Department of Clinical Pharmaceutical Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan.
J Ethnopharmacol. 2010 Apr 21;128(3):672-8. doi: 10.1016/j.jep.2010.02.019. Epub 2010 Feb 26.
Eucommia ulmoides Oliv. leaf is a traditional Chinese medicine that exhibits an anti-diabetic action. This study was designed to investigate whether long-term administration of Eucommia ulmoides Oliv. leaves extract (ELE) ameliorates pre-diabetic state of insulin resistance and abnormal perivascular innervation in the hyperinsulinemic state.
ELE at doses of 500 and 1000mg/kg was administered orally once daily for 4 weeks in fructose-drinking rats (FDRs). Plasma levels of insulin, blood glucose levels, and perivascular innervation were assessed using biochemical and immunohistochemical methods.
FDR showed significant increase in plasma levels of insulin, an index for insulin resistance (Homeostasis Model Assessment ratio-HOMA-IR) and systolic blood pressure (SBP), but not blood glucose levels, as compared with control rats. Immunohistochemical study showed significantly greater density of tyrosine hydroxylase (TH)-like immunoreactivity (LI)-containing nerves and significantly lower density of calcitonin gene-related peptide (CGRP)-LI-containing nerves in mesenteric arteries of FDR than those in control. A 4-week treatment with ELE (500 and 1000mg/kg, p.o.) significantly decreased plasma levels of insulin and HOMA-IR without affecting blood glucose levels and significantly lowered SBP in FDR. ELE treatment in FDR resulted in significant increase in CGRP-LI never fiber density and significant decrease in TH-LI never fiber density in mesenteric arteries of FDR.
These results suggest that long-term ELE treatment effectively prevents insulin resistance development and ameliorates abnormal perivascular innervation in FDR.
杜仲叶是一种传统的中药，具有降血糖作用。本研究旨在探讨长期给予杜仲叶提取物（ELE）是否能改善高胰岛素血症状态下的胰岛素抵抗前期和异常的血管周围神经支配。
在果糖灌胃大鼠（FDR）中，ELE 以 500 和 1000mg/kg 的剂量每天口服一次，连续 4 周。采用生化和免疫组织化学方法评估血浆胰岛素水平、血糖水平和血管周围神经支配。
与对照组大鼠相比，FDR 显示血浆胰岛素水平显著升高，这是胰岛素抵抗的一个指标（稳态模型评估比-HOMA-IR）和收缩压（SBP），但血糖水平没有升高。免疫组织化学研究显示，FDR 肠系膜动脉中酪氨酸羟化酶（TH）样免疫反应（LI）阳性神经的密度显著增加，降钙素基因相关肽（CGRP）-LI 阳性神经的密度显著降低。4 周的 ELE（500 和 1000mg/kg，口服）治疗可显著降低 FDR 血浆胰岛素和 HOMA-IR 水平，而不影响血糖水平，并显著降低 FDR 的 SBP。ELE 治疗可使 FDR 肠系膜动脉中 CGRP-LI 无纤维密度显著增加，TH-LI 无纤维密度显著降低。
这些结果表明，长期 ELE 治疗可有效预防 FDR 胰岛素抵抗的发生，并改善异常的血管周围神经支配。
