Sridhar M G, Vinayagamoorthi R, Arul Suyambunathan V, Bobby Z, Selvaraj N
Department of Biochemistry, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry-605 006, India.
Br J Nutr. 2008 Apr;99(4):806-12. doi: 10.1017/S000711450783176X. Epub 2007 Oct 17.
The aim of this present study was to investigate the effect of bitter gourd extract on insulin sensitivity and proximal insulin signalling pathways in high-fat-fed rats. High-fat feeding of male Wistar rats for 10 weeks decreased the glucose tolerance and insulin sensitivity compared to chow-fed control rats. Bitter gourd extract supplementation for 2 weeks (9th and 10th) of high-fat feeding improved the glucose tolerance and insulin sensitivity. In addition bitter gourd extract reduced the fasting insulin (43 (se 4.4) v. 23 (se 5.2) microU/ml, P < 0.05), TAG (134 (se 12) v. 96 (se 5.5) mg/dl, P < 0.05), cholesterol (97 (se 6.3) v. 72 (se 5.2) mg/dl, P < 0.05) and epidydimal fat (4.8 (se 0.29) v. 3.6 (se 0.24) g, P < 0.05), which were increased by high-fat diet (HFD). High-fat feeding and bitter gourd supplementation did not have any effect on skeletal muscle insulin receptor, insulin receptor subtrate-1 (IRS-1) and insulin- stimulated insulin receptor tyrosine phosphorylation compared to chow-fed control rats. However high-fat feeding for 10 weeks reduced the insulin-stimulated IRS-1 tyrosine phosphorylation compared to control rats. Bitter gourd supplementation together with HFD for 2 weeks improved the insulin-stimulated IRS-1 tyrosine phosphorylation compared to rats fed with HFD alone. Our results show that bitter gourd extract improves insulin sensitivity, glucose tolerance and insulin signalling in HFD-induced insulin resistance. Identification of potential mechanism(s) by which bitter gourd improves insulin sensitivity and insulin signalling in high-fat-fed rats may open new therapeutic targets for the treatment of obesity/dyslipidemia-induced insulin resistance.
本研究的目的是调查苦瓜提取物对高脂喂养大鼠胰岛素敏感性及近端胰岛素信号通路的影响。与正常饮食的对照大鼠相比，雄性Wistar大鼠高脂喂养10周后葡萄糖耐量和胰岛素敏感性降低。高脂喂养第9周和第10周补充苦瓜提取物2周可改善葡萄糖耐量和胰岛素敏感性。此外，苦瓜提取物降低了空腹胰岛素水平（43（标准误4.4）对23（标准误5.2）微单位/毫升，P<0.05）、甘油三酯水平（134（标准误12）对96（标准误5.5）毫克/分升，P<0.05）、胆固醇水平（97（标准误6.3）对72（标准误5.2）毫克/分升，P<0.05）以及附睾脂肪量（4.8（标准误0.29）对3.6（标准误0.24）克，P<0.05），这些指标在高脂饮食（HFD）后均升高。与正常饮食的对照大鼠相比，高脂喂养和苦瓜补充对骨骼肌胰岛素受体、胰岛素受体底物-1（IRS-1）以及胰岛素刺激的胰岛素受体酪氨酸磷酸化均无影响。然而，与对照大鼠相比，高脂喂养10周降低了胰岛素刺激的IRS-1酪氨酸磷酸化。与仅高脂喂养的大鼠相比，高脂喂养同时补充苦瓜2周改善了胰岛素刺激的IRS-1酪氨酸磷酸化。我们的结果表明，苦瓜提取物可改善高脂饮食诱导的胰岛素抵抗中的胰岛素敏感性、葡萄糖耐量和胰岛素信号。确定苦瓜改善高脂喂养大鼠胰岛素敏感性和胰岛素信号的潜在机制可能为治疗肥胖/血脂异常诱导的胰岛素抵抗开辟新 的治疗靶点。
