thyrotropin releasing hormone receptor expression in thyroid follicular cells a new paracrine role of c cells

• DOI: 10.14670/hh-20.713
• Publication Date: 2005-01-01
• Authors: De Miguel, M.; Fernández-Santos,...; Utrilla, J.C.; Carrillo-Vico, A.; Borrero, J.; Conde, E.; Guerrero, J.M.; Martín Lacave, Inés
• Keywords: 0303 health sciences; Follicular cells; Reverse Transcriptase Polymerase Chain Reaction; Rat thyroid; Receptors, Thyrotropin-Releasing Hormone; Thyroid Gland; Fluorescent Antibody Technique; Gene Expression; 3. Good health; Cell Line; Rats; 03 medical and health sciences; :6 - Ciencias aplicadas::61 - Medicina [CDU]; Paracrine Communication; CDU::6 - Ciencias aplicadas::61 - Medicina; Animals; RNA, Messenger

Thyrotropin-releasing hormone (TRH) synthesized in the hypothalamus has the capability of inducing the release of thyroid-stimulating hormone (TSH) from the anterior pituitary, which in turn stimulates the production of thyroid hormones in the thyroid gland. Immunoreactivity for TRH and TRH-like peptides has been found in some tissues outside the nervous system, including thyroid. It has been demonstrated that thyroid C-cells express authentic TRH, affecting thyroid hormone secretion by follicular cells. Therefore, C-cells could have a paracrine role in thyroid homeostasis. If this hypothesis is true, follicular cells should express TRH receptors (TRH-Rs) for the paracrine modulation carried out by C-cells. In order to elucidate whether or not C-cell TRH production could act over follicular cells modulating thyroid function, we studied TRH-Rs expression in PC C13 follicular cells from rat thyroid, by means of immunofluorescence technique and RT-PCR analysis. We also investigated the possibility that C-cells present TRH-Rs for the autocrine control of its own TRH production. Our results showed consistent expression for both receptors, TRH-R1 and TRH-R2, in 6-23 C-cells, and only for TRH-R2 in PC C13 follicular cells. Our data provide new evidence for a novel intrathyroidal regulatory pathway of thyroid hormone secretion via paracrine/autocrine TRH signaling.