Momordica charantia extract on insulin resistance and the skeletal muscle GLUT4 protein in fructose-fed rats.
OBJECTIVE
We investigated the preventive effect of Momordica charantia Linn. (Cucurbitaceae) fruit, commonly known as bitter melon, on hyperglycemia and insulin resistance in rats fed with a fructose-enriched diet.


METHODS
First, rats were divided randomly into two groups: the control group was fed with control diet, whereas the experimental group was fed with a 60% high-fructose diet for 8 weeks. After the first 6 weeks, the fructose-treated rats were further subdivided into six groups and were orally fed with or without Momordica charantia L. or rosiglitazone (ROS) for 2 weeks while rats were still on fructose diet.


RESULTS
We demonstrated that bitter melon was effective in ameliorating the fructose diet-induced hyperglycemia, hyperleptinemia, hyperinsulinemia, and hypertriglyceridemia as well as in decreasing the levels of free fatty acid (FFA) (P<0.001, P<0.05, P<0.05, P<0.05, P<0.05, respectively). Bitter melon reversed fructose diet-induced hypoadiponectinemia (P<0.05), which provides a therapeutic advantage to insulin resistance in improving insulin sensitivity. Additionally, bitter melon decreased the weights of epididymal (P<0.05) and retroperitoneal white adipose tissue (WAT) (P<0.05). Bitter melon increased the expression of peroxisome proliferator-activated receptor gamma (PPAR gamma) in white adipose tissue (WAT). Conversely, bitter melon decreased the expression of leptin in WAT. Furthermore, we demonstrate that bitter melon significantly increases the mRNA expression and protein of glucose transporter 4 (GLUT4) in skeletal muscle.


CONCLUSIONS
This study demonstrates, for the first time, the beneficial effects of two different extracts of bitter melon on insulin resistance in rats fed a high-fructose diet thereby producing evidence of the role of changes in expression of PPAR gamma and GLUT4.
Shih
Chun-Ching
CC
Institute of Pharmaceutical Science and Technology, College of Health Science, Central Taiwan University of Science and Technology, 11, Po-Tze Lane, Takun, Taichung 406, Taiwan, ROC. ccshih@ctust.edu.tw
Lin
Cheng-Hsiu
CH
Lin
Wei-Li
WL
Wu
Jin-Bin
JB
D052242:Adiponectin / Q000097:blood; D000818:Animals; D001483:Base Sequence; D001786:Blood Glucose / Q000032:analysis; D015153:Blotting, Western; D001835:Body Weight / Q000187:drug effects; D017931:DNA Primers; D051275:Glucose Transporter Type 4 / Q000235:genetics / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D029777:Momordica charantia / Q000737:chemistry*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D052242:Adiponectin; D001786:Blood Glucose; D017931:DNA Primers; D051275:Glucose Transporter Type 4; D007328:Insulin; D010936:Plant Extracts; C495694:Slc2a4 protein, rat