1
|
Caffeine-Induced Acute and Delayed Responses in Cerebral Metabolism of Control and Schizophrenia-Like Wisket Rats. Int J Mol Sci 2022; 23:ijms23158186. [PMID: 35897774 PMCID: PMC9331118 DOI: 10.3390/ijms23158186] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/21/2022] [Accepted: 07/23/2022] [Indexed: 12/04/2022] Open
Abstract
Recently, morphological impairments have been detected in the brain of a triple-hit rat schizophrenia model (Wisket), and delayed depressive effects of caffeine treatment in both control and Wisket animals have also been shown. The aims of this study were to determine the basal and caffeine-induced acute (30 min) and delayed (24 h) changes in the cerebral 18fluorodeoxyglucose (18F-FDG) uptake by positron emission tomography (PET) in control and Wisket rats. No significant differences were identified in the basal whole-brain metabolism between the two groups, and the metabolism was not modified acutely by a single intraperitoneal caffeine (20 mg/kg) injection in either group. However, one day after caffeine administration, significantly enhanced 18F-FDG uptake was detected in the whole brain and the investigated areas (hippocampus, striatum, thalamus, and hypothalamus) in the control group. Although the Wisket animals showed only moderate enhancements in the 18F-FDG uptake, significantly lower brain metabolism was observed in this group than in the caffeine-treated control group. This study highlights that the basal brain metabolism of Wisket animals was similar to control rats, and that was not influenced acutely by single caffeine treatment at the whole-brain level. Nevertheless, the distinct delayed responsiveness to this psychostimulant in Wisket model rats suggests impaired control of the cerebral metabolism.
Collapse
|
2
|
Fritschi L, Lindmar JH, Scheidl F, Lenk K. Neuronal and Astrocytic Regulations in Schizophrenia: A Computational Modelling Study. Front Cell Neurosci 2021; 15:718459. [PMID: 34512269 PMCID: PMC8428975 DOI: 10.3389/fncel.2021.718459] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/26/2021] [Indexed: 11/15/2022] Open
Abstract
According to the tripartite synapse model, astrocytes have a modulatory effect on neuronal signal transmission. More recently, astrocyte malfunction has been associated with psychiatric diseases such as schizophrenia. Several hypotheses have been proposed on the pathological mechanisms of astrocytes in schizophrenia. For example, post-mortem examinations have revealed a reduced astrocytic density in patients with schizophrenia. Another hypothesis suggests that disease symptoms are linked to an abnormality of glutamate transmission, which is also regulated by astrocytes (glutamate hypothesis of schizophrenia). Electrophysiological findings indicate a dispute over whether the disorder causes an increase or a decrease in neuronal and astrocytic activity. Moreover, there is no consensus as to which molecular pathways and network mechanisms are altered in schizophrenia. Computational models can aid the process in finding the underlying pathological malfunctions. The effect of astrocytes on the activity of neuron-astrocyte networks has been analysed with computational models. These can reproduce experimentally observed phenomena, such as astrocytic modulation of spike and burst signalling in neuron-astrocyte networks. Using an established computational neuron-astrocyte network model, we simulate experimental data of healthy and pathological networks by using different neuronal and astrocytic parameter configurations. In our simulations, the reduction of neuronal or astrocytic cell densities yields decreased glutamate levels and a statistically significant reduction in the network activity. Amplifications of the astrocytic ATP release toward postsynaptic terminals also reduced the network activity and resulted in temporarily increased glutamate levels. In contrast, reducing either the glutamate release or re-uptake in astrocytes resulted in higher network activities. Similarly, an increase in synaptic weights of excitatory or inhibitory neurons raises the excitability of individual cells and elevates the activation level of the network. To conclude, our simulations suggest that the impairment of both neurons and astrocytes disturbs the neuronal network activity in schizophrenia.
Collapse
Affiliation(s)
- Lea Fritschi
- Department of Mathematics, ETH Zurich, Zurich, Switzerland
| | | | - Florian Scheidl
- Department of Computer Science, ETH Zurich, Zurich, Switzerland
| | - Kerstin Lenk
- Computational Biophysics and Imaging Group (CBIG), Faculty of Medicine and Health Technology, BioMediTech, Tampere University, Tampere, Finland
- Institute of Neural Engineering, Graz University of Technology, Graz, Austria
| |
Collapse
|
3
|
Han Z, Chai W, Wang Z, Xiao F, Dai J. Quantum energy levels of glutamate modulate neural biophotonic signals. Photochem Photobiol Sci 2021; 20:343-356. [PMID: 33721274 DOI: 10.1007/s43630-021-00022-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/03/2021] [Indexed: 02/07/2023]
Abstract
Glutamate is the most abundant excitatory neurotransmitter in the brain, and it plays an essential and important role in neural functions. Current studies have shown that glutamate can induce neural biophotonic activity and transmission, which may involve the mechanism of photon quantum brain; however, it is unclear whether such a mechanism follows the principle of quantum mechanics. Here we show that the action of glutamate on its receptors leads to a decrease in its quantum energy levels, and glutamate then partially or completely loses its function to further induce the biophotonic activity in mouse brain slices. The reduced quantum energy levels of glutamate can be restored by direct-current electrical discharges and the use of energy transfer of chloroplast photosynthesis; hence, the quantum energy recovered glutamate can again induce significant biophotonic activity. Furthermore, the changes in quantum energy levels of glutamate are related to the exchange and transfer of electron energy on its active hydrogen atom. These findings suggest that the glutamate-induced neural biophotonic signals may be involved in the transfer of the quantum energy levels of glutamate, which implies a quantum mechanism of neurotransmitter action.
Collapse
Affiliation(s)
- Zhengrong Han
- Wuhan Institute for Neuroscience and Neuroengineering (WINN), South-Central University for Nationalities, Minzu Dadao 182, Wuhan, 430074, China.,Department of Neurobiology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, China
| | - Weitai Chai
- Wuhan Institute for Neuroscience and Neuroengineering (WINN), South-Central University for Nationalities, Minzu Dadao 182, Wuhan, 430074, China.,Department of Neurobiology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, China
| | - Zhuo Wang
- Wuhan Institute for Neuroscience and Neuroengineering (WINN), South-Central University for Nationalities, Minzu Dadao 182, Wuhan, 430074, China.,Department of Neurobiology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, China
| | - Fangyan Xiao
- Wuhan Institute for Neuroscience and Neuroengineering (WINN), South-Central University for Nationalities, Minzu Dadao 182, Wuhan, 430074, China.,Department of Neurobiology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, China
| | - Jiapei Dai
- Wuhan Institute for Neuroscience and Neuroengineering (WINN), South-Central University for Nationalities, Minzu Dadao 182, Wuhan, 430074, China. .,Department of Neurobiology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, China.
| |
Collapse
|
4
|
Hermes DJ, Jacobs IR, Key MC, League AF, Yadav-Samudrala BJ, Xu C, McLane VD, Nass SR, Jiang W, Meeker RB, Ignatowska-Jankowska BM, Lichtman AH, Li Z, Wu Z, Yuan H, Knapp PE, Hauser KF, Fitting S. Escalating morphine dosing in HIV-1 Tat transgenic mice with sustained Tat exposure reveals an allostatic shift in neuroinflammatory regulation accompanied by increased neuroprotective non-endocannabinoid lipid signaling molecules and amino acids. J Neuroinflammation 2020; 17:345. [PMID: 33208151 PMCID: PMC7672881 DOI: 10.1186/s12974-020-01971-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 09/29/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Human immunodeficiency virus type-1 (HIV-1) and opiates cause long-term inflammatory insult to the central nervous system (CNS) and worsen disease progression and HIV-1-related neuropathology. The combination of these proinflammatory factors reflects a devastating problem as opioids have high abuse liability and continue to be prescribed for certain patients experiencing HIV-1-related pain. METHODS Here, we examined the impact of chronic (3-month) HIV-1 transactivator of transcription (Tat) exposure to short-term (8-day), escalating morphine in HIV-1 Tat transgenic mice that express the HIV-1 Tat protein in a GFAP promoter-regulated, doxycycline (DOX)-inducible manner. In addition to assessing morphine-induced tolerance in nociceptive responses organized at spinal (i.e., tail-flick) and supraspinal (i.e., hot-plate) levels, we evaluated neuroinflammation via positron emission tomography (PET) imaging using the [18F]-PBR111 ligand, immunohistochemistry, and cytokine analyses. Further, we examined endocannabinoid (eCB) levels, related non-eCB lipids, and amino acids via mass spectrometry. RESULTS: Tat-expressing [Tat(+)] transgenic mice displayed antinociceptive tolerance in the tail withdrawal and hot-plate assays compared to control mice lacking Tat [Tat(-)]. This tolerance was accompanied by morphine-dependent increases in Iba-1 ± 3-nitrotryosine immunoreactive microglia, and alterations in pro- and anti-inflammatory cytokines, and chemokines in the spinal cord and striatum, while increases in neuroinflammation were absent by PET imaging of [18F]-PBR111 uptake. Tat and morphine exposure differentially affected eCB levels, non-eCB lipids, and specific amino acids in a region-dependent manner. In the striatum, non-eCB lipids were significantly increased by short-term, escalating morphine exposure, including peroxisome proliferator activator receptor alpha (PPAR-α) ligands N-oleoyl ethanolamide (OEA) and N-palmitoyl ethanolamide (PEA), as well as the amino acids phenylalanine and proline. In the spinal cord, Tat exposure increased amino acids leucine and valine, while morphine decreased levels of tyrosine and valine but did not affect eCBs or non-eCB lipids. CONCLUSION Overall results demonstrate that 3 months of Tat exposure increased morphine tolerance and potentially innate immune tolerance evidenced by reductions in specific cytokines (e.g., IL-1α, IL-12p40) and microglial reactivity. In contrast, short-term, escalating morphine exposure acted as a secondary stressor revealing an allostatic shift in CNS baseline inflammatory responsiveness from sustained Tat exposure.
Collapse
Affiliation(s)
- Douglas J Hermes
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Ian R Jacobs
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Megan C Key
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Alexis F League
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | | | - Changqing Xu
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Virginia D McLane
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Sara R Nass
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Wei Jiang
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, USA
- Division of Infectious Diseases, Department of Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - Rick B Meeker
- Department of Neurology, University of North Carolina, Chapel Hill, NC, USA
| | | | - Aron H Lichtman
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Zibo Li
- Department of Radiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Zhanhong Wu
- Department of Radiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Hong Yuan
- Department of Radiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Pamela E Knapp
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA, USA
| | - Kurt F Hauser
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA, USA
| | - Sylvia Fitting
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA.
| |
Collapse
|
5
|
Joo YH, Kim YK, Choi IG, Kim HJ, Son YD, Kim HK, Cumming P, Kim JH. In vivo glucose metabolism and glutamate levels in mGluR5 knockout mice: a multimodal neuroimaging study using [ 18F]FDG microPET and MRS. EJNMMI Res 2020; 10:116. [PMID: 33006705 PMCID: PMC7532251 DOI: 10.1186/s13550-020-00716-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/24/2020] [Indexed: 12/21/2022] Open
Abstract
Background Perturbed functional coupling between the metabotropic glutamate receptor-5 (mGluR5) and N-methyl-d-aspartate (NMDA) receptor-mediated excitatory glutamatergic neurotransmission may contribute to the pathophysiology of psychiatric disorders such as schizophrenia. We aimed to establish the functional interaction between mGluR5 and NMDA receptors in brain of mice with genetic ablation of the mGluR5. Methods We first measured the brain glutamate levels with magnetic resonance spectroscopy (MRS) in mGluR5 knockout (KO) and wild-type (WT) mice. Then, we assessed brain glucose metabolism with [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography before and after the acute administration of an NMDA antagonist, MK-801 (0.5 mg/kg), in the same mGluR5 KO and WT mice. Results Between-group comparisons showed no significant differences in [18F]FDG standardized uptake values (SUVs) in brain of mGluR5 KO and WT mice at baseline, but widespread reductions in mGluR5 KO mice compared to WT mice after MK-801 administration (p < 0.05). The baseline glutamate levels did not differ significantly between the two groups. However, there were significant negative correlations between baseline prefrontal glutamate levels and regional [18F]FDG SUVs in mGluR5 KO mice (p < 0.05), but no such correlations in WT mice. Fisher’s Z-transformation analysis revealed significant between-group differences in these correlations (p < 0.05). Conclusions This is the first multimodal neuroimaging study in mGluR5 KO mice and the first report on the association between cerebral glucose metabolism and glutamate levels in living rodents. The results indicate that mGluR5 KO mice respond to NMDA antagonism with reduced cerebral glucose metabolism, suggesting that mGluR5 transmission normally moderates the net effects of NMDA receptor antagonism on neuronal activity. The negative correlation between glutamate levels and glucose metabolism in mGluR5 KO mice at baseline may suggest an unmasking of an inhibitory component of the glutamatergic regulation of neuronal energy metabolism.
Collapse
Affiliation(s)
- Yo-Han Joo
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea
| | - Yun-Kwan Kim
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea
| | - In-Gyu Choi
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea
| | - Hyeon-Jin Kim
- Department of Biomedical Sciences, Seoul National University, Seoul, Republic of Korea.,Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Young-Don Son
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea.,Department of Biomedical Engineering, College of Health Science, Gachon University, Incheon, Republic of Korea.,Gachon Advanced Institute for Health Science and Technology, Graduate School, Gachon University, Incheon, South Korea
| | - Hang-Keun Kim
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea.,Department of Biomedical Engineering, College of Health Science, Gachon University, Incheon, Republic of Korea.,Gachon Advanced Institute for Health Science and Technology, Graduate School, Gachon University, Incheon, South Korea
| | - Paul Cumming
- Institute of Nuclear Medicine, Inselspital, Bern University, Bern, Switzerland.,School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia
| | - Jong-Hoon Kim
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea. .,Gachon Advanced Institute for Health Science and Technology, Graduate School, Gachon University, Incheon, South Korea. .,Department of Psychiatry, Research Center for Psychiatry and Behavioral Sciences, Neuroscience Research Institute, Gachon University College of Medicine, Gil Medical Center, Gachon University, 1198 Guwol-dong, Namdong-gu, Incheon, 405-760, South Korea.
| |
Collapse
|
6
|
Perkins DO, Jeffries CD, Do KQ. Potential Roles of Redox Dysregulation in the Development of Schizophrenia. Biol Psychiatry 2020; 88:326-336. [PMID: 32560962 PMCID: PMC7395886 DOI: 10.1016/j.biopsych.2020.03.016] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 03/03/2020] [Accepted: 03/22/2020] [Indexed: 12/20/2022]
Abstract
Converging evidence implicates redox dysregulation as a pathological mechanism driving the emergence of psychosis. Increased oxidative damage and decreased capacity of intracellular redox modulatory systems are consistent findings in persons with schizophrenia as well as in persons at clinical high risk who subsequently developed frank psychosis. Levels of glutathione, a key regulator of cellular redox status, are reduced in the medial prefrontal cortex, striatum, and thalamus in schizophrenia. In humans with schizophrenia and in rodent models recapitulating various features of schizophrenia, redox dysregulation is linked to reductions of parvalbumin containing gamma-aminobutyric acid (GABA) interneurons and volumes of their perineuronal nets, white matter abnormalities, and microglia activation. Importantly, the activity of transcription factors, kinases, and phosphatases regulating diverse aspects of neurodevelopment and synaptic plasticity varies according to cellular redox state. Molecules regulating interneuron function under redox control include NMDA receptor subunits GluN1 and GluN2A as well as KEAP1 (regulator of transcription factor NRF2). In a rodent schizophrenia model characterized by impaired glutathione synthesis, the Gclm knockout mouse, oxidative stress activated MMP9 (matrix metalloprotease 9) via its redox-responsive regulatory sites, causing a cascade of molecular events leading to microglia activation, perineural net degradation, and impaired NMDA receptor function. Molecular pathways under redox control are implicated in the etiopathology of schizophrenia and are attractive drug targets for individualized drug therapy trials in the contexts of prevention and treatment of psychosis.
Collapse
Affiliation(s)
- Diana O. Perkins
- corresponding author: CB 7160, Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, Office: 919-962-1401, Cell: 919-360-1602,
| | - Clark D. Jeffries
- Renaissance Computing Institute, University of North Carolina, Chapel Hill NC
| | - Kim Q. Do
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital-CHUV, Prilly-Lausanne, Switzerland
| |
Collapse
|
7
|
Translating preclinical findings in clinically relevant new antipsychotic targets: focus on the glutamatergic postsynaptic density. Implications for treatment resistant schizophrenia. Neurosci Biobehav Rev 2019; 107:795-827. [DOI: 10.1016/j.neubiorev.2019.08.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 07/20/2019] [Accepted: 08/22/2019] [Indexed: 02/07/2023]
|
8
|
Kosten L, Chowdhury GMI, Mingote S, Staelens S, Rothman DL, Behar KL, Rayport S. Glutaminase activity in GLS1 Het mouse brain compared to putative pharmacological inhibition by ebselen using ex vivo MRS. Neurochem Int 2019; 129:104508. [PMID: 31326460 DOI: 10.1016/j.neuint.2019.104508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/28/2019] [Accepted: 07/18/2019] [Indexed: 01/13/2023]
Abstract
Glutaminase mediates the recycling of neurotransmitter glutamate, supporting most excitatory neurotransmission in the mammalian central nervous system. A constitutive heterozygous reduction in GLS1 engenders in mice a model of schizophrenia resilience and associated increases in Gln, reductions in Glu and activity-dependent attenuation of excitatory synaptic transmission. Hippocampal brain slices from GLS1 heterozygous mice metabolize less Gln to Glu. Whether glutaminase activity is diminished in the intact brain in GLS1 heterozygous mice has not been assessed, nor the regional impact. Moreover, it is not known whether pharmacological inhibition would mimic the genetic reduction. We addressed this using magnetic resonance spectroscopy to assess amino acid content and 13C-acetate loading to assess glutaminase activity, in multiple brain regions. Glutaminase activity was reduced significantly in the hippocampus of GLS1 heterozygous mice, while acute treatment with the putative glutaminase inhibitor ebselen did not impact glutaminase activity, but did significantly increase GABA. This approach identifies a molecular imaging strategy for testing target engagement by comparing genetic and pharmacological inhibition, across brain regions.
Collapse
Affiliation(s)
- Lauren Kosten
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Golam M I Chowdhury
- Department of Psychiatry, Magnetic Resonance Research Center, Yale University School of Medicine, USA
| | - Susana Mingote
- Department of Psychiatry, Columbia University, USA; Department of Molecular Therapeutics, NYS Psychiatric Institute, USA; Neuroscience, Advanced Science Research Center at the Graduate Center of the City University of New York, USA
| | - Steven Staelens
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Douglas L Rothman
- Department of Radiology & Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, USA
| | - Kevin L Behar
- Department of Psychiatry, Magnetic Resonance Research Center, Yale University School of Medicine, USA.
| | - Stephen Rayport
- Department of Psychiatry, Columbia University, USA; Department of Molecular Therapeutics, NYS Psychiatric Institute, USA.
| |
Collapse
|
9
|
Servaes S, Kara F, Glorie D, Stroobants S, Van Der Linden A, Staelens S. In Vivo Preclinical Molecular Imaging of Repeated Exposure to an N-methyl-d-aspartate Antagonist and a Glutaminase Inhibitor as Potential Glutamatergic Modulators. J Pharmacol Exp Ther 2018; 368:382-390. [PMID: 30552293 DOI: 10.1124/jpet.118.252635] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 11/19/2018] [Indexed: 12/30/2022] Open
Abstract
Glutamate is the principal excitatory neurotransmitter in the brain and is at the base of a wide variety of neuropathologies, including epilepsy, autism, Fragile X, and obsessive compulsive disorder. Glutamate has also become the target for novel drugs in treatment and in fundamental research settings. However, much remains unknown on the working mechanisms of these drugs and the effects of chronic administration on the glutamatergic system. This study investigated the chronic effects of two glutamate-modulating drugs with imaging techniques to further clarify their working mechanisms for future research opportunities. Animals were exposed to saline (1 ml/kg), (5S,10R)-(+)-5-Methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801) (0.3 mg/kg), or ebselen (10 mg/kg) for 7 consecutive days. At the sixth injection, animals underwent a positron emission tomography (PET)/computed tomography (CT) with (3-(6-methyl-pyridin-2-ylethynyl)-cyclohex-2-enone-O-11C-methyl-oxime) (ABP-688) to visualize the metabotropic G protein-coupled glutamate receptor 5 (mGluR5). After the seventh injection, animals underwent a magnetic resonance spectroscopy (MRS) scan to visualize glutamate and glutamine content. Afterward, results were verified by mGluR5 immunohistochemistry (IHC). PET/CT analysis revealed that animals receiving chronic MK-801 or ebselen had a significant (P < 0.05) higher binding potential (2.90 ± 0.47 and 2.87 ± 0.46, respectively) when compared with saline (1.97 ± 0.39) in the caudate putamen. This was confirmed by mGluR5 IHC, with 60.83% ± 6.30% of the area being highlighted for ebselen and 57.14% ± 9.23% for MK-801 versus 50.21% ± 5.71% for the saline group. MRS displayed significant changes on the glutamine level when comparing chronic ebselen (2.20 ± 0.40 µmol/g) to control (2.72 ± 0.34 µmol/g). Therefore, although no direct effects on glutamate were visualized, the changes in glutamine suggest changes in the total glutamate-glutamine pool. This highlights the potential of both drugs to modulate glutamatergic pathologies.
Collapse
Affiliation(s)
- Stijn Servaes
- Molecular Imaging Center Antwerp (Sti.S., D.G., Si.S., Ste.S.) and Bio-Imaging Laboratory (F.K., A.V.D.L.), University of Antwerp, Wilrijk, Antwerp, Belgium; and Department of Nuclear Medicine, University Hospital Antwerp, Edegem, Antwerp, Belgium (Si.S.)
| | - Firat Kara
- Molecular Imaging Center Antwerp (Sti.S., D.G., Si.S., Ste.S.) and Bio-Imaging Laboratory (F.K., A.V.D.L.), University of Antwerp, Wilrijk, Antwerp, Belgium; and Department of Nuclear Medicine, University Hospital Antwerp, Edegem, Antwerp, Belgium (Si.S.)
| | - Dorien Glorie
- Molecular Imaging Center Antwerp (Sti.S., D.G., Si.S., Ste.S.) and Bio-Imaging Laboratory (F.K., A.V.D.L.), University of Antwerp, Wilrijk, Antwerp, Belgium; and Department of Nuclear Medicine, University Hospital Antwerp, Edegem, Antwerp, Belgium (Si.S.)
| | - Sigrid Stroobants
- Molecular Imaging Center Antwerp (Sti.S., D.G., Si.S., Ste.S.) and Bio-Imaging Laboratory (F.K., A.V.D.L.), University of Antwerp, Wilrijk, Antwerp, Belgium; and Department of Nuclear Medicine, University Hospital Antwerp, Edegem, Antwerp, Belgium (Si.S.)
| | - Annemie Van Der Linden
- Molecular Imaging Center Antwerp (Sti.S., D.G., Si.S., Ste.S.) and Bio-Imaging Laboratory (F.K., A.V.D.L.), University of Antwerp, Wilrijk, Antwerp, Belgium; and Department of Nuclear Medicine, University Hospital Antwerp, Edegem, Antwerp, Belgium (Si.S.)
| | - Steven Staelens
- Molecular Imaging Center Antwerp (Sti.S., D.G., Si.S., Ste.S.) and Bio-Imaging Laboratory (F.K., A.V.D.L.), University of Antwerp, Wilrijk, Antwerp, Belgium; and Department of Nuclear Medicine, University Hospital Antwerp, Edegem, Antwerp, Belgium (Si.S.)
| |
Collapse
|
10
|
Kosten L, Deleye S, Stroobants S, Wyffels L, Mingote S, Rayport S, Staelens S. Molecular Imaging of mGluR5 Availability with [ 11C]ABP68 in Glutaminase Heterozygous Mice. Cell Mol Neurobiol 2018; 39:255-263. [PMID: 30552621 DOI: 10.1007/s10571-018-0645-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 12/10/2018] [Indexed: 11/26/2022]
Abstract
Many PET tracers enable determination of fluctuations in neurotransmitter release, yet glutamate specifically can not be visualized in a noninvasive manner. Several studies point to the possibility of visualizing fluctuations in glutamate release by changes in affinity of the mGluR5 radioligand [11C]ABP688. These studies use pharmacological challenges to alter glutamate levels, and so probe release, but have not measured chronic alterations in receptor occupancy due to altered neurotransmission relevant to chronic neuropsychiatric disorders or their treatment. In this regard, the GLS1 heterozygous mouse has known reductions in activity of the glutamate-synthetic enzyme glutaminase, brain glutamate levels and release. We imaged this model to elucidate glutamatergic systems. Dynamic [11C]ABP688 microPET scans were performed for mGluR5. Western blot was used as an ex vivo validation. No significant differences were found in BPND between WT and GLS1 Hets. SPM showed voxel-wise increased in BPND in GLS1 Hets compared to WT consistent with lower synaptic glutamate. This was not due to alterations in mGluR5 levels, as western blot results showed lower mGluR5 levels in GLS1 Hets. We conclude that because of the chronic glutaminase deficiency and subsequent decrease in glutamate, the mGluR5 protein levels are lowered. Due to these decreased endogenous glutamate levels, however, there is increased [11C]ABP688 binding to the allosteric site in selected regions. We speculate that lower endogenous glutamate leads to less conformational change to the receptors, and thus higher availability of the binding site. The lower mGluR5 levels, however, lessen [11C]ABP688 binding in GLS1 Hets, in part masking the increase in binding due to diminished endogenous glutamate levels as confirmed with voxel-wise analysis.
Collapse
Affiliation(s)
- Lauren Kosten
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Steven Deleye
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Sigrid Stroobants
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
- Department of Nuclear Medicine, University Hospital Antwerp, Antwerp, Belgium
| | - Leonie Wyffels
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
- Department of Nuclear Medicine, University Hospital Antwerp, Antwerp, Belgium
| | - Susana Mingote
- Department of Psychiatry, Columbia University, New York, USA
- Molecular Therapeutics, NYS Psychiatric Institute, New York, USA
| | - Stephen Rayport
- Department of Psychiatry, Columbia University, New York, USA
- Molecular Therapeutics, NYS Psychiatric Institute, New York, USA
| | - Steven Staelens
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium.
| |
Collapse
|
11
|
Bertoglio D, Kosten L, Verhaeghe J, Thomae D, Wyffels L, Stroobants S, Wityak J, Dominguez C, Mrzljak L, Staelens S. Longitudinal Characterization of mGluR5 Using 11C-ABP688 PET Imaging in the Q175 Mouse Model of Huntington Disease. J Nucl Med 2018; 59:1722-1727. [DOI: 10.2967/jnumed.118.210658] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/22/2018] [Indexed: 11/16/2022] Open
|