Synthesis and biological evaluation of superactive agonists of growth hormone-releasing hormone.
Analogs of the 29 amino acid sequence of human growth hormone-releasing hormone (hGH-RH) with agmatine (Agm) in position 29, desaminotyrosine (Dat) in position 1, norleucine (Nle) in position 27, and L-alpha-aminobutyric acid (Abu) in position 15 have been synthesized, and their biological activity was evaluated. Some peptides contained one or two residues of ornithine (Orn) instead of Lys in positions 12 and 21 and additional replacements in positions 8 and 28. All analogs were found to be more potent than hGH-RH-(1-29)-NH2 in the superfused rat pituitary cell system. In tests in vivo in rats after subcutaneous administration, the analogs JI-22, [Dat1, Orn12,21, Abu15, Nle27, Agm29]hGH-RH-(1-29); JI-34, [Dat1, Orn12,21,Abu15,Nle27, Asp28, Agm29]hGH-RH-(1-29); JI-36, [Dat1, Thr8, Orn12,21, Abu15,Nle27,Asp28,Agm29]hGH-RH-(1-29); and JI-38, [Dat1,Gln8, Orn12,21,Abu15,Nle27,Asp28,Agm29]hGH-RH-(1 -29) displayed a potency 44.6,80.9,95.8, and 71.4 times greater, respectively, than that of hGH-RH-(1-29)-NH2 at 15 min and 217.1, 89.7, 87.9, and 116.8 times greater at 30 min. After intravenous administration, JI-22, JI-36, and JI-38 were 3.2-3.8 times more potent than hGH-RH-(1-29)-NH2 at 5 min and 6.1-8.5 times more active at 15 min. All analogs were found to have higher binding affinities for GH-RH receptors on rat pituitary cells than hGH-RH-(1-29)-NH2. Because of high activity and greater stability, these analogs could be considered for therapy of patients with growth hormone deficiency.
Izdebski
J
J
Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70146, USA.
Pinski
J
J
Horvath
J E
JE
Halmos
G
G
Groot
K
K
Schally
A V
AV
D000595:Amino Acid Sequence; D000818:Animals; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000819:agonists / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018013:Receptors, Neuropeptide / Q000378:metabolism; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000378:metabolism; D013329:Structure-Activity Relationship
D009842:Oligopeptides; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; C048250:somatotropin releasing hormone receptor