On the Digital Psychopharmacology of Valproic Acid in Mice

Abstract

ObjectiveAntiepileptic drugs (AEDs) require daily ingestion for maximal seizure prophylaxis. Adverse psychiatric consequences of AEDs present as: (i) reversible changes in mood, anger, anxiety and/or irritability that often necessitate drug discontinuation, and (ii) autism and/or cognitive/psychomotor developmental delays following fetal exposure. Technical advances in quantifying naturalistic rodent behaviors may provide sensitive preclinical estimates of AED psychiatric tolerability and neuropsychiatric teratogenicity. MethodsUsing instrumented home-cage monitoring, we assessed how valproic acid (VPA, dissolved in sweetened drinking water) alters home-cage behavior in adult C57BL/6J mice and in the adult offspring of VPA-exposed breeder pairs. By utilizing a pup open field assay, we also examined how prenatal VPA exposure impacts early spontaneous exploratory behavior. ResultsAt 500-600mg/kg/d, chronic VPA produced hyperphagia and increased wheel-running without impacting sleep, activity and measures of risk aversion. When applied chronically to breeder pairs of mice, VPA prolonged the latency to viable litters without affecting litter size. Two-week old VPA-exposed pups displayed open field hypoactivity without alterations in thigmotaxis. As adults, prenatal VPA-exposed mice displayed active state fragmentation, hypophagia and increased wheel running, together with subtle alterations in home-cage dyadic behavior. InterpretationThrough automated home-cage assessments of C57BL/6J mice, we capture an ethologically centered psychopharmacological profile of enterally administered VPA that is aligned with human clinical experience. By characterizing the effects of pangestational VPA exposure, we discover novel murine expressions of pervasive neurodevelopment. Incorporating rigorous comprehensive assessments of neuropsychiatric tolerability may inform the design of future AEDs with improved neuropsychiatric safety profiles, both for patients and their offspring.