Study summary · research use only
Growth hormone-releasing peptide-2 (GHRP-2) does not act via the human growth hormone-releasing factor receptor in GC cells
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This in vitro study used rat pituitary GC cells with or without stable transfection of human GRF receptor cDNA (GC/R+ or GC/R-) to test whether growth hormone-releasing peptide-2 (GHRP-2) acts via the GRF receptor. The abstract reports GRF receptor mRNA was undetectable in GC/R- cells and highly expressed in GC/R+ cells. In GC/R- cells, up to 10(-7)M hGRF or GHRP-2 did not alter cAMP, [Ca2+]i, or GH secretion. In GC/R+ cells, hGRF (10(-11)-10(-7)M) increased cAMP up to 20-fold, blocked by the antagonist [Ac-Tyr1, D-Arg2]-GRF 1-29 but not by the Ca2+ channel blocker NiCl2 (0.5 mM), though GH secretion and [Ca2+]i were not increased. GHRP-2 did not modify cAMP in transfected cells. The authors conclude GHRP-2 does not act through the GRF receptor.
Abstract
Effect of growth hormone-releasing peptide-2 (GHRP-2) on ovine somatotrophs is abolished by a growth hormone-releasing factor (GRF) receptor antagonist, which raises the possibility that GHRP-2 may act on GRF receptors. In the present study, we used rat pituitary GC cells with or without stable transfection of cDNA coding for the human GRF receptor (GC/R+ or GC/R-) to determine whether or not GHRP-2 acts via the GRF receptor. Northern blot analysis indicated that GRF receptor mRNA was undetectable in GC/R-cells, whereas a high level of expression occurred in GC/R+ cells that were transfected by GRF receptor cDNA. In GC/R- cells, incubation with up to 10(-7)M of either hGRF or GHRP-2 did not alter the intracellular cAMP, [Ca2+]i, or GH secretion. In GC/R+ cells, hGRF (10(-11)-10(-7)M) increased cAMP levels in a concentration-dependent manner up to 20-fold. This increase in cAMP levels was blocked by a GRF receptor antagonist, [Ac-Tyr1, D-Arg2]-GRF 1-29, but not by a Ca2+ channel blocker, NiCl2 (0.5 mM). GH secretion and [Ca2+]i were, however, not increased by hGRF. Incubation of the transfected cells with 10(-1)-10(-8)MGH RP-2 did not modify intracellular cAMP levels. This result suggests that GHRP-2 does not act through the GRF receptor.
pepmg summarizes the peer-reviewed literature and links to every source — it sells nothing, ships nothing, and gives no medical, dosing, or human-use guidance. Don't just trust this summary: follow the citation to its source and read it yourself. Research use only.