Received 1 April 2009; received in revised form 11 June 2009; accepted 26 June 2009. published online 17 August 2009.
Abstract
We investigated the presence of thyrotropin receptor (TSHR) mRNA in chicken pituitary and brain, and quantified the changes in its expression during the last week of embryonic development. We found that in the pituitary gland, TSHR mRNA co-localizes with folliculo-stellate cells but not with thyrotropic cells, suggesting the existence of a paracrine ultra-short thyrotropin feedback loop. TSHR mRNA was also present throughout the diencephalon and various other brain regions, which implies a more general function for thyrotropin in the avian brain. During late embryogenesis, when the activity of the hypothalamo-pituitary-thyroidal axis increases markedly, a significant rise in TSHR mRNA expression was observed in pituitary, which may signify an important change in pituitary ultra-short thyrotropin feedback regulation around the period of hatching.
Research group of Comparative Endocrinology, Animal Physiology and Neurobiology Section, Department of Biology, Catholic University of Leuven, Naamsestraat 61, B3000 Leuven, Belgium
Corresponding author at: Research group of Comparative Endocrinology, Naamsestraat 61 – box 2464, B3000 Leuven, Belgium. Tel.: +32 16 32 39 85; fax: +32 16 32 42 62.
ABSTRACT