Abstract
We conducted this study to investigate the mechanisms of action of growth hormone-releasing peptide-2 (D-Ala-D-βNal-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 μM) 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 μM). Nifedipine (10 μM), a voltage-dependent Ca 2+ channel blocker, inhibited (P < .01) GHRP-2-stimulated GH release. The GH release in response to GHRP-2 and 4β-phorbol-12-myristate-13-acetate (10-7 M), a protein kinase C activator, was additive (P < .01). Forskolin (30 μM), 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.
Original language | English |
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Pages (from-to) | 2744-2748 |
Number of pages | 5 |
Journal | Journal of animal science |
Volume | 75 |
Issue number | 10 |
DOIs | |
Publication status | Published - 1997 Oct |
Externally published | Yes |
Keywords
- Cattle
- Growth Hormone
- Hypothalamic Releasing Hormones
- Pituitary Gland
ASJC Scopus subject areas
- Food Science
- Animal Science and Zoology
- Genetics