Gastrodia elata Blume water extracts improve insulin resistance by decreasing body fat in diet-induced obese rats: vanillin and 4-hydroxybenzaldehyde are the bioactive candidates.
BACKGROUND
Insulin resistance is a common symptom of metabolic diseases such as obesity, type 2 diabetes and hyperlipidemia.


OBJECTIVE
We investigated whether Gastrodia elata Blume water extract(GEB), containing phenolic compounds, had a beneficial action on insulin resistance in male Sprague-Dawley rats fed a high fat diet(HFD) and determined how this effect was produced. In addition, the bioactive candidates involved were identified.


METHODS
Rats fed HFD were daily administered with 0.3 g GEB(GEB-L), 1 g GEB(GEB-H), or 1 g cellulose(control) per kg body weight for 8 weeks, while rats in the fourth group were fed a low fat diet(LFD). In vitro study, 4 major components of GEB were tested for their impact on fat accumulation.


RESULTS
Rats in the control group exhibited a higher weight gain of epididymal and retroperitoneal fat pads than those fed LFD, while GEB prevented such an increment in a dose-dependent manner. GEB-H significantly decreased energy intake partly through potentiating STAT3 phosphorylation and attenuating AMPK phosphorylation in the hypothalamus. GEB-H also increased energy expenditure with the increase in fat oxidation. GEB-H increased whole body glucose disposal rates and decreased hepatic glucose output compared to the control. Among the major components of GEB, 4-hydroxybenzaldehyde and vanillin decreased triglyceride accumulation by modulating the expression of genes involved in fat metabolism in 3T3-L1 adipocytes. They increased insulin-stimulated glucose uptake to reduce insulin resistance.


CONCLUSIONS
GEB-H, mainly as a result of the action of 4-hydroxybenzaldehyde and vanillin, reduces insulin resistance by decreasing fat accumulation in adipocytes by activating fat oxidation and potentiating leptin signaling in diet-induced obese rats.
Park
Sunmin
S
Department of Food and Nutrition, Hoseo University, 165 Sechul-Ri, BaeBang-Yup, Asan-Si, ChungNam-Do, South Korea. smpark@hoseo.edu
Kim
Da Sol
DS
Kang
Suna
S
D000263:Adenylate Kinase / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects*; D000818:Animals; D001547:Benzaldehydes / Q000494:pharmacology*; D001835:Body Weight; D002460:Cell Line; D018752:Diet, Fat-Restricted; D004041:Dietary Fats / Q000008:administration & dosage; D002149:Energy Intake; D004734:Energy Metabolism; D031668:Gastrodia / Q000737:chemistry*; D005951:Glucose Tolerance Test; D007031:Hypothalamus / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D020738:Leptin / Q000378:metabolism; D008297:Male; D051379:Mice; D009765:Obesity / Q000188:drug therapy*; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D050796:STAT3 Transcription Factor / Q000378:metabolism
D001547:Benzaldehydes; D004041:Dietary Fats; D007328:Insulin; D020738:Leptin; D010936:Plant Extracts; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; C100058:vanillin; D000263:Adenylate Kinase; C011483:4-hydroxybenzaldehyde