Neuroprotective effect of topiramate on hypoxic ischemic brain injury in neonatal rats
Introduction
Topiramate [2,3:4,5-bis-o-(1-methylethylidene) β-d-fructo-pyranose sulfamate; TPM] is widely used as an antiepileptic drug (Angehagen et al., 2003a, Shank et al., 1994). It is a chemically novel antiepileptic drug that has a broad spectrum of antiepileptic activities in both experimental and clinical studies (White, 1997). Its anticonvulsant activity is probably due to suppressing excitatory tone and/or enhancing inhibitory currents (Angehagen et al., 2003a, Poulsen et al., 2004, Skradski and White, 2000, White et al., 1997, White et al., 2000b). Among its many actions, TPM has an antiglutamatergic action, and it has been suggested that TPM may be effective against many brain pathologies mediated by glutamatergic excitotoxicity. For instance, ischemic brain injury rapidly stimulates synaptic glutamate release, and the aberrant activation of glutamate receptors leads to an increase in intracellular calcium concentration that triggers a chain of events resulting in neuronal death. Activation of glutamate receptors appears to play an essential role in this cascade since glutamate receptor antagonists are efficient at protecting neurons from ischemia-induce death (Calabresi et al., 2003, Johnston et al., 2001). Therefore, drug(s) which prevent the activation of glutamatergic receptors might be clinically useful in brain ischemia (Calabresi et al., 2003). Although several studies have challenged this idea (for review, White et al., 2000a), recent studies have shown that TPM reduces the spread of neuronal damage induced by transient global cerebral ischemia in the adult rodent model (Edmonds et al., 2001, Lee et al., 2000, Yang et al., 1998). Furthermore, TPM in combination with hypothermia is also neuroprotective in perinatal rats (Liu et al., 2004), although the mechanism involved is less clear.
There is substantial evidence that the immature brain differs in its susceptibility to ischemic injury and glutamatergic excitotoxicity (Herlenius and Lagercrantz, 2004, Johnston et al., 2001, Marini et al., 2001, Penning et al., 1991, Ikonomidou et al., 1989). This is due in part to differences in the expression of glutamate receptor subunits during brain development (Bahn et al., 1994, Jakowec et al., 1998, Monyer et al., 1994, Pagliusi et al., 1994) so that bursts of glutamate induced by hypoxia–ischemia (H–I) activate different types of receptor depending on age. In this study, we present evidence that TPM reduces neuronal damage caused by oxygen–glucose deprivation (OGD)-induced ischemia in vitro, mainly as a result of blockade of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor, and that it reduces perinatal hypoxic ischemic injury in vivo.
Section snippets
Primary cerebral cortical cell culture
Primary cerebral cortical neuron cultures were prepared from embryonic 17 days Sprague–Dawley rat (Sun et al., 2002). Briefly, the cerebral cortex was dissected and digested with 0.25% trypsin-EDTA (Gibco BRL). The dissociated cells were plated on poly-d-lysine (50 μg/ml)-coated coverslips at a density of 2 × 105 cells/24-well. The complete growth medium consisted of Neurobasal medium (Gibco BRL) containing B27 supplement (Gibco BRL), 200 mM l-gutamine (Gibco BRL), 5 mM glutamic acid
Protective effect of TPM against OGD-induced neuronal injury
Following exposure of cells to OGD for 60 min, there was progressive deterioration of cortical neurons during the reperfusion period. After 24 h of reperfusion, less than 5% of the neurons maintained their cellular integrity as defined by NeuN-immunoreactivity (Fig. 1). The morphology and viability of the neurons were similar to those previously reported (Choi, 1993). Viability of the OGD-treated cells was significantly enhanced by the treatment with TPM in a dose-dependent manner. By 30–300 μM
Discussion
We have shown that TPM has a potent neuroprotective effect on OGD-induced neuronal death in vitro and on damage due to H–I in the immature brain in vivo. Furthermore, neurobehavioral analyses revealed that TPM reduced the behavioral consequences of H–I-induced neurological complications. TPM therefore seems to have potential application in a wide range of clinical situations, because both pre- and post-treatments were highly effective by both routes (i.p. injection and oral administration).
Acknowledgments
We thank Drs. Sangduk Kim (Korea University) and Won Ki Kim (Ewha Womans University) for valuable comments on the manuscript. This work was supported by a grant from the Korean Health 21 R&D Project, Ministry of Health and Welfare, Republic of Korea (02-PJ1-PG1-CH06-0001). A part of this work was supported technically by a core facility service of the 21C Frontier Brain Research Center.
References (44)
- et al.
TPM protects against glutamate- and kainate-induced neurotoxicity in primary neuronal–astroglial cultures
Epilepsy Res.
(2003) NMDA receptors and AMPA/kainate receptors mediate parallel injury in cerebral cortical cultures subjected to oxygen–glucose deprivation
Prog. Brain Res.
(1993)- et al.
TPM as a neuroprotectant in a rat model of global ischemia-induced neurodegeneration
Life Sci.
(2001) - et al.
Therapeutic doses of topiramate are not toxic to the developing rat brain
Exp. Neurol.
(2004) - et al.
Mitochondrial permeability transition: a common pathway to necrosis and apoptosis
Biochem. Biophys. Res. Commun.
(2003) - et al.
Spatial learning enhances the expression of inositol 1,4,5-trisphosphate 3-kinase A in the hippocampal formation of rat
Brain Res. Mol. Brain Res.
(2004) - et al.
Protective effect of TPM against hippocampal neuronal damage after global ischemia in the gerbils
Neurosci. Lett.
(2000) - et al.
Parallel information processing in the water maze: evidence for independent memory systems involving dorsal striatum and hippocampus
Behav. Neural Biol.
(1994) - et al.
Developmental and regional expression in the rat brain and functional properties of four NMDA receptors
Neuron
(1994) - et al.
Age-related changes in expression of AMPA-selective glutamate receptor subunits: is calcium-permeability altered in hippocampal neurons?
Neuroscience
(1994)
TPM alters excitatory synaptic transmission in mouse hippocampus
Epilepsy Res.
TPM: a review of preclinical, pharmacokinetic, and clinical data
Clin. Therapeutics
Recovery of function after brain damage: severe and chronic disruption by diazepam
Brain Res.
Localization and functional role of hepatocyte growth factor (HGF) and its receptor c-met in the rat developing cerebral cortex
Brain Res. Mol. Brain Res.
Effective treatment with fucoidin for perinatal hypoxic–ischemic encephalopathy in rats
Neurosci. Lett.
TPM enhances GABA-mediated chloride flux and GABA-evoked chloride currents in murine brain neurons and increases seizure threshold
Epilepsy Res.
Brain ischemia and reperfusion: molecular mechanisms of neuronal injury
J. Neurol. Sci.
Neuroprotection by delayed administration of TPM in a rat model of middle cerebral artery embolization
Brain Res.
Novel mechanisms of action of three antiepileptic drugs, vigabatrin, tiagabine, and TPM
Neurochem. Res.
Kainate receptor gene expression in the developing rat brain
J. Neurosci.
Pharmacokinetics and metabolism of TPM
Drugs Today (Barc.)
Antiepileptic drugs as a possible neuroprotective strategy in brain ischemia
Ann. Neurol.
Cited by (0)
- 1
These two authors contributed equally to this work and are co-first authors.