Changes in relaxin production by the theca during the preovulatory period of the pig.
Theca and granulosa layers were isolated from the preovulatory follicles of prepubertal gilts which were untreated (Group A), killed 72 h after 1000 i.u. PMSG (Group B), killed 84 h after PMSG (Group C), or killed 84 h after PMSG + 500 i.u. hCG given at 72 h (Group D). The tissues from individual follicles were cultured for 24 h alone (C), with FSH (F) or with LH (L), and the content of immunoreactive relaxin in the culture media was measured by RIA. Concentrations of relaxin-like material were close to the limit of detection of the assay in all granulosa cell cultures, and in the thecal cultures from the untreated gilts. However, thecal cultures from all 19 treated gilts produced relaxin. The mean +/- s.e.m. concentrations (pg/follicle) in Groups AC, BC, CC and DC were 26 X 5 +/- 3 X 04, 93 X 1 +/- 4 X 6, 138 +/- 16 X 4 and 285 X 6 +/- 54 X 1 respectively. Therefore relaxin production was stimulated by PMSG (P less than 0 X 05), with hCG treatment in vivo leading to a further significant increase (P less than 0 X 05). In-vitro treatment with gonadotrophins had no effect in Groups A, C and D, but in Group-B gilts LH produced a significant (P less than 0 X 05) rise in relaxin levels. These studies indicate that the theca is the principal source of relaxin in the porcine preovulatory follicle. The increased production before ovulation suggests that relaxin may be involved in follicular growth or rupture.
D000818:Animals; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006064:Gonadotropins, Equine / Q000494:pharmacology; D006107:Granulosa Cells / Q000378:metabolism; D007986:Luteinizing Hormone / Q000494:pharmacology; D010060:Ovulation; D012065:Relaxin / Q000096:biosynthesis*; D013552:Swine; D013799:Theca Cells / Q000187:drug effects / Q000378:metabolism*
D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D012065:Relaxin