Folic acid and pantothenic acid protection against valproic acid-induced neural tube defects in CD-1 mice

https://doi.org/10.1016/j.taap.2005.07.008Get rights and content

Abstract

In utero exposure to valproic acid (VPA) during pregnancy is associated with an increased risk of neural tube defects (NTDs). Although the mechanism by which VPA mediates these effects is unknown, VPA-initiated changes in embryonic protein levels have been implicated. The objectives of this study were to investigate the effect of in utero VPA exposure on embryonic protein levels of p53, NF-κB, Pim-1, c-Myb, Bax, and Bcl-2 in the CD-1 mouse. We also evaluated the protective effects of folic acid and pantothenic acid on VPA-induced NTDs and VPA-induced embryonic protein changes in this model. Pregnant CD-1 mice were administered a teratogenic dose of VPA prior to neural tube closure and embryonic protein levels were analyzed. In our study, VPA (400 mg/kg)-induced NTDs (24%) and VPA-exposed embryos with an NTD showed a 2-fold increase in p53, and 4-fold decreases in NF-κB, Pim-1, and c-Myb protein levels compared to their phenotypically normal littermates (P < 0.05). Additionally, VPA increased the ratio of embryonic Bax/Bcl-2 protein levels (P < 0.05). Pretreatment of pregnant dams with either folic acid or pantothenic acid prior to VPA significantly protected against VPA-induced NTDs (P < 0.05). Folic acid also reduced VPA-induced alterations in p53, NF-κB, Pim-1, c-Myb, and Bax/Bcl-2 protein levels, while pantothenic acid prevented VPA-induced alterations in NF-κB, Pim-1, and c-Myb. We hypothesize that folic acid and pantothenic acid protect CD-1 embryos from VPA-induced NTDs by independent, but not mutually exclusive mechanisms, both of which may be mediated by the prevention of VPA-induced alterations in proteins involved in neurulation.

Section snippets

Animals

All animal procedures complied with the Canadian Council for Animal Care and were approved by the Queen's University Animal Care Committee. CD-1 mice (Charles River Canada Inc., St. Constant, Quebec) weighing 24–28 g were kept in a temperature-controlled room with a 12-h light–dark cycle automatically maintained. Food (Purina Rodent Chow, Ren's Feed and Supply, Oakville, Ontario) and tap water were provided ad libitum. One male mouse was housed with three females overnight between 4:30 pm and

VPA-induced neural tube defects in CD-1 mice

A dose–response profile of VPA-induced exencephaly was created by exposing time-controlled pregnant CD-1 mice to 0, 300, 400, and 600 mg/kg of VPA on GD 9 prior to the period of neural tube closure in these embryos. The neural tube closure status of these mice was evaluated 36 h later, on GD 10.5. VPA (300, 400, and 600 mg/kg) caused a 14 ± 7%, 24 ± 10%, and 40 ± 18.5% incidence of exencephaly, respectively, as compared to control animals (0%), indicating that VPA exposure on GD 9 induces NTDs

Discussion

In previous studies, Padmanabhan and Shafiullah (2003), using the same FA dosing regime used in this study, demonstrated a decrease in VPA-induced NTDs from 38% to 18% in the TO mouse model. Likewise, Sato et al. (1995), using the same PTA dosing regime used in our study, showed a decrease in VPA-induced NTDs from 13.7% to 3.8% in ICR mice. Consistent with these previous studies, in our studies, we found that FA and PTA decreased VPA-induced NTDs from 23.6% to 3.0% and 6.8%, respectively.

The

References (40)

  • A.L. Bhakar et al.

    Constitutive nuclear factor-kappa B activity is required for central neuron survival

    J. Neurosci.

    (2002)
  • J.M. Burgoon et al.

    Investigation of the effects of folate deficiency on embryonic development through the establishment of a folate deficient mouse model

    Teratology

    (2002)
  • M.S. Byun et al.

    Dual effect of oxidative stress on NF-kappakB activation in HeLa cells

    Exp. Mol. Med.

    (2002)
  • A.J. Copp et al.

    Neural tube defects: prevention by folic acid and other vitamins

    Indian J. Pediatr.

    (2000)
  • P. Crawford

    Epilepsy and pregnancy

    Seizure

    (2002)
  • L.V. Dansky et al.

    Mechanisms of teratogenesis: folic acid and antiepileptic therapy

    Neurology

    (1992)
  • E.L. Fernandez et al.

    Cadmium-induced changes in apoptotic gene expression levels and DNA damage in mouse embryos are blocked by zinc

    Toxicol. Sci.

    (2003)
  • R.H. Finnell et al.

    Molecular basis of environmentally induced birth defects

    Annu. Rev. Pharmacol. Toxicol.

    (2002)
  • E. Giavini et al.

    Gene–teratogen interactions in chemically induced congenital malformations

    Biol. Neonate

    (2004)
  • M. Harris et al.

    Mini-Review: toward understanding mechanisms of genetic neural tube defects in mice

    Teratology

    (1999)
  • Cited by (61)

    • Characterizing the effects of in utero valproic acid exposure on NF-κB signaling in CD-1 mouse embryos during neural tube closure

      2021, Neurotoxicology and Teratology
      Citation Excerpt :

      In order to be activated NF-κB undergoes a variety of posttranslational modifications including phosphorylation of p65 by Pim-1 at Ser276 which stabilizes p65 (Nihira et al., 2010). As our laboratory reported reduced levels of phosphorylated p65 at Ser276 following VPA exposure in P19 cells (Lamparter et al., 2017) and a significant downregulation in Pim-1 protein levels in VPA-exposed GD10 mouse embryos (Dawson et al., 2006), we examined Pim-1 gene expression in this study. The observed VPA-induced decreases in transcript levels of Pim-1 (Fig. 3a), could be responsible for the depleted levels of phosphorylated/active p65 in VPA-exposed mouse embryos.

    • Role of environmental factors and epigenetics in autism spectrum disorders

      2020, Progress in Molecular Biology and Translational Science
    • M2-like cells from the macrophage lineage might play a central role in closure of the embryonic neural tube

      2019, Medical Hypotheses
      Citation Excerpt :

      Therefore, it is is possible that sildenafil rescues VPA induced teratogenesis both by attenuating peroxynitrite induced inhibition of the NMDA receptor and also by attenuating peroxynitrite induced apoptosis in macrophages. Given that nitric oxide teratogenicity for the neural tube is rescued by folic acid, it may come as no surprise that, in mice, VPA induced teratogenicity to the neural tube is also rescuable by folic acid [54,55]. To demonstrate that M2-like macrophages play a role in influencing neural tube closure on a structural level, one would need to demonstrate that M2-like macrophages are capable of exerting effects, either directly or indirectly, on factors which contribute to the structural integrity of the developing embryo.

    View all citing articles on Scopus

    These studies were supported by a grant from the Canadian Institutes of Health Research (to L.M.W. FRN57920) and from the J.P. Bickell Foundation. A preliminary report of this research was presented at the 43rd annual meeting of the Society of Toxicology (U.S.A.) Toxicol. Sci. Suppl. No. 182.

    View full text