title: The dynamics of the steroidogenic response of perifused Xenopus ovarian explants to gonadotropins.
abstract: Steroid release before and during maturation was studied in Xenopus ovarian follicles under various conditions of stimulation of LH in a perifusion system. Acute stimulation by 15 micrograms of LH induces a 10-fold increase in the androgen (testosterone and androstenedione) level which reaches a maximum 4 hr later and then slowly decreases until the 25th hour. Repeated stimulations every 2 or 4 hr are followed by the same androgen increase during the first 8 or 10 hr and then by a slow decrease in the secretion despite new LH injections. A significant increase in progesterone secretion is seen only after at least two stimulations (8 hr). Estradiol secretion slowly increases to a moderate level during the first 5 hr and then remains stable whatever the stimulation. During continuous stimulation (LH 0.5 microgram/ml) androgen levels reach an initial maximum after 4 hr and then fluctuate with a 2-hr period. Addition of theophyllin to the medium enhances these fluctuations. After 12 hr when the progesterone has increased, androgen secretion diminishes to reach a basal level without fluctuations. Germinal vesicle breakdown occurs only in follicles that have been appropriately stimulated to secrete androgens and progesterone during the required time.
authors.affiliation: Laboratoire de Biologie de la Reproduction (UA 256 CNRS), Université de Rennes 1, France.
authors.forename: G
authors.initials: G
authors.lastname: el-Zein
authors.forename: D
authors.initials: D
authors.lastname: Boujard
authors.forename: D H
authors.initials: DH
authors.lastname: Garnier
authors.forename: J
authors.initials: J
authors.lastname: Joly
mesh_terms: D000728:Androgens / Q000378:metabolism*; D000735:Androstenedione / Q000378:metabolism; D000818:Animals; D004958:Estradiol / Q000378:metabolism; D004967:Estrogens / Q000378:metabolism*; D004970:Estrone / Q000378:metabolism; D005260:Female; D007986:Luteinizing Hormone / Q000494:pharmacology*; D010053:Ovary / Q000187:drug effects* / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism; D013997:Time Factors; D014982:Xenopus laevis
chemical_list: D000728:Androgens; D004967:Estrogens; D004970:Estrone; D013739:Testosterone; D000735:Androstenedione; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone