Developmental toxicity of methanol: Pathogenesis in CD-1 and C57BL/6J mice exposed in whole embryo culture.
BACKGROUND
Methanol causes axial skeleton and craniofacial defects in both CD-1 and C57BL/6J mice during gastrulation, but C57BL/6J embryos are more severely affected. We evaluated methanol-induced pathogenesis in CD-1 and C57BL/6J embryos exposed during gastrulation in whole embryo culture.


METHODS
Conceptuses with five to seven somites were exposed to 0, 1, 2, 3, 4, or 6 mg methanol/ml culture medium for 24 hr and embryonic morphology was assessed. Cell death was evaluated by histology and LysoTracker red staining, and cell-cycle distribution was evaluated by flow cytometry.


RESULTS
In C57BL/6J embryos, craniofacial defects were observed at 3 mg methanol/ml and greater. The response for CD-1 embryos was different, with increased dysmorphology only at 6 mg/ml. However, protein content in CD-1 embryos was reduced at 3 mg methanol/ml and above, indicating growth retardation. Yolk sac toxicity occurred only at 6 mg methanol/ml in both strains. Methanol caused only small changes in cell-cycle distribution, while cell death was induced at 4 and 6 mg methanol/ml in both strains after 8 hr. The extent of cell death after 8 hr was greater in C57BL/6J embryos, and increased over time through 18 hr; in contrast, CD-1 embryos showed less cell death at 18 than at 8 hr, suggesting recovery.


CONCLUSIONS
Cell death plays a prominent role in methanol-induced dysmorphogenesis, while cell-cycle perturbation may not. Differences in the extent of cell death between CD-1 and C57BL/6J embryos correlated with differences in the severity of dysmorphogenesis.
Degitz
Sigmund J
SJ
United States Environmental Protection Agency, Research Triangle Park, North Carolina, USA. degitz.sigmund@epa.gov
Rogers
John M
JM
Zucker
Robert M
RM
Hunter
E Sidney
ES
D000014:Abnormalities, Drug-Induced / Q000196:embryology / Q000209:etiology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001842:Bone and Bones / Q000002:abnormalities*; D002453:Cell Cycle / Q000187:drug effects; D047108:Embryonic Development / Q000187:drug effects*; D005775:Gastrula / Q000187:drug effects; D066298:In Vitro Techniques; D000432:Methanol / Q000009:adverse effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D012997:Solvents / Q000009:adverse effects*; D013045:Species Specificity
D012997:Solvents; D000432:Methanol