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Wachsmuth L, Hebbelmann L, Prade J, Kohnert LC, Lambers H, Lüttjohann A, Budde T, Hess A, Faber C. Epilepsy-related functional brain network alterations are already present at an early age in the GAERS rat model of genetic absence epilepsy. Front Neurol 2024; 15:1355862. [PMID: 38529038 PMCID: PMC10961455 DOI: 10.3389/fneur.2024.1355862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 02/16/2024] [Indexed: 03/27/2024] Open
Abstract
Introduction Genetic Absence Epilepsy Rats from Strasbourg (GAERS) represent a model of genetic generalized epilepsy. The present longitudinal study in GAERS and age-matched non-epileptic controls (NEC) aimed to characterize the epileptic brain network using two functional measures, resting state-functional magnetic resonance imaging (rs-fMRI) and manganese-enhanced MRI (MEMRI) combined with morphometry, and to investigate potential brain network alterations, following long-term seizure activity. Methods Repeated rs-fMRI measurements at 9.4 T between 3 and 8 months of age were combined with MEMRI at the final time point of the study. We used graph theory analysis to infer community structure and global and local network parameters from rs-fMRI data and compared them to brain region-wise manganese accumulation patterns and deformation-based morphometry (DBM). Results Functional connectivity (FC) was generally higher in GAERS when compared to NEC. Global network parameters and community structure were similar in NEC and GAERS, suggesting efficiently functioning networks in both strains. No progressive FC changes were observed in epileptic animals. Network-based statistics (NBS) revealed stronger FC within the cortical community, including regions of association and sensorimotor cortex, and with basal ganglia and limbic regions in GAERS, irrespective of age. Higher manganese accumulation in GAERS than in NEC was observed at 8 months of age, consistent with higher overall rs-FC, particularly in sensorimotor cortex and association cortex regions. Functional measures showed less similarity in subcortical regions. Whole brain volumes of 8 months-old GAERS were higher when compared to age-matched NEC, and DBM revealed increased volumes of several association and sensorimotor cortex regions and of the thalamus. Discussion rs-fMRI, MEMRI, and volumetric data collectively suggest the significance of cortical networks in GAERS, which correlates with an increased fronto-central connectivity in childhood absence epilepsy (CAE). Our findings also verify involvement of basal ganglia and limbic regions. Epilepsy-related network alterations are already present in juvenile animals. Consequently, this early condition seems to play a greater role in dynamic brain function than chronic absence seizures.
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Affiliation(s)
- Lydia Wachsmuth
- Clinic of Radiology, University of Münster, Münster, Germany
| | - Leo Hebbelmann
- Clinic of Radiology, University of Münster, Münster, Germany
| | - Jutta Prade
- Department of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Laura C. Kohnert
- Department of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | | | | | - Thomas Budde
- Institute of Physiology I, University of Münster, Münster, Germany
| | - Andreas Hess
- Department of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
- Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
- FAU NeW – Research Center for New Bioactive Compounds, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Cornelius Faber
- Clinic of Radiology, University of Münster, Münster, Germany
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Manninen E, Chary K, De Feo R, Hämäläinen E, Andrade P, Paananen T, Sierra A, Tohka J, Gröhn O, Pitkänen A. Acute Hippocampal Damage as a Prognostic Biomarker for Cognitive Decline but Not for Epileptogenesis after Experimental Traumatic Brain Injury. Biomedicines 2022; 10:2721. [PMID: 36359242 PMCID: PMC9687561 DOI: 10.3390/biomedicines10112721] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/23/2022] [Accepted: 10/25/2022] [Indexed: 11/02/2023] Open
Abstract
It is necessary to develop reliable biomarkers for epileptogenesis and cognitive impairment after traumatic brain injury when searching for novel antiepileptogenic and cognition-enhancing treatments. We hypothesized that a multiparametric magnetic resonance imaging (MRI) analysis along the septotemporal hippocampal axis could predict the development of post-traumatic epilepsy and cognitive impairment. We performed quantitative T2 and T2* MRIs at 2, 7 and 21 days, and diffusion tensor imaging at 7 and 21 days after lateral fluid-percussion injury in male rats. Morris water maze tests conducted between 35-39 days post-injury were used to diagnose cognitive impairment. One-month-long continuous video-electroencephalography monitoring during the 6th post-injury month was used to diagnose epilepsy. Single-parameter and regularized multiple linear regression models were able to differentiate between sham-operated and brain-injured rats. In the ipsilateral hippocampus, differentiation between the groups was achieved at most septotemporal locations (cross-validated area under the receiver operating characteristic curve (AUC) 1.0, 95% confidence interval 1.0-1.0). In the contralateral hippocampus, the highest differentiation was evident in the septal pole (AUC 0.92, 95% confidence interval 0.82-0.97). Logistic regression analysis of parameters imaged at 3.4 mm from the contralateral hippocampus's temporal end differentiated between the cognitively impaired rats and normal rats (AUC 0.72, 95% confidence interval 0.55-0.84). Neither single nor multiparametric approaches could identify the rats that would develop post-traumatic epilepsy. Multiparametric MRI analysis of the hippocampus can be used to identify cognitive impairment after an experimental traumatic brain injury. This information can be used to select subjects for preclinical trials of cognition-improving interventions.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Asla Pitkänen
- A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland
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Yang J, Li Q. Manganese-Enhanced Magnetic Resonance Imaging: Application in Central Nervous System Diseases. Front Neurol 2020; 11:143. [PMID: 32161572 PMCID: PMC7052353 DOI: 10.3389/fneur.2020.00143] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 02/07/2020] [Indexed: 12/12/2022] Open
Abstract
Manganese-enhanced magnetic resonance imaging (MEMRI) relies on the strong paramagnetism of Mn2+. Mn2+ is a calcium ion analog and can enter excitable cells through voltage-gated calcium channels. Mn2+ can be transported along the axons of neurons via microtubule-based fast axonal transport. Based on these properties, MEMRI is used to describe neuroanatomical structures, monitor neural activity, and evaluate axonal transport rates. The application of MEMRI in preclinical animal models of central nervous system (CNS) diseases can provide more information for the study of disease mechanisms. In this article, we provide a brief review of MEMRI use in CNS diseases ranging from neurodegenerative diseases to brain injury and spinal cord injury.
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Affiliation(s)
- Jun Yang
- Department of Radiology, The Third Affiliated Hospital of Kunming Medical University, Yunnan Cancer Hospital & Cancer Center, Kunming, China
| | - Qinqing Li
- Department of Radiology, The Third Affiliated Hospital of Kunming Medical University, Yunnan Cancer Hospital & Cancer Center, Kunming, China
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Cha M, Lee K, Won JS, Lee BH. Manganese-enhanced magnetic resonance imaging of the spinal cord in rats with formalin-induced pain. Neurosci Res 2019; 149:14-21. [PMID: 30685495 DOI: 10.1016/j.neures.2019.01.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 01/02/2019] [Accepted: 01/21/2019] [Indexed: 11/29/2022]
Abstract
Manganese-enhanced magnetic resonance imaging (MEMRI) is based on neuronal activity-dependent manganese uptake, and provides information about nervous system function. However, systematic studies of pain processing using MEMRI are rare, and few investigations of pain using MEMRI have been performed in the spinal cord. Herein, we investigated the pain dependence of manganese ions administered in the rat spinal cord. MnCl2 was administered into the spinal cord via an intrathecal catheter before formalin injection into the right hind paw (50 μL of 5% formalin). The duration of flinching behavior was recorded and analyzed to measure formalin-induced pain. After the behavioral test, rats were sacrificed with an overdose of urethane (50 mg/kg), and spine samples were extracted and post-fixed in 4% paraformaldehyde solution. The samples were stored in 30% sucrose until molecular resonance (MR) scanning was performed. In axial Mn2+ enhancement images of the spinal cord, Mn2+ levels were found to be significantly elevated on the ipsilateral side of the spinal cord in formalin-injected rats. To confirm pain-dependent Mn enhancement in the spinal cord, c-Fos expression was analyzed, and was found to be increased in the formalin-injected rats. These results indicate that MEMRI is useful for functional analysis of the spinal cord under pain conditions. The gray matter appears to be the focus of intense paramagnetic signals. MEMRI may provide an effective technique for visualizing activity-dependent patterns in the spinal cord.
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Affiliation(s)
- Myeounghoon Cha
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Kyuhong Lee
- Inhalation Toxicology Research Center, Korea Institute of Toxicology, Jeonbuk 56212, Republic of Korea
| | - Jun Sik Won
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Bae Hwan Lee
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Republic of Korea.
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Neuroimaging Biomarkers of Experimental Epileptogenesis and Refractory Epilepsy. Int J Mol Sci 2019; 20:ijms20010220. [PMID: 30626103 PMCID: PMC6337422 DOI: 10.3390/ijms20010220] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 12/31/2018] [Accepted: 01/03/2019] [Indexed: 11/17/2022] Open
Abstract
This article provides an overview of neuroimaging biomarkers in experimental epileptogenesis and refractory epilepsy. Neuroimaging represents a gold standard and clinically translatable technique to identify neuropathological changes in epileptogenesis and longitudinally monitor its progression after a precipitating injury. Neuroimaging studies, along with molecular studies from animal models, have greatly improved our understanding of the neuropathology of epilepsy, such as the hallmark hippocampus sclerosis. Animal models are effective for differentiating the different stages of epileptogenesis. Neuroimaging in experimental epilepsy provides unique information about anatomic, functional, and metabolic alterations linked to epileptogenesis. Recently, several in vivo biomarkers for epileptogenesis have been investigated for characterizing neuronal loss, inflammation, blood-brain barrier alterations, changes in neurotransmitter density, neurovascular coupling, cerebral blood flow and volume, network connectivity, and metabolic activity in the brain. Magnetic resonance imaging (MRI) is a sensitive method for detecting structural and functional changes in the brain, especially to identify region-specific neuronal damage patterns in epilepsy. Positron emission tomography (PET) and single-photon emission computerized tomography are helpful to elucidate key functional alterations, especially in areas of brain metabolism and molecular patterns, and can help monitor pathology of epileptic disorders. Multimodal procedures such as PET-MRI integrated systems are desired for refractory epilepsy. Validated biomarkers are warranted for early identification of people at risk for epilepsy and monitoring of the progression of medical interventions.
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Saar G, Koretsky AP. Manganese Enhanced MRI for Use in Studying Neurodegenerative Diseases. Front Neural Circuits 2019; 12:114. [PMID: 30666190 PMCID: PMC6330305 DOI: 10.3389/fncir.2018.00114] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 12/10/2018] [Indexed: 12/13/2022] Open
Abstract
MRI has been extensively used in neurodegenerative disorders, such as Alzheimer’s disease (AD), frontal-temporal dementia (FTD), mild cognitive impairment (MCI), Parkinson’s disease (PD), Huntington’s disease (HD) and amyotrophic lateral sclerosis (ALS). MRI is important for monitoring the neurodegenerative components in other diseases such as epilepsy, stroke and multiple sclerosis (MS). Manganese enhanced MRI (MEMRI) has been used in many preclinical studies to image anatomy and cytoarchitecture, to obtain functional information in areas of the brain and to study neuronal connections. This is due to Mn2+ ability to enter excitable cells through voltage gated calcium channels and be actively transported in an anterograde manner along axons and across synapses. The broad range of information obtained from MEMRI has led to the use of Mn2+ in many animal models of neurodegeneration which has supplied important insight into brain degeneration in preclinical studies. Here we provide a brief review of MEMRI use in neurodegenerative diseases and in diseases with neurodegenerative components in animal studies and discuss the potential translation of MEMRI to clinical use in the future.
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Affiliation(s)
- Galit Saar
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, MD, United States
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, MD, United States
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Cloyd RA, Koren SA, Abisambra JF. Manganese-Enhanced Magnetic Resonance Imaging: Overview and Central Nervous System Applications With a Focus on Neurodegeneration. Front Aging Neurosci 2018; 10:403. [PMID: 30618710 PMCID: PMC6300587 DOI: 10.3389/fnagi.2018.00403] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 11/23/2018] [Indexed: 12/16/2022] Open
Abstract
Manganese-enhanced magnetic resonance imaging (MEMRI) rose to prominence in the 1990s as a sensitive approach to high contrast imaging. Following the discovery of manganese conductance through calcium-permeable channels, MEMRI applications expanded to include functional imaging in the central nervous system (CNS) and other body systems. MEMRI has since been employed in the investigation of physiology in many animal models and in humans. Here, we review historical perspectives that follow the evolution of applied MRI research into MEMRI with particular focus on its potential toxicity. Furthermore, we discuss the more current in vivo investigative uses of MEMRI in CNS investigations and the brief but decorated clinical usage of chelated manganese compound mangafodipir in humans.
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Affiliation(s)
- Ryan A Cloyd
- Department of Physiology, University of Kentucky, Lexington, KY, United States.,College of Medicine, University of Kentucky, Lexington, KY, United States.,Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Shon A Koren
- Department of Physiology, University of Kentucky, Lexington, KY, United States.,Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States.,Department of Neuroscience & Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States
| | - Jose F Abisambra
- Department of Physiology, University of Kentucky, Lexington, KY, United States.,Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States.,Department of Neuroscience & Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States.,Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY, United States
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Imaging biomarkers of epileptogenecity after traumatic brain injury - Preclinical frontiers. Neurobiol Dis 2018; 123:75-85. [PMID: 30321600 DOI: 10.1016/j.nbd.2018.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 10/04/2018] [Accepted: 10/11/2018] [Indexed: 02/06/2023] Open
Abstract
Posttraumatic epilepsy (PTE) is a major neurodegenerative disease accounting for 20% of symptomatic epilepsy cases. A long latent phase offers a potential window for prophylactic treatment strategies to prevent epilepsy onset, provided that the patients at risk can be identified. Some promising imaging biomarker candidates for posttraumatic epileptogenesis have been identified, but more are required to provide the specificity and sensitivity for accurate prediction. Experimental models and preclinical longitudinal, multimodal imaging studies allow follow-up of complex cascade of events initiated by traumatic brain injury, as well as monitoring of treatment effects. Preclinical imaging data from the posttraumatic brain are rich in information, yet examination of their specific relevance to epilepsy is lacking. Accumulating evidence from ongoing preclinical studies in TBI support insight into processes involved in epileptogenesis, e.g. inflammation and changes in functional and structural brain-wide connectivity. These efforts are likely to produce both new biomarkers and treatment targets for PTE.
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Bertoglio D, Amhaoul H, Van Eetveldt A, Houbrechts R, Van De Vijver S, Ali I, Dedeurwaerdere S. Kainic Acid-Induced Post-Status Epilepticus Models of Temporal Lobe Epilepsy with Diverging Seizure Phenotype and Neuropathology. Front Neurol 2017; 8:588. [PMID: 29163349 PMCID: PMC5681498 DOI: 10.3389/fneur.2017.00588] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 10/20/2017] [Indexed: 12/28/2022] Open
Abstract
The aim of epilepsy models is to investigate disease ontogenesis and therapeutic interventions in a consistent and prospective manner. The kainic acid-induced status epilepticus (KASE) rat model is a widely used, well-validated model for temporal lobe epilepsy (TLE). As we noted significant variability within the model between labs potentially related to the rat strain used, we aimed to describe two variants of this model with diverging seizure phenotype and neuropathology. In addition, we evaluated two different protocols to induce status epilepticus (SE). Wistar Han (Charles River, France) and Sprague-Dawley (Harlan, The Netherlands) rats were subjected to KASE using the Hellier kainic acid (KA) and a modified injection scheme. Duration of SE and latent phase were characterized by video-electroencephalography (vEEG) in a subgroup of animals, while animals were sacrificed 1 week (subacute phase) and 12 weeks (chronic phase) post-SE. In the 12 weeks post-SE groups, seizures were monitored with vEEG. Neuronal loss (neuronal nuclei), microglial activation (OX-42 and translocator protein), and neurodegeneration (Fluorojade C) were assessed. First, the Hellier protocol caused very high mortality in WH/CR rats compared to SD/H animals. The modified protocol resulted in a similar SE severity for WH/CR and SD/H rats, but effectively improved survival rates. The latent phase was significantly shorter (p < 0.0001) in SD/H (median 8.3 days) animals compared to WH/CR (median 15.4 days). During the chronic phase, SD/H rats had more seizures/day compared to WH/CR animals (p < 0.01). However, neuronal degeneration and cell loss were overall more extensive in WH/CR than in SD/H rats; microglia activation was similar between the two strains 1 week post-SE, but higher in WH/CR rats 12 weeks post-SE. These neuropathological differences may be more related to the distinct neurotoxic effects of KA in the two rat strains than being the outcome of seizure burden itself. The divergences in disease progression and seizure outcome, in addition to the histopathological dissimilarities, further substantiate the existence of strain differences for the KASE rat model of TLE.
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Affiliation(s)
- Daniele Bertoglio
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Halima Amhaoul
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Annemie Van Eetveldt
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Ruben Houbrechts
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | | | - Idrish Ali
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
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10
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Neuroimaging in animal models of epilepsy. Neuroscience 2017; 358:277-299. [DOI: 10.1016/j.neuroscience.2017.06.062] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 02/06/2023]
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Huang H, Lovell JF. Advanced Functional Nanomaterials for Theranostics. ADVANCED FUNCTIONAL MATERIALS 2017; 27:1603524. [PMID: 28824357 PMCID: PMC5560626 DOI: 10.1002/adfm.201603524] [Citation(s) in RCA: 136] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Nanoscale materials have been explored extensively as agents for therapeutic and diagnostic (i.e. theranostic) applications. Research efforts have shifted from exploring new materials in vitro to designing materials that function in more relevant animal disease models, thereby increasing potential for clinical translation. Current interests include non-invasive imaging of diseases, biomarkers and targeted delivery of therapeutic drugs. Here, we discuss some general design considerations of advanced theranostic materials and challenges of their use, from both diagnostic and therapeutic perspectives. Common classes of nanoscale biomaterials, including magnetic nanoparticles, quantum dots, upconversion nanoparticles, mesoporous silica nanoparticles, carbon-based nanoparticles and organic dye-based nanoparticles, have demonstrated potential for both diagnosis and therapy. Variations such as size control and surface modifications can modulate biocompatibility and interactions with target tissues. The needs for improved disease detection and enhanced chemotherapeutic treatments, together with realistic considerations for clinically translatable nanomaterials will be key driving factors for theranostic agent research in the near future.
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Affiliation(s)
- Haoyuan Huang
- Department of Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, New York, 14260, United States
| | - Jonathan F Lovell
- Department of Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, New York, 14260, United States
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Vieira ÉLM, de Oliveira GNM, Lessa JMK, Gonçalves AP, Oliveira ACP, Bauer ME, Sander JW, Cendes F, Teixeira AL. Peripheral leukocyte profile in people with temporal lobe epilepsy reflects the associated proinflammatory state. Brain Behav Immun 2016; 53:123-130. [PMID: 26640228 DOI: 10.1016/j.bbi.2015.11.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 11/25/2015] [Accepted: 11/26/2015] [Indexed: 12/20/2022] Open
Abstract
INTRODUCTION Markers of low-grade peripheral inflammation have been reported amongst people with epilepsy. The mechanisms underlying this phenomenon are unknown. We attempted to characterize peripheral immune cells and their activation status in people with temporal lobe epilepsy (TLE) and healthy controls. METHODS AND RESULTS Twenty people with TLE and 19 controls were recruited, and peripheral blood lymphocyte and monocyte subsets evaluated ex vivo by multi-color flow cytometry. People with TLE had higher expression of HLA-DR, CD69, CTLA-4, CD25, IL-23R, IFN-γ, TNF and IL-17 in CD4(+) lymphocytes than controls. Granzyme A, CTLA-4, IL-23R and IL-17 expression was also elevated in CD8(+) T cells from people with TLE. Frequency of HLA-DR in CD19(+) B cells and regulatory T cells CD4(+)CD25(+)Foxp3(+) producing IL-10 was higher in TLE when compared with controls. A negative correlation between CD4(+) expressing co-stimulatory molecules (CD69, CD25 and CTLA-4) with age at onset of seizures was found. The frequency of CD4(+)CD25(+)Foxp3(+) cells was also positively correlated with age at onset of seizures. CONCLUSION Immune cells of people with TLE show an activation profile, mainly in effector T cells, in line with the low-grade peripheral inflammation.
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Affiliation(s)
- Érica Leandro Marciano Vieira
- Neuroscience Division, Interdisciplinary Laboratory of Medical Investigation, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
| | - Guilherme Nogueira M de Oliveira
- Epilepsy Treatment Advanced Centre (NATE), Felício Rocho Hospital, Belo Horizonte, MG, Brazil; Medicine School, Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), Diamantina, MG, Brazil
| | - João Marcelo K Lessa
- Neuroscience Division, Interdisciplinary Laboratory of Medical Investigation, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ana Paula Gonçalves
- Neuroscience Division, Interdisciplinary Laboratory of Medical Investigation, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil; Epilepsy Treatment Advanced Centre (NATE), Felício Rocho Hospital, Belo Horizonte, MG, Brazil
| | - Antônio Carlos P Oliveira
- Neuroscience Division, Interdisciplinary Laboratory of Medical Investigation, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Moises E Bauer
- Laboratório de Imunologia do Envelhecimento, Instituto de Pesquisas Biomédicas, PUCRS, Porto Alegre, RS, Brazil
| | - Josemir W Sander
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands; NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, Queen Square, London WC1N 3BG, Epilepsy Society, Chalfont St Peter, SL9 0RJ, UK
| | | | - Antônio Lúcio Teixeira
- Neuroscience Division, Interdisciplinary Laboratory of Medical Investigation, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
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Imaging microstructural damage and plasticity in the hippocampus during epileptogenesis. Neuroscience 2015; 309:162-72. [DOI: 10.1016/j.neuroscience.2015.04.054] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/28/2015] [Accepted: 04/21/2015] [Indexed: 12/19/2022]
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14
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Amhaoul H, Hamaide J, Bertoglio D, Reichel SN, Verhaeghe J, Geerts E, Van Dam D, De Deyn PP, Kumar-Singh S, Katsifis A, Van Der Linden A, Staelens S, Dedeurwaerdere S. Brain inflammation in a chronic epilepsy model: Evolving pattern of the translocator protein during epileptogenesis. Neurobiol Dis 2015; 82:526-539. [PMID: 26388398 DOI: 10.1016/j.nbd.2015.09.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 08/24/2015] [Accepted: 09/16/2015] [Indexed: 11/27/2022] Open
Abstract
AIMS A hallmark in the neuropathology of temporal lobe epilepsy is brain inflammation which has been suggested as both a biomarker and a new mechanistic target for treatments. The translocator protein (TSPO), due to its high upregulation under neuroinflammatory conditions and the availability of selective PET tracers, is a candidate target. An important step to exploit this target is a thorough characterisation of the spatiotemporal profile of TSPO during epileptogenesis. METHODS TSPO expression, microglial activation, astrocyte reactivity and cell loss in several brain regions were evaluated at five time points during epileptogenesis, including the chronic epilepsy phase in the kainic acid-induced status epilepticus (KASE) model (n = 52) and control Wistar Han rats (n = 33). Seizure burden was also determined in the chronic phase. Furthermore, ¹⁸F-PBR111 PET/MRI scans were acquired longitudinally in an additional four KASE animals. RESULTS TSPO expression measured with in vitro and in vivo techniques was significantly increased at each time point and peaked two weeks post-SE in the limbic system. A prominent association between TSPO expression and activated microglia (p < 0.001; r = 0.7), as well as cell loss (p < 0.001; r = -0.8) could be demonstrated. There was a significant positive correlation between spontaneous seizures and TSPO upregulation in several brain regions with increased TSPO expression. CONCLUSIONS TSPO expression was dynamically upregulated during epileptogenesis, persisted in the chronic phase and correlated with microglia activation rather than reactive astrocytes. TSPO expression was correlating with spontaneous seizures and its high expression during the latent phase might possibly suggest being an important switching point in disease ontogenesis which could be further investigated by PET imaging.
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Affiliation(s)
- Halima Amhaoul
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | - Julie Hamaide
- Department of Translational Neurosciences, University of Antwerp, Belgium; Bio-Imaging Lab, University of Antwerp, Belgium
| | - Daniele Bertoglio
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | | | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium
| | - Elly Geerts
- Laboratory of Neurochemistry and Behaviour, University of Antwerp, Belgium
| | - Debby Van Dam
- Laboratory of Neurochemistry and Behaviour, University of Antwerp, Belgium
| | - Peter Paul De Deyn
- Laboratory of Neurochemistry and Behaviour, University of Antwerp, Belgium; Department of Neurology and Memory Clinic, Hospital Network Antwerp (ZNA) Middelheim and Hoge Beuken, Belgium; Department of Neurology and Alzheimer Research Center, University of Groningen and University Medical Center Groningen (UMCG), The Netherlands
| | - Samir Kumar-Singh
- Laboratory of Cell Biology & Histology, University of Antwerp, Belgium
| | - Andrew Katsifis
- Department of PET and Nuclear Medicine, Royal Prince Alfred Hospital, Australia
| | | | - Steven Staelens
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium
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15
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In the grey zone between epilepsy and schizophrenia: alterations in group II metabotropic glutamate receptors. Acta Neurol Belg 2015; 115:221-32. [PMID: 25539775 DOI: 10.1007/s13760-014-0407-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/05/2014] [Indexed: 01/09/2023]
Abstract
Glutamate is the major excitatory neurotransmitter in the brain. The glutamate system plays an important role in the formation of synapses during brain development and synaptic plasticity. Dysfunctions in glutamate regulation may lead to hyperexcitatory neuronal networks and neurotoxicity. Glutamate excess is possibly of great importance in the pathophysiology of several neurological and psychiatric disorders such as epilepsy and schizophrenia. Interestingly, cross talk between these disorders has been well documented: psychiatric comorbidities are frequent in epilepsy and temporal lobe epilepsy is one of the highest risk factors for developing psychosis. Therefore, dysfunctions in glutamatergic neurotransmission might constitute a common pathological mechanism. A major negative feedback system is regulated by the presynaptic group II metabotropic glutamate (mGlu) receptors including mGlu2/3 receptors. These receptors are predominantly localised extrasynaptically in basal ganglia and limbic structures. Hence, mGlu2/3 receptors are an interesting target for the treatment of disorders like epilepsy and schizophrenia. A dysfunction in the glutamate system may be associated with alterations in mGlu2/3 receptor expression. In this review, we describe the localization of mGlu2/3 receptors in the healthy brain of mice, rats and humans. Secondly, changes in mGlu2/3 receptor density of the brain regions affected in epilepsy and schizophrenia are summarised. Increased mGlu2/3 receptor density might represent a compensatory mechanism of the brain to regulate elevated glutamate levels, while reduced mGlu2/3 receptor density in some brain regions may further contribute to the aberrant hyperexcitability. Further research considering the mGlu2/3 receptor can contribute significantly to the understanding of the etiological and therapeutic role of group II mGlu receptor in epilepsy, epilepsy with psychosis and schizophrenia.
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16
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Malheiros JM, Paiva FF, Longo BM, Hamani C, Covolan L. Manganese-Enhanced MRI: Biological Applications in Neuroscience. Front Neurol 2015. [PMID: 26217304 PMCID: PMC4498388 DOI: 10.3389/fneur.2015.00161] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Magnetic resonance imaging (MRI) is an excellent non-invasive tool to investigate biological systems. The administration of the paramagnetic divalent ion manganese (Mn2+) enhances MRI contrast in vivo. Due to similarities between Mn2+ and calcium (Ca2+), the premise of manganese-enhanced MRI (MEMRI) is that the former may enter neurons and other excitable cells through voltage-gated Ca2+ channels. As such, MEMRI has been used to trace neuronal pathways, define morphological boundaries, and study connectivity in morphological and functional imaging studies. In this article, we provide a brief overview of MEMRI and discuss recently published data to illustrate the usefulness of this method, particularly in animal models.
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Affiliation(s)
- Jackeline Moraes Malheiros
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil ; Centro de Imagens e Espectroscopia In vivo por Ressonância Magnética, Institute of Physics of São Carlos, Universidade de São Paulo , São Carlos , Brazil
| | - Fernando Fernandes Paiva
- Centro de Imagens e Espectroscopia In vivo por Ressonância Magnética, Institute of Physics of São Carlos, Universidade de São Paulo , São Carlos , Brazil
| | - Beatriz Monteiro Longo
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil
| | - Clement Hamani
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil ; Research Imaging Centre, Centre for Addiction and Mental Health , Toronto, ON , Canada ; Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute , Toronto, ON , Canada
| | - Luciene Covolan
- Department of Physiology, Universidade Federal de São Paulo - UNIFESP , São Paulo , Brazil
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17
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Bade AN, Zhou B, McMillan J, Narayanasamy P, Veerubhotla R, Gendelman HE, Boska MD, Liu Y. Potential of N-acetylated-para-aminosalicylic acid to accelerate manganese enhancement decline for long-term MEMRI in rodent brain. J Neurosci Methods 2015; 251:92-8. [PMID: 26004847 DOI: 10.1016/j.jneumeth.2015.05.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 05/14/2015] [Accepted: 05/15/2015] [Indexed: 11/25/2022]
Abstract
BACKGROUND Manganese (Mn(2+))-enhanced MRI (MEMRI) is a valuable imaging tool to study brain structure and function in normal and diseased small animals. The brain retention of Mn(2+) is relatively long with a half-life (t1/2) of 51-74 days causing a slow decline of MRI signal enhancement following Mn(2+) administration. Such slow decline limits using repeated MEMRI to follow the central nervous system longitudinally in weeks or months. This is because residual Mn(2+) from preceding administrations can confound the interpretation of imaging results. We investigated whether the Mn(2+) enhancement decline could be accelerated thus enabling repeated MEMRI, and as a consequence broadens the utility of MEMRI tests. NEW METHODS We investigated whether N-acetyl-para-aminosalicylic acid (AcPAS), a chelator of Mn(2+), could affect the decline of Mn(2+) induced MRI enhancement in brain. RESULTS AND CONCLUSION Two-week treatment with AcPAS (200mg/kg/dose×3 daily) accelerated the decline of Mn(2+) induced enhancement in MRI. In the whole brain on average the enhancement declined from 100% to 17% in AcPAS treated mice, while in PBS controls the decline is from 100% to 27%. We posit that AcPAS could enhance MEMRI utility for evaluating brain biology in small animals. COMPARISON WITH EXISTING METHODS To the best of our knowledge, no method exists to accelerate the decline of the Mn(2+) induced MRI enhancement for repeated MEMRI tests.
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Affiliation(s)
- Aditya N Bade
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, 68198-5800, United States
| | - Biyun Zhou
- Department of Anesthesiology, Tongji Medical College, Huanzhong University of Science and Technology, China
| | - JoEllyn McMillan
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, 68198-5800, United States
| | - Prabagaran Narayanasamy
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, 68198-5800, United States; Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198-5900, United States
| | - Ram Veerubhotla
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, 68198-5800, United States
| | - Howard E Gendelman
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, 68198-5800, United States
| | - Michael D Boska
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, 68198-5800, United States; Department of Radiology, University of Nebraska Medical Center, Omaha, NE, 68198-1045, United States
| | - Yutong Liu
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, 68198-5800, United States; Department of Radiology, University of Nebraska Medical Center, Omaha, NE, 68198-1045, United States.
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18
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Abstract
Epilepsy is one of the most common chronic neurological conditions worldwide. Anti-epileptic drugs (AEDs) can suppress seizures, but do not affect the underlying epileptic state, and many epilepsy patients are unable to attain seizure control with AEDs. To cure or prevent epilepsy, disease-modifying interventions that inhibit or reverse the disease process of epileptogenesis must be developed. A major limitation in the development and implementation of such an intervention is the current poor understanding, and the lack of reliable biomarkers, of the epileptogenic process. Neuroimaging represents a non-invasive medical and research tool with the ability to identify early pathophysiological changes involved in epileptogenesis, monitor disease progression, and assess the effectiveness of possible therapies. Here we will provide an overview of studies conducted in animal models and in patients with epilepsy that have utilized various neuroimaging modalities to investigate epileptogenesis.
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Affiliation(s)
- Sandy R Shultz
- Department of Medicine, The Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Building 144, Royal Parade, Parkville, VIC, 3010, Australia,
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Manganese enhanced magnetic resonance imaging (MEMRI): a powerful new imaging method to study tinnitus. Hear Res 2014; 311:49-62. [PMID: 24583078 DOI: 10.1016/j.heares.2014.02.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 02/05/2014] [Accepted: 02/10/2014] [Indexed: 12/31/2022]
Abstract
Manganese enhanced magnetic resonance imaging (MEMRI) is a method used primarily in basic science experiments to advance the understanding of information processing in central nervous system pathways. With this mechanistic approach, manganese (Mn(2+)) acts as a calcium surrogate, whereby voltage-gated calcium channels allow for activity driven entry of Mn(2+) into neurons. The detection and quantification of neuronal activity via Mn(2+) accumulation is facilitated by "hemodynamic-independent contrast" using high resolution MRI scans. This review emphasizes initial efforts to-date in the development and application of MEMRI for evaluating tinnitus (the perception of sound in the absence of overt acoustic stimulation). Perspectives from leaders in the field highlight MEMRI related studies by comparing and contrasting this technique when tinnitus is induced by high-level noise exposure and salicylate administration. Together, these studies underscore the considerable potential of MEMRI for advancing the field of auditory neuroscience in general and tinnitus research in particular. Because of the technical and functional gaps that are filled by this method and the prospect that human studies are on the near horizon, MEMRI should be of considerable interest to the auditory research community. This article is part of a Special Issue entitled <Annual Reviews 2014>.
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Malheiros JM, Persike DS, Castro LUCD, Sanches TRC, Andrade LDC, Tannús A, Covolan L. Reduced hippocampal manganese-enhanced MRI (MEMRI) signal during pilocarpine-induced status epilepticus: edema or apoptosis? Epilepsy Res 2014; 108:644-52. [PMID: 24630048 DOI: 10.1016/j.eplepsyres.2014.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 01/13/2014] [Accepted: 02/04/2014] [Indexed: 10/25/2022]
Abstract
Manganese-enhanced MRI (MEMRI) has been considered a surrogate marker of Ca(+2) influx into activated cells and tracer of neuronal active circuits. However, the induction of status epilepticus (SE) by kainic acid does not result in hippocampal MEMRI hypersignal, in spite of its high cell activity. Similarly, short durations of status (5 or 15min) induced by pilocarpine did not alter the hippocampal MEMRI, while 30 min of SE even reduced MEMRI signal Thus, this study was designed to investigate possible explanations for the absence or decrease of MEMRI signal after short periods of SE. We analyzed hippocampal caspase-3 activation (to evaluate apoptosis), T2 relaxometry (tissue water content) and aquaporin 4 expression (water-channel protein) of rats subjected to short periods of pilocarpine-induced SE. For the time periods studied here, apoptotic cell death did not contribute to the decrease of the hippocampal MEMRI signal. However, T2 relaxation was higher in the group of animals subjected to 30min of SE than in the other SE or control groups. This result is consistent with higher AQP-4 expression during the same time period. Based on apoptosis and tissue water content analysis, the low hippocampal MEMRI signal 30min after SE can potentially be attributed to local edema rather than to cell death.
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Affiliation(s)
- Jackeline Moraes Malheiros
- Departamento de Fisiologia, Universidade Federal de São Paulo-UNIFESP, São Paulo 04023-06, SP, Brazil; Centro de Imagens e Espectroscopia in vivo por Ressonância Magnética (CIERMag), Instituto de Física de São Carlos, Universidade de São Paulo (IFSC-USP), São Carlos 13566-590, SP, Brazil
| | - Daniele Suzete Persike
- Departamento de Neurologia e Neurocirurgia, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, Brazil
| | | | | | | | - Alberto Tannús
- Centro de Imagens e Espectroscopia in vivo por Ressonância Magnética (CIERMag), Instituto de Física de São Carlos, Universidade de São Paulo (IFSC-USP), São Carlos 13566-590, SP, Brazil
| | - Luciene Covolan
- Departamento de Fisiologia, Universidade Federal de São Paulo-UNIFESP, São Paulo 04023-06, SP, Brazil.
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Vivash L, Gregoire MC, Bouilleret V, Berard A, Wimberley C, Binns D, Roselt P, Katsifis A, Myers DE, Hicks RJ, O'Brien TJ, Dedeurwaerdere S. In vivo measurement of hippocampal GABAA/cBZR density with [18F]-flumazenil PET for the study of disease progression in an animal model of temporal lobe epilepsy. PLoS One 2014; 9:e86722. [PMID: 24466212 PMCID: PMC3897736 DOI: 10.1371/journal.pone.0086722] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 12/15/2013] [Indexed: 11/18/2022] Open
Abstract
Purpose Imbalance of inhibitory GABAergic neurotransmission has been proposed to play a role in the pathogenesis of temporal lobe epilepsy (TLE). This study aimed to investigate whether [18F]-flumazenil ([18F]-FMZ) PET could be used to non-invasively characterise GABAA/central benzodiazepine receptor (GABAA/cBZR) density and affinity in vivo in the post-kainic acid status epilepticus (SE) model of TLE. Methods Dynamic [18F]-FMZ -PET scans using a multi-injection protocol were acquired in four male wistar rats for validation of the partial saturation model (PSM). SE was induced in eight male Wistar rats (10 weeks of age) by i.p. injection of kainic acid (7.5–25 mg/kg), while control rats (n = 7) received saline injections. Five weeks post-SE, an anatomic MRI scan was acquired and the following week an [18F]-FMZ PET scan (3.6–4.6 nmol). The PET data was co-registered to the MRI and regions of interest drawn on the MRI for selected structures. A PSM was used to derive receptor density and apparent affinity from the [18F]-FMZ PET data. Key Findings The PSM was found to adequately model [18F]-FMZ binding in vivo. There was a significant decrease in hippocampal receptor density in the SE group (p<0.01), accompanied by an increase in apparent affinity (p<0.05) compared to controls. No change in cortical receptor binding was observed. Hippocampal volume reduction and cell loss was only seen in a subset of animals. Histological assessment of hippocampal cell loss was significantly correlated with hippocampal volume measured by MRI (p<0.05), but did not correlate with [18F]-FMZ binding. Significance Alterations to hippocampal GABAA/cBZR density and affinity in the post-kainic acid SE model of TLE are detectable in vivo with [18F]-FMZ PET and a PSM. These changes are independent from hippocampal cell and volume loss. [18F]-FMZ PET is useful for investigating the role that changes GABAA/cBZR density and binding affinity play in the pathogenesis of TLE.
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Affiliation(s)
- Lucy Vivash
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Marie-Claude Gregoire
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Viviane Bouilleret
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Alexis Berard
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Catriona Wimberley
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - David Binns
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Peter Roselt
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Andrew Katsifis
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Damian E. Myers
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Rodney J. Hicks
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Terence J. O'Brien
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
| | - Stefanie Dedeurwaerdere
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- Department of Translational Neurosciences, University of Antwerp, Wilrijk, Belgium
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Kamsu JM, Constans JM, Lamberton F, Courtheoux P, Denise P, Philoxene B, Coquemont M, Besnard S. Structural layers of ex vivo rat hippocampus at 7T MRI. PLoS One 2013; 8:e76135. [PMID: 24086700 PMCID: PMC3784442 DOI: 10.1371/journal.pone.0076135] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 08/26/2013] [Indexed: 11/18/2022] Open
Abstract
Magnetic resonance imaging (MRI) applied to the hippocampus is challenging in studies of the neurophysiology of memory and the physiopathology of numerous diseases such as epilepsy, Alzheimer’s disease, ischemia, and depression. The hippocampus is a well-delineated cerebral structure with a multi-layered organization. Imaging of hippocampus layers is limited to a few studies and requires high magnetic field and gradient strength. We performed one conventional MRI sequence on a 7T MRI in order to visualize and to delineate the multi-layered hippocampal structure ex vivo in rat brains. We optimized a volumic three-dimensional T2 Rapid Acquisition Relaxation Enhancement (RARE) sequence and quantified the volume of the hippocampus and one of its thinnest layers, the stratum granulare of the dentate gyrus. Additionally, we tested passive staining by gadolinium with the aim of decreasing the acquisition time and increasing image contrast. Using appropriated settings, six discrete layers were differentiated within the hippocampus in rats. In the hippocampus proper or Ammon’s Horn (AH): the stratum oriens, the stratum pyramidale of, the stratum radiatum, and the stratum lacunosum moleculare of the CA1 were differentiated. In the dentate gyrus: the stratum moleculare and the stratum granulare layer were seen distinctly. Passive staining of one brain with gadolinium decreased the acquisition time by four and improved the differentiation between the layers. A conventional sequence optimized on a 7T MRI with a standard receiver surface coil will allow us to study structural layers (signal and volume) of hippocampus in various rat models of neuropathology (anxiety, epilepsia, neurodegeneration).
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Affiliation(s)
| | - Jean-Marc Constans
- Service de Radiologie, Centre Hospitalier Universitaire D’Amiens, Amiens, France
| | - Franck Lamberton
- Unité Mixte de Recherche, UMR 6194 Centre National de Recherche Scientifique (CNRS), Commissariat à l’energie atomique (CEA), Université de Caen et Paris, Paris, France
| | - Patrick Courtheoux
- Unité Imagerie par Résonance Magnétique Pôle Imagerie, Centre Hospitalier Universitaire Côte de Nacre, Caen, France
- Service d’histologie, Hôpital Côte de Nacre, Centre Hospitalier Universitaire Côte de Nacre, Université de Caen, Caen, France
| | - Pierre Denise
- Unité Mixte de Recherche, UMR 1075, Université de Caen, Caen, France
| | - Bruno Philoxene
- Unité Mixte de Recherche, UMR 1075, Université de Caen, Caen, France
| | - Maelle Coquemont
- Unité Imagerie par Résonance Magnétique Pôle Imagerie, Centre Hospitalier Universitaire Côte de Nacre, Caen, France
- Service d’histologie, Hôpital Côte de Nacre, Centre Hospitalier Universitaire Côte de Nacre, Université de Caen, Caen, France
| | - Stephane Besnard
- Unité Mixte de Recherche, UMR 1075, Université de Caen, Caen, France
- * E-mail:
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23
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Obenaus A. Neuroimaging biomarkers for epilepsy: advances and relevance to glial cells. Neurochem Int 2013; 63:712-8. [PMID: 23665337 DOI: 10.1016/j.neuint.2013.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 04/24/2013] [Accepted: 05/01/2013] [Indexed: 12/11/2022]
Abstract
Glial cells play an important role in normal brain function and emerging evidence would suggest that their dysfunction may be responsible for some epileptic disease states. Neuroimaging of glial cells is desirable, but there are no clear methods to assess neither their function nor localization. Magnetic resonance imaging (MRI) is now part of a standardized epilepsy imaging protocol to assess patients. Structural volumetric and T2-weighted imaging changes can assist in making a positive diagnosis in a majority of patients. The alterations reported in structural and T2 imaging is predominantly thought to reflect early neuronal loss followed by glial hypertrophy. MR spectroscopy for myo-inositol is a being pursued to identify glial alterations along with neuronal markers. Diffusion weighted imaging (DWI) is ideal for acute epileptiform events, but is not sensitive to either glial cells or neuronal long-term changes found in epilepsy. However, DWI variants such as diffusion tensor imaging or q-space imaging may shed additional light on aberrant glial function in the future. The sensitivity and specificity of PET radioligands, including those targeting glial cells (translocator protein) hold promise in being able to image glial cells. As the role of glial function/dysfunction in epilepsy becomes more apparent neuroimaging methods will evolve to assist the clinician and researcher in visualizing their location and function.
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Affiliation(s)
- Andre Obenaus
- Department of Pediatrics, School of Medicine, Loma Linda University, Loma Linda, CA, USA; Division of Interdisciplinary Studies, School of Behavioral Health, Loma Linda University, Loma Linda, CA, USA; Cell and Molecular Development and Biology Program, University of California, Riverside, CA, USA; Neuroscience Graduate Program, University of California, Riverside, CA, USA.
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