Mechanism of anti-hyperglycemic action of Vatairea macrocarpa (Leguminosae): investigation in peripheral tissues.
OBJECTIVE
Previous studies in our laboratory have demonstrated that the treatment of diabetic rats during 21 days with V. macrocarpa stem-bark ethanolic extract (VmE), reduced glycemia, urinary glucose and urea, increased liver glycogen content and improved other parameters diabetes related. The objective of this study was to evaluate if the anti-hyperglycemic mechanisms of VmE could be caused by improvement in the insulin signaling pathway in the peripheral tissues (liver, adipose and skeletal muscle).


METHODS
Streptozotocin-diabetic rats were separated into two groups: diabetic control (DC) and diabetic treated with VmE (DT) during 21 days. The alterations on the insulin signaling in liver, retroperitoneal adipose tissue (RET) and extensor digitorum longus (EDL) muscles were investigated through determination of insulin receptor (IR), protein kinase B/AKT content and AKT phosphorylation levels using Western blotting analysis. This same methodology was used to evaluate the phosphoenolpyruvate carboxykinase (PEPCK) levels in the liver from these animals.


RESULTS
The treatment with the extract increased the content of IR and the basal phosphorylation of AKT in the three tissues. In the liver from diabetic treated group, the insulin-stimulated AKT phosphorylation was higher and the PEPCK protein levels were reduced.


CONCLUSIONS
Data from this work suggest that the anti-hyperglycemic activity of stem-bark extract of V. macrocarpa can occur through stimulation of insulin signaling pathways in peripheral tissues from diabetic rats, mainly in liver and adipose tissue, probably promoting increase in the glucose uptake and liver glycogen synthesis. The concomitant decreasing in hepatic PEPCK levels could be associated to inhibition of gluconeogenesis, which can also contribute to glycemia reduction.
Baviloni
Paula Domingues
PD
Department of Chemistry, Federal University of Mato Grosso, Av. Fernando Correa da Costa s/n, Coxipó, 78060-900 Cuiabá, Mato Grosso, Brazil.
dos Santos
Maísa Pavani
MP
Aiko
Gustavo Mitsuo
GM
Reis
Silvia Regina de Lima
SR
Latorraca
Márcia Queiroz
MQ
da Silva
Virginia Claudia
VC
Dall'Oglio
Evandro Luiz
EL
de Sousa
Paulo Teixeira
PT
Lopes
Carbene França
CF
Baviera
Amanda Martins
AM
Kawashita
Nair Honda
NH
D000273:Adipose Tissue / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000502:physiology; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy; D007887:Fabaceae; D007004:Hypoglycemic Agents / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D007328:Insulin / Q000097:blood; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D024301:Plant Bark; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D018547:Plant Stems; D051381:Rats; D017208:Rats, Wistar
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D010936:Plant Extracts