Finding a Proper Valproic Acid-Based Autism Spectrum Disorder Model in Zebrafish: Early and Long-term Neurobehavioral Studies

Abstract

Background: Valproic acid (VPA), which is often used to treat epilepsy, causes a variety of neurobehavioral impairments that closely resemble the phenotype of autism spectrum disorder (ASD) in prenatally exposed individuals. Although the neurobehavioral effects of extremely low concentrations of VPA have received limited research attention, several investigations have shown that the impact of VPA is connected with the concentration and exposure length. Objectives: In the current study, the aim was to find the lowest dose of VPA with the fewest side effects to induce behavioral phenotypes related to ASD in zebrafish. Methods: Zebrafish embryos were first exposed to various concentrations of VPA (i.e., 1, 5, 15, 25, 48, and 75 µM) for 120 hours. Then, 42 days after conception, the survival rate, quality of hatching, and presence of deformity were assessed. Afterward, a 1 µM VPA was chosen based on observations, and behavioral experiments were carried out at 7, 21, and 42 days after fertilization (dpf). Additionally, 7dpf gene expression analysis was evaluated. Results: According to the obtained findings, behavioral abnormalities resembling ASD were induced in 7 and 21 dpf but not in 42 dpf after 120 hours of exposure to 1µM VPA. Real-time analysis in 7 dpf revealed significant changes in a number of genes linked to ASD, including lrp6, gsk3beta, chd8, and ctnnb. Conclusions: In conclusion, 120 hours of exposure of zebrafish embryos to 1 µM of VPA might produce suitable VPA induces autism-like behavior models in zebrafish larvae to research early and long-term neurobehavioral and gene expression alterations. Studies on drug development might adopt this approach.