title: The ginsenoside Rg3 has a stimulatory effect on insulin signaling in L6 myotubes.
abstract: The ginsenoside Rg3 is known to have a protective effect against hyperglycemia, obesity and diabetes in vivo. In this study, we examined the effect of Rg3 on insulin signaling and glucose uptake in cultured L6 myotubes. Rg3 increased glucose uptake both in the basal and insulin-induced states of L6 myotubes. Consistent with the increase in glucose uptake, Rg3 stimulated the phosphorylation of IRS-1 and Akt. Interestingly, Rg3 dramatically increased IRS-1 protein levels, while the protein level of Akt was not affected. Rg3 regulated IRS-1 expression at the transcriptional level and also increased the level of GLUT4 mRNA. Treatment of ginsam, in which Rg3 is the major compound of ginsenosides, increased the IRS-1 protein levels in OLEFT rats. In addition, we found that this effect of Rg3 on insulin signaling was not mediated by the AMPK pathway. In conclusion, these results suggest that Rg3 improves insulin signaling and glucose uptake primarily by stimulating the expression of IRS-1 and GLUT4.
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Republic of Korea.
authors.forename: Min
authors.initials: M
authors.lastname: Kim
authors.forename: Byung Yong
authors.initials: BY
authors.lastname: Ahn
authors.forename: Ji Seon
authors.initials: JS
authors.lastname: Lee
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Chung
authors.forename: Soo
authors.initials: S
authors.lastname: Lim
authors.forename: Sang Gyu
authors.initials: SG
authors.lastname: Park
authors.forename: Hye Seung
authors.initials: HS
authors.lastname: Jung
authors.forename: Hong Kyu
authors.initials: HK
authors.lastname: Lee
authors.forename: Kyong Soo
authors.initials: KS
authors.lastname: Park
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D000818:Animals; D002460:Cell Line; D036145:Ginsenosides / Q000494:pharmacology*; D051275:Glucose Transporter Type 4 / Q000096:biosynthesis; D007328:Insulin / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins / Q000096:biosynthesis; D018485:Muscle Fibers, Skeletal / Q000187:drug effects* / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D036145:Ginsenosides; D051275:Glucose Transporter Type 4; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D012333:RNA, Messenger; C495694:Slc2a4 protein, rat; C097367:ginsenoside Rg3; D011494:Protein Kinases; D000091162:AMP-Activated Protein Kinase Kinases