Horm Metab Res 2007; 39(12): 894-898
DOI: 10.1055/s-2007-993154
Animals, Clinical

© Georg Thieme Verlag KG Stuttgart · New York

Increase of β-Endorphin Secretion by Syringin, an Active Principle of Eleutherococcus senticosus, to Produce Antihyperglycemic Action in Type 1-like Diabetic Rats

H-S. Niu 1 , F-L. Hsu 1 , I-M. Liu 2 , J-T. Cheng 3
  • 1Graduate Institute of Pharmacognosy, College of Pharmacy, Taipei Medical University, Taipei City, Taiwan, R.O.C.
  • 2Department of Pharmacy, Tajen University, Yen-Pou, Ping Tung Shien, Taiwan, R.O.C.
  • 3Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan City, Taiwan, R.O.C.
Further Information

Publication History

received 21.02.2007

accepted 09.07.2007

Publication Date:
13 December 2007 (online)


We employed streptozotocin-induced diabetic rats (STZ-diabetic rats) as type 1 diabetes-like animal models to investigate the mechanism(s) of antihyperglycemic action produced by syringin, an active principle purified from the rhizome and root parts of Eleutherococcus senticosus (Araliaceae). Bolus intravenous (i. v.) injection of syringin dose-dependently decreased the plasma glucose of STZ-diabetic rats in 30 minutes in a way parallel to the increase of plasma β-endorphin-like immunoreactivity (BER). Syringin enhanced BER release from the isolated adrenal medulla of STZ-diabetic rats in a concentration-dependent manner from 0.001 to 10 μmol/l. Bilateral adrenalectomy in STZ-diabetic rats eliminated the activities of syringin (1 mg/kg, i. v.) including the plasma glucose-lowering effect and the plasma BER-elevating effect. Also, syringin failed to lower plasma glucose in the presence of μ-opioid receptor antagonists and/or in the μ-opioid receptor knockout diabetic mice. In conclusion, the obtained results suggest that syringin can enhance the secretion of β-endorphin from adrenal medulla to stimulate peripheral μ-opioid receptors resulting in a decrease of plasma glucose in diabetic rats lacking insulin.


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Prof. J-T. Cheng

Department of Pharmacology

College of Medicine

National Cheng Kung University

Tainan City

70101 Taiwan


Phone: +886/6/237 27 06

Fax: +886/6/238 65 48

Email: jtcheng@mail.ncku.edu.tw