Presence and distribution of urocortin and corticotrophin-releasing hormone receptors in the bovine thyroid gland

Urocortin (UCN), a 40 amino acid peptide is a Corticotrophin-Releasing Hormone (CRH) related peptide. The biological actions of CRH family peptides are mediated via two types of G-protein coupled receptors, CRH type 1 (CRHR1) and CRH type 2 (CRHR2). The aim of the present study was to investigate the expression of UCN, CRHR1 and CRHR2 by immunoprecipitation, Western blot, immunohistochemistry and RT-PCR in the bovine thyroid gland. Immunoprecipitation and Western blot analysis showed that tissue extracts reacted with the anti-UCN, -CRHR1 and –CRHR2 antibodies. RT-PCR experiments demonstrated that mRNAs of UCN, CRHR1 and CRHR2 were expressed. UCN-immunoreactivity (IR) and CRHR2–IR were found in the thyroid follicular and parafollicular cells and CRHR1-IR in the smooth muscle of the blood vessels. These results suggest that a regulatory system exists in the bovine thyroid gland based on UCN, CRHR1 and CRHR2 and that UCN plays a role in the regulation of thyroid physiological functions through an autocrine/paracrine mechanism