Relationship of embryotoxicity to disposition of 2-methoxyethanol in mice

Journal Article · Fri Apr 01 04:00:00 EST 1988 · Toxicol. Appl. Pharmacol.; (United States)

DOI:https://doi.org/10.1016/0041-008X(88)90120-2· OSTI ID:6991715

Sleet, R B; Greene, J A; Welsch, F

Paw development of CD-1 mice is uniquely sensitive to 2-methoxyethanol (ME) given by gavage (po) on gestation day (gd) 11 (copulation plug day = gd 0). The relation between induction of paw dysmorphogenesis and disposition of po ME in the maternal and conceptus compartments was investigated. The expression of digit malformations depends on metabolism of ME to methoxyacetic acid (MAA). ME and MAA were equipotent in causing teratogenicity. Alcohol dehydrogenase (ADH) catalyzes the initial rate-limiting oxidation that leads to embryotoxicity. The ADH inhibitor 4-methylpyrazole or ethanol reduced the incidence of malformations 60-100%, depending on the dosing regimen. Elimination of 14C from 1,2-14C-ME occurred predominantly via urine where 80% of a teratogenic dose was excreted and 6% appeared in CO2. Oxidation of ME to MAA was nearly complete after 1 hr when approximately 90% of 14C in maternal plasma and conceptus coeluted with authentic 14C-MAA upon HPLC. 14C-MAA levels in embryos were 1.2 X those in plasma 1 and 6 hr after dosing, although by 6 hr concentrations had declined to approximately 50% of 1-hr values. Concomitant ethanol did not affect 14C kinetics as measured in maternal blood after oral 14C-ME, but retarded ME conversion to MAA by about 2 hr. Furthermore, embryo 14C-MAA levels then reached only 50% of the peak in embryos from dams dosed with ME alone, an effect that coincided with less 14C incorporation into macromolecules synthesized by the embryo within 6 hr. These data imply that the attenuation of digit malformations by concomitant ethanol may be explained by changes in MAA disposition. However, delayed ethanol reduced teratogenicity by 25%, although MAA was present in the embryo up to 5 hr.

• Research Organization: Chemical Industry Institute of Toxicology, Research Triangle Park, NC (USA)
• OSTI ID: 6991715
• Journal Information: Toxicol. Appl. Pharmacol.; (United States), Journal Name: Toxicol. Appl. Pharmacol.; (United States) Vol. 93:2; ISSN TXAPA
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALCOHOL DEHYDROGENASE
ALCOHOLS
ANIMALS
AZOLES
ENZYME ACTIVITY
ENZYMES
ETHANOL
FETAL MEMBRANES
HEMIACETAL DEHYDROGENASES
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
MAMMALS
MEMBRANES
METABOLISM
MICE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDOREDUCTASES
PLACENTA
PYRAZOLES
RODENTS
TERATOGENESIS
TOXICITY
VERTEBRATES