| First Author | Müller-Fielitz H | Year | 2017 |
| Journal | Nat Commun | Volume | 8 |
| Issue | 1 | Pages | 484 |
| PubMed ID | 28883467 | Mgi Jnum | J:252758 |
| Mgi Id | MGI:5926977 | Doi | 10.1038/s41467-017-00604-6 |
| Citation | Muller-Fielitz H, et al. (2017) Tanycytes control the hormonal output of the hypothalamic-pituitary-thyroid axis. Nat Commun 8(1):484 |
| abstractText | The hypothalamic-pituitary-thyroid (HPT) axis maintains circulating thyroid hormone levels in a narrow physiological range. As axons containing thyrotropin-releasing hormone (TRH) terminate on hypothalamic tanycytes, these specialized glial cells have been suggested to influence the activity of the HPT axis, but their exact role remained enigmatic. Here, we demonstrate that stimulation of the TRH receptor 1 increases intracellular calcium in tanycytes of the median eminence via Galphaq/11 proteins. Activation of Galphaq/11 pathways increases the size of tanycyte endfeet that shield pituitary vessels and induces the activity of the TRH-degrading ectoenzyme. Both mechanisms may limit the TRH release to the pituitary. Indeed, blocking TRH signaling in tanycytes by deleting Galphaq/11 proteins in vivo enhances the response of the HPT axis to the chemogenetic activation of TRH neurons. In conclusion, we identify new TRH- and Galphaq/11-dependent mechanisms in the median eminence by which tanycytes control the activity of the HPT axis.The hypothalamic-pituitary-thyroid (HPT) axis regulates a wide range of physiological processes. Here the authors show that hypothalamic tanycytes play a role in the homeostatic regulation of the HPT axis; activation of TRH signaling in tanycytes elevates their intracellular Ca2+ via Galphaq/11 pathway, ultimately resulting in reduced TRH release into the pituitary vessels. |
