Biomaterial Database

Effects of the antiprogesterone RU 486 on preterm birth in the rat. 1987

R E Garfield, and J M Gasc, and E E Baulieu

Department of Neurosciences, McMaster University, Hamilton, Ontario, Canada.

The effects of the antiprogesterone compound RU 486 on preterm delivery, myometrial gap junctions, and plasma levels of steroid hormones were investigated in pregnant rats. Injection of RU 486 on day 16 of gestation resulted in prolonged delivery beginning after 24 hours. The preterm birth initiated by RU 486 was preceded and accompanied by the extensive development of gap junctions between myometrial cells. R 5020, but neither progesterone nor dexamethasone, prevented preterm birth and the development of gap junctions. Estrogen and progesterone levels declined after RU 486 treatment but only after a major proportion of the fetuses were delivered. This study indicates that progesterone may normally inhibit uterine contractility by suppressing the genome responsible for the expression of gap junctions.

UI	MeSH Term	Description	Entries
D007365	Intercellular Junctions	Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)	Cell Junctions,Cell Junction,Intercellular Junction,Junction, Cell,Junction, Intercellular,Junctions, Cell,Junctions, Intercellular
D007752	Obstetric Labor, Premature	Onset of OBSTETRIC LABOR before term (TERM BIRTH) but usually after the FETUS has become viable. In humans, it occurs sometime during the 29th through 38th week of PREGNANCY. TOCOLYSIS inhibits premature labor and can prevent the BIRTH of premature infants (INFANT, PREMATURE).	Preterm Labor,Labor, Premature,Premature Labor,Premature Obstetric Labor,Labor, Premature Obstetric,Labor, Preterm
D009215	Myometrium	The smooth muscle coat of the uterus, which forms the main mass of the organ.	Uterine Muscle,Muscle, Uterine,Muscles, Uterine,Uterine Muscles
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011255	Pregnancy Maintenance	Physiological mechanisms that sustain the state of PREGNANCY.	Maintenance, Pregnancy,Maintenances, Pregnancy,Pregnancy Maintenances
D011374	Progesterone	The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS.	Pregnenedione,Progesterone, (13 alpha,17 alpha)-(+-)-Isomer,Progesterone, (17 alpha)-Isomer,Progesterone, (9 beta,10 alpha)-Isomer
D011919	Rats, Inbred Strains	Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.	August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
D004963	Estrenes	Unsaturated derivatives of the ESTRANES with methyl groups at carbon-13, with no carbon at carbon-10, and with no more than one carbon at carbon-17. They must contain one or more double bonds.	19-Norandrostenes,19 Norandrostenes
D005260	Female		Females
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia