A prolonged experimental febrile seizure results in motor map reorganization in adulthood Aylin Y. Reid a, b, ⁎, Quentin J. Pittman a, c , G. Campbell Teskey a, c, d, e a Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1 b Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada T2N 4N1 c Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1 d Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada T2N 4N1 e Department of Psychology, University of Calgary, Calgary, Alberta, Canada T2N 4N1 abstract article info Article history: Received 16 August 2011 Revised 22 September 2011 Accepted 16 October 2011 Available online 25 October 2011 Keywords: Intracortical microstimulation FAST rat GABA Glutamate NKCC1 KCC2 Cation-chloride co-transporter Lipopolysaccharide Kainic acid Introduction: Clinical studies have suggested that children experiencing a febrile seizure (FS) before the age of 1 year have persistent deficits, but it is unknown whether these seizures lead to permanent cortical reorga- nization and alterations in function. A FS on the background of increased genetic seizure susceptibility may also lead to negative long-term consequences. Alterations in neocortical motor map expression provide a measure of neocortical reorganization and have been reported in both adults with frontal lobe epilepsy and following seizure induction in experimental models. The objectives of the present study were to deter- mine whether 1) an infantile FS leads to changes to motor map expression in adulthood; 2) long-term corti- cal reorganization is a function of the age at FS or genetic seizure susceptibility; and 3) different levels of GABA A or glutamate receptor subunits or cation-chloride-co-transporters (CCCs) at the time of FS correlate with alterations to motor map expression. Materials and methods: FSs were induced in postnatal day 10 (P10) or P14 Long–Evans (LE) rats or in P14 seizure-prone FAST rats by the administration of the bacterial endotoxin lipopolysaccharide (LPS) and a sub- convulsant dose of kainic acid. Ten weeks later intracortical microstimulation was performed to generate motor maps of forelimb movement representations. Sensorimotor neocortex samples were also dissected from naïve P10 FAST and P10 and P14 LE pups for western blotting with antibodies against various GABA A , NMDA, and AMPA receptor subunits and for CCCs. Results: Adult FAST rats had larger motor maps with lower stimulation thresholds after a FS at P14, while adult LE rats had significantly lower map stimulation thresholds but similar sized maps after a FS at P10 com- pared to controls. There were no differences in neocortical motor map size or stimulation thresholds in adult LE rats after a FS at P14. Both P10 LE and P14 FAST rats had significantly lower levels of the GABA A receptor α1 subunit, higher levels of the α2 subunit, and a higher NKCC1/KCC2 ratio in the sensorimotor cortex com- pared with the P14 LE rat. In addition, the P14 FAST rats had lower levels of the GluR2 and NR2A receptor subunits in the sensorimotor cortex compared with the P14 LE rats. Conclusions: A single infantile FS can have long-term effects on neocortical reorganization in younger individ- uals and those with underlying seizure susceptibility. These changes may be related to an increased level of excitability in the neocortex of younger or genetically seizure-prone rats, as suggested by immaturity of their GABAergic and CCC systems. Given the high incidence of FSs in children, it will be important to gain a better understanding of how age and genetic seizure predisposition may contribute to the long-term sequelae of these events. © 2011 Elsevier Inc. All rights reserved. Introduction Febrile seizures (FSs) are the most common type of childhood sei- zures, affecting 2–5% of children between the ages of 6 months and 5 years in the United States and Western Europe (Berg and Shinnar, 1996). Nonetheless, they are still poorly understood and many long term sequelae remain unknown. While alterations in hippocampal func- tion (Werboff and Havlena, 1963; Nealis et al., 1978; Kornelsen et al., 1996; Chang et al., 2003; Mesquita et al., 2006; Lemmens et al., 2009) and the subsequent development of spontaneous temporal lobe seizures (Dubé et al., 2006; Scantlebury et al., 2005) after experimental FSs have been reported, a compelling question is whether or not seizure induced changes may occur in other areas of the juvenile brain and lead to Neurobiology of Disease 45 (2012) 692–700 ⁎ Corresponding author at: Health Sciences Center, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1. Fax: +1 403 283 2700. E-mail address: areid@ucalgary.ca (A.Y. Reid). Available online on ScienceDirect (www.sciencedirect.com). 0969-9961/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.nbd.2011.10.013 Contents lists available at SciVerse ScienceDirect Neurobiology of Disease journal homepage: www.elsevier.com/locate/ynbdi