刺五加及其有效成分syringin對血糖及血壓影響的研究

Antihyperglycemic actions and Antihypertensive actions of Eleutherococcus senticosus and syringin

劉科佑(Ko-Yu Liu)

指導教授 ： 吳永昌 ； 鄭瑞棠

高雄醫學大學/藥學院/天然藥物研究所碩士班/碩士(2004年)

摘要

刺五加乃是我國固有的草藥。在動物 (in vivo) 實驗方面，經口灌食刺五加水萃取物到正常老鼠後，可產生劑量相關方式(dose-dependent)的降血糖作用。同樣地，靜脈注射syringin（刺五加所含有效成分）到正常老鼠後，也產生類似的作用。而且，血中胰島素濃度也因而隨之增高；表示此降血糖作用可能與胰島素有關。以腹腔注射atropine或scopolamine再靜脈注射syringin，發現它們皆可抑制其降血糖的作用。若先給予physostigmine再同樣投予syringin，則可增強其降血糖的作用；顯示syringin的降血糖作用與副交感神經有關。另外，給予vesamicol或hemichoninium，將神經末端acetylcholine濃度減少，則syringin的降血糖作用也跟著減少；表示這項降血糖作用與神經末端acetylcholine釋放有關。若給予M3受體阻斷劑4-DAMP mustard，發現它會以劑量相關方式(dose-dependent)阻斷syringin的降血糖作用；表示其降血糖作用與M3受體有關。可是，給予aexamethonium或pentolinium再投予，發現syringin的降血糖效果不變，故其降血糖作用與自主神經節的活化無關。由此可知，刺五加的syringin是藉由副交感神經尾端刺激acetylcholine釋放，使之作用在胰臟的M3受體，導致胰島素分泌來產生降血糖作用。另一方面，經口灌食刺五加水萃取物到高血壓老鼠(spontaneous hypertensive rats SHR)後，產生劑量相關方式(dose-dependent)的降血壓作用。可是，靜脈注射syringin到高血壓老鼠(spontaneous hypertensive rats SHR)，却沒有任何的變化。分析刺五加的水抽取層、70%酒精抽取層、95%酒精抽取層等三部份的syringin含量，得知syringin主要含在水抽取層。而且，灌食刺五加的95%酒精抽取層到高血壓老鼠(spontaneous hypertensive rats SHR)會有顯著的降血壓效果，灌食水抽取層的降血壓效果則較差。因此，刺五加的降血壓成份乃是含在酒精抽取層的物質而非syringin。由此可知，刺五加會藉由不同的有效成份來產生血糖下降和改善高血壓的作用。

關鍵字

血壓 ； 血糖 ； 刺五加

並列摘要

Xie-Wu-Jia is the Chinese of herb Eleutherococcus senticosus (Rupr. & Maxim.) Maxim. It is also named as Siberian Ginseng because the same family (Araliaceae) as ginseng. In an attempt to develop the agent suitable for patients with diabetes and hypertension, Xie-Wu-Jia was investigated in the present study. Oral administration of Xie-Wu-Jia produced a dose-dependent decrease of plasma glucose in Wistar rats. Intravenous injection of syringin into Wistar rats, one of the active principles of Xie-Wu-Jia, resulted in a reduction of plasma glucose. Increase of plasma insulin was also observed in rats received similar injection of syringin. Atropine or scopolamine inhibited the syringin-induced plasma glucose lowering action while physostigmine increased this action of syringin in rats, indicating the involvement of parasympathetic nervous system in syringin induced plasma glucose lowering action in rats. The plasma glucose lowering effect of syringin in Wistar rats was abolished by pretreatment of vesamicol or hemichoninium at the dose sufficient to lower endogenous acetylcholine. Release of acetylcholine from peripheral parasympathetic nervous system by syringin can thus be considered. Moreover, the action of syringin was abolished by 4-DAMP mustard at the dose effective to block M3 receptor. But the plasma glucose lowering action of syringin was not abolished by pretreatment with nicotinic receptor antagonist, either hexamethonium or pentolinum, indicating that syringin lowered plasma glucose in rats was not by activation of the nicotinic receptor. Moreover, the plasma glucose lowering action of Xie-Wu-Jia was also blocked by 4-DAMP mustard. The obtained results suggest that release of acetylcholine from the peripheral parasympathetic nerve is responsible for the lowering of plasma glucose induced by Xie-Wu-Jia via syringin in Wistar rats through an activation of muscarinic M3 receptor in the islets to enhance insulin secretion. Similar response was observed in rats received an intravenous injection of syringin. Otherwise, Xie-Wu-Jia can decrease the blood pressure in spontaneous hypertensvie rats (SHR). However, syringin did not modify the blood pressure in SHR. Identification of the fractionations in Xie-Wu-Jia, syringin was highest in aqueous extraction and less in ethanol-extracted fraction. Antihypertensive action was mainly obtained in SHR received ethanol extracts. The active principle(s) for reduction of blood pressure in ethanol-extracted fraction of Xie-Wu-Jia can thus be considered. In conclusion, the obtained data suggest that Xie-Wu-Jia has the ability to lower plasma glucose and blood pressure depending on the difference of active principles while syringin is responsible for lowering of plasma glucose but not for the reduction of blood pressure.

並列關鍵字

syringin

參考文獻

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