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Astragalus polysaccharides alleviates glucose toxicity and restores glucose homeostasis in diabetic states via activation of AMPK.

Zou F, Mao XQ, Wang N, Liu J, Ou-Yang JP - Acta Pharmacol. Sin. (2009)

Bottom Line: The hyperglycemia status, insulin sensitivity, glucose uptake, and activation level of AMPK in diabetic rats were improved in response to APS administration.APS could also alleviate glucose toxicity in cultured mouse cells by the activation of AMPK.APS can alleviate glucose toxicity by increasing liver glycogen synthesis and skeletal muscle glucose translocation in the T2DM rat model, via activation of AMPK.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathophysiology, Medical College of Wuhan University, Wuhan, China.

ABSTRACT

Aim: To establish the mechanism underlying the improvement of glucose toxicity by Astragalus polysaccharide (APS), which occurred via an AMP activated protein kinase (AMPK)-dependent pathway.

Methods: In vivo and in vitro effects of APS on glucose homeostasis were examined in a type 2 diabetes mellitus (T2DM) rat model. The T2DM rat model was duplicated by a high-fat diet (58% fat, 25.6% carbohydrate, and 16.4% protein) and a small dose of streptozotocin (STZ, 25 mg/kg, ip). After APS therapy (700 mg.kg(-1).d(-1), ig) for 8 weeks, blood glucose, glycosylated hemoglobin, and serum insulin were measured. Insulin sensitivity was evaluated by the comprehensive analysis of oral glucose tolerance tests (OGTT) and HOMA IR index. Hepatic glycogen was observed by the PAS staining method. The expression and activity of skeletal muscle AMPKalpha and acetyl-CoA carboxylase (ACC), and the phosphorylation of hepatic glycogen synthase (GS), the glycogen synthase (GS),were measured by Western blotting. Glucose uptake was measured with the 2-deoxy-[(3)H]-D-glucose method in C2C12 cells.

Results: The hyperglycemia status, insulin sensitivity, glucose uptake, and activation level of AMPK in diabetic rats were improved in response to APS administration. APS could also alleviate glucose toxicity in cultured mouse cells by the activation of AMPK.

Conclusion: APS can alleviate glucose toxicity by increasing liver glycogen synthesis and skeletal muscle glucose translocation in the T2DM rat model, via activation of AMPK.

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Related in: MedlinePlus

Concentration for insulin (100 nmol/L, 15 min), APS (200 μg/mL, 48 h), AICAR (5 mmol/L, 30 min), and Compound C (20 μmol/L, 30 min) treatment on 2-deoxy-[3H]-D-glucose uptake in differentiated C2C12 cells. All data are expressed by mean±SEM. n=4. bP<0.05 vs DMSO group; eP<0.05 vs APS group.
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fig6: Concentration for insulin (100 nmol/L, 15 min), APS (200 μg/mL, 48 h), AICAR (5 mmol/L, 30 min), and Compound C (20 μmol/L, 30 min) treatment on 2-deoxy-[3H]-D-glucose uptake in differentiated C2C12 cells. All data are expressed by mean±SEM. n=4. bP<0.05 vs DMSO group; eP<0.05 vs APS group.

Mentions: APS at 200 μg/mL appeared to be the best concentration for showing significant effects on the activation of AMPK and this was used for all subsequent experiments. APS treatment increased glucose uptake significantly (Figure 6, P<0.05). We further attempted to determine whether APS-enhanced glucose uptake was mediated by AMPK. Compound C, which is a highly-selective AMPK inhibitor, as assessed by a direct enzyme assay29, had no effect on insulin-induced glucose uptake. It could, however, effectively block APS-induced glucose uptake (Figure 6, P<0.05), indicating involvement of the AMPK pathway in these APS effects.


Astragalus polysaccharides alleviates glucose toxicity and restores glucose homeostasis in diabetic states via activation of AMPK.

Zou F, Mao XQ, Wang N, Liu J, Ou-Yang JP - Acta Pharmacol. Sin. (2009)

Concentration for insulin (100 nmol/L, 15 min), APS (200 μg/mL, 48 h), AICAR (5 mmol/L, 30 min), and Compound C (20 μmol/L, 30 min) treatment on 2-deoxy-[3H]-D-glucose uptake in differentiated C2C12 cells. All data are expressed by mean±SEM. n=4. bP<0.05 vs DMSO group; eP<0.05 vs APS group.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4007496&req=5

fig6: Concentration for insulin (100 nmol/L, 15 min), APS (200 μg/mL, 48 h), AICAR (5 mmol/L, 30 min), and Compound C (20 μmol/L, 30 min) treatment on 2-deoxy-[3H]-D-glucose uptake in differentiated C2C12 cells. All data are expressed by mean±SEM. n=4. bP<0.05 vs DMSO group; eP<0.05 vs APS group.
Mentions: APS at 200 μg/mL appeared to be the best concentration for showing significant effects on the activation of AMPK and this was used for all subsequent experiments. APS treatment increased glucose uptake significantly (Figure 6, P<0.05). We further attempted to determine whether APS-enhanced glucose uptake was mediated by AMPK. Compound C, which is a highly-selective AMPK inhibitor, as assessed by a direct enzyme assay29, had no effect on insulin-induced glucose uptake. It could, however, effectively block APS-induced glucose uptake (Figure 6, P<0.05), indicating involvement of the AMPK pathway in these APS effects.

Bottom Line: The hyperglycemia status, insulin sensitivity, glucose uptake, and activation level of AMPK in diabetic rats were improved in response to APS administration.APS could also alleviate glucose toxicity in cultured mouse cells by the activation of AMPK.APS can alleviate glucose toxicity by increasing liver glycogen synthesis and skeletal muscle glucose translocation in the T2DM rat model, via activation of AMPK.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathophysiology, Medical College of Wuhan University, Wuhan, China.

ABSTRACT

Aim: To establish the mechanism underlying the improvement of glucose toxicity by Astragalus polysaccharide (APS), which occurred via an AMP activated protein kinase (AMPK)-dependent pathway.

Methods: In vivo and in vitro effects of APS on glucose homeostasis were examined in a type 2 diabetes mellitus (T2DM) rat model. The T2DM rat model was duplicated by a high-fat diet (58% fat, 25.6% carbohydrate, and 16.4% protein) and a small dose of streptozotocin (STZ, 25 mg/kg, ip). After APS therapy (700 mg.kg(-1).d(-1), ig) for 8 weeks, blood glucose, glycosylated hemoglobin, and serum insulin were measured. Insulin sensitivity was evaluated by the comprehensive analysis of oral glucose tolerance tests (OGTT) and HOMA IR index. Hepatic glycogen was observed by the PAS staining method. The expression and activity of skeletal muscle AMPKalpha and acetyl-CoA carboxylase (ACC), and the phosphorylation of hepatic glycogen synthase (GS), the glycogen synthase (GS),were measured by Western blotting. Glucose uptake was measured with the 2-deoxy-[(3)H]-D-glucose method in C2C12 cells.

Results: The hyperglycemia status, insulin sensitivity, glucose uptake, and activation level of AMPK in diabetic rats were improved in response to APS administration. APS could also alleviate glucose toxicity in cultured mouse cells by the activation of AMPK.

Conclusion: APS can alleviate glucose toxicity by increasing liver glycogen synthesis and skeletal muscle glucose translocation in the T2DM rat model, via activation of AMPK.

Show MeSH
Related in: MedlinePlus