Sequential developmental changes in holoprosencephalic mouse embryos exposed to ethanol during the gastrulation period.
BACKGROUND
Prenatal exposure to ethanol induces holoprosencephalic malformations in both humans and laboratory animals. However, its teratogenic window for inducing holoprosencephaly is narrow, and the teratogenic mechanism is not well understood. In the present study, we examined the morphological changes in the craniofacial structures of mouse embryos/fetuses at intervals following ethanol treatment and evaluated gene expression patterns in the embryos.


METHODS
Pregnant C57BL/6J mice were given two doses of ethanol (30 mg/kg in total) on the morning (7:00 and 11:00 AM) of day 7. The fetuses were observed at E10.5 and E15.5 grossly and/or histologically. The expression of Shh and Nkx2.1 gene transcripts was examined at E8.5 by in situ hybridization.


RESULTS
Gross and histological abnormalities of the brain and face were found in ethanol-exposed fetuses, and their midline structures were most frequently affected. The midline commissural fibers were often lacking in ethanol-exposed fetuses, even in those cases without external gross malformations. In situ hybridization revealed down-regulation of Shh and Nkx2.1 genes in ethanol-exposed embryos.


CONCLUSIONS
The results indicate that ethanol may perturb the expression of some developmental genes at a critical stage of embryonic development and induce holoprosencephaly and other midline craniofacial malformations, including histological brain abnormalities.
Higashiyama
Daisuke
D
Department of Anatomy and Developmental Biology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Saitsu
Hirotomo
H
Komada
Munekazu
M
Takigawa
Toshiya
T
Ishibashi
Makoto
M
Shiota
Kohei
K
D000014:Abnormalities, Drug-Induced; D000015:Abnormalities, Multiple / Q000139:chemically induced*; D000818:Animals; D002492:Central Nervous System Depressants / Q000633:toxicity*; D047108:Embryonic Development / Q000187:drug effects*; D000431:Ethanol / Q000633:toxicity*; D005260:Female; D005775:Gastrula / Q000187:drug effects*; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism; D016142:Holoprosencephaly / Q000139:chemically induced*; D017403:In Situ Hybridization; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011247:Pregnancy; D000074482:Thyroid Nuclear Factor 1; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D002492:Central Nervous System Depressants; D053823:Hedgehog Proteins; C000614414:Nkx2-1 protein, mouse; D009687:Nuclear Proteins; C465570:Shh protein, mouse; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D000431:Ethanol