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Oxidative Medicine and Cellular Longevity
Volume 2014, Article ID 145641, 10 pages
http://dx.doi.org/10.1155/2014/145641
Research Article

Dietary Lycium barbarum Polysaccharide Induces Nrf2/ARE Pathway and Ameliorates Insulin Resistance Induced by High-Fat via Activation of PI3K/AKT Signaling

1Department of Endocrinology, Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
2Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Ningxia Medical University, Yinchuan 750004, China
3Biochemistry and Molecular Biology, Ningxia Medical University, Yinchuan 750004, China
4Central Laboratory, Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
5Institute of Endocrinology, Shandong Academy of Clinical Medicine, Jinan 250021, China

Received 27 March 2014; Accepted 3 June 2014; Published 22 June 2014

Academic Editor: José L. Quiles

Copyright © 2014 Yi Yang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Lycium barbarum polysaccharide (LBP), an antioxidant from wolfberry, displays the antioxidative and anti-inflammatory effects on experimental models of insulin resistance in vivo. However, the effective mechanism of LBP on high-fat diet-induced insulin resistance is still unknown. The objective of the study was to investigate the mechanism involved in LBP-mediated phosphatidylinositol 3-kinase (PI3K)/AKT/Nrf2 axis against high-fat-induced insulin resistance. HepG2 cells were incubated with LBP for 12 hrs in the presence of palmitate. C57BL/6J mice were fed a high-fat diet supplemented with LBP for 24 weeks. We analyzed the expression of nuclear factor-E2-related factor 2 (Nrf2), Jun N-terminal kinases (JNK), and glycogen synthase kinase 3β (GSK3β) involved in insulin signaling pathway in vivo and in vitro. First, LBP significantly induced phosphorylation of Nrf2 through PI3K/AKT signaling. Second, LBP obviously increased detoxification and antioxidant enzymes expression and reduced reactive oxygen species (ROS) levels via PI3K/AKT/Nrf2 axis. Third, LBP also regulated phosphorylation levels of GSK3β and JNK through PI3K/AKT signaling. Finally, LBP significantly reversed glycolytic and gluconeogenic genes expression via the activation of Nrf2-mediated cytoprotective effects. In summary, LBP is novel antioxidant against insulin resistance induced by high-fat diet via activation of PI3K/AKT/Nrf2 pathway.