title: In vivo and in vitro comparisons of biological activities of bovine, ovine and rat CRF (corticotrophin-releasing factor).
abstract: The biological activity of partially purified bovine hypothalamic CRF (corticotrophin- releasing factor) was compared to those of synthetic CRFs (ovine, rat) sauvagine and vasopressin in vivo and in vitro. ACTH-primed hypophysectomized rats with heterotopically transplanted pituitaries and medial basal hypothalamic ablation (H-T + MBHA ), and intact rats pre-treated with chlorpromazine, morphine and Nembutal (C-M-N) were used for in vivo CRF assays. Perifused rat adenohypophyseal fragments were employed for in vitro studies. CRF-A (void volume fractions, 'big' CRF) and CRF-B (Kav = 0.583) purified from bovine hypophyseal stalk, synthetic ovine and rat CRF, and sauvagine all induced significant stimulation of ACTH and/or corticosterone secretion in these systems. Synthetic ovine and rat CRF and sauvagine showed comparable CRF potency. The CRF dose-response slopes for bovine CRF were somewhat steeper than those for ovine CRF or sauvagine in the in vitro system. Vasopressin had the least steep dose-response slope. Intravenous bolus administration of ovine CRF caused a more prolonged (greater than 20 min) elevation of plasma ACTH compared to a relatively short duration after bovine CRF-A. These data suggest that bovine hypothalamus contains substance(s) which exhibits different CRF characteristics from those of ovine CRF.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D029845:Amphibian Proteins; D000818:Animals; D002417:Cattle; D003345:Corticosterone / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D007016:Hypophysectomy; D007030:Hypothalamo-Hypophyseal System / Q000637:transplantation; D008297:Male; D036361:Peptide Hormones; D010455:Peptides / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012756:Sheep; D013045:Species Specificity; D014667:Vasopressins / Q000378:metabolism
chemical_list: D029845:Amphibian Proteins; D036361:Peptide Hormones; D010455:Peptides; D014667:Vasopressins; C025727:sauvagine; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone