Research Article Anxious and Nonanxious Mice Show Similar Hippocampal Sensory Evoked Oscillations under Urethane Anesthesia: Difference in the Effect of Buspirone János Horváth, 1 Balázs Barkóczi, 1 Géza Müller, 2 and Viktor Szegedi 3 1 Department of Medical Chemistry, University of Szeged, Dom Square 8, Szeged 6720, Hungary 2 Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Temesvari K¨ or´ ut 32, Szeged 6726, Hungary 3 Biological Research Centre, Hungarian Academy of Sciences, Temesvari K¨ or´ ut 32, Szeged 6726, Hungary Correspondence should be addressed to Viktor Szegedi; szegedi.viktor@brc.mta.hu Received 21 December 2014; Revised 17 March 2015; Accepted 17 March 2015 Academic Editor: Preston E. Garraghty Copyright © 2015 J´ anos Horv´ ath et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Hippocampal oscillations recorded under urethane anesthesia are proposed to be modulated by anxiolytics. All classes of clinically efective anxiolytics were reported to decrease the frequency of urethane theta; however, recent indings raise concerns about the direct correlation of anxiolysis and the frequency of hippocampal theta. Here, we took advantage of our two inbred mouse strains displaying extremes of anxiety (anxious (AX) and nonanxious (nAX)) to compare the properties of hippocampal activity and to test the efect of an anxiolytic drugs. No diference was observed in the peak frequency or in the peak power between AX and nAX strains. Buspirone (Bus) applied in 2.5 mg/kg decreased anxiety of AX but did not have any efect on nAX as was tested by elevated plus maze and open ield. Interestingly, Bus treatment increased hippocampal oscillatory frequency in the AX but letit unaltered in nAX mice. Saline injection did not have any efect on the oscillation. Paired-pulse facilitation was enhanced by Bus in the nAX, but not in the AX strain. Collectively, these results do not support the hypothesis that hippocampal activity under urethane may serve as a marker for potential anxiolytic drugs. Moreover, we could not conirm the decrease of frequency ater anxiolytic treatment. 1. Introduction Anxiety disorders are among the most abundant afective dis- orders, with a prevalence of 1% in the Western countries. he neurochemistry behind this set of conditions are relatively well described: the imbalance of the serotoninergic system has been implicated in regulating permanently elevated anxious mood, and a prominent class of anxiolytic drugs used in the clinic exert their action via the serotonergic system including serotonin reuptake inhibitors and agonists of the serotonin 1A receptor (5-HT1AR) [1, 2]. his receptor is most abundant in the hippocampal CA1 [3, 4], suggesting a primary role of this brain part in regulating anxiety. Brain oscillations are thought to govern cognitive pro- cesses, providing temporal functional linkage between dif- ferent brain parts and allowing the temporal separation of functionally distinct neuronal assemblies. Among the rich repertoire of the prominent hippocampal oscillations, theta activity is implicated in various cognitive processes, including locomotion, learning and memory, and alert (fear and anxi- ety) [5, 6]. his rhythm is subject to serotonergic inluences originating in the raphe nuclei [7–11]. Of particular interest here, almost all classes of clinically efective anxiolytics and compounds in the preclinical stage reduce the frequency of hippocampal theta activity elicited by stimulation of the retic- ular formation in freely behaving or anesthetized animals [12]. Notable exception includes direct bilateral histamine infusion into the lateral septum, which decreased anxiety- like responses in two models of anxiety, the elevated plus maze and novelty-induced suppression of feeding test in rats, but, instead of decreasing, the same infusion signiicantly increased hippocampal theta frequency elicited by reticular stimulation in urethane-anesthetized rats [13]. Similar results were reported for direct septal infusion of muscimol, which also increased theta frequency evoked by brainstem stim- ulation and reduced anxiety-like behaviors [14]. Moreover, Hindawi Publishing Corporation Neural Plasticity Volume 2015, Article ID 186323, 9 pages http://dx.doi.org/10.1155/2015/186323