Neuronal death by repetitive cortical spreading depression in juvenile rat brain Homa Sadeghian a, b , Maryam Jafarian a, b , Fariba Karimzadeh a, b , Laya Kafami a , Hadi Kazemi a, c , Philippe Coulon d , Mojdeh Ghabaee b , Ali Gorji d, ⁎ a Shefa Neuroscience Research Center, Tehran, Iran b School of Medicine, Tehran University of Medical Sciences, Tehran, Iran c Pediatric Department, Shahed University, Tehran, Iran d Institut für Physiologie I, Westfälische Wilhelms-Universität Münster, Münster, Germany abstract article info Article history: Received 31 August 2011 Revised 13 October 2011 Accepted 10 November 2011 Available online xxxx Keywords: Migraine with aura Stroke Brain hemorrhage Neuronal damage Brain development Spreading depression (SD) is an intrinsic bioelectrical property of the human central nervous system, which plays a key role in neurological disorders. In the present study, we investigated whether experimentally in- duced repetitive SD caused neuronal death in cortical and subcortical regions of the juvenile rat brain. The animals were anesthetized and the electrodes as well as a cannula were implanted over the brain. Repetitive cortical SD events were induced by KCl injection. The brains were removed after 4 weeks. Repetitive SD en- hanced the production of dark neurons, reduced the mean volume of normal neurons, increased the number of apoptotic neurons, and enhanced expression of the NR 2B subunit of NMDA receptors as well as the GluR1 subunit of AMPA receptors in various regions of the juvenile rat brain. In addition, induction of repetitive SD enhanced long-term potentiation in CA1 hippocampal area. We observed a correlation between cell injury/ neuronal death induced by repetitive SD and changes in glutamate receptor expression. The data indicate that repetitive cortical SD in juvenile rats causes neuronal damage in both cortical and subcortical areas of the brain. This may play an important role in the pathophysiology of SD-related neurological disorders, espe- cially in children. © 2011 Elsevier Inc. All rights reserved. Introduction Spreading depression (SD) is a transient wave of profound neu- ronal and glial depolarization that slowly propagates throughout the brain tissue and is characterized by a high amplitude negative DC shift (Leão, 1944). Clinical as well as experimental investiga- tions indicate the crucial role of SD in some neurological disorders including migraine with aura, cerebrovascular diseases, epilepsy, transient global amnesia, and spinal cord disease (Gorji, 2001; Lauritzen et al., 2011). SD-like waves were observed during ap- pearance of visual aura in migraine attacks (Hadjikhani et al., 2001) and negative DC waves of depolarization were recorded in human brain tissues of patients suffering from aneurismal sub- arachnoid hemorrhage, delayed ischemic stroke after subarachnoid hemorrhage, malignant hemispheric stroke, spontaneous intracere- bral hemorrhage, or traumatic brain injury (Dreier, 2011; Lauritzen et al., 2011). It is generally believed that in contrast to SD under physiological conditions, SD waves are responsible for neuronal death under path- ological conditions, such as ischemia (Dreier et al., 2007; Yanamoto et al., 2005). It has been shown that SD in normal brains of adult rats did not induce cell damage or death (Nedergaard and Hansen, 1988). However, recent studies challenge the concept that SD is harmless in normal brain tissue. It is suggested that repetitive cortical SD in intact brains of juvenile rats may cause neuronal damage in cor- tical and subcortical regions. Repetitive SD-like events produced dark neurons and/or reduced the volume-weighted mean volume of nor- mal neurons in layer V of the temporal cortex and in the granular layer of the dentate gyrus as well as in the caudate-putamen of juve- nile rats (Jafarian et al., 2010). Repeated SD episodes also caused neu- ronal and glial injuries in slice cultures of metabolically competent normally oxygenated but immature hippocampal tissues (Pomper et al., 2006). Neuronal damage, as well as cell death, is reported in several SD-related disorders such as brain ischemia, epilepsy, and brain trauma; both in clinical and experimental investigations. Neuro- nal death due to repeated SD in intact juvenile brains may be relevant for the pathogenesis of neurological disorders in infants and children (Somjen, 2006). In the present study, we investigate whether repetitive SD leads to neuronal death in juvenile rat brain tissues. Furthermore, we studied the effect of repetitive SD on neuronal volume, expression of NR 2B subunit of NMDA receptors as well as GluR1 and GluR2 subunits of AMPA receptors, and changes of synaptic plasticity in different brain regions of juvenile rats. Experimental Neurology xxx (2011) xxx–xxx ⁎ Corresponding author at: Institut für Physiologie I, Universität Münster, Robert- Koch-Strasse 27a, D-48149 Münster, Germany. Fax: + 49 251 8355551. E-mail address: gorjial@uni-muenster.de (A. Gorji). YEXNR-10977; No. of pages: 9; 4C: 4, 6, 7 0014-4886/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.expneurol.2011.11.017 Contents lists available at SciVerse ScienceDirect Experimental Neurology journal homepage: www.elsevier.com/locate/yexnr Please cite this article as: Sadeghian, H., et al., Neuronal death by repetitive cortical spreading depression in juvenile rat brain, Exp. Neurol. (2011), doi:10.1016/j.expneurol.2011.11.017