基于11β-HSD1探讨桑白皮"泻肺"调节黄芪散改善胰岛素抵抗的作用机制

Diabetes Mellitus is clinically treated as "XiaoKe" in Traditional Chinese Medicine. However, no study on the mechanism of "ShangXiao" treatment by "draining the lung" is reported presently. 11β- Hydroxysteroid Dehydrogenase type 1 (11β-HSD1) is the key in the impact of cortisol on glucose and lipid metabolism, by activating cortisone to cortisol, to reduce insulin sensitivity. An ancient prescription for "XiaoKe", HuangQi San (HQS) can improve insulin sensitivity, modulate glucose and lipid metabolism. Preliminary research shows that HQS with, was prior to Radix astragali - Radix Pueraria with no Cortex Mori, in reducing the activity of 11β-HSD1 in adipose and skeletal muscle in type Ⅱ diabetic mice, with the subsequently improvement of hyperglycemia and hyperlipidemia. So we hypothesis that Cortex Mori with the character of "draining the lung", inhibits the activity of 11β-HSD1, subsequently inactivates glucocorticoid, so it plays an important role in the effect of HQS on insulin sensitivity. In this project, 3 classic animal models, involving glucocorticoid or streptozotocin plus high fat diet induced, and genetic mutation ob/ob diabetic mice, and cell lines, involving primary cultured or 3T3-L1 preadipocyte, L6 skeletal muscle cell, are applied into the investigation of effects of HQS different components, "draining the lung" or non-"draining the lung", on 11β-HSD1 gene and protein expression, enzyme activity, insulin sensitivity, and relative parameters. Finally the mechanism of improvement of insulin sensitivity by "draining the lung" is to be classified.

：糖尿病在中医临床常按"消渴"辨治，未见用"泻肺"治疗"上消"的相关基础研究。11β-羟基类固醇脱氢酶1（11β-HSD1）通过激活肝、脂肪、骨骼肌等组织中皮质激素，降低胰岛素敏感性，是糖尿病皮质激素影响糖脂代谢的关键环节。治疗消渴的古方黄芪散能改善胰岛素敏感性，调节糖脂代谢，拆方研究显示含桑白皮的原方降低糖尿病模型小鼠的肺、脂肪、骨骼肌组织中11β-HSD1的活性，改善高血糖、高血脂状态的作用优于不含桑白皮的黄芪-葛根。故设想"泻肺"的桑白皮是通过抑制11β-HSD1，灭活皮质激素，帮助黄芪散改善胰岛素敏感性。采用经典的糖皮质激素、STZ+高脂诱导，及基因变异ob/ob糖尿病小鼠模型，原代及体外培养的脂肪、骨骼肌细胞株，拆方探讨黄芪散"泻肺"与非"泻肺"药物对11β-HSD1基因和蛋白表达、酶活性、及胰岛素敏感性等相关指标的影响，以期阐释"泻肺"改善胰岛素敏感性的科学内涵。

本研究通过拆方探讨桑白皮“泻肺”调节黄芪散通过对 11β-HSD1 基因和蛋白表达、酶活性及胰岛素敏感性等相关指标的影响，阐释了桑白皮“泻肺”调节了黄芪散改善胰岛素敏感性的科学内涵。对不同配比的黄芪散进行含量测定并采用多元线性回归分析其量效关系，得出黄芪散复方中各成分对糖尿病影响最大的是异黄酮类，其次是总皂苷与异戊烯基黄铜；对胆固醇的影响效果较突出的是异黄酮与异戊烯基黄铜。在建立STZ+高脂诱导的糖尿病大鼠模型、糖皮质激素+高脂诱导的糖尿病大鼠模型、高脂诱导的糖尿病大鼠模型基础上，实验给药黄芪散改方（处方1）、黄芪散原方（处方2）、不含桑白皮处方（处方3）及桑白皮，结果表明含桑白皮的处方（处方1、2）和桑白皮均可不同程度的在肝脏、脂肪、骨骼肌及肺中下调11β-HSD1的基因和蛋白表达，从而调节局部糖皮质激素水平，减少皮质醇的含量，改善肥胖和胰岛素抵抗。然而不含桑白皮的处方（处方3）对脏器中11β-HSD1的基因和蛋白表达水平无明显影响。在肝脏中，各给药组都有不同程度使糖异生关键酶PEPCK的表达明显降低，糖异生作用减轻。在脂肪组织中，各给药组都有不同程度使PPARγ的表达显著增加，PPARγ对于维持胰岛素敏感性和糖脂代谢有重要的作用。在骨骼肌中，各给药组都有不同程度使葡萄糖转运蛋白GLUT4的表达显著增加，它对胰岛素反应敏感、迅速，在葡萄糖的吸收和利用中起了关键限速作用。结果显示桑白皮在黄芪散方中有着重要且不可替代的作用，桑白皮的“泻肺”功能增强了黄芪散调控11β-HSD1达到了改善胰岛素敏感性的作用。