Natural vanadium-containing Jeju ground water stimulates glucose uptake through the activation of AMP-activated protein kinase in L6 myotubes

Abstract

The aim of this study was to elucidate the effects of natural vanadium-containing Jeju ground water on glucose uptake in L6 myotubes and adipogensesis in 3T3 L1 cells. The Jeju ground water samples containing vanadium components were designated as S1 (8.0 ± 0.9 μg/l), S2 (24.0 ± 2.0 μg/l), and S3 (26.0 ± 2.0 μg/l), respectively. To investigate the effects of the Jeju ground water on glucose uptake in L6 myotubes, L6 cells were differentiated in media containing deionized distilled water (DDW group) and the water samples (S1, S2, and S3 groups). After daily changes in cultured media containing the Jeju ground water samples for 1 week, all samples had increased glucose uptake compared to the DDW group and the order of glucose uptake increased in parallel with vanadium content (S3 > S2 > S1). In addition, S3 significantly stimulated the phosphorylation of the Thr-172 residue of the AMP-activated protein kinase-α subunit and the Ser-79 subunit of acetyl-CoA carboxylase compared to the DDW group. The effect of glucose uptake by S3 was reversed by pretreatment with Compound C, an AMPK inhibitor. Interestingly, vanadium pentoxide also increased glucose uptake and activated AMPK activity in a dose-dependent manner. Furthermore, as compared to the DDW treated group, S3 treatment inhibited adipogenesis of 3T3-L1 cells by down regulation of expressions of adipogenic transcription factors. Taken together, these findings suggest that S3 displays beneficial effects in the treatment of diabetes, at least in part through the activation of AMPK activity.