Aim To reveal the main active components and the action mechanisms of Radix astragali on insulin sensitivity improvement, we have investigated the effects of polysaccharide portion and saponin portion of Radix astraga...Aim To reveal the main active components and the action mechanisms of Radix astragali on insulin sensitivity improvement, we have investigated the effects of polysaccharide portion and saponin portion of Radix astragali extracts on blood biochemical indices and related gene expression of dexamethasone-induced SD rats. Methods SD rats （6 per group） received 2 μg/day subcutaneous dexamethasone for 4 weeks plus same dose （10 g material/kg） of polysaccharide or saponin extracts of Radix astragali. Blood samples, kidney tissues and epididymal fat pads were taken at the end of the experiment. Serum triglyceride （TG）, total cholesterol （TC）, low density lipoprotein cholesterol （LDLC）, high density lipoprotein cholesterol （HDLC）, glucose （GLU） and insulin （INS） levels were measured, respectively, mRNA levels of angiotensinogen in kidney, adiponectin and leptin as well as TNF-α in epididymal fats were determined by RT-PCR assay using GAPDH gene as an internal control. Results Both of polysaccharide and saponin extracts of Radix astragali exhibited positive effects in reducing serum triglycerides, glucose, and insulin levels of dexamethasone-induced SD rats. The saponin group showed more improvements on quantitive insulin sensitivity check index （QUICKI） than the polysaccharide group did. Both of the extracts down-regulated kidney angiotensinogen and fat TNF-α mRNA levels while they were simultaneously up-regulating fat adiponectin and leptin mRNA levels. No significant difference was found between actions of the two extracts. Conclusion Both of polysaccharide and saponin extracts of Radix astragali can improve insulin sensitivity. This action might be closely related to down-regulation of angiotensinogen, TNF-α and up-regulation of adiponectin and leptin expression. The results partly explained the improvement of type Ⅱ diabetes and diabetic nephropathy by Radix astragali. The similar actions of the two crude extracts suggest that unknown key active compounds might exist in both and remain to be discovered.展开更多
文摘Aim To reveal the main active components and the action mechanisms of Radix astragali on insulin sensitivity improvement, we have investigated the effects of polysaccharide portion and saponin portion of Radix astragali extracts on blood biochemical indices and related gene expression of dexamethasone-induced SD rats. Methods SD rats （6 per group） received 2 μg/day subcutaneous dexamethasone for 4 weeks plus same dose （10 g material/kg） of polysaccharide or saponin extracts of Radix astragali. Blood samples, kidney tissues and epididymal fat pads were taken at the end of the experiment. Serum triglyceride （TG）, total cholesterol （TC）, low density lipoprotein cholesterol （LDLC）, high density lipoprotein cholesterol （HDLC）, glucose （GLU） and insulin （INS） levels were measured, respectively, mRNA levels of angiotensinogen in kidney, adiponectin and leptin as well as TNF-α in epididymal fats were determined by RT-PCR assay using GAPDH gene as an internal control. Results Both of polysaccharide and saponin extracts of Radix astragali exhibited positive effects in reducing serum triglycerides, glucose, and insulin levels of dexamethasone-induced SD rats. The saponin group showed more improvements on quantitive insulin sensitivity check index （QUICKI） than the polysaccharide group did. Both of the extracts down-regulated kidney angiotensinogen and fat TNF-α mRNA levels while they were simultaneously up-regulating fat adiponectin and leptin mRNA levels. No significant difference was found between actions of the two extracts. Conclusion Both of polysaccharide and saponin extracts of Radix astragali can improve insulin sensitivity. This action might be closely related to down-regulation of angiotensinogen, TNF-α and up-regulation of adiponectin and leptin expression. The results partly explained the improvement of type Ⅱ diabetes and diabetic nephropathy by Radix astragali. The similar actions of the two crude extracts suggest that unknown key active compounds might exist in both and remain to be discovered.
