The intracellular
thiol glutathione is known to protect cells against the toxicity of certain drugs and reactive intermediates. In this study, the role of
glutathione in protecting the embryo against two embryolethal and teratogenic metabolites of
cyclophosphamide, and anticancer
drug, was assessed in vitro using the rat whole embryo culture system. Day 10.5 rat embryos were cultured in rat serum medium containing
phosphoramide mustard (1, 10, or 25 microM) or
acrolein (10, 25, 50 or 100 microM), with and without
buthionine sulfoximine (10 or 100 microM), a compound which depletes
glutathione by inhibiting its synthesis. After 45 hr, embryos were assessed for viability, malformations, growth and development, and the
glutathione content of embryos exposed to
buthionine sulfoximine alone was assayed. The
glutathione levels of the embryos and their yolk sacs were decreased significantly by 100 microM
buthionine sulfoximine, whereas 10 microM
buthionine sulfoximine decreased
glutathione levels in the yolk sacs only.
Phosphoramide mustard alone, at concentrations of 10 and 25 microM, did not produce
embryo deaths but did cause malformations and growth retardation in 100% of the exposed embryos. The addition of
buthionine sulfoximine (100 microM) had no effect on the teratogenicity or growth-retarding effects of
phosphoramide mustard.
Acrolein alone produced a 25 and 48% incidence of
embryo deaths at 50 and 100 microM, respectively, and a 46% incidence of embryo malformations, as well as significant growth retardation, among the surviving embryos at 100 microM.
Buthionine sulfoximine (10 or 100 microM) significantly enhanced the embryotoxic effects of
acrolein. The addition of 10 microM
buthionine sulfoximine resulted in 100% embryolethality at 100 microM
acrolein; this
buthionine sulfoximine concentration decreased the EC50 values for
embryo deaths and malformations to 50% of those for
acrolein alone. The addition of 100 microM butionine sulfoximine significantly potentiated the embryolethality of
acrolein at 25, 50 and 100 microM; the combination of 100 microM
acrolein plus 100 microM
buthionine sulfoximine was 100% embryolethal. The incidence of embryo malformations was enhanced significantly
at 10 and 25 microM
acrolein by 100 microM
buthionine sulfoximine. The EC50 values for
embryo deaths and malformations were decreased to 50 and 20%, respectively, of those values for
acrolein alone. Both butionine sulfoximine concentrations produced significant growth retardation at all
acrolein concentrations compared to either
acrolein or
buthionine sulfoximine alone.(ABSTRACT TRUNCATED AT 400 WORDS)