Bitter gourd (Momordica charantia) improves insulin sensitivity by increasing skeletal muscle insulin-stimulated IRS-1 tyrosine phosphorylation in high-fat-fed rats.
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.
Sridhar
M G
MG
Department of Biochemistry, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry-605 006, India. sridhar_biochem@yahoo.co.in
Vinayagamoorthi
R
R
Arul Suyambunathan
V
V
Bobby
Z
Z
Selvaraj
N
N
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D002784:Cholesterol / Q000097:blood; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage*; D019587:Dietary Supplements; D005951:Glucose Tolerance Test; D007328:Insulin / Q000097:blood; D055504:Insulin Receptor Substrate Proteins; D007333:Insulin Resistance; D008297:Male; D029777:Momordica charantia; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D014280:Triglycerides / Q000097:blood; D014443:Tyrosine / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D004041:Dietary Fats; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D009124:Muscle Proteins; D014280:Triglycerides; D014443:Tyrosine; D002784:Cholesterol