Effect of antipsychotic drugs on gene expression in the prefrontal cortex and nucleus accumbens in the spontaneously hypertensive rat (SHR) Marcos Leite Santoro a,b , Vanessa Kiyomi Ota a,b , Roberta Sessa Stilhano c , Patrícia Natália Silva a,b , Camila Maurício Santos b,d , Mariana Cepollaro Diana b,d , Ary Gadelha b , Rodrigo Affonseca Bressan b , Maria Isabel Melaragno a , Sang Won Han c , Vanessa Costhek Abílio b,d , Sintia Iole Belangero a,b, ⁎ a Genetics Division, Department of Morphology and Genetics, Universidade Federal de Sao Paulo (UNIFESP), Rua Botucatu, 740, Edifício Leitao da Cunha, 1° andar, CEP 04023-900 São Paulo, Brazil b LiNC — Interdisciplinary Lab of Clinical Neurosciences, Department of Psychiatry, UNIFESP, Rua Pedro de Toledo, 669, 3° floor, CEP 05039-032 São Paulo, Brazil c Department of Biophysics and Investigation Center for Gene Therapy, Universidade Federal de Sao Paulo (UNIFESP), Rua Mirassol 207, CEP:04044-010, Brazil d Department of Pharmacology, Universidade Federal de Sao Paulo (UNIFESP), Rua Pedro de Toledo 669, 5th floor, CEP: 04039032, Brazil abstract article info Article history: Received 3 December 2013 Received in revised form 3 April 2014 Accepted 5 May 2014 Available online 2 June 2014 Keywords: Spontaneously hypertensive rats Antipsychotic Gene expression DNA methylation Glra1 Brs3 Drd2 Drd3 Galr3 Gabrr1 Antipsychotic drugs (APDs) are the standard treatment for schizophrenia. The therapeutic effect of these drugs is dependent upon the dopaminergic D2 blockade, but they also modulate other neurotransmitter pathways. The exact mechanisms underlying the clinical response to APDs are not fully understood. In this study, we compared three groups of animals for the expression of 84 neurotransmitter genes in the prefrontal cortex (PFC) and nucleus accumbens (NAcc). Each group was treated with a different APD (risperidone, clozapine or haloperidol), and with a non-treated group of spontaneously hypertensive rats (SHRs), which is an animal model for schizophrenia. This study also explored whether or not differential expression was regulated by DNA methylation in the promoter region (PR). In the clozapine group, we found that Chrng was downregulated in the NAcc and six genes were down- regulated in the PFC. In the haloperidol group, Brs3 and Glra1 were downregulated, as was Drd2 in the clozapine group and Drd3, Galr3 and Gabrr1 in the clozapine and haloperidol groups. We also encountered four hypermethylated CG sites in the Glra1 PR, as well as three in the risperidone group and another in the haloperidol group, when compared to non-treated rats. Following the APD treatment, the gene expression results revealed the involvement of genes that had not previously been described, in addition to the activity of established genes. The investigation of the involvement of these novel genes can lead to better understanding about the specific mecha- nisms of action of the individual APDs studied. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Schizophrenia, a complex disorder resulting from a gene-environment interaction, affects 0.3 to 1.6% of the general population (Kessler et al., 2005). Genetics plays a central role in schizophrenia vulnerability, with a heritability of approximately 80% (Cannon et al., 1998). Despite these findings, no single gene has been identified that can explain a substantial proportion of this estimated heritability (Allen et al., 2008). Although alterations in several neurotransmitter pathways have been identified, such as the cholinergic and GABA-ergic (gamma aminobutyric acid) systems, the dopamine system has been proposed to be the final pathway (Seeman, 1987; Stephens et al., 2009; Volk et al., 2000). Hyperdopaminergic neurotransmission in the striatal area has been consistently reported to be related to the positive symptoms of the disease (Laruelle and Abi-Dargham, 1999). Conversely, reduction of dopamine transmission in other areas, such as the prefrontal cortex (PFC), has been proposed to trigger the negative symptoms (Howes and Kapur, 2009; Sequeira et al., 2012). APDs can be divided into two categories: typical APDs, which are mainly D2-like antagonists, and atypical APDs, which act not only on D2-like receptors, but also on other dopamine receptors and pathways, such as serotonin, histamine and acetylcholine, among others (Lopez- Munoz and Alamo, 2011). Receptor affinity studies have shown that additional receptors are involved in the molecular action of APDs (Roth et al., 2004), suggesting that multiple intracellular signal trans- duction cascades could be involved in APD action (Girgenti et al., 2010). Considering the high heritability and the limited results of genomic studies, investigations of gene expression can provide additional in- formation and may improve our understanding of the neurobiological processes related to the disorder and the subsequent response to APD treatment. Several studies have investigated gene expression changes in postmortem brain samples from patients with schizophrenia, and have reported alterations in gene expression related to multiple Schizophrenia Research 157 (2014) 163–168 ⁎ Corresponding author at: Disciplina de Genética/UNIFESP, Rua Botucatu, 740, Ed. Leitao da Cunha, 1° andar, CEP 04023-900 Sao Paulo, Brazil. Tel.: +55 11 5576 4260, +55 11 5576 4264. E-mail address: sinbelangero@gmail.com (S.I. Belangero). http://dx.doi.org/10.1016/j.schres.2014.05.015 0920-9964/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Schizophrenia Research journal homepage: www.elsevier.com/locate/schres