Thyrotropin-releasing factor: distribution in neural and gastrointestinal tissues.

Specimens of several rat tissues were purified with methanol extraction, gel filtration and cation exchange chromatography and measured for thyrotropin-releasing factor (TRF) concentration by radioimmunoassay. TRF immunoreactivity of neural tissues (hypothalamus, spinal cord, medulla, cerebrum and cerebellum) and gastrointestinal tissues (pancreas, stomach, duodenum and colon) behaved as synthetic TRF during the purification. This dual distribution suggests that TRF-secreting cells have their origin in the embryonal neuroectoderm.