British Journal of Nutrition

Full Papers

Bitter melon (Momordica charantia L.) inhibits adipocyte hypertrophy and down regulates lipogenic gene expression in adipose tissue of diet-induced obese rats

Hui-Ling Huanga1a2, Ya-Wen Honga1, You-Hong Wonga3, Ying-Nien Chena4, Jong-Ho Chyuana5, Ching-Jang Huanga6a7 and Pei-Min Chaoa1a3 c1

a1 Institute of Nutrition, China Medical University, Taichung, Taiwan

a2 Department of Health and Nutrition, Chia Nan University of Pharmacy and Science, Tainan, Taiwan

a3 Department of Nutrition, China Medical University, Taichung, Taiwan

a4 Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung 404, Taiwan

a5 Hualien District Agricultural Research and Extension Station, Hualien, Taiwan

a6 Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan

a7 Division of Nutritional Science, Institute of Microbiology and Biochemistry, College of Life Science, National Taiwan University, Taipei, Taiwan

Abstract

Bitter melon (Momordica charantia; BM) has been shown to ameliorate diet-induced obesity and insulin resistance. To examine the effect of BM supplementation on cell size and lipid metabolism in adipose tissues, three groups of rats were respectively fed a high-fat diet supplemented without (HF group) or with 5 % lyophilised BM powder (HFB group), or with 0·01 % thiazolidinedione (TZD) (HFT group). A group of rats fed a low-fat diet was also included as a normal control. Hyperinsulinaemia and glucose intolerance were observed in the HF group but not in HFT and HFB groups. Although the number of large adipocytes (>180 μm) of both the HFB and HFT groups was significantly lower than that of the HF group, the adipose tissue mass, TAG content and glycerol-3-phosphate dehydrogenase activity of the HFB group were significantly lower than those of the HFT group, implying that BM might reduce lipogenesis in adipose tissue. Experiment 2 was then conducted to examine the expression of lipogenic genes in adipose tissues of rats fed low-fat, HF or HFB diets. The HFB group showed significantly lower mRNA levels of fatty acid synthase, acetyl-CoA carboxylase-1, lipoprotein lipase and adipocyte fatty acid-binding protein than the HF group (P < 0·05). These results indicate BM can reduce insulin resistance as effective as the anti-diabetic drug TZD. Furthermore, BM can suppress the visceral fat accumulation and inhibit adipocyte hypertrophy, which may be associated with markedly down regulated expressions of lipogenic genes in the adipose.

(Received February 23 2007)

(Revised May 15 2007)

(Accepted June 11 2007)

Correspondence:

c1 Corresponding author: Dr Pei-Min Chao, fax +886 4 2206 2891, email pmchao@mail.cmu.edu.tw

Footnotes

Abbreviations: ACC-1, acetyl-CoA carboxylase-1; ADD1/SREBP-1c, adipocyte determination and differentiation factor 1/sterol regulatory element-binding protein-1c; aP2, adipocyte fatty acid-binding protein; BM, bitter melon; DIO, diet-induced obesity; FAS, fatty acid synthase; G3PDH, glycerol-3-phosphate dehydrogenase; HF, high-fat, HFB, high-fat and bitter melon; HFT, high-fat and thiazolidinedione; LF, low-fat; LPL, lipoprotein lipase; TZD, thiazolidinedione

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