Abstract
Summary
The LH-releasing factor (LH-RF) in crude acidic extracts of beef stalk-median eminence was purified. Extract was first subjected to extensive heat treatment to inactivate LH, and the pH was adjusted to neutrality to decrease contamination with protein. The resultant clear supernatant was placed on a column of sephadex G-25, and gel filtration was performed using 1 MH Ac as the solvent. LH-releasing activity was determined both by ovarian ascorbic acid depletion following i.v. injection of fractions into immature females pretreated with gonadotro-phins and by the increment in plasma LH activity which followed i.v. injection of extract into ovariectomized, estrogen progesterone-blocked rats. The peak of LH-releasing activity was found to overlap that of pressor activity but was displaced slightly so that some fractions with LH-releasing activity were devoid of pressor activity. Fractions with LH-releasing activity were devoid of ACTH-releasing activity even when the dose was increased to five times the MED for LH release. It was concluded that the LH-RF is a small polypeptide dissimilar from vaso-pressin and CRF.
Get full access to this article
View all access options for this article.