Separation of Growth Hormone-Releasing Factor (GHRF) from Corticotrophin-Releasing Factor (CRF)

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Abstract
Glacial acetic acid extracts derived from acetone powders of sheep stalk-median eminence tissue were subjected to gel filtration on Sephadex G-25. CRF contaminated with ACTH-like activity emerged from the column in a wide zone, beginning immediately after the void volume as determined by adrenal ascorbic acid depletion, both in rats with median eminence lesions and in hypophysectomized animals. This was followed in an overlapping zone by the GHRF, as determined by depletion of pituitary GH [growth hormone], the GH being determined by the tibial epiphyseal cartilage test. The overlapping zone with GHRF and CRF activity was chromatographed on CMC. GHRF emerged from the column just prior to the emergence of CRF in 2 separate experiments. Although some CRF and GHRF were not retained on the column in the 1st passage through CMC, they were well retained on rechromatography. CRF was free of significant contamination with ACTH-like activity after the CMC step. The amino acid compositions of the highly purified CRF and GHRF differed significantly from each other and from highly purified LHRF. All three releasing factors lacked sulfur containing amino acids. It was concluded that CRF and GHRF are distinct chemical entities.

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