Comparative study of sodium valproate-induced skeletal malformations using single or double staining methods

Predictive assays for craniofacial malformations: evaluation in Xenopus laevis embryos exposed to triadimefon

Craniofacial defects are one of the most frequent abnormalities at birth, but their experimental evaluation in animal models requires complex procedures. The aim of the present work is the comparison of different methodologies to identify dose- and stage-related craniofacial malformations in Xenopus laevis assay (R-FETAX, where the full cartilage evaluation, including flat mount technique, is the gold standard for skeletal defect detection). Different methods (external morphological evaluation of fresh samples, deglutition test, whole mount cartilage evaluation and Meckel-palatoquadrate angle measurements) were applied. Triadimefon (FON) was selected as the causative molecule as it is known to induce craniofacial defects in different animal models, including the amphibian X. laevis.FON exposure (0-31.25 μM) was scheduled to cover the whole 6-day test (from gastrula to free swimming tadpole stage) or each crucial developmental phases: gastrula, neurula, early morphogenesis, late morphogenesis, tadpole. Dose-dependent effects (fusions among craniofacial cartilages) were evident for groups exposed during the morphogenetic periods (neurula, early morphogenesis, late morphogenesis); gastrula was insensitive to the tested concentrations, tadpole group showed malformations only at 31.25 μM. The overall NOAEL was set at 3.9 μM. Results were evaluated applying benchmark dose (BMD) approach. The comparison of relative potencies from different methods showed deglutition as the only assay comparable with the gold standard (cartilage full evaluation).In conclusion, we suggest deglutition test as a reliable method for a rapid screening of craniofacial abnormalities in the alternative model X. laevis. This is a rapid, inexpensive and vital test allowing to preserve samples for the application of further morphological or molecular investigations.

Repairability of skeletal alterations induced by sodium valproate in rats

The present study aimed at examining postnatal repairability of sodium valproate-induced skeletal alterations in rats. Sodium valproate (400 mg/kg) or the vehicle (distilled water) was orally administrated to pregnant Sprague-Dawley rats from gestation days 9 to 11. Fetuses and pups were obtained on gestation day 21 and postnatal day 11, respectively, and their skeletons were stained with Alizarin red S and Alcian blue and examined. Sodium valproate-induced costal and vertebral alterations in the fetuses included discontinued rib cartilage, fused rib, full or short supernumerary rib, bipart ossification of thoracic centrum, supernumerary lumbar vertebrae, and lumbarization. In pups, however, discontinued rib cartilage was not observed, and the incidence of a short supernumerary rib was significantly lower than that in the fetuses, suggesting that these alterations are postnatally repairable.

Maternal exposure to nanosized titanium dioxide suppresses embryonic development in mice

Although nanoscale titanium dioxide (nano-TiO2) has been extensively used in industrial food applications and daily products for pregnant women, infants, and children, its potential toxicity on fetal development has been rarely studied. The main objective of this investigation was to establish the effects of maternal exposure of nano-TiO2 on developing embryos. Female imprinting control region mice were orally administered nano-TiO2 from gestational day 0 to 17. Our findings showed that Ti concentrations in maternal serum, placenta, and fetus were increased in nano-TiO2-exposed mice when compared to controls, which resulted in reductions in the contents of calcium and zinc in maternal serum, placenta, and fetus, maternal weight gain, placental weight, fetal weight, number of live fetuses, and fetal crown-rump length as well as cauda length, and caused an increase in the number of both dead fetuses and resorptions. Furthermore, maternal nano-TiO2 exposure inhibited development of the fetal skeleton, suggesting a significant absence of cartilage, reduced or absent ossification, and an increase in the number of fetuses with dysplasia, including exencephaly, spina bifida, coiled tail, scoliosis, rib absence, and sternum absence. These findings indicated that nano-TiO2 can cross the blood-fetal barrier and placental barrier, thereby delaying the development of fetal mice and inducing skeletal malformation. These factors may be associated with reductions in both calcium and zinc in maternal serum and the fetus, and both the placenta and embryos may be major targets of developmental toxicity following maternal exposure to nano-TiO2 during the prenatal period. Therefore, the application of nano-TiO2 should be carried out with caution.

Fetal Valproate Syndrome

BACKGROUND

There have been several reports of congenital malformations in the offspring of mothers who took valproic acid (VPA) during pregnancy as a treatment for epilepsy.

METHODS

Herein, we describe four cases with typically similar facial features of fetal valproate syndrome accompanied to minor skeletal abnormalities.

RESULTS

The first case was a 16-month-old girl, presenting with facial dysmorphism, and finger abnormalities. Her mother took VPA (1500 mg/d) up to the 10^th gestational week and at a dosage of 1000 mg/d through the pregnancy. The second patient was 5-year-old boy with speech disability, bilateral cryptorchidism, facial dysmorphism, and finger abnormalities whose mother took VPA (1000 mg/d) through pregnancy. The third 19-month-old patient was the brother of the second patient who had facial dysmorphism, bilateral cryptorchidism, and finger abnormalities. His mother also took VPA (1000 mg/d) through pregnancy. The fourth 3-year and 6 month-old boy with minor facial dysmorphism and sternum deformity was exposed to VPA (500 mg/d) in utero.

CONCLUSION

In conclusion, there is a recognizable spectrum of abnormalities in some infants exposed to VPA without dose-depence and the common facial dysmorphic features and minor skeletal abnormalities that may occur within the both low and high dose VPA use.

Teratology study of amide derivatives of branched aliphatic carboxylic acids with 4-aminobenzensulfonamide in NMRI mice

BACKGROUND

Valproic acid (VPA), widely used to treat epilepsy, bipolar disorders, and migraine prophylaxis, is known to cause neural tube and skeletal defects in humans and animals. Aminobenzensulfonamide derivatives of VPA with branched aliphatic carboxylic acids, namely 2-methyl-N-(4-sulfamoyl-phenyl)-pentanamide (MSP), 2-ethyl-N-(4-sulfamoyl-phenyl)-butyramide (ESB), 2-ethyl-4-methyl-N-(4-sulfamoyl-phenyl)-pentanamide (EMSP), and 2-ethyl-N-(4-sulfamoyl-benzyl)-butyramide (ESBB), have shown more potent anticonvulsant activity than VPA in preclinical testing. Here, we investigated the teratogenic effects of these analogous compounds of VPA in NMRI mice.

METHODS

Pregnant NMRI mice were given a single subcutaneous injection of either VPA at 1.8 or 3.6 mmol/kg, or MSP, ESB, EMSP, or ESBB at 1.8, 3.6, or 4.8 mmol/kg on gestation day (GD) 8. Cesarean section was performed on GD 18, and the live fetuses were examined for external and skeletal malformations.

RESULTS

Compared with VPA, which induced neural tube defects (NTDs) in fetuses at 1.8 and 3.6 mmol/kg, the analog derivatives induced no NTDs at dose levels up to 4.8 mmol/kg (except for a single case of exencephaly at 4.8 mmol/kg MSP). Skeletal examination showed several abnormalities mainly at the axial skeletal level with VPA at 1.8 mmol/kg. Fused vertebrae and/or fused ribs were also observed with MSP, ESB, EMSP, and ESBB, they were less severe and seen at a lower incidence that those induced by VPA at the same dose level.

CONCLUSIONS

In addition to exerting more potent preclinical antiepileptic activity, teratology comparison indicates that aminobenzensulfonamide analogs are generally more weakly teratogenic than VPA.

Increases in discontinuous rib cartilage and fused carpal bone in rat fetuses exposed to the teratogens, busulfan, acetazolamide, vitamin A, and ketoconazole

Skeletal changes induced by treatment of pregnant rats with four potent teratogens, busulfan, acetazolamide, vitamin A palmitate, and ketoconazole, were evaluated using Alizarin Red S and Alcian Blue double-staining to investigate the relationship between drug-induced skeletal malformations and cartilaginous changes in the fetuses. Pregnant rats (N = 8/group) were treated once or twice between gestation days (GDs) 10 to 13 with busulfan at doses of 3, 10, or 30 mg/kg; acetazolamide at 200, 400, or 800 mg/kg; vitamin A palmitate at 100,000, 300,000, or 1,000,000 IU/kg; or ketoconazole at doses of 10, 30, or 100 mg/kg. Uterine evaluations and fetal external and skeletal examinations were conducted on GD 20. Marked skeletal abnormalities in ribs and hand/forelimb bones such as absent/ short/bent ribs, fused rib cartilage, absent/fused forepaw phalanx, and misshapen carpal bones were induced at the mid- and high-doses of busulfan and acetazolamide and at the high-dose of vitamin A palmitate and ketoconazole. Increased incidences of discontinuous rib cartilage (DRC) and fused carpal bone (FCB) were observed from the low- or mid-dose in the busulfan and acetazolamide groups, and incidences of FCB were increased from the mid-dose in the vitamin A palmitate and ketoconazole groups. Therefore, DRC and FCB were detected at lower doses than those at which ribs and hand/forelimb malformations were observed in the four potent teratogens.

Boric acid inhibits embryonic histone deacetylases: a suggested mechanism to explain boric acid-related teratogenicity

Histone deacetylases (HDAC) control gene expression by changing histonic as well as non histonic protein conformation. HDAC inhibitors (HDACi) are considered to be among the most promising drugs for epigenetic treatment for cancer. Recently a strict relationship between histone hyperacetylation in specific tissues of mouse embryos exposed to two HDACi (valproic acid and trichostatin A) and specific axial skeleton malformations has been demonstrated. The aim of this study is to verify if boric acid (BA), that induces in rodents malformations similar to those valproic acid and trichostatin A-related, acts through similar mechanisms: HDAC inhibition and histone hyperacetylation. Pregnant mice were treated intraperitoneally with a teratogenic dose of BA (1000 mg/kg, day 8 of gestation). Western blot analysis and immunostaining were performed with anti hyperacetylated histone 4 (H4) antibody on embryos explanted 1, 3 or 4 h after treatment and revealed H4 hyperacetylation at the level of somites. HDAC enzyme assay was performed on embryonic nuclear extracts. A significant HDAC inhibition activity (compatible with a mixed type partial inhibition mechanism) was evident with BA. Kinetic analyses indicate that BA modifies substrate affinity by a factor alpha=0.51 and maximum velocity by a factor beta=0.70. This work provides the first evidence for HDAC inhibition by BA and suggests such a molecular mechanism for the induction of BA-related malformations.

Myo-inositol enhances teratogenicity of valproic acid in the mouse

BACKGROUND

Valproic acid (VPA) is an anticonvulsant drug that is widely used therapeutically for a variety of neurological conditions. VPA is also well known for its teratogenic potential in both humans and experimental animal models. The typical malformations observed following VPA exposure include neural tube defects (NTDs) and craniofacial and skeletal malformations. Nevertheless, the mechanisms underlying VPA's anticonvulsant efficacy or its teratogenicity remain to be elucidated. It was recently suggested that a relationship exists between VPA exposure and the cellular depletion of myo-inositol (INO). Furthermore, INO has been shown to rescue NTDs in the curly tail mouse. The aim of this study was to investigate the interactions of VPA and INO in the developing embryo.

METHODS

For this purpose, 2 strains of mice were used: SWV/Fnn (known to be sensitive to VPA) and LM/Bc (known to be resistant to VPA-induced NTDs). Pregnant females were randomly assigned to 4 experimental groups: control, VPA (600 mg/kg), INO (400 mg/kg), and VPA plus INO. VPA was injected IP at 8.5 days postcoitum (dpc). INO was administered PO twice a day from 6.5 to 10.5 dpc. At term the dams were killed, the uteri were removed, and all of the general toxicological parameters (number of implants, resorptions, dam weight, and fetus weight) were recorded and statistically analyzed.

RESULTS

Postimplantation loss in the SWV/Fnn strain and NTDs in the LM/Bc strain were significantly increased after the coadministration of VPA and INO.

CONCLUSIONS

This work clearly indicates that INO enhances VPA-induced teratogenicity in the mouse.

The effects of valproic acid, vitamin E and folic acid on ribs of rat fetuses in the prenatal period

The present study was undertaken to determine histopathologic differences in the ribs of Wistar-albino rat fetuses prenatally exposed to valproic acid (VPA), folic acid (FA) and vitamin E (Vit E), and to compare their differential developmental susceptibility and morphological association with skeletal anomalies. VPA (300 mg/ kg), FA (300mg/kg) and Vit E (250mg/kg) were administered to rats on each of gestation days (GD) 7-9. Fetuses were collected on GD 21 and their ribs were examined for malformations. The fetuses were divided into four groups: blind-trial group, VPA group (vpa), VPA and Vit E group (vpa+vit e), valproic and FA group (vpa+fa). In each group; drug procedure, surgical procedure and histological methods were performed. Later, weights and lengths of fetuses in each group were compared and analyzed by one-way Anova test. As a result, maLformations in fetuses were determined and photographed by Nikon SMZ-2 steromicroscopy, using 2 x objective. Administration of single doses of VPA (300 mg/kg) resulted in weight and length loss between blind-trial and vpa group. However, length and weight differences between the other groups were not significant. The objective of the present study is to analyze morphological and histopathologic changes which may occur in a high-risk experimental model after the administration of VPA. In addition, protective roles of the administration of FA and Vit E are assessed.

Teratology study of derivatives of tetramethylcyclopropyl amide analogues of valproic acid in mice

BACKGROUND

Although valproic acid (VPA) is used extensively for treating various kinds of epilepsies, it is well known that it causes neural tube and skeletal defects in both humans and animals. The amide and urea derivatives of the tetramethylcylcopropyl VPA analogue, N-methoxy-2,2,3,3-tetramethylcyclopropanecarboxamide (N-methoxy-TMCD) and 2,2,3,3-tetramethylcyclopropanecarbonylurea (TMC-urea), were synthesized and shown to have a more potent anticonvulsant activity than VPA. The objective of this study was to investigate the teratogenic effects of these compounds in NMRI mice.

METHODS

Pregnant NMRI mice were given a single subcutaneous injection of either VPA, N-methoxy-TMCD, or TMC-urea at 1.8 and 3.6 mmol/kg on gestation day (GD) 8. Cesarean section was performed on GD 18. First, the live fetuses were examined to detect any external malformations, then their skeletons were double-stained for bone and cartilage and subsequently examined.

RESULTS

Significant increases in fetal losses and neural tube defects were observed with administration of VPA at 3.6 mmol/kg when compared to the vehicle control. In contrast, upon cesarean section, there were no significant differences between either N-methoxy-TMCD or TMC-urea and the control groups for any parameter. Skeletal examination revealed that a number of the abnormalities were induced by VPA dose-dependently at high rates of incidence. These abnormalities were mainly at the axial skeletal level. However, lower frequencies of skeletal abnormality were observed with N-methoxy-TMCD and TMC-urea than with VPA.

CONCLUSIONS

In addition to their more potent antiepileptic activity, these findings clearly indicate that N-methoxy-TMCD and TMC-urea are distinctly less teratogenic than VPA in NMRI mice.

Amidic modification of valproic acid reduces skeletal teratogenicity in mice

BACKGROUND

The antiepileptic drug valproic acid (VPA) is well known to cause neural tube and skeletal defects in both humans and animals. The amidic VPA analogues valpromide (VPD) and valnoctamide (VCD) have much lower teratogenicity than VPA inducing exencephaly in mice. The objective of this study was to investigate the teratogenic effects of VPA, VPD, and VCD on the skeleton of NMRI mice.

METHODS

Pregnant NMRI mice were given a single subcutaneous injection of VPA (400 and 800 mg/kg), VPD (800 mg/kg), or VCD (800 mg/kg) on the morning of gestation day (GD) 8. Cesarean section was carried out on GD 18. Live fetuses were double-stained for bone and cartilage and their skeletons were examined.

RESULTS

Significant increases in fetal loss and exencephaly rate were observed with VPA at 800 mg/kg compared to the vehicle control. There were no significant differences between either VPD or VCD and the control groups for any parameter at cesarean section. A number of abnormalities were dose-dependently induced at high incidences by VPA in both the cartilage and bone of vertebrae, ribs and sternum. In contrast, lower frequencies of abnormality were exhibited with VPD and VCD than VPA in all skeletons affected by VPA.

CONCLUSIONS

These findings clearly indicate that VPD and VCD are distinctly less teratogenic than VPA in the induction of not only neural tube defects, but also skeletal abnormalities. A structure-teratogenicity relationship of VPA on the skeleton is suspected.