title: Embryonic mortality and intrauterine growth retardation (IUGR) associated with placental alterations in pregnant rats treated with methyl methanesulfonate (MMS) at the peri-implantation stage.
abstract: Embryonic mortality and intrauterine growth retardation (IUGR) are induced by exposure of rodents to xenobiotic agents during the pregastrulation period of development. We examined the time course of the effects of methyl methanesulfonate (MMS), an alkylating agent, on conceptus development in order to clarify the relative roles of the embryo and the placenta in their induction. Pregnant rats were treated orally with a single dose of MMS (200 mg/kg) in the morning of gestation day (GD) 6 (peri-implantation stage). Embryonic mortality was increased on GD12 and thereafter by MMS treatment, with newly dead embryos showing placental hypoplasia at GD12. Embryo or fetal weight was also smaller for MMS-treated dams than for control dams from GD14 to GD20. The labyrinth zone and junctional zone (JZ) of the placenta were thinner in MMS-treated rats from GD12 to GD17 and from GD12 to GD20 (except for GD17), respectively. Furthermore, MMS-treated dams showed a smaller number of glycogen cells in the JZ on GD14. In contrast, the placental glycogen concentration was higher and the expression of glucose transporter 1 in the JZ remained at GD20. These results indicate that exposure of pregnant rats to MMS at the peri-implantation stage of embryogenesis affects placental development and growth. The placental impairment induced by MMS was likely responsible for the embryonic death observed 6 days after exposure of dams to this agent as well as for the IUGR of surviving embryos or fetuses throughout the gestation period.
authors.affiliation: Interdisciplinary Graduate School of Science and Technology, Shinshu University, Kamiina, Nagano, Japan. ryohei_yokoi@pharm.kissei.co.jp
authors.forename: Ryohei
authors.initials: R
authors.lastname: Yokoi
authors.forename: Morimichi
authors.initials: M
authors.lastname: Hayashi
authors.forename: Toru
authors.initials: T
authors.lastname: Tamura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Junji
authors.initials: J
authors.lastname: Kuroda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kusama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kagami
authors.forename: Tamao
authors.initials: T
authors.lastname: Ono
mesh_terms: D000477:Alkylating Agents / Q000633:toxicity*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D020964:Embryo Loss / Q000139:chemically induced* / Q000473:pathology; D047108:Embryonic Development / Q000187:drug effects*; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects; D005260:Female; D047109:Fetal Development / Q000187:drug effects; D005317:Fetal Growth Retardation / Q000139:chemically induced* / Q000473:pathology; D005865:Gestational Age; D008297:Male; D008741:Methyl Methanesulfonate / Q000633:toxicity*; D010920:Placenta / Q000187:drug effects* / Q000473:pathology; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D014599:Uterus / Q000187:drug effects / Q000473:pathology
chemical_list: D000477:Alkylating Agents; D001786:Blood Glucose; D008741:Methyl Methanesulfonate