3.012
MORPHOLOGICAL CHANGES OF THE JUVENILE HIPPOCAMPUS ARE SIMILAR AFTER SINGLE VERSES MULTIPLE EARLY-LIFE SEIZURES
Abstract
Grace LaTorre11Neuroscience, New York Collge of Osteopathic Medicine, Old Westbury, NY, S. Majumudar11Neuroscience, New York Collge of Osteopathic Medicine, Old Westbury, NY, G. Torres11Neuroscience, New York Collge of Osteopathic Medicine, Old Westbury, NY, J. Chabla11Neuroscience, New York Collge of Osteopathic Medicine, Old Westbury, NY and L. K. Friedman11Neuroscience, New York Collge of Osteopathic Medicine, Old Westbury, NY (
1Neuroscience, New York Collge of Osteopathic Medicine, Old Westbury, NY
)
Rationale: We recently have shown that multiple early-life seizures attenuate glutamate stimulated calcium permeability which may increase adaptive responses later in life that lead to neuroprotection. An important function of dendritic spines may be to protect neurons from highly elevated concentrations of calcium that follow sustained early-life seizures.
Methods: Our previously established model was used to determine whether typical changes in morphology of CA1 pyramidal and granule cell neurons induced by a single episode of status epilepticus in prepubescent animals are attenuated by early-life seizures. The Golgi method was used for morphological analysis of the hippocampus of postnatal (P) day 20 rats 72 hrs after a single kainate (KA) seizure (1x KA) or following three seizures (3x KA), induced on P6, P9 and P20.
Results: After 1x KA in the CA1, a large decrease in the number of apical, but not basal branches, was observed. Long thin and short stubby dendritic spine density was significantly reduced. Spine loss was accompanied by swellings and shortening of dendritic segments. In the dentate gyrus, a five fold increase in basal dendrites of granule neurons was measured relative to naive P20 controls. After 3x KA, relatively similar decreases or increases were observed among respective pyramidal and granule cell populations.
Conclusions: The lack of further CA1 dendritic pruning after 3x KA may be due to adaptive responses whereby significant loss in excitatory morphology may be complete after the initial insult. Similarly, non-progressive changes in granule cell basal dendrite number or outgrowth present evidence for their role in adaptation following early-life seizures possibly by reducing calcium permeability.
3.013
SYNERGISM OF LACOSAMIDE AND FIRST-GENERATION AND NOVEL ANTIEPILEPTIC DRUGS IN THE 6 HZ SEIZURE MODEL IN MICE
Abstract
Thomas Stoehr11Schwarz Biosciences, Monheim, Germany, P. Shandra33Odessa National University, Odessa, Ukraine, O. Kashenko22Odessa State Medical University, Odessa, Ukraine and A. Shandra22Odessa State Medical University, Odessa, Ukraine (
1Schwarz Biosciences, Monheim, Germany; 2Odessa State Medical University, Odessa, Ukraine and 3Odessa National University, Odessa, Ukraine
)
Rationale: Lacosamide (LCM) is a functionalized amino acid that shows a more potent and effective anticonvulsant profile in animal models when compared to conventional antiepileptics. New antiepileptic drugs (AEDs) are initially licensed as add-on treatment, often with no evidence to suggest which existing therapies they should be employed with. In addition, approximately 30% of patients with epilepsy are prescribed polytherapy regimes. There is, thus, a clear need to develop a rational basis for AED polytherapy. The objective of this study was the isobolographic evaluation of the interaction between LCM and a number of other AEDs.
Methods: The anticonvulsant effect of LCM with other AEDs (carbamazepine (CBZ), phenytoin (PHT), valproate (VPA), lamotrigine (LTG), topiramate (TPM), gabapentin (GBP) and levetiracetam (LEV)) at fixed ratios of 1:3, 1:1 and 3:1 was evaluated in the 6 Hz-induced seizure model in mice. The protective action of an AED was defined as the absence of seizure. Furthermore, motor side effects of AED combinations was assessed in the rotarod test.
Results: All studied AEDs produced dose-dependent anticonvulsant effects against 6 Hz induced seizures. Combinations of LCM with CBZ, LTG, TPM, GBP or LEV were supraadditive (synergistic). All other LCM/AED combinations displayed additive effects with a tendency towards supraadditivity. Furthermore, no enhanced adverse effects were induced by combinations of LCM with these AEDs as assessed in the rotarod test.
Conclusions: The isobolographic analysis revealed that combinations of LCM with novel AEDs (TPM, GBP, LTG or LEV) or with CBZ are associated with supraadditive anticonvulsant effects. Similar but less profound supraadditive effects were seen with LCM in combination with PHT or VPA. In contrast, infra-additive effects were seen on motor side effects for combinations in comparison to equipotent doses of AEDs alone. (Research funding provided by Schwarz Biosciences).
3.014
ANALYSIS OF RESTING-STATE FMRI REVEALS ABNORMAL HIPPOCAMPUS-PRECUNEUS CONNECTIVITY IN PATIENTS WITH TEMPORAL LOBE EPILEPSY
Roman Rodionov1,21Department of Clinical and Experimental Epilepsy, Institute of Neurology, University Colledge London, London, United Kingdom2National Society for Epilepsy, London, United Kingdom, H. Laufs1,31Department of Clinical and Experimental Epilepsy, Institute of Neurology, University Colledge London, London, United Kingdom3Brain Imaging Center and Klinik für Neurologie, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany, R. Thornton1,21Department of Clinical and Experimental Epilepsy, Institute of Neurology, University Colledge London, London, United Kingdom2National Society for Epilepsy, London, United Kingdom, M. Chupin1,21Department of Clinical and Experimental Epilepsy, Institute of Neurology, University Colledge London, London, United Kingdom2National Society for Epilepsy, London, United Kingdom, J. S. Duncan1,21Department of Clinical and Experimental Epilepsy, Institute of Neurology, University Colledge London, London, United Kingdom2National Society for Epilepsy, London, United Kingdom and L. Lemieux1,21Department of Clinical and Experimental Epilepsy, Institute of Neurology, University Colledge London, London, United Kingdom2National Society for Epilepsy, London, United Kingdom (
1Department of Clinical and Experimental Epilepsy, Institute of Neurology, University Colledge London, London, United Kingdom; 2National Society for Epilepsy, London, United Kingdom and 3Brain Imaging Center and Klinik für Neurologie, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany
)
Rationale: Refractory temporal lobe epilepsy (TLE) can be treated by resection of the affected temporal lobe including the hippocampus. Functional MRI can be used as a diagnostic tool to assess hippocampal functional connections non-invasively. In a previous resting-state EEG-fMRI study [1] it was shown that spike-correlated increases in BOLD activity in the hippocampus of the affected temporal lobe are typically associated with decreased BOLD signal in the precuneus. Here using fMRI data only we investigated whether the functional connectivity (FC) between the hippocampus and the precuneus was different in patients with TLE compared to healthy volunteers and thus may serve to identify abnormal temporal lobe activity.
Methods: Eighteen TLE patients and nine healthy controls were studied. Resting-state T2*-sensitive echo planar images were acquired at 3T (GE Signa Excite HDX) and 1.5 T (GE Signa Horizon Echospeed). Using SPM5, images were realigned and normalized (
http://www.fil.ion.ucl.ac.uk/). The following ROI's were defined for each subject: (1) individually segmented hippocampi using high resolution T1 images [2], (2) precuneus defined as a ROI according to the WFU PickAtlas (
http://www.ansir.wfubmc.edu). Following regression of head motion and cardiac-related effects, and of signal changes from the CSF and white matter, BOLD signal time courses were extracted by averaging across each ROI using MarsBar (
http://marsbar.sourceforge.net). Correlation coefficients were calculated as a measure of FC. Non-parametric statistical tests (Wilcoxon rank sum criterion and t-test) were performed to test whether hippocampal-precuneal (Hc-PC) FC differ (i.e. towards anti-correlation) in patients than in controls (one sided t-test).
Results: FC was significantly (p < 0.01) different for patients compared to controls (see Table). Specifically, correlation coefficients in patients were significantly lower than those in the control group reflecting a tendency towards anti-correlation in the former. There was no significant difference in Hc-PC FC between patients scanned at 1.5T vs 3T (p > 0.2).
Conclusions: We demonstrated that resting state fMRI Hc-PC functional connectivity in a group of TLE patients was significantly different from that in healthy subjects. This result can be seen as generalisation of previous findings based on EEG-correlated fMRI and motivates further studies testing whether the proposed approach can provide a reliable marker of TLE and possibly focus lateralisation. (This work is supported by Medical Research Council grant #G0301067)
References:
1. Laufs H., et al., Hum Brain Map, 2006 Nov 28; [Epub ahead of print]
2. Chupin M., et al., Neuroimage, 2007, 34(3):996–1019.
Significance of difference in LHc-PC and RHc-PC functional connectivity
3.015
HOW DOES PILOCARPINE AFFECT BLOOD-BRAIN BARRIER FUNCTION?
Abstract
Chiara Caponi11Lerner Research Institute, Cleveland, OH, F. Bertolini11Lerner Research Institute, Cleveland, OH, N. Marchi11Lerner Research Institute, Cleveland, OH, A. Batra11Lerner Research Institute, Cleveland, OH and D. Janigro11Lerner Research Institute, Cleveland, OH (
1Lerner Research Institute, Cleveland, OH
)
Rationale: The most widely used model of temporal lobe epilepsy consists of peripheral administration of the cholinergic muscarinic agonist pilocarpine which leads to status epilepticus and subsequent spontaneous seizures. It has been generally accepted that these effects are primarily due to cholinergic activation of limbic cortex and hippocampus. However, recent evidence pointed to an alternative mechanism of action that involved peripheral inflammation and leakage across the blood-brain barrier (1, 2).The exact mechanisms of this unexpected cerebrovascular effect of pilocarpine are not yet understood. This prompted us to further investigate the actions of pilocarpine on white blood cells and brain endothelium.
Methods: The effect of pilocarpine on BBB permeability was evaluated in vitro using a Transwell system obtained with a co-culture of human derived brain endothelial cells and human astrocytes in the presence or not of monocytes. Cytokine (IL-6, TNF-alpha and IL-1beta) release from monocytes co-cultured with endothelial cells following exposure to pilocarpine was measured by ELISA test. Morphological changes of endothelial cells were evaluated by fluorescent immunocytochemistry using beta-actin staining. MMP activity was evaluated by zymography. NO production by monocyte was quantified through amperometric detection. Real time NO measurements were taken with nano-molar sensitivity in a flow-based system obtained by a co-culture of human derived brain endothelial cells with circulating mononuclear blood cells.
Results: Pilocarpine increased BBB permeability to serum protein in vivo, and decreased trans-endothelial electrical resistance in vitro. Following exposure to pilocarpine (1.4 mM), we measured a rapid (minutes) release of nitric oxide, paralleled by increased levels of IL-6, but not TNF-alpha or IL-1beta. This was primarily due to activation of receptors on white blood cells occurring in spite of pretreatment with scopolamine (4 μM) and it was associated with MMP2 and MMP9 increased activity. The downstream effects of nitric oxide and cytokine/MMP release by white blood cells consisted of polymerization of endothelial cell beta-actin with subsequent loss of junctional integrity.
Conclusions: Our results suggest that proinflammatory changes induced by peripherally administered pilocarpine consist of a cascade of events that include white blood cell activation and BBB damage induced by cytokine- and NO-mediated actions on endothelial cells.
(Supported by NIH-NS43284, NIH-HL51614, NIH-NS46513, NIH-NS049514 and NIH-NS38195)
1)
Marchi, N. et al. In vivo and in vitro effects of pilocarpine: relevance to epileptogenesis. Epilepsia in press, (2007).
2)
Janigro D. et al. Adenosine-induced release of nitric oxide from cortical astrocytes. Neuroreport (1996 Jul 8)