Inhibition of growth hormone secretagogue receptor antagonist, [D-Lys-3]-GHRP-6, in adipogenesis of ovine and rat adipocytes

Ghrelin and growth hormone secretagogues receptor (GHS-R or ghrelin receptor) have been reported as being one of the factors of adipogenesis in adipocytes. To investigate the involvement of ghrelin and GHS-R in adipocytes, the effect of the GHS-R antagonist, [D-Lys-3]-GHRP-6 (His-D-Trp-D-Lys-Trp-D-Phe-Lys-NH2), on the process of adipogenesis in ovine and rat adipocytes was evaluated. [D-Lys-3]-GHRP-6 (10−7 mol/L) significantly inhibited adipogenic differentiation of ovine and rat preadipocytes prepared from adipose tissues. The level of peroxisome proliferator activated receptor (PPAR)-γ2 mRNA, an adipogenic marker, was decreased during the differentiation of adipocytes treated with [D-Lys-3]-GHRP-6 for 10 days. Ghrelin stimulated adipogenesis, also causing an increment of glycerol-3-phosphate dehydrogenase and upregulation of PPAR-γ2. Furthermore, the antilipolytic effect of ghrelin was attenuated by treatment with [D-Lys-3]-GHRP-6 in both types of isolated adipocytes. Overall, the results of the present study highlight that GHS-R in adipogenesis can be blocked by treatment with [D-Lys-3]-GHRP-6.