The role of ghrelin and growth hormone secretagogues receptor on rat adipogenesis.
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 gamma 2 (PPAR-gamma 2) 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-gamma 2 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.
Choi
Kichoon
K
Department of Food Resource Science, Faculty of Agriculture, Shinshu University, Nagano-ken 399-4598, Japan.
Roh
Sang-Gun
SG
Hong
Yeon-Hee
YH
Shrestha
Yogendra B
YB
Hishikawa
Daisuke
D
Chen
Chen
C
Kojima
Masayasu
M
Kangawa
Kenji
K
Sasaki
Shin-Ichi
S
D017667:Adipocytes / Q000737:chemistry / Q000166:cytology; D000273:Adipose Tissue / Q000254:growth & development*; D000818:Animals; D002454:Cell Differentiation; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D054439:Ghrelin; D007545:Isoproterenol / Q000494:pharmacology; D008066:Lipolysis / Q000187:drug effects; D008297:Male; D036361:Peptide Hormones / Q000494:pharmacology / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000235:genetics / Q000502:physiology*; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics; D043562:Receptors, G-Protein-Coupled; D054440:Receptors, Ghrelin; D013234:Stem Cells / Q000166:cytology; D014157:Transcription Factors / Q000235:genetics
D054439:Ghrelin; D036361:Peptide Hormones; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D043562:Receptors, G-Protein-Coupled; D054440:Receptors, Ghrelin; D014157:Transcription Factors; D007545:Isoproterenol