Short communication Anxiogenic- and antidepressant-like behavior in corneally kindled rats Piotr Wlaz ´ a, *, Ewa Poleszak b , Anna Serefko b , Aleksandra Wlaz ´ c , Chris Rundfeldt d a Department of Animal Physiology, Institute of Biology, Faculty of Biology and Biotechnology, Maria Curie-Sklodowska University, Lublin, Poland b Chair and Department of Applied Pharmacy, Medical University of Lublin, Lublin, Poland c Department of Pathophysiology, Medical University of Lublin, Lublin, Poland d Drug-Consult.Net, Magdeburg, Germany Introduction Anxiety and depression are common co-morbidities accompa- nying epilepsy [1–3]. Their etiologies are difficult to determine, as they are truly complex. These co-morbidities can be caused by the underlying epilepsy, they may also be of psychosocial nature, and finally they can be the result of antiepileptic therapy. Therefore, the link between seizures and emotional behaviors is difficult to study in epileptic patients. Experimental studies in epileptic animals allow some of the factors that might obscure the results of clinical trials to be avoided. One of the most suitable models to study psychobehavioral events during interictal and ictal periods is the kindling model of epilepsy. Kindling refers to the phenomenon where repetitively administered electrical or chemical stimuli, while initially ineffective, eventually produce full-blown general- ized seizures in response to the stimulus. This increased sensitivity to the stimulation represents a persistent change in the responsiveness to the stimulus. In contrast to models involving animals with spontaneous seizures or with epilepsy, seizures only occur in response to the respective stimulus, and hence can be timed, and so preventing spontaneous seizures and post-ictal depression from causing interference with experimental proce- dures including behavioral testing. The most common way to produce this state is electrical stimulation either via surgically implanted depth electrodes in discrete brain structures, e.g. the amygdala, hippocampus or piriform cortex [4], or via corneal electrodes [5]. Corneal kindling in rats, which meets the criteria for a model suitable for routine anticonvulsant drug screening, had been successfully used for several years by the Antiepileptic Drug Development Program of the National Institute of Neurological Disorders and Stroke [5,6]. In this model, periodic electrical stimulation of an animal can be accomplished without prior surgery and implantation of depth electrodes, or, as in the case of chemical kindling, without repetitive administration of a chemical, usually pentylenetetrazole (PTZ). In amygdala kindled rats, increased sensitivity to the psychoto- mimetic activity of antagonists of the N-methyl-D-aspartate (NMDA) receptor could be shown, and this increased sensitivity in this model reflects the respective findings in epileptic patients, demonstrating that this animal model is suitable for the evaluation Pharmacological Reports 67 (2015) 349–352 A R T I C L E I N F O Article history: Received 14 September 2014 Received in revised form 14 October 2014 Accepted 15 October 2014 Available online 29 October 2014 Keywords: Corneal kindling Anxiety Depression Forced swim test Elevated plus maze A B S T R A C T Background: Anxiety and depression affect epileptic patients much more often than individuals from the general population. We were interested in whether corneal kindling in rats, which is a model of complex partial seizures with secondary generalization, would influence animal behavior in models of anxiety and depression. Methods: Kindling was achieved by transcorneal electric stimulation and fully kindled rats were used in this study. Kindled and sham-stimulated rats were subjected to the elevated plus maze and forced swim test which are believed to be predictive models for anxiety and depression in humans, respectively. Results: Kindling significantly decreased the percentage of time spent by the rats in open arms relative to time spent in open plus closed arms and it reduced immobility time in the swim test as compared with sham-stimulated rats. Conclusions: Our results suggest that corneal kindling produces antidepressant- and anxiety-like effects in rats and it may be a useful model to study epilepsy-associated anxiety. ß 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved. * Corresponding author. E-mail address: piotr.wlaz@umcs.lublin.pl (P. Wlaz ´). Contents lists available at ScienceDirect Pharmacological Reports jou r nal h o mep ag e: w ww .elsevier .co m /loc ate/p h arep http://dx.doi.org/10.1016/j.pharep.2014.10.012 1734-1140/ß 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.