Pharmacology & Pharmacy, 2017, 8, 339-353 http://www.scirp.org/journal/pp ISSN Online: 2157-9431 ISSN Print: 2157-9423 DOI: 10.4236/pp.2017.810025 Oct. 24, 2017 339 Pharmacology & Pharmacy Differential Effects of Valproic Acid on Immobility Responses and Locomotor Activity in Female and Male Rats Oscar Morales-Dionisio 1 , Fidel de la Cruz 1 , Margarita Franco-Colín 1 , Oriana Hidalgo-Alegría 1 , Gonzalo Flores 2 , José Luna-Muñoz 3 , Linda Garcés-Ramírez 1 1 Departamento de Fisiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México 2 Laboratorio de Neuropsiquiatría, Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México 3 Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, México Abstract Valproic acid (VPA) is used in the treatment of epilepsy and behavioral dis- orders. However, the exposure to VPA during pregnancy increases the risk of having offspring with autism spectrum disorder (ASD). Reports indicate that men are more likely to suffer ASD than women who were exposed to VPA prenatally. Few studies have related the sex differences and behavioral changes in the ASD rat model. Our aim was to determinate whether male and female Wistar rats whose mothers were exposed to either VPA (600 mg/kg; animal model for ASD) or saline (0.9%) i.p. at 12.5 day of gestation, have different ef- fects on immobility induce by clamping (IC), dorsal immobility (DI), catalep- sy, locomotor activity, stereotypes, and analgesia (tail flick). For this purpose, we made four groups (n = 8). Group: A) saline male rats, B) saline female rats, C) VPA male rats and D) VPA female rats. At 35 (prepubertal age), 56 (post- pubertal age) and 180 days, we tested the behaviors previously mentioned. Finding that VPA has the same effect on IC, catalepsy, and analgesia in male and female rats, the time of these tests was increased. However, VPA only has an effect on DI in males but not in female rats. On the contrary, there is hyperactivity and an increase of stereotypes in female but not in male rats. Thereby, VPA has an effect on the three immobility responses tested (IC, DI and catalepsy), locomotor activity and analgesia but in a differential way on DI, stereotypes and locomotor activity between male and female rats. Keywords Autism, Immobility Responses, Animal Model for ASD, Locomotor Activity, Valproic Acid How to cite this paper: Morales-Dionisio, O., de la Cruz, F., Franco-Colín, M., Hidalgo-Alegría, O., Flores, G., Luna-Muñoz, J. and Garcés-Ramírez, L. (2017) Differential Effects of Valproic Acid on Immobility Res- ponses and Locomotor Activity in Female and Male Rats. Pharmacology & Pharmacy, 8, 339-353. https://doi.org/10.4236/pp.2017.810025 Received: September 26, 2017 Accepted: October 21, 2017 Published: October 24, 2017 Copyright © 2017 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access