The anti-epileptic drug valproic acid causes malformations in the developing craniofacial skeleton of zebrafish larvae. (September 2020)

• Record Type: Journal Article
• Authors: Gebuijs, I.G.E.; Metz, J.R.; Zethof, J.; Carels, C.E.L.; Wagener, F.A.D.T.G.; Von den Hoff, J.W.
• Is Part Of: Mechanisms of development. Volume 163(2020)
• Publication Date: 2020-09
• Subjects: Valproic acid -- Craniofacial development -- Zebrafish -- Embryology -- Bone -- Cartilage; Developmental biology -- Periodicals; Molecular biology -- Periodicals; Developmental Biology -- Periodicals; Molecular Biology -- Periodicals; Biologie du développement -- Périodiques; Biologie moléculaire -- Périodiques; Developmental biology; Molecular biology; Periodicals; Electronic journals; 571.8
• DOI: 10.1016/j.mod.2020.103632
• Languages: English
• ISSNs: 0925-4773

Abstract

Abstract: Valproic acid (VPA) is an anti-epileptic drug known to cause congenital craniofacial abnormalities, including orofacial clefts (OFC). The exact mechanisms by which VPA leads to craniofacial skeletal malformations are poorly understood. In this study, we investigated the effects of VPA on cartilage and bone formation in the zebrafish larval head during 1–13 hpf (early) and 25–37 hpf (late) development in which cranial neural crest cells (CNCCs) arise and then proliferate and differentiate, respectively. Double-staining for cartilage and bone at 5 dpf revealed that VPA reduced cartilage and bone formation in a dose-dependent manner after both early or late exposure. Several different CNCC-derived cartilage and bone elements were affected in both groups. In the early group (100 μM VPA), the posterior head length and the ethmoid plate were reduced in length (both p < 0.01), while mineralization of 4 out of 9 bone elements was often lacking (all p < 0.01). In the late group (100 μM VPA), also the posterior head length was reduced as well as the length of the ceratohyals (both p < 0.01). Similar to early exposure, mineralization of 3 out of 9 bone elements was often lacking (all p < 0.01). These results indicate that both CNCC formation (early) and differentiation (late) are hampered by VPA treatment, of which the consequences for bone and cartilage formation are persistent at 5 dpf. Indeed, we also found that the expression of several genes related to cartilage and bone was upregulated at 5 dpf. These data indicate a compensatory reaction to the lack of cartilage and bone. Altogether, VPA seems to induce craniofacial malformations via disturbed CNCC function leading to defects in cartilage and bone formation. Highlights: Valproic acid causes craniofacial malformation in zebrafish larvae. Valproic acid affects the formation of cartilage elements as well as mineralized elements. Valproic acid seems to affect both CNCC formation and differentiation. Skeletal gene expression at 5 dpf indicate a compensatory reaction to the lack of cartilage and bone.