Preimplantation mouse embryo development as a target of the pesticide methoxychlor.
Effects of methoxychlor (MXC) and estradiol-17beta (E) were studied in mouse preimplantation embryos. Pregnant mice received s.c. injections of sesame oil only, 10 microg E, or 0.5 mg purified (95%) MXC on Days 2-4 of pregnancy (plug = Day 1). Another group received a single dose of 2.5 microg E on Day 2 only. Based on the average weight of pregnant females, 10 microg of estradiol was equivalent to 0.33 mg/kg of bw, 2.5 microg of estradiol was equivalent to 0.082 mg/kg of bw, and the 0.5-mg dose of MXC was equivalent to 16.5 mg/kg of bw. All embryos were collected for analyses on Day 4. MXC and both estradiol-17beta doses suppressed embryonic development to blastocyst, decreased embryo cell numbers, and caused abnormal blastocyst formation. The high estradiol-17beta dose significantly increased the percent degenerating embryos and caused a tube-locking effect, with retention of embryos in the oviduct. In contrast to estradiol-17beta, MXC at the dose used in this study did not alter tubal transport of embryos. Also in contrast to estradiol-17beta, MXC increased the percentage of nuclear fragmentation and micronuclei. In preimplantation embryos, MXC and estradiol-17beta both suppressed embryo development. MXC effects were, however, different from those of estradiol-17beta, indicating a difference in mechanism of action, possibly due to cytotoxicity and induction of apoptosis.
Amstislavsky
Sergei Y
SY
Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Division, Novosibirsk State University, Novosibirsk, Russia.
Kizilova
Elena A
EA
Eroschenko
Victor P
VP
Amstislavksy
Sergei Y
SY
D000014:Abnormalities, Drug-Induced; D000818:Animals; D001755:Blastocyst / Q000187:drug effects / Q000473:pathology; D002467:Cell Nucleus / Q000187:drug effects / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D047108:Embryonic Development / Q000502:physiology*; D005314:Embryonic and Fetal Development / Q000187:drug effects*; D004958:Estradiol / Q000008:administration & dosage / Q000633:toxicity; D005260:Female; D007279:Injections, Subcutaneous; D007306:Insecticides / Q000008:administration & dosage / Q000633:toxicity*; D008297:Male; D008731:Methoxychlor / Q000008:administration & dosage / Q000633:toxicity*; D051379:Mice; D008813:Mice, Inbred ICR; D048629:Micronuclei, Chromosome-Defective / Q000187:drug effects / Q000473:pathology; D011247:Pregnancy
D007306:Insecticides; D004958:Estradiol; D008731:Methoxychlor