title: Effect of ovarian regression and molt on plasma concentrations of thymosin beta 4 in domestic hens (Gallus domesticus).
abstract: Molt induced by infusion of a gonadotropin-releasing hormone agonist (GnRH-A, ([D-leu6,Pro9]-GnRH N-ethylamide]) or feed withdrawal (FW) has been used as a model to study interactions between ovarian activity and thymosin beta 4 during molting in domestic hens. Thirty-three laying hens were divided into three groups: 1, controls, 2, GnRH-A infusion induced molt (GnRH-A), or 3, FW induced molt. All groups had reduced daylength. Blood was sampled weekly and assayed for concentrations of thymosin beta 4 and progesterone (P4). Plasma P4 concentrations were significantly depressed in both treatment groups compared to controls, indicating ovarian regression. Plasma P4 concentrations had returned to control values in the GnRH-A group by 28 d after the start of treatment, while P4 was still depressed in the FW group at day 42 when the experiment ended. Plasma concentrations of thymosin beta 4 were elevated relative to controls from day 7 through day 14 in the GnRH-A group and from day 7 until day 28 in the FW group. It is concluded that plasma concentrations of thymosin beta 4 are elevated during molting in domestic hens, but the elevation is not attributable to depressed P4 concentrations.
authors: Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
authors: R W
authors: RW
authors: Dickerman
authors: T H
authors: TH
authors: Wise
authors: J M
authors: JM
authors: Bahr
mesh_terms: D000818:Animals; D002645:Chickens / Q000502:physiology*; D005241:Feathers / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005508:Food Deprivation / Q000502:physiology; D016729:Leuprolide / Q000494:pharmacology; D010053:Ovary / Q000502:physiology*; D010060:Ovulation / Q000502:physiology; D011374:Progesterone / Q000097:blood; D013947:Thymosin / Q000031:analogs & derivatives* / Q000097:blood; D000099201:Thymosin beta(4)
chemical_list: D016729:Leuprolide; D011374:Progesterone; D013947:Thymosin; D000099201:Thymosin beta(4)