| Background:Diabetes mellitus (DM), one of the most common chronic and systemic disease in the world, is characterized by hyperglycemia resulting from defects in insulin secretion, insulin action or both. It is classified into two types:type 1 (insulin-dependent) and type 2 (insulin-independent). Type 1 diabetes is caused by an absolute deficiency of insulin secretion fromβ-pancreatic cells. In the other, type 2 diabetes is closely associated with obesity and is characterized by a combination of resistance to insulin action and an inadequate compensatory insulin-secretory response.Corn silk (Stigma maydis L.) is the capital of Zea mays L., and its water extract has been used for the herbal therapy of diabetes in one of the principles of Traditional Chinese Medicine in China, containing saponin, alkaloid, polysaccharide, polyphenol, and flavones which possess antioxidative, diuretic effects and glycation inhibitory activity. However, there is a lack of reliable data to explain the effect of CS on diabetic animal models. Considering that there is a marked difference between type 1 and 2 diabetes mellitus either in human beings or in animal models, we focused on effectivity of water extracts of CS both on type 1 and type 2 diabetic mice induced by alloxan. In this research, the physiologic and biochemical changes were examined. Furthermore, we identified notables in the expression level of the gene related to glycemia and lipids metabolism to confirm the results.Objectives:To investigate the hypoglycemic effects of corn silk (Stigma maydis L.) in alloxan induced type 1 and type 2 diabetic mice and its mechanism of action, and provide a basis for the guidance clinical application of corn silk.Methods:In this study, corn silk was boiled with 10 L distilled water for 3 hours and repeated for 3 times. Then the extract was filtered and the filtrate was then concentrated to dryness under reduced pressure and further freeze-dried to give the water extract. The powder dissolved in distilled water as 0.12g·mL-1 with an equivalent dose of 18g·kg-1 body weight (BW) right before use. Total cholesterol (TC), triglycerides (TG), blood glucose (GLU), superoxide dismutase (SOD), malondialdehyde (MDA), non-esterified fatty acid (NEFA) and muscle glycogen (MG) levels were estimated by commercially available kits to provide a theoretical basis for the further application and development of corn silk functional medicine. Meantime, we also performed quantitative real-time RT-PCR analysis to examine gene expression of the livers of corn silk-treated diabetic mice. The gene including Fatty acid synthetase (Fasn),3-hydroxy-3-methylglutarylcoenzyme A reductase (Hmgcr), glucokinase (Gck) and glucose-6-phosphatase catalytic (G6pc).Results:1 Corn silk make a gradual improvement in the spirit of diabetic mice, increased activity, weight gain, water intake and food intake.2 Corn silk significantly reduced the levels of GLU, TC, TG, NEFA and MDA (P<0.05), and significantly increased SOD and MG (P<0.05) in type one and type two alloxan-induced diabetic mice.3 Fatty acid synthetase (Fasn), 3-hydroxy-3-methylglutarylcoenzyme A reductase (Hmgcr) and glucokinase (Gck) were up-regulated significantly whilst glucose-6-phosphatase catalytic (G6pc) was down-regulated in corn silk-treated diabetic mice.4 In the OGTT, administration of glucose load increased serum glucose levels significantly (P<0.05) after 0.5 h of glucose loading both in alloxan treated type 1 and type 2 diabetic mice. In addition, the elevation of blood glucose level in mice treated with corn silk extract was significently suppressed in type 1 diabetic (P<0.05) and type 2 diabetic (P<0.05), but was still higher than the C group (P<0.05).Conclusions:In conclusion, the present study found that corn silk extract prevented hyperglycemia and dyslipidemia in diabetic mice. Gene expression analysis revealed that corn silk extract treatment affected expression level of the genes related to lipid metabolism and glycometabolism. Therefore, corn silk should be considered as a candidate for future studies on diabetes. In addition, further comprehensive pharmacologic investigations, including experimental long-term studies, should be carried out on corn silk or its bioactive compound. |
