title: Ghrelin augments the expressions and secretions of proinflammatory adipokines, VEGF120 and MCP-1, in differentiated 3T3-L1 adipocytes.
abstract: Ghrelin is a physiological-active peptide with growth hormone-releasing activity, orexigenic activity, etc. In addition, the recent study has also suggested that ghrelin possesses the pathophysiological abilities related with type 2 diabetes. However, the ghrelin-direct-effects implicated in type 2 diabetes on peripheral tissues have been still unclear, whereas its actions on the central nervous system (CNS) appear to induce the development of diabetes. Thus, to assess its peripheral effects correlated with diabetes, we investigated the regulatory mechanisms about adipokines, which play a central role in inducing peripheral insulin resistance, secreted from mature 3T3-L1 adipocytes stimulated with ghrelin in vitro . The stimulation with 50 nmol/L ghrelin for 24 h resulted in the significant 1.9-fold increase on vascular endothelial growth factor-120 (VEGF(120)) releases (p < 0.01) and the 1.7-fold on monocyte chemoattractant protein-1 (MCP-1) (p < 0.01) from 3T3-L1 adipocytes, respectively, while ghrelin failed to enhance tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, IL-10 and adiponectin secretions. In addition, Akt phosphorylation on Ser473 and c-Jun NH2 -terminal protein kinase (JNK) phosphorylation on Thr183/Tyr185 were markedly enhanced 1.4-fold (p < 0.01) and 1.6-fold (p < 0.01) in the ghrelin-stimulated adipocytes, respectively. Furthermore, the treatment with LY294002 (50 μmol/L) and Wortmannin (10nmol/L), inhibitors of phosphatidylinositol 3-kinase (PI3K), significantly decreased the amplified VEGF(120) secretion by 29% (p < 0.01) and 28% (p < 0.01) relative to the cells stimulated by ghrelin alone, respectively, whereas these inhibitors had no effects on increased MCP-1 release. On the other hand, JNK inhibitor SP600125 (10 μmol/L) clearly reduced the increased MCP-1, but not VEGF(120), release by 35% relative to the only ghrelin-stimulated cells (p < 0.01). In conclusion, ghrelin can enhance the secretions of proinflammatory adipokines, VEGF(120) and MCP-1, but fails to affect IL-10 and adiponectin which are considered to be anti-inflammatory adipokines. Moreover, this augmented VEGF(120) release is invited through the activation of PI3K pathways and the MCP-1 is through JNK pathways. Consequently, our results strongly suggest that ghrelin can induce the development of diabetes via its direct-action in peripheral tissues as well as via in CNS.
authors: Third Department of Internal Medicine.
authors: Atsuko
authors: A
authors: Kitahara
authors: Kazuto
authors: K
authors: Takahashi
authors: Rie
authors: R
authors: Moriya
authors: Hirohisa
authors: H
authors: Onuma
authors: Keiko
authors: K
authors: Handa
authors: Yoshikazu
authors: Y
authors: Sumitani
authors: Toshiaki
authors: T
authors: Tanaka
authors: Hidenori
authors: H
authors: Katsuta
authors: Susumu
authors: S
authors: Nishida
authors: Takuya
authors: T
authors: Sakurai
authors: Kouichi
authors: K
authors: Inukai
authors: Hideki
authors: H
authors: Ohno
authors: Hitoshi
authors: H
authors: Ishida
mesh_terms: D016475:3T3 Cells; D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism; D052242:Adiponectin / Q000096:biosynthesis; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D002460:Cell Line; D018932:Chemokine CCL2 / Q000378:metabolism*; D002867:Chromones / Q000494:pharmacology; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D054439:Ghrelin / Q000494:pharmacology*; D016753:Interleukin-10 / Q000096:biosynthesis; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D000077191:Wortmannin
chemical_list: D052242:Adiponectin; D000730:Androstadienes; D000873:Anthracenes; C491768:Ccl2 protein, mouse; D018932:Chemokine CCL2; D002867:Chromones; D054439:Ghrelin; C556062:IL10 protein, mouse; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D016753:Interleukin-10; C432165:pyrazolanthrone; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases; D055372:AMP-Activated Protein Kinases; D000077191:Wortmannin
keywords: 3T3-L1 adipocytes; Ghrelin; Leptin; MCP-1; VEGF120