Pharmacological and chemical properties of astressin, antisauvagine-30 and alpha-helCRF: significance for behavioral experiments.
Corticotropin releasing factor (CRF) represents an early chemical signal in the stress response and modulates various brain functions through G protein-coupled receptors. Two CRF receptor subtypes, CRF(1) and CRF(2), have been identified. Since the physicochemical properties of CRF receptor antagonists might influence their biological potency, the peptidic antagonists astressin, alpha-helical CRF(9-41) (alpha-helCRF) and antisauvagine-30 (aSvg-30) have been analyzed. The rank order of solubility of these compounds in artificial cerebrospinal fluid (aCSF, pH 7.4) was aSvg-30>alpha-helCRF>>astressin, whereas the rank order of relative lipophilicity as determined with RP-HPLC was alpha-helCRF>astressin>aSvg-30. The calculated isoelectric points were 4.1 (alpha-helCRF), 7.4 (astressin) and 10.0 (aSvg-30). According to Schild analysis of the CRF receptor-dependent cAMP production of transfected HEK cells, aSvg-30 exhibited a competitive antagonism and displayed a 340 fold selectivity for mCRF(2 beta) receptor. For astressin, however, the pharmacodynamic profile could not be explained by a simple competitive mechanism as indicated by Schild slopes >1 for rCRF(1) or mCRF(2 beta) receptor. Behavioral experiments demonstrated that after i.c.v. injection, alpha-helCRF reduced oCRF-induced anxiety-like behavior in the elevated plus-maze, whereas astressin, despite its higher in vitro potency, did not. These findings could be explained by different physicochemical properties of the antagonists employed.
Brauns
O
O
Max Planck Institute for Experimental Medicine, Department of Molecular Neuroendocrinology, Hermann Rein Str. 3, 37075 Goettingen, Germany. brauns@mail.em.mpg.de
Liepold
T
T
Radulovic
J
J
Spiess
J
J
D000818:Animals; D001007:Anxiety / Q000523:psychology; D001522:Behavior, Animal / Q000187:drug effects*; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003346:Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009479:Neuropeptides / Q000494:pharmacology; D018696:Neuroprotective Agents / Q000737:chemistry / Q000494:pharmacology*; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000494:pharmacology*; D018019:Receptors, Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors; D012995:Solubility
D009479:Neuropeptides; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D018019:Receptors, Corticotropin-Releasing Hormone; C116607:antisauvagine 30; C104416:astressin; D003346:Corticotropin-Releasing Hormone; C045089:corticotropin releasing hormone (9-41); D000242:Cyclic AMP