title: Expression of ovarian inhibin during pregnancy in the rat.
abstract: We have examined the expression of the rat inhibin genes in the maternal ovary during pregnancy. RNA blot analysis indicates that the inhibin-alpha chain mRNA is expressed in the ovary throughout gestation at levels comparable to those observed in cycling rats. In situ hybridization shows that the inhibin-alpha and -beta A mRNAs are produced in the granulosa cells of developing antral follicles; little or no hybridization to functional corpora lutea is observed. Early in pregnancy, a large number of follicles hybridize to both alpha- and beta A-inhibin cDNA probes. Many of these follicles undergo atresia during the first half of pregnancy, and the number of inhibin-expressing follicles reaches a nadir on day 15. This is followed by an increase in inhibin-producing follicles, which peaks just before parturition. The increase in inhibin-expressing follicles observed in late pregnancy corresponds to a small rise in serum inhibin levels, as measured using an alpha chain-specific RIA. After the first postpartum ovulation, few hybridizing follicles are observed. Ovariectomy in either early (day 6) or mid (day 15) pregnancy results in a significant fall in serum inhibin levels and a robust increase in serum FSH levels 9 h after surgery. These results suggest that inhibin is produced by the maternal ovary during pregnancy, that its synthesis is modulated during late gestation, and that inhibin may play a role in regulating FSH secretion during pregnancy.
authors.affiliation: Department of Biochemistry, Northwestern University, Evanston, Illinois 60208.
authors.forename: T K
authors.initials: TK
authors.lastname: Woodruff
authors.forename: J
authors.initials: J
authors.lastname: Ackland
authors.forename: J O
authors.initials: JO
authors.lastname: Rahal
authors.forename: N B
authors.initials: NB
authors.lastname: Schwartz
authors.forename: K E
authors.initials: KE
authors.lastname: Mayo
mesh_terms: D000818:Animals; D001345:Autoradiography; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D007265:Inhibins / Q000235:genetics / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000097:blood; D009693:Nucleic Acid Hybridization; D006080:Ovarian Follicle / Q000378:metabolism; D010052:Ovariectomy; D010053:Ovary / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood / Q000378:metabolism*; D011374:Progesterone / Q000097:blood; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
chemical_list: D012333:RNA, Messenger; D011374:Progesterone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone