Folic acid supplementation rescues valproic acid-induced developmental neurotoxicity and behavioral alterations in zebrafish embryos

Maram Muhsen, Jaclyn Youngs, Anne Riu, Jan Åke Gustafsson, Vijay Sai Kondamadugu, Elefterios Garyfalidis, Maria Bondesson

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Objective: Fetal exposure to the anticonvulsant drug valproic acid (VPA), used to treat certain types of epilepsy, increases the risk for birth defects, including neural tube defects, as well as learning difficulties and behavioral problems. Here, we investigated neurotoxic effects of VPA exposure using zebrafish as a model organism. The capacity of folic acid (FA) supplementation to rescue the VPA-induced neuronal and behavioral perturbations was also examined. Methods: Zebrafish embryos of different transgenic lines with neuronal green fluorescent protein expression were exposed to increasing concentrations of VPA with or without FA supplementation. Fluorescence microscopy was used to visualize alterations in brain structures and neural progenitor cells, as well as motor neurons and neurite sprouting. A twitching behavioral assay was used to examine the functional consequences of VPA and FA treatment. Results: In zebrafish embryos, VPA exposure caused a decrease in the midbrain size, an increase in the midline gap of the hindbrain, and perturbed neurite sprouting of secondary motor neurons, in a concentration-dependent manner. VPA exposure also decreased the fluorescence intensity of neuronal progenitor cells in early developmental stages, indicating fewer cells. Furthermore, VPA exposure significantly altered embryonic twitching activity, causing hyperactivity in dark and hypoactivity in light. Supplementation of FA rescued the VPA-induced smaller midbrain size and hindbrain midline gap defects. FA treatment also increased the number of neuronal progenitor cells in VPA-treated embryos and salvaged neurite sprouting of the secondary motor neurons. FA rescued the VPA-induced alterations in twitching activity in light but not in dark. Significance: We conclude that VPA exposure induces specific neurotoxic perturbations in developing zebrafish embryos, and that FA reversed most of the identified defects. The results demonstrate that zebrafish is a promising model to study VPA-induced teratogenesis and to screen for countermeasures.

Original languageEnglish (US)
Pages (from-to)1689-1700
Number of pages12
Issue number7
StatePublished - Jul 2021


  • brain
  • developmental neurotoxicity
  • folic acid
  • neuron
  • transgenic zebrafish
  • twitching activity
  • valproic acid
  • vitamin B9
  • Rhombencephalon/anatomy & histology
  • Vitamins/therapeutic use
  • Neural Tube Defects/chemically induced
  • Anticonvulsants/toxicity
  • Behavior, Animal/drug effects
  • Lighting
  • Mesencephalon/anatomy & histology
  • Neurotoxicity Syndromes/prevention & control
  • Animals, Genetically Modified
  • Neural Stem Cells/drug effects
  • Zebrafish
  • Valproic Acid/antagonists & inhibitors
  • Motor Neurons/drug effects
  • Animals
  • Larva
  • Folic Acid/therapeutic use
  • Embryonic Development/drug effects
  • Dietary Supplements
  • Neurites/drug effects

ASJC Scopus subject areas

  • Clinical Neurology
  • Neurology


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