Clozapine administration reverses behavioral, neuronal, and nitric oxide disturbances in the neonatal ventral hippocampus rat Maria Elena Bringas a , Julio César Morales-Medina b, c , Yaredi Flores-Vivaldo a , Jose Vicente Negrete-Diaz a , Patricia Aguilar-Alonso e , Bertha Alicia León-Chávez e , Zayda Lazcano-Ortiz a , Elibeth Monroy a , Antonio Rodríguez-Moreno f , Rémi Quirion b, d , Gonzalo Flores a, * a Laboratorio de Neuropsiquiatría, Instituto de Fisiología, Universidad Autónoma de Puebla, Puebla, Mexico b Department of Neurology & Neurosurgery, McGill University, Montréal, Quebec, Canada c Douglas Mental Health University Institute, McGill University, Montréal, Quebec, Canada d Department of Psychiatry, McGill University, Montréal, Quebec, Canada e Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, Puebla, Mexico f Laboratorio de Neurociencia Celular y Plasticidad, Universidad Pablo de Olavide, Spain article info Article history: Received 7 June 2011 Received in revised form 18 November 2011 Accepted 7 December 2011 Keywords: Clozapine Golgi cox Locomotor activity Neonatal ventral hippocampus lesion Nitric oxide Schizophrenia abstract Clozapine is widely used in the treatment of schizophrenia; however its complete mechanism of action is not fully established. The neonatal ventral hippocampal lesion (nVHL) has emerged as a model of schizophrenia-related behavior. Our group has previously shown hyperresponsiveness to novel environment, neuronal atrophy in prefrontal cortex (PFC) and nucleus accumbens (NAcc) neurons as well as abnormal levels of nitric oxide (NO) in the PFC of the nVHL rat. In the present study, we aimed to investigate the role of repeated clozapine administration (2 mg/kg/day for 21 days) in a novel envi- ronment, neuronal rearrangement in PFC, NAcc and basolateral amygdala (BLA) as well as NO levels in this model. Clozapine administration reversed the hyperlocomotion observed in a novel environment in the nVHL rat with no effect on locomotion in sham animals. Quantitative morphological analysis demonstrated a retracted neuronal arborization and decreased spinogenesis in the NAcc, PFC and BLA in nVHL rat. Interestingly, clozapine administration also rescued neuronal atrophy in these brain regions. The nVHL also displayed increased NO levels in PFC, striatum and occipital cortex. Clozapine adminis- tration selectively reversed these abnormal levels of NO in striatum in nVHL rat while NO levels were increased in the PFC of sham animals. Our results further extend the usefulness of the nVHL as a model of schizophrenia-related behavior and suggest that clozapine reverses behavioral deficits in these animals by modulating neuronal reorganization and NO levels in the brain. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The neonatal ventral hippocampal lesion (nVHL) has been proposed as a neurodevelopmental model of schizophrenia-related behaviors in the rat (Flores et al., 1996a; Lipska and Weinberger, 2000). These behaviors include hyperresponsiveness to novel environment and psychostimulant administration (Flores et al., 1996a; Lipska et al., 1993), deficits in sensory gating (Sams-Dodd et al., 1997) and working memory impairments (Chambers et al., 1996), which appear only after puberty. Additionally, nVHL induces neuronal rearrangements (Alquicer et al., 2008; Flores et al., 2005), disrupted cholinergic and dopaminergic (DA) trans- mission (Laplante et al., 2005, 2008) and deregulated expression of proteins including STXb1 and clathrin light chain B associated with neurotransmitter release (Vercauteren et al., 2007), as observed in schizophrenic patients. The ventral hippocampus sends excitatory projections to several cortico-limbic regions including the prefrontal cortex (PFC) and nucleus accumbens (NAcc) (Jay and Witter, 1991). Previously, this neonatal lesion was shown to induce a long lasting neuronal atrophy in the PFC and NAcc in the rat (Alquicer et al., 2004; Flores et al., 2005). However, little attention has been given to another limbic structure, the basolateral amygdala (BLA) which is interconnected with these brain regions and also plays a critical role in memory and emotional processing (Chen et al., 2011). These behaviors are often disturbed in schizophrenic subjects (Benes, 2010). Moreover, * Corresponding author. Laboratorio de Neuropsiquiatría, Instituto de Fisiología, Universidad Autónoma de Puebla,14 Sur 6301, Puebla, CP. 72570, Mexico. Tel.: þ52 222 295500x7322; fax: þ52 222 295500x7301. E-mail addresses: gonzaloflores56@gmail.com, gonzalo.flores@correo.buap.mx (G. Flores). Contents lists available at SciVerse ScienceDirect Neuropharmacology journal homepage: www.elsevier.com/locate/neuropharm 0028-3908/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.neuropharm.2011.12.008 Neuropharmacology 62 (2012) 1848e1857