Mechanisms of action of growth hormone-releasing peptide-2 in bovine pituitary cells

• Published in: Journal of animal science 1997-10, Vol.75 (10), p.2744-2748
• Main Authors: Roh, S.G, He, M.L, Matsunaga, N, Hidaka, S, Hidari, H
• Format: Article
• Language: English
• Subjects: Animal productions; Animals; Biological and medical sciences; BOVIN; CALCIO; CALCIUM; Calcium Channel Blockers - pharmacology; CATION; CATIONES; CATIONS; CATTLE; Cattle - metabolism; CELL CULTURE; Cells, Cultured; Colforsin - pharmacology; CULTIVO DE CELULAS; CULTURE DE CELLULE; Cyclic AMP - analysis; Cyclic AMP - metabolism; Cyclic AMP - pharmacology; Dose-Response Relationship, Drug; Enzyme Activation - drug effects; Fundamental and applied biological sciences. Psychology; GANADO BOVINO; GLANDULA PITUITARIA; Growth Hormone - analysis; Growth Hormone - metabolism; Growth Hormone-Releasing Hormone - pharmacology; Growth Hormone-Releasing Hormone - physiology; HORMONAS; HORMONAS LIBERADORAS; HORMONE; HORMONE RECEPTORS; HORMONES; Hormones - pharmacology; Hormones and neuropeptides. Regulation; HYPOPHYSE; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Male; NIFEDIPINE; Nifedipine - pharmacology; OLIGOPEPTIDES; Oligopeptides - pharmacology; PEPTIDE; PEPTIDES; PEPTIDOS; PITUITARY GLAND; Pituitary Gland, Anterior - cytology; Pituitary Gland, Anterior - drug effects; Pituitary Gland, Anterior - metabolism; PROTEIN KINASE; Protein Kinase C - metabolism; PROTEINA QUINASA; PROTEINE KINASE; RECEPTEUR D'HORMONE; RECEPTORES DE HORMONAS; RELEASING HORMONE; RELEASING HORMONES; SECRECION; SECRETION; SOMATOLIBERIN; SOMATOSTATIN; Somatostatin - pharmacology; SOMATOSTATINA; SOMATOSTATINE; SOMATOTROPIN; SOMATOTROPIN-RELEASING FACTOR RECEPTOR ANTAGONIST; SOMATOTROPINA; SOMATOTROPINE; Studies; Terrestrial animal productions; Tetradecanoylphorbol Acetate - pharmacology; Vertebrates; Vertebrates: endocrinology
• ISSN: 0021-8812; 1525-3163; 0021-8812
• DOI: 10.2527/1997.75102744x

We conducted this study to investigate the mechanisms of action of growth hormone-releasing peptide-2 (D-Ala-D-beta Nal-Ala-Trp-D-Phe-Lys-NH2; GHRP-2) in bovine anterior pituitary primary cell culture. Doses of GHRP-2 from 10(-13) to 10(-7) M increased (P .05) GH secretion. The GHRP-2 (10(-7) M) and GH-releasing factor (GRF; 10(-7) M) administered together had an additive effect on the release of GH (P .05). Somatostatin (1 micromolar) decreased GH secretion in response to GHRP-2 and(or) GRF (P .05). Secretion of GH in response to GHRP-2 was blocked (P .01) by a GRF receptor antagonist (.1 micromolar). Nifedipine (10 micromolar), a voltage-dependent Ca2+ channel blocker, inhibited (P .01) GHRP-2-stimulated GH release. The GH release in response to GHRP-2 and 4 beta-phorbol-12-myristate-13-acetate (10(-7) M), a protein kinase C activator, was additive (P .01). Forskolin (30 micromolar), a cAMP elevating agent, further stimulated (P .01) the GH release in response to GHRP-2. Bovine GH concentrations in culture media were assayed by indirect competitive enzymeimmunoassay. These results showed that GHRP-2 (1) stimulates GH secretion from bovine pituitary cells, (2) may partially act via GRF receptor, (3) has GH secretion activity caused by Ca2+ influx via Ca2+ channels, and (4) may increase GH secretion via protein kinase C and cAMP pathways