Figure 6.

Effect of increasing concentrations of ghrelin (AG, 10⁻¹¹M–10⁻⁷M) on osteoprotegerin (OPG) expression measured by real-time PCR at 24 h after AG treatment in primary cultures of rat osteoblast-like cells (a). Effect of pretreatment (30 min before) with the GHSR-1a antagonist D-Lys³-GHRP-6 (D, 10⁻⁷M) on the stimulatory action of AG (10⁻¹⁰M for 24 h) on OPG expression (b). Ratio of RANKL/OPG relative expression measured in untreated and AG 10⁻¹⁰M treated rat osteoblasts after 24 h (c). OPG and RANKL expression were normalized to that of GAPDH and expressed as 2^−ΔΔCt. Three replicates were performed for each experimental point and experiments were repeated three times. ^* P < 0.05; ^** P < 0.01 versus untreated cells. ^§§§ P < 0.001 versus AG treated cells.