| 摘要: | 電針改善大鼠葡萄糖耐受機轉之探討
邱瑞發1 林昭庚2 張世良1
1中國醫藥大學 針灸研究所
2中國醫藥大學 中國醫學研究所
目前已知電針可改善正常大鼠與類固醇誘導的糖尿病鼠葡萄糖耐受量（glucose tolerance）之現象，本研究的目的是進一步探討電針兩側足三里（ST 36）對正常大鼠葡萄糖耐受試驗的影響與其相關機轉。
我們利用雄性威斯特 (wistar) 大鼠，做靜脈注射葡萄糖耐受試驗（intravenous Glucose Tolerance Test 、ivGTT）。利用副交感神經阻斷劑阿脫品（atropine）、HC-3（hemicholinium-3）抑制乙醯膽鹼（Ach）的生成與一氧化氮合成酶抑制劑（NG-nitro-L-arginine methyl ester，L-NAME）阻斷一氧化氮合成酶 (NOS) 的生成。大鼠經空腹12小時以上，在麻醉下皆接受ivGTT，實驗組接受電針兩側足三里，電針劑量15 Hz，10 mA，60 min；控制組不電針。在實驗開始後0、15、30、60、90 min抽血檢測血糖值。並單獨或同時給予atropine、HC-3與L-NAME，觀察電針與不電針兩組的差異性。並利用atropine與L-NAME觀察電針在ivGTT下對游離脂肪酸（free fatty acid，FFA）變化量的影響效應。再利用大鼠骨骼肌做蛋白質西方轉漬法分析（western blotting assay）檢測骨骼肌中胰島素訊息蛋白IRS-1、PI3-Kinase、Akt1、GLUT4 、nNOS及Actin的含量，觀察電針與不電針兩組的差異性。
結果我們發現在葡萄糖耐受試驗下，電針處置後血糖下降較不電針組明顯，有統計上顯著差異。以atropine或L-NAME阻斷劑單獨進行阻斷，電針與不電針組血糖下降仍有差異。同時以L-NAME及atropine、L-NAME及HC-3阻斷劑電針血糖下降，與非電針組無顯著差異。電針在ivGTT下也有下降FFA的作用，其下降作用也可以被atropine與L-NAME阻斷劑所阻斷。同時，胰島素訊息蛋白IRS-1與nNOS相對含量，電針組顯著高於不電針組。
綜合以上，我們的結論是電針足三里能明顯提升正常大鼠ivGTT的血糖下降程度，可能透過副交感神經的乙醯膽鹼（ACh）及一氧化氮合成酶（NOS）降低血中FFA達到較佳降糖作用，而且電針可使胰島素訊息蛋白IRS-1與nNOS相對含量增加。因此，我們推論電針可同時透過副交感神經及NOS來提升大鼠對葡萄糖之耐受性。
Investigation of the mechanisms for improvement of
Glucose tolerance in rats by electroacupuncture
The purpose of this investigation is to evaluate the effect and mechanisms of electroacupunture（EA）at the bilateral zusanli acupoint (ST-36) on glucose intolerance in normal wistar rats.
The male wistar rats are applied in this test, The intravenous glucose tolerance test (ivGTT) is carried out to compare the glucose tolerance of normal rats. The parasympathetic inhibitor, atropine, HC-3 blocks the parasympathetic activity and nitric oxide synthase (NOS) antagonists, NG-nitro-L-arginine methyl ester (L-NAME) inhibit the release of nitric oxide (NO) in rats. Both of them have been treated for blocking the effect of EA in this test. After fasting for 12 hrs, then the rats are took the ivGTT. The experimental group (EG) is proceeded the EA on bilateral Zusanli acupoint (ST-36), and then carried out with the frequency, 15Hz and a fixed intensity of 10 mA for 60 min; the control group (CG) is not proceeded the EA. At the time 0, 15, 30, 60, 90 min later plasma glucose levels and FFA levels were obtained for assaying. Further, the atropine and L-NAME have been injected to Wistar rats alone or simultaneously, that is performed to investigate the difference of plasma glucose levels between these two groups. The western blot assay is also applied to realize the activity of skeletal muscle insulin signaling protein (IRS-1、PI3-Kinase、Akt1 and GLUT4) and nNOS to exam the correlation to EA improving glucose tolerance.
According to the results, we suggested this EG is significantly lowered the plasma glucose levels more than CG does under intravenous glucose tolerance test (ivGTT). When the L-NAME、atropine or HC-3 treated animal alone, the plasma glucose level still has difference between EG and CG. But, L-NAME and atropine, HC-3 and L-NAME combined treatment in ivGTT, there are no significant difference levels of plasma glucose. Also, this EA decreased FFA level and enhancing the skeletal muscle insulin signaling protein IRS-1 and nNOS activity under ivGTT.
Taken together, we concluded this EA at zusanli acupoint significantly can lower plasma glucose levels of normal Wistar rats under ivGTT. Therefore, the action of EA can through parasympathetic system and NO release via lowering the plasma FFA to enhance glucose tolerance. Further, that may activate insulin signaling protein IRS1 and enhancing nNOS activity to improve the glucose tolerance . |
