Structural Biology, Vídeňská 1083, 14220 Prague 4, Czech Republic
| | - Martin G Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, 1550 Orleans Street, Baltimore, MD 21231, USA
| | - Jacek Lubkowski
- Center for Cancer Research, Frederick National Laboratory for Cancer Research, Macromolecular Crystallography Laboratory, Frederick, MD 21702, USA
| | - Cyril Barinka
- Institute of Biotechnology, Academy of Sciences of the Czech Republic, v.v.i., Laboratory of Structural Biology, Vídeňská 1083, 14220 Prague 4, Czech Republic.
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15
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Huang XJ, Li WP, Lin Y, Feng JF, Jia F, Mao Q, Jiang JY. Blockage of the upregulation of voltage-gated sodium channel nav1.3 improves outcomes after experimental traumatic brain injury. J Neurotrauma 2013; 31:346-57. [PMID: 24313291 DOI: 10.1089/neu.2013.2899] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Excessive active voltage-gated sodium channels are responsible for the cellular abnormalities associated with secondary brain injury following traumatic brain injury (TBI). We previously presented evidence that significant upregulation of Nav1.3 expression occurs in the rat cortex at 2 h and 12 h post-TBI and is correlated with TBI severity. In our current study, we tested the hypothesis that blocking upregulation of Nav1.3 expression in vivo in the acute stage post-TBI attenuates the secondary brain injury associated with TBI. We administered either antisense oligodeoxynucleotides (ODN) targeting Nav1.3 or artificial cerebrospinal fluid (aCSF) at 2 h, 4 h, 6 h, and 8 h following TBI. Control sham animals received aCSF administration at the same time points. At 12 h post-TBI, Nav1.3 messenger ribonucleic acid (mRNA) levels in bilateral hippocampi of the aCSF group were significantly elevated, compared with the sham and ODN groups (p<0.01). However, the Nav1.3 mRNA levels in the uninjured contralateral hippocampus of the ODN group were significantly lowered, compared with the sham group (p<0.01). Treatment with antisense ODN significantly decreased the number of degenerating neurons in the ipsilateral hippocampal CA3 and hilar region (p<0.01). A set of left-to-right ratio value analyzed by magnetic resonance imaging T2 image on one day, three days, and seven days post-TBI showed marked edema in the ipsilateral hemisphere of the aCSF group, compared with that of the ODN group (p<0.05). The Morris water maze memory retention test showed that both the aCSF and ODN groups took longer to find a hidden platform, compared with the sham group (p<0.01). However, latency in the aCSF group was significantly higher than in the ODN group (p<0.05). Our in vivo Nav1.3 inhibition studies suggest that therapeutic strategies to block upregulation of Nav1.3 expression in the brain may improve outcomes following TBI.
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Affiliation(s)
- Xian-Jian Huang
- 1 Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, China
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16
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Walker KR, Tesco G. Molecular mechanisms of cognitive dysfunction following traumatic brain injury. Front Aging Neurosci 2013; 5:29. [PMID: 23847533 PMCID: PMC3705200 DOI: 10.3389/fnagi.2013.00029] [Citation(s) in RCA: 179] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/18/2013] [Indexed: 12/12/2022] Open
Abstract
Traumatic brain injury (TBI) results in significant disability due to cognitive deficits particularly in attention, learning and memory, and higher-order executive functions. The role of TBI in chronic neurodegeneration and the development of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic Lateral Sclerosis (ALS) and most recently chronic traumatic encephalopathy (CTE) is of particular importance. However, despite significant effort very few therapeutic options exist to prevent or reverse cognitive impairment following TBI. In this review, we present experimental evidence of the known secondary injury mechanisms which contribute to neuronal cell loss, axonal injury, and synaptic dysfunction and hence cognitive impairment both acutely and chronically following TBI. In particular we focus on the mechanisms linking TBI to the development of two forms of dementia: AD and CTE. We provide evidence of potential molecular mechanisms involved in modulating Aβ and Tau following TBI and provide evidence of the role of these mechanisms in AD pathology. Additionally we propose a mechanism by which Aβ generated as a direct result of TBI is capable of exacerbating secondary injury mechanisms thereby establishing a neurotoxic cascade that leads to chronic neurodegeneration.
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Affiliation(s)
- Kendall R Walker
- Alzheimer's Disease Research Laboratory, Department of Neuroscience, Tufts University School of Medicine Boston, MA, USA
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Garay PA, Hsiao EY, Patterson PH, McAllister AK. Maternal immune activation causes age- and region-specific changes in brain cytokines in offspring throughout development. Brain Behav Immun 2013; 31:54-68. [PMID: 22841693 PMCID: PMC3529133 DOI: 10.1016/j.bbi.2012.07.008] [Citation(s) in RCA: 247] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 07/17/2012] [Accepted: 07/18/2012] [Indexed: 01/16/2023] Open
Abstract
Maternal infection is a risk factor for autism spectrum disorder (ASD) and schizophrenia (SZ). Indeed, modeling this risk factor in mice through maternal immune activation (MIA) causes ASD- and SZ-like neuropathologies and behaviors in the offspring. Although MIA upregulates pro-inflammatory cytokines in the fetal brain, whether MIA leads to long-lasting changes in brain cytokines during postnatal development remains unknown. Here, we tested this possibility by measuring protein levels of 23 cytokines in the blood and three brain regions from offspring of poly(I:C)- and saline-injected mice at five postnatal ages using multiplex arrays. Most cytokines examined are present in sera and brains throughout development. MIA induces changes in the levels of many cytokines in the brains and sera of offspring in a region- and age-specific manner. These MIA-induced changes follow a few, unexpected and distinct patterns. In frontal and cingulate cortices, several, mostly pro-inflammatory, cytokines are elevated at birth, followed by decreases during periods of synaptogenesis and plasticity, and increases again in the adult. Cytokines are also altered in postnatal hippocampus, but in a pattern distinct from the other regions. The MIA-induced changes in brain cytokines do not correlate with changes in serum cytokines from the same animals. Finally, these MIA-induced cytokine changes are not accompanied by breaches in the blood-brain barrier, immune cell infiltration or increases in microglial density. Together, these data indicate that MIA leads to long-lasting, region-specific changes in brain cytokines in offspring-similar to those reported for ASD and SZ-that may alter CNS development and behavior.
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Affiliation(s)
- Paula A. Garay
- Center for Neuroscience, University of California Davis, Davis, CA 95618, USA
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Gurkoff GG, Feng JF, Van KC, Izadi A, Ghiasvand R, Shahlaie K, Song M, Lowe DA, Zhou J, Lyeth BG. NAAG peptidase inhibitor improves motor function and reduces cognitive dysfunction in a model of TBI with secondary hypoxia. Brain Res 2013; 1515:98-107. [PMID: 23562458 DOI: 10.1016/j.brainres.2013.03.043] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 03/22/2013] [Accepted: 03/27/2013] [Indexed: 10/27/2022]
Abstract
Immediately following traumatic brain injury (TBI) and TBI with hypoxia, there is a rapid and pathophysiological increase in extracellular glutamate, subsequent neuronal damage and ultimately diminished motor and cognitive function. N-acetyl-aspartyl glutamate (NAAG), a prevalent neuropeptide in the CNS, is co-released with glutamate, binds to the presynaptic group II metabotropic glutamate receptor subtype 3 (mGluR3) and suppresses glutamate release. However, the catalytic enzyme glutamate carboxypeptidase II (GCP II) rapidly hydrolyzes NAAG into NAA and glutamate. Inhibition of the GCP II enzyme with NAAG peptidase inhibitors reduces the concentration of glutamate both by increasing the duration of NAAG activity on mGluR3 and by reducing degradation into NAA and glutamate resulting in reduced cell death in models of TBI and TBI with hypoxia. In the following study, rats were administered the NAAG peptidase inhibitor PGI-02776 (10mg/kg) 30 min following TBI combined with a hypoxic second insult. Over the two weeks following injury, PGI-02776-treated rats had significantly improved motor function as measured by increased duration on the rota-rod and a trend toward improved performance on the beam walk. Furthermore, two weeks post-injury, PGI-02776-treated animals had a significant decrease in latency to find the target platform in the Morris water maze as compared to vehicle-treated animals. These findings demonstrate that the application of NAAG peptidase inhibitors can reduce the deleterious motor and cognitive effects of TBI combined with a second hypoxic insult in the weeks following injury.
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Affiliation(s)
- Gene G Gurkoff
- Department of Neurological Surgery, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
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Cao P, Liang Y, Gao X, Zhao MG, Liang GB. Administration of MS-275 improves cognitive performance and reduces cell death following traumatic brain injury in rats. CNS Neurosci Ther 2013; 19:337-45. [PMID: 23551690 DOI: 10.1111/cns.12082] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/02/2013] [Accepted: 02/03/2013] [Indexed: 11/30/2022] Open
Abstract
AIMS The MS-275 is a selective inhibitor of class I histone deacetylases (HDACs), which has been reported as a potential strategy in some central nervous system diseases associated with neurodegeneration and disturbed learning. However, its role in traumatic brain injury is not well defined. In this study, we examined the behavioral-cognitive performance as well as histology outcome in adult rats to evaluate whether postinjury administration of MS-275 (15 and 45 mg/kg) would provide neuroprotection benefits and ameliorate cognitive deficits following fluid percussion injury. METHODS Traumatic brain injury (˜2.15 ATMs) was produced using a fluid percussion device with the lateral orientation. MS-275 was administered (15 and 45 mg/kg) systemically once daily for 7 days starting at 30 min after lateral fluid percussion TBI. Acquisition of spatial learning and memory retention was assessed using the Morris water maze (MWM) on days 10-14 after TBI. Brain tissues were collected and stained with Fluoro-Jade B histofluorescence (for degenerating neurons) at 24 h after injury and cresyl violet (for long-term neuronal survival) on day 14 postinjury. RESULTS Behavioral outcome after TBI revealed MS-275 treatment groups, at all doses examined, performed significantly better in the Morris Water Maze (P < 0.001). Acute histology analysis demonstrated that 45 mg/kg MS-275 significantly reduced the number of degenerating neurons in the ipsilateral CA2-3 hippocampus at 24 h postinjury (P = 0.007). There was a trend for MS-275 to increase the survival of neurons in the CA2-3 hippocampus on 14 days after TBI (P = 0.164). CONCLUSION Our present data highlight the fact that MS-275 may provide neuroprotective effect and improve cognitive performance after TBI. We concluded that MS-275 is a potential novel treatment and will have an ameliorative effect on some of the pathological features associated with TBI.
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Affiliation(s)
- Peng Cao
- Department of Neurosurgery, Shenyang Northern Hospital, Shenyang, China
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20
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Inhibition of glutamate carboxypeptidase II (GCPII) activity as a treatment for cognitive impairment in multiple sclerosis. Proc Natl Acad Sci U S A 2012; 109:20101-6. [PMID: 23169655 DOI: 10.1073/pnas.1209934109] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Half of all patients with multiple sclerosis (MS) experience cognitive impairment, for which there is no pharmacological treatment. Using magnetic resonance spectroscopy (MRS), we examined metabolic changes in the hippocampi of MS patients, compared the findings to performance on a neurocognitive test battery, and found that N-acetylaspartylglutamate (NAAG) concentration correlated with cognitive functioning. Specifically, MS patients with cognitive impairment had low hippocampal NAAG levels, whereas those with normal cognition demonstrated higher levels. We then evaluated glutamate carboxypeptidase II (GCPII) inhibitors, known to increase brain NAAG levels, on cognition in the experimental autoimmune encephalomyelitis (EAE) model of MS. Whereas GCPII inhibitor administration did not affect physical disabilities, it increased brain NAAG levels and dramatically improved learning and memory test performance compared with vehicle-treated EAE mice. These data suggest that NAAG is a unique biomarker for cognitive function in MS and that inhibition of GCPII might be a unique therapeutic strategy for recovery of cognitive function.
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Feng JF, Gurkoff GG, Van KC, Song M, Lowe DA, Zhou J, Lyeth BG. NAAG peptidase inhibitor reduces cellular damage in a model of TBI with secondary hypoxia. Brain Res 2012; 1469:144-52. [PMID: 22750589 DOI: 10.1016/j.brainres.2012.06.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 06/11/2012] [Accepted: 06/15/2012] [Indexed: 11/26/2022]
Abstract
Traumatic brain injury (TBI) leads to a rapid and excessive glutamate elevation in the extracellular milieu, resulting in neuronal degeneration and astrocyte damage. Posttraumatic hypoxia is a clinically relevant secondary insult that increases the magnitude and duration of glutamate release following TBI. N-acetyl-aspartyl glutamate (NAAG), a prevalent neuropeptide in the CNS, suppresses presynaptic glutamate release by its action at the mGluR3 (a group II metabotropic glutamate receptor). However, extracellular NAAG is rapidly converted into NAA and glutamate by the catalytic enzyme glutamate carboxypeptidase II (GCPII) reducing presynaptic inhibition. We previously reported that the GCPII inhibitor ZJ-43 and its prodrug di-ester PGI-02776 reduce the deleterious effects of excessive extracellular glutamate when injected systemically within the first 30 min following injury. We now report that PGI-02776 (10mg/kg) is neuroprotective when administered 30 min post-injury in a model of TBI plus 30 min of hypoxia (FiO(2)=11%). 24h following TBI with hypoxia, significant increases in neuronal cell death in the CA1, CA2/3, CA3c, hilus and dentate gyrus were observed in the ipsilateral hippocampus. Additionally, there was a significant reduction in the number of astrocytes in the ipsilateral CA1, CA2/3 and in the CA3c/hilus/dentate gyrus. Administration of PGI-02776 immediately following the cessation of hypoxia significantly reduced neuronal and astrocytic cell death across all regions of the hippocampus. These findings indicate that NAAG peptidase inhibitors administered post-injury can significantly reduce the deleterious effects of TBI combined with a secondary hypoxic insult.
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Affiliation(s)
- Jun-Feng Feng
- Department of Neurological Surgery, University of California at Davis, One Shields Ave., Davis, CA 95616, USA
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