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Title: Pterostilbene improves glycaemic control in rats fed an obesogenic diet: Involvement of skeletal muscle and liver

Author
item GOMEZ-ZORITA, SAIOA - University Of Basque Country
item FERNANDEZ-QUINTELA, ALFREDO - University Of Basque Country
item AQUIRRE, LEIXURI - University Of Basque Country
item MACARULLA, MARIA - University Of Basque Country
item Rimando, Agnes
item PORTILLO, MARIA PUY - University Of Basque Country

Submitted to: Food & Function
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2015
Publication Date: 5/11/2015
Publication URL: http://handle.nal.usda.gov/10113/62271
Citation: Gomez-Zorita, S., Fernandez-Quintela, A., Aquirre, L., Macarulla, M.T., Rimando, A.M., Portillo, M. 2015. Pterostilbene improves glycaemic control in rats fed an obesogenic diet: Involvement of skeletal muscle and liver. Food and Function. 6:1968-1976.

Interpretive Summary: This study aimed to determine whether pterostilbene improved regulation and maintenance of blood glucose levels in rats showing insulin resistance induced by high-fat diet. Rats were fed high-fat diet fortified with pterostilbene at either15 mg/kg body weight/day (PT15 group) or 30 mg/kg body weight/day of (PT30 group). The index for insulin resistance decreased in both treated groups. Both groups showed improvement in the control of sugar blood levels. Data indicated improved glucose uptake in the skeletal muscle. The beneficial effect of pterostilbene was more evident with the lower dose (PT15), probably because in this group both muscle and liver were contributing to this effect, while in PT30 group the effect was only seen with the skeletal muscle. An increase in the activity of an enzyme participating in the metabolism of sugars in the liver, as well as increase in skeletal muscle glucose uptake, seems to be involved in the anti-diabetic effect of this phenolic compound.

Technical Abstract: This study aimed to determine whether pterostilbene improved glycaemic control in rats showing insulin resistance induced by an obesogenic diet. Rats were divided into 3 groups: control group and two groups treated with either 15 mg/kg/d (PT15) or 30 mg/kg/d of pterostilbene (PT30). HOMA-IR was decreased in both pterostilbene-treated groups, but this reduction was greater in PT15 group (-44.7% and -21.7% respectively vs control group). The improvement in glycaemic control was not due to a delipidating effect of pterostilbene on skeletal muscle. By contrast, GLUT4 protein expression was increased (+58% and +52% vs control group), suggesting an improved glucose uptake. The phosphorylated-Akt/total Akt ratio was significantly enhanced in PT30 group (+25%), and therefore a more efficient translocation of GLUT4 is likely. Additionally, in this group the amount of cardiotrophin-1 was significantly increased (+65%). These data suggest that the effect of pterostilbene on Akt is likely mediated by this cytokine. In liver, glucokinase activity was significantly increased only in PT15 group (+34%), and no changes were observed in glucose-6-phosphatase activity. The beneficial effect of pterostilbene on glycaemic control was more evident with the lower dose, probably because in PT15 group both muscle and liver were contributing to this effect, while in PT30 group only skeletal muscle was involved. In conclusion, pterostilbene improves glycaemic control in rats showing insulin resistance induced by an obesogenic diet. An increase in hepatic glucokinase activity, as well as in skeletal muscle glucose uptake, seems to be involved in the anti-diabetic effect of this phenolic compound.