Direct Comparison of Two Commonly Used Prenatal Valproate Doses Identifies Different Sex- and Age-Related Neurobehavioral Outcomes Across Development

Valproic acid (VPA) is a widely used anticonvulsant and mood stabilizer and a known teratogen associated with neural tube defects and neurodevelopmental disorders, including autism spectrum disorder (ASD). Prenatal VPA exposure is widely used to model ASD-like behaviors in rodents; however, direct comparisons between commonly used doses are lacking. We compared two widely used VPA doses (300 and 600 mg/kg) administered to pregnant mice on embryonic day 12.5 (E12.5). Male and female offspring were evaluated longitudinally for early neurological development, ultrasonic vocalizations, locomotor activity, anxiety-related behavior, sociability, and spontaneous alternation. Early development was largely preserved, although VPA300 delayed cliff aversion acquisition. Total ultrasonic vocalization production was unaffected, while selected call types were altered. Later behavioral effects differed across dose, sex, and age. In males, locomotor activity and center exploration were preserved, sociability was reduced by both VPA doses, and spontaneous alternation was reduced by VPA300 at postnatal day 70 (PND70). In females, locomotor activity was reduced by VPA600 at PND30 and VPA300 at PND70, center exploration was reduced by VPA600, and sociability was reduced by VPA300 at both ages and VPA600 at PND70. VPA600 was also associated with greater embryonic mortality. These findings show that the two VPA doses were associated with differing patterns of developmental and behavioral outcomes, without a consistent increase in severity at the higher dose.