The Role of Ghrelin and Growth Hormone Secretagogues Receptor on Rat Adipogenesis

• Published in: Endocrinology (Philadelphia) 2003-03, Vol.144 (3), p.754-759
• Main Authors: Choi, Kichoon, Roh, Sang-Gun, Hong, Yeon-Hee, Shrestha, Yogendra B, Hishikawa, Daisuke, Chen, Chen, Kojima, Masayasu, Kangawa, Kenji, Sasaki, Shin-Ichi
• Format: Article
• Language: English
• Subjects: Adipocytes; Adipocytes - chemistry; Adipocytes - cytology; Adipogenesis; Adipose tissue; Adipose Tissue - growth & development; Animals; Biological and medical sciences; Body composition; Cell Differentiation; Differentiation; Female; Fundamental and applied biological sciences. Psychology; Gene Expression - drug effects; Ghrelin; Glycerol-3-phosphate; Glycerol-3-phosphate dehydrogenase; Growth hormones; Isoproterenol - pharmacology; Lipolysis; Lipolysis - drug effects; Male; mRNA; Peptide Hormones - pharmacology; Peptide Hormones - physiology; Peroxisome proliferator-activated receptors; Preadipocytes; Rats; Rats, Wistar; Receptors; Receptors, Cell Surface - genetics; Receptors, Cell Surface - physiology; Receptors, Cytoplasmic and Nuclear - genetics; Receptors, G-Protein-Coupled; Receptors, Ghrelin; RNA, Messenger - analysis; RNA, Messenger - genetics; Stem Cells - cytology; Transcription Factors - genetics
• ISSN: 0013-7227; 1945-7170
• DOI: 10.1210/en.2002-220783

Recent research progress indicates a close link between ghrelin, a natural ligand of GH secretagogues receptor (GHS-R), and both the metabolic balance and body composition. To clarify the involvement of ghrelin and GHS-R in the process of adipogenesis, we measured the expression of GHS-R and peroxisome proliferator-activated receptor γ 2 (PPAR-γ2) mRNA in rat adipocytes using semiquantitative RT-PCR methods. The levels of GHS-R mRNA increased by up to 4-fold in adipose tissue from epididymal and parametrial regions as the rat aged from 4–20 wk and were significantly elevated during the differentiation of preadipocytes in vitro. Ghrelin (10−8 m for 10 d) stimulated the activity of glycerol-3-phosphate dehydrogenase and the differentiation of rat preadipocytes in vitro. Ghrelin treatment also significantly increased the levels of PPAR-γ2 mRNA in primary cultured rat differentiated adipocytes. In addition, isoproterenol (10−8 m, 40 min)-stimulated lipolysis was significantly reduced by simultaneous ghrelin treatment in a dose-dependent manner in vitro. In conclusion, the expression of GHS-R in rat adipocytes increases with the age and during adipogenesis. Ghrelin in vitro stimulates the differentiation of preadipocytes and antagonizes lipolysis. Ghrelin may therefore play an important role in the process of adipogenesis in rats.