Bioactives from bitter melon enhance insulin signaling and modulate acyl carnitine content in skeletal muscle in high-fat diet-fed mice

Zhong Q. Wang, Xian H. Zhang, Yongmei Yu, Alexander Poulev, David Ribnicky, Z. Elizabeth Floyd, William T. Cefalu

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Bioactive components from bitter melon (BM) have been reported to improve glucose metabolism in vivo, but definitive studies on efficacy and mechanism of action are lacking. We sought to investigate the effects of BM bioactives on body weight, muscle lipid content and insulin signaling in mice fed a high-fat diet and on insulin signaling in L6 myotubes. Male C57BL/6J mice were randomly divided into low-fat diet control (LFD), high-fat diet (HFD) and HFD plus BM (BM) groups. Body weight, body composition, plasma glucose, leptin, insulin and muscle lipid profile were determined over 12 weeks. Insulin signaling was determined in the mouse muscle taken at end of study and in L6 myotubes exposed to the extract. Body weight, plasma glucose, insulin, leptin levels and HOMA-IR values were significantly lower in the BM-fed HFD group when compared to the HFD group. BM supplementation significantly increased IRS-2, IR β, PI 3K and GLUT4 protein abundance in skeletal muscle, as well as phosphorylation of IRS-1, Akt1 and Akt2 when compared with HFD (P<.05 and P<.01). BM also significantly reduced muscle lipid content in the HFD mice. BM extract greatly increased glucose uptake and enhanced insulin signaling in L6 myotubes. This study shows that BM bioactives reduced body weight, improved glucose metabolism and enhanced skeletal muscle insulin signaling. A contributing mechanism to the enhanced insulin signaling may be associated with the reduction in skeletal muscle lipid content. Nutritional supplementation with this extract, if validated for human studies, may offer an adjunctive therapy for diabetes.

Original languageEnglish (US)
Pages (from-to)1064-1073
Number of pages10
JournalJournal of Nutritional Biochemistry
Volume22
Issue number11
DOIs
StatePublished - Nov 2011

All Science Journal Classification (ASJC) codes

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Molecular Biology
  • Nutrition and Dietetics
  • Clinical Biochemistry

Keywords

  • Acyl carnitine
  • Bitter melon extract
  • High-fat diet
  • IRS-1
  • PI 3Kinase

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