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Astragalus polysaccharide improves insulin sensitivity in KKAy mice: Regulation of PKB/GLUT4 signaling in skeletal muscle

Authors Liu, Min; Wu, Ke; Mao, Xianqing; Wu, Yong; Ouyang, Jingping

Journal JOURNAL OF ETHNOPHARMACOLOGY , JAN 8 2010,1:127

DOI 10.1016/j.jep.2009.09.055 PubMed 19800959

Abstract Ethnopharmacological relevance: Astragalus polysaccharide (APS) is an important bioactive component of Astragalus membranaceus Bunge (Leguminosae) that has been used in traditional Chinese medicine for treating diabetes.Aim of the study: To study the mechanisms by which APS ameliorates diabetes, we examined whether treatment with APS improves insulin sensitivity in insulin-resistant mice and whether this is associated with an improvement of dysregulated protein kinase B and glucose transporter 4 expressions in skeletal muscle.Methods: APS (700 mgkg(-1) day(-1)) or vehicle was administered to 12-week-old diabetic KKAy and nondiabetic C57BL/6J mice for 8 weeks. Changes in body weight, blood glucose level, insulin resistance index, and oral glucose tolerance were routinely evaluated. The expressions of protein kinase B and glucose transporter 4 in skeletal muscle tissues were determined with Western blot.Results: KKAy mice developed persistent hyperglycemia, impaired glucose tolerance and insulin resistance. Insulin-stimulated protein kinase B phosphorylation and glucose transporter 4 translocation were significantly decreased in KKAy compared to age-matched C57BL/6J mice. APS treatment ameliorated hyperglycemia and insulin resistance. Although the content of protein kinase B and glucose transporter 4 in KKAy skeletal muscle were not affected by APS, insulin-induced protein kinase B Ser-473 phosphorylation and glucose transporter 4 translocation in skeletal muscle were partially restored by APS treatment. In contrast, APS did not have any effect on C57BL/6J mice.Conclusions: These results indicate that APS can regulate part of the insulin signaling in insulin-resistant skeletal muscle, and that APS could be a potential insulin sensitizer for the treatment of type 2 diabetes. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Species covered 黄芪 Astragalus membranaceus