知母乙醇提取物可刺激健康Wistar大鼠和糖尿病Goto-Kakizaki大鼠的分离胰岛分泌胰岛素。

Insulin secretion is stimulated by ethanol extract of Anemarrhena asphodeloides in isolated islet of healthy Wistar and diabetic Goto-Kakizaki Rats.

作者信息

Hoa N K, Phan D V, Thuan N D, Ostenson C-G

机构信息

Department of Pharmacology, Hanoi Medical University, Hanoi, Vietnam.

出版信息

Exp Clin Endocrinol Diabetes. 2004 Oct;112(9):520-5. doi: 10.1055/s-2004-821309.

DOI:10.1055/s-2004-821309

PMID:15505760

Abstract

BACKGROUND

The hypoglycemic effect of extract of Anemarrhena asphodeloides has been accounted for by the substance mangiferin which increases insulin sensitivity. The present study aimed to investigate whether an ethanol extract of Anemarrhena asphodeloides would stimulate insulin secretion and if so, further elucidate the mechanism behind this effect.

METHODS

Isolated pancreatic islets of normal Wistar rats and spontaneously diabetic Goto-Kakizaki (GK) rats were batch incubated or perifused to study effect of Anemarrhena asphodeloides extract (TH2) on insulin release.

RESULTS

At 3.3 mM glucose, 2, 4, and 8 mg/ml TH2 increased the insulin release of Wistar rat islets 2.5-, 4.1-, and 5.7-fold, respectively (p < 0.05) and of GK rat islets 1.7-, 3.0-, and 6.3-fold, respectively (p < 0.01). Similarly at 16.7 mM glucose, 2, 4 and 8 mg/ml TH2 increased insulin release of Wistar rat islets 1.5-, 2.2-, and 3.8-fold, respectively (p < 0.05) and of GK rat 2.5-, 4.2-, and 11.9-fold, respectively (p < 0.01). In perifusions of islets, TH2 also increased insulin secretion that returned to basal levels when TH2 was omitted from the perifusate. Mangiferin had no effect on insulin secretion of islets. In islets depolarized by 30 mM KCl and B-cell K-ATP channels kept open by 0.25 mM diazoxide, TH2 (8 mg/ml) further enhanced insulin secretion at 3.3 but not at 16.7 mM glucose. Pertussis toxin suppressed the insulin stimulating effect of 2 and 8 mg/ml TH2 by 35 % and 47 % (p < 0.05 and p < 0.001, respectively).

CONCLUSIONS

Ethanol extract of the roots of Anemarrhena asphodeloides contains a substance, TH2, that stimulates insulin secretion both at 3.3 and 16.7 mM glucose in islets of normal Wistar and diabetic GK rats. The mechanism behind TH2-stimulated insulin secretion involves an effect on the exocytotic machinery of the B-cell, mediated via pertussis toxin-sensitive Gi- (or Ge-) proteins.

摘要

背景

知母提取物的降血糖作用是由能增加胰岛素敏感性的芒果苷导致的。本研究旨在探究知母乙醇提取物是否会刺激胰岛素分泌，若会，则进一步阐明其作用机制。

方法

将正常Wistar大鼠和自发性糖尿病Goto-Kakizaki（GK）大鼠分离出的胰岛进行批量孵育或灌流，以研究知母提取物（TH2）对胰岛素释放的影响。

结果

在3.3 mM葡萄糖浓度下，2、4和8 mg/ml的TH2分别使Wistar大鼠胰岛的胰岛素释放增加2.5倍、4.1倍和5.7倍（p < 0.05），使GK大鼠胰岛的胰岛素释放增加1.7倍、3.0倍和6.3倍（p < 0.01）。同样，在16.7 mM葡萄糖浓度下，2、4和8 mg/ml的TH2分别使Wistar大鼠胰岛的胰岛素释放增加1.5倍、2.2倍和3.8倍（p < 0.05），使GK大鼠胰岛的胰岛素释放增加2.5倍、4.2倍和11.9倍（p < 0.01）。在胰岛灌流实验中，TH2也能增加胰岛素分泌，当灌流液中去除TH2时，胰岛素分泌恢复到基础水平。芒果苷对胰岛的胰岛素分泌没有影响。在由30 mM KCl使胰岛去极化且由0.25 mM二氮嗪使B细胞K-ATP通道保持开放的情况下，8 mg/ml的TH2在3.3 mM葡萄糖浓度时能进一步增强胰岛素分泌，但在16.7 mM葡萄糖浓度时则不能。百日咳毒素使2和8 mg/ml的TH2对胰岛素的刺激作用分别降低35%和47%（分别为p < 0.05和p < 0.001）。