Sex-Dependent Behavioral and Biochemical Alterations in a Prenatal Oral Valproic Acid Rat Model of Autism

Autism spectrum disorder (ASD) is a multifactorial neurodevelopmental condition characterized by impaired sociability, repetitive behaviors, and communication deficits. Animal models have been instrumental in elucidating the mechanisms underlying ASD, with prenatal exposure to valproic acid (VPA) being one of the most widely validated approaches. However, most studies rely on intraperitoneal administration, which poorly reflects human exposure. Here, we investigated the effects of oral prenatal VPA exposure in Wistar rats, focusing on behavioral outcomes, biochemical alterations, and sex-dependent differences. Pregnant females received VPA (500 mg/kg) by gavage on gestational days 11-13, and offspring were monitored from neonatal to juvenile stages. VPA-exposed pups exhibited delayed physical maturation, including postponed eye opening, tooth eruption, and locomotor development, along with reduced body weight gain. In the juvenile phase, VPA impaired sociability, reduced exploratory activity, and increased repetitive self-grooming. Importantly, behavioral effects were sex-specific: males showed more pronounced deficits in social interaction, whereas females exhibited stronger stereotyped and anxiety-like behaviors. Biochemical assays revealed elevated malondialdehyde (MDA) and nitrite levels, consistent with oxidative and nitrosative stress, especially in the hippocampus and PFC. Additionally, VPA-exposed females showed a marked reduction in hippocampal glutathione (GSH), while males exhibited increased glutamate and γ-aminobutyric acid (GABA) levels in the PFC, indicating disrupted excitatory/inhibitory balance. Collectively, our findings demonstrate that oral VPA administration induces autism-like phenotypes and region-specific neurochemical alterations in a sex-dependent manner. This study reinforces the translational validity of the oral VPA model and identifies oxidative stress and neurotransmitter imbalance as potential biomarkers for ASD pathophysiology and therapeutic intervention.