六味地黃丸產生降血糖及胰島素增敏作用機轉之研究

The Mechanisms of Glucose Lowering Activity and Increase of Insulin Sensitivity Induced by Traditional Chinese Medicine Liu- Wei-Die-Huang-Wan.

許仁豪(Jen-Hao Hsu)

指導教授 ： 鄭瑞棠

共同指導教授 ： 吳永昌(Yang-Chang Wu)

高雄醫學大學/藥學院/天然藥物研究所碩士班/博士(2007年)

https://doi.org/10.6832/KMU.2007.00001

摘要

文獻指出六味地黃丸正常老鼠有降血糖的功能，是經由增進分泌胰島素而來，並指出六味地黃丸中山茱萸(Cornus officinalis Sieb.) 是增進胰島素分泌的主要藥物，而其作用機轉仍不明確。因此，本研究利用山茱萸中的主成分oleanolic acid 繼續研究山茱萸的降血糖作用機轉。結果發現，在禁食的大白鼠腹部注射oleanolic acid ( 20 mg/kg)九十分鐘後，隨著血中的胰島素及C-peptide 的增加而同步地調降血糖，顯見oleanolic acid確實會刺激胰臟釋放胰島素來產生降血糖的作用。而oleanolic acid所引發的這個效果可以被muscarinic 接受器阻斷劑反轉，但無法被神經節nicotinic 拮抗劑pentolinium 或hexamethonium所影響。進一步，利用胆素吸收抑制劑hemicholinium-3或乙醯胆素轉輸抑制劑vesamicol都可以去除oleanolic acid的降血糖作用，而且乙醯胆素分解酶抑制劑physostigmine可以加強oleanolic acid的功效。因此，oleanolic acid可能是透過刺激神經末梢釋放的乙醯胆素來促進胰島素分泌作用。此外，M3 接受器阻斷劑4-diphenylacetoxy-N-methylpiperdine methiodide (4-DAMP)會抑制oleanolic acid所引起的降血糖作用。結果顯示oleanolic acid 的作用可能與M3 接受器有關，是透過興奮神經末梢分泌乙醯胆素，然後刺激胰臟上的M3 接受器，增加胰島素的分泌，進而調降血糖。因此可以推測山茱萸的oleanolic acid 是增加正常老鼠胰島素分泌的有效成分。此外，文獻指出口服六味地黃丸可以延緩老鼠胰島素抗性(insulin resistance)的形成。為了解六味地黃丸中何種藥物具有延緩老鼠胰島素抗性的作用，使用60%果糖飼料來誘發老鼠產生胰島素抗性。結果發現，對具有胰島素抗性的大鼠，單獨給予山藥(4.2 mg/kg)( Dioscorea opposita Thunb. )與六味地黃丸一樣產生降血糖的功能(28.9 ± 7.6 % vs. 26.4 ± 4.6 %, n=8, p< 0.01)，而其他五種中藥則沒有這個作用。進一步，第一型糖尿病大鼠在持續以山藥治療後，對於胰島素治療的敏感性也增強了。結果證明六味地黃丸中的山藥確實是造成胰島素增敏作用的主要作用藥。由上述成果可知六味地黃丸中山茱萸中的oleanolic acid為促進胰島素分泌的主要作用藥物，而六味地黃丸中的山藥則是改善胰島素抗性的主要作用藥。因此，山茱萸及山藥確實可作為臨床上治療糖尿病病患的輔助用藥。

關鍵字

糖尿病鼠 ； 胰島素阻抗 ； 六味地黃丸 ； 山藥 ； 山茱萸

並列摘要

It has been documented that Die-Huang-Wan showed an ability to lower the plasma glucose in normal rats via an increase of insulin secretion. Then, the herb of cornus (Cornus officinalis Sieb.) that is also called as San-Zu-Yee in Chinese has been indicated as a major factor for an increase of insulin secretion induced by Die-Huang-Wan. The present study was then conducted to understand the role of oleanolic acid from cornus (Cornus officinalis Sieb.) as an active principle responsible for the release of insulin. After an intraperitoneal injection into the fasting Wistar rats after 90 min, oleanolic acid (20 mg/kg) decreased the plasma glucose in a dose-dependent manner in parallel to an increase of plasma levels of insulin as well as C-peptide. The effects of oleanolic acid was reversed by a blockade of muscarinic receptors with atropine, but not affected by the ganglionic nicotinic antagonists, pentolinium or hexamethonium. Disruption of synaptic available acetylcholine (ACh) using an inhibitor of choline uptake, hemicholinium-3, or vesicular acetylcholine transport, vesamicol, negated this action of oleanolic acid. Also, physostigmine at concentration sufficient to inhibit acetylcholinesterase enhanced the action of oleanolic acid. Mediation of ACh release from the nerve terminals to enhance insulin secretion of oleanolic acid can thus be considered. Both the plasma glucose lowering action and the raised plasma levels of insulin and C-peptide by oleanolic acid were also inhibited by 4-diphenylacetoxy-N-methylpiperdine methiodide (4-DAMP), indicating the mediation of muscarinic M3 receptors. The results suggest that oleanolic acid can raise the release of ACh from nerve terminals, which stimulate muscarinic M3 receptors in the pancreatic cells and augment the insulin release resulting in a plasma glucose lowering action. Thus, oleanolic acid can be considered as one of the active principles for the increase of plasma insulin produced by cornus in normal rats.
In addition, administration of Die-Huang-Wan has been found to delay the formation of insulin resistance in rats. The major herb contained in Die-Huang-Wan for this action was also investigated. In rats with insulin resistance induced by fructose-rich food, dioscorea(4.2mg/kg) ( Dioscorea opposita Thunb.) named as San-Yaw in Chinese showed the plasma glucose lowering action (28.9 ± 7.6 % vs. 26.4 ± 4.6 %, n=8, p< 0.01)in a way similar to Die-Huang-Wan while another 5 herbs failed to produce same action. Also, deletion of dioscorea from Die-Huang-Wan negated the plasma glucose lowering action. Moreover, a similar action of dioscorea produced by Die-Huang-Wan was characterized using the reduction of glucose-insulin index. In STZ-induced diabetic rats, daily oral administration of Die-Huang-Wan caused an increase of response to exogenous insulin 7 days later, indicating an increase of insulin sensitivity. The present study found that oral administration of dioscorea can increase insulin sensitivity produced by Die-Huang-Wan and the absence of dioscorea in Die-Huang-Wan failed to produce this action. Thus, dioscorea can be considered as the major herb in Die-Huang-Wan for the improvement of insulin resistance.
In conclusion, now we found the mechanism(s) for two actions of Die-Huang-Wan in the regulation of plasma glucose in rats. Oleanolic acid was observed to be one of the active principles for the increase of plasma insulin produced by cornus which is the major herb in Die-Huang-Wan for increase of insulin secretion. The main herb in Die-Huang-Wan for improvement of insulin resistance was identified as dioscorea. Therefore, cornus and discorea may be used as an adjuvant for the handling of diabetic patients with insulin resistance in clinics.

並列關鍵字

diabetic rats ； insulin resistance ； Liu-wei-die-Huang-Wan ； dioscorea ； cornus

參考文獻

1. Chou P, Chen CH, Chen HH, Chang MS.Epidemiology of isolated systolic hypertension in Pu-Li Taiwan. Int J Cardiol. 35:219-226,1992.

2. Tai TY, Yang CL, Chang CJ, Chang SM, Chen YH, Lin BJ, Ko LS, Chen MS, Chen CJ. Epidemiology of diabetes mellitus among adults in Taiwan, R.O.C. J Med Assoc Thai.70:42-48,1987.

3. Eizirik DL, Sandler S, Palmer JP. Repair of pancreatic beta-cells. A relevant phenomenon in early IDDM? Diabetes. 42:1383-1391,1993.

4. Goldstein DA, Massry SG.. Diabetic nephropathy: clinical course and effect of hemodialysis. Nephron. 20:286-296,1978.

5. Weidmann P, Boehlen LM, de Courten M. Pathogenesis and treatment of hypertension associated with diabetes mellitus. Am Heart J. 125:1498-1513, 1993.