Thyrotropin releasing hormone, a hormone secreted by the hypothalamus that stimulates release of thyrotropin. TRH can also be detected in other areas of the body including the gastrointestinal system and pancreatic islets. Thyroid-stimulating hormone, also known as thyrotropin, is secreted from cells in the anterior pituitary called thyrotrophs. The most important controller of TSH secretion is thyroid-releasing hormone.

TRH is produced by the hypothalamus in medial neurons of the paraventricular nucleus. Initially, it is synthesized as a 242 amino acid precursor polypeptide that contains 6 copies of the sequence -Glu-His-Pro-Gly-, flanked by di-basic peptides that are later processed through proteolysis to give the mature TRH molecule.