1) Endocrine 2) Hormone 3) Internal secretion 4) Thyrotropin-releasing factor 5) Thyrotropin-releasing hormone 1) Trf 2) Trh 
<chemical> A tripeptide hormone that originates in the hypothalamus and stimulates the secretion of thyrotropin from the pituitary gland. In humans, it also acts as a prolactin-releasing factor. It is also a neurotransmitter in the central nervous system. ... Chemical name: L-Prolinamide, 5-oxo-L-prolyl-L-histidyl- ... (12 Dec 1998) ... 
(pro-ti´rә-lin) a synthetic preparation of thyrotropin-releasing hormone, used diagnostically.
See thyrotrophic-releasing hormone.