Gonadotropin-stimulated estradiol production in small ovarian follicles of the hen is suppressed by physiological concentrations of prolactin in vitro.
The in vitro effects of physiological levels of prolactin (PRL) on luteinizing hormone (LH)-stimulated estradiol production by four classes of small follicles (super small (SS) less than 1 mm; small white (SW) 1-2 mm; large white (LW) 3-5 mm; and small yellow (SY) 5-10 mm) were compared in laying and out-of-lay (OL) Gifujidori hens. All classes of follicles responded to increasing doses of LH in a dose-dependent manner and the estradiol content of the media increased two to five-fold when 8 ng/ml of ovine LH was included in the incubation media. Ovine PRL (up to 1 micrograms/ml) had no effect on the LH-stimulated rise in media content of estradiol from SW or LW follicles from either the laying or OL hens, whereas the rise in the estradiol content of the media from SS follicles was blocked or reduced by 500 ng/ml PRL in the laying and OL hens, respectively. This suggests that the SS follicles are a target organ for PRL and that PRL may act, in part, at the level of the ovary to reduce estradiol production at the onset of incubation behavior and thus cause ovarian regression.
Zadworny
D
D
Department of Animal Physiology, Faculty of Agriculture, Nagoya University, Japan.
Shimada
K
K
Ishida
H
H
Sato
K
K
D000818:Animals; D002645:Chickens; D004958:Estradiol / Q000096:biosynthesis*; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D007986:Luteinizing Hormone / Q000494:pharmacology*; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000494:pharmacology*
D004958:Estradiol; D011388:Prolactin; D007986:Luteinizing Hormone