Thyrotropin-releasing hormone (TRH), also called thyrotropin-releasing factor (TRF), thyroliberin or protirelin, is a tripeptide hormonethat stimulates the release of thyroid-stimulating hormoneand prolactinby the anterior pituitary. TRH is produced by the hypothalamus, near the paraventricular nucleus. It travels across the median eminenceto the pituitary via the hypophyseal portal system. It is released from cells called thyrotropes. In addition to the brain, TRH can also be detected in other areas of the body including the gastrointestinal systemand pancreatic islets.Protirelin stimulates the secretion of pituitary thyroid stimulating hormone from the anterior pituitary and has been shown that protirelin increases secretion of prolactin. Protirelin is identified as 5-oxo-L-prolyl-L-histidyl-L-proline amide. It is a synthetic tripeptide that is believed to be structurally identical to the naturally-occurring thyrotropin-releasing hormone produced by the hypothalamus Synonyms: Thyroliberin, TRH, MGC125964, MGC125965, Protirelin, TRF.