The role of thyroid hormones in regulation of chicken ovarian steroidogenesis
AbstractIn all vertebrates, including birds, the normal development of the ovary and ovarian follicles is under the regulatory influence of hormones produced by the reproductive axis. In recent years, it has become clear that in birds an adequate level of thyroid hormones (THs), i.e. thyroxine (T4) and triiodothyronine (T3), in blood circulation is of primary importance for normal female reproductive functions. In avian species, characterized by seasonal reproduction, THs are involved in the photoperiodic regulation of reproduction acting at the mediobasal hypothalamus. In domestic fowl, where the seasonality of reproduction has been eliminated, the role of THs in ovarian function is not fully elucidated. Recent studies have revealed that ovarian follicles of the laying hen express mRNAs of TH nuclear receptors (TRα and TRβ0) as well as integrin (αVβ3) plasma membrane receptors, indicating genomic and nongenomic action of THs in the chicken ovary. In vivo experiments carried out on laying hens have showed that the bolus injection of T3 decreases levels of luteinizing hormone (LH) and estradiol (E2) in blood, and a hyperthyroid state evoked by administration of T3 for few days diminishes LH, E2 and progesterone (P4) levels, reduces the weight of the ovary, induces atresia of preovulatory follicles and eventually causes stoppage of egg laying. In vitro studies have demonstrated that T3 decreases E2 secretion from white nonhierarchical follicles and the theca layer of yellow preovulatory follicles, while on the other hand, it elevates P4 production from the granulosa layer of these follicles. These effects have been associated with steroidogenic enzyme expression and cyclic AMP synthesis. This review summarizes the current knowledge concerning the role of THs in regulation of steroidogenesis in chicken ovarian follicles.
|Journal series||General and Comparative Endocrinology, ISSN 0016-6480, (A 25 pkt)|
|Publication size in sheets||0.5|
|Keywords in English||Ovarian follicles, Steroidogenesis, Thyroid hormone, Chicken|
|Publication indicators||= 18; : 2013 = 1.212; : 2013 = 2.674 (2) - 2013=3.055 (5)|
|Citation count*||10 (2016-06-03)|
|Finansowanie||This work was supported by grants no. 2 P06D 031 29 (2005–2008) and N N311 006436 (2009–2010) from the Ministry of Science and Higher Education of Poland to A.S and DS-3243/KFiEZ|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.