Thioglycollate-stable luteinizing hormone and corticotrophin-releasing factors

¹ Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania

Crude acidic extracts of beef stalk-median eminence tissue depleted ovarian ascorbic acid on injection into immature rats pretreated with gonadotrophins. They also elevated plasma luteinizing hormone (LH) activity in ovariectomized rats which had been pretreated with both estrogen and progesterone. This activity could not be explained by possible LH contamination of the extracts. Since cerebral cortical extracts prepared similarly possessed little or no activity, it is concluded that beef stalk-median eminence tissue contains a specific LH-releasing factor (LH-RF). These same extracts possessed an ACTH-releasing action, as judged by adrenal ascorbic acid depletion induced in rats with median eminence lesions, which could not be accounted for by the minimal contamination of the extract with ACTH itself. Thioglycollate failed to alter either the LH or ACTH-releasing activities of these extracts under conditions which markedly reduce the activity of Pitressin. It is concluded that the LH-RF and corticotrophin-releasing factor resident in beef hypothalamic tissue are dissimilar from the known neurohypophysial polypeptides.

Key Words: beef luteinizing hormone-releasing factor

Submitted on September 30, 1963