title: Repeated transcranial magnetic stimulation prevents kindling-induced changes in electrophysiological properties of rat hippocampal CA1 pyramidal neurons.
abstract: The mechanisms underlying antiepileptic or antiepileptogenic effects of repeated transcranial magnetic stimulation (rTMS) are poorly understood. In this study, we investigated the effect of rTMS applied during rapid amygdala kindling on some electrophysiological properties of hippocampal CA1 pyramidal neurons. Male Wistar rats were kindled by daily electrical stimulation of the basolateral amygdala in a semi-rapid manner (12 stimulations/day) until they achieved stage-5 seizure. One group (kindled+rTMS (KrTMS)) of animals received rTMS (1Hz for 4min) 5min after termination of daily kindling stimulations. Twenty four hours following the last kindling stimulation electrophysiological properties of hippocampal CA1 pyramidal neurons were investigated using whole-cell patch-clamp technique. Amygdala kindling significantly depolarized the resting membrane potential and increased the input resistance, spontaneous firing activity, number of evoked spikes and half-width of the first evoked spike. Kindling also decreased the first-spike latency and amplitude significantly. Application of rTMS during kindling somehow prevented the development of seizures and protected CA1 pyramidal neurons of hippocampus against deleterious effect of kindling on both passive and active neuronal electrophysiological properties. Interestingly, application of rTMS alone enhanced the excitability of CA1 pyramidal neurons significantly. Based on the results of our study, it may be suggested that rTMS exerts its anticonvulsant effect, in part, through preventing the amygdala kindling-induced changes in electrophysiological properties of hippocampal CA1 pyramidal neurons. It seems that rTMS exerts protective effects on the neural circuits involved in spreading the seizures from the focus to other parts of the brain.
authors.affiliation: Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Shojaei
authors.affiliation: Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Semnanian
authors.affiliation: Neurophysiology Research Center and Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Janahmadi
authors.affiliation: Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: H
authors.initials: H
authors.lastname: Moradi-Chameh
authors.affiliation: Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: S M
authors.initials: SM
authors.lastname: Firoozabadi
authors.affiliation: Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Electronic address: mirnajaf@modares.ac.ir.
authors.forename: J
authors.initials: J
authors.lastname: Mirnajafi-Zadeh
mesh_terms: D000818:Animals; D066272:Basolateral Nuclear Complex / Q000503:physiopathology; D056547:CA1 Region, Hippocampal / Q000503:physiopathology*; D004195:Disease Models, Animal; D017097:Electric Impedance; D058542:Implantable Neurostimulators; D007696:Kindling, Neurologic / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000503:physiopathology*; D011897:Random Allocation; D017208:Rats, Wistar; D012640:Seizures / Q000503:physiopathology* / Q000628:therapy*; D046509:Tissue Culture Techniques; D050781:Transcranial Magnetic Stimulation / Q000379:methods*
keywords: epilepsy; hippocampus; kindling; transcranial magnetic stimulation; whole-cell recording