Sasa borealis extract exerts an antidiabetic effect via activation of the AMP-activated protein kinase

Leaf of Sasa borealis, a species of bamboo, has been reported to exhibit anti-hyperglycemic effect. However, its antidiabetic mechanism is not fully understood. In this study, we examined whether an extract of S. borealis activates AMP-activated protein kinase (AMPK) and exerts anti-hyperglycemic effects. Treatment with the S. borealis extract increased insulin signaling and phosphorylation of AMPK and stimulated the expression of its downstream targets, including PPARalpha, ACO, and CPT-1 in C2C12 cells and PPARalpha in HepG2 cells. However, inhibition of AMPK activation attenuated insulin signaling and prevented the stimulation of AMPK target genes. The S. borealis extract increased glucose uptake in C2C12 cells and suppressed expression of the gluconeogenic gene, PEPCK in HepG2 cells. The extract significantly reduced blood glucose and triglyceride levels in STZ-induced diabetic mice. The extract enhanced AMPK phosphorylation and increased Glut-4 expression in the skeletal muscle of the mice. These findings demonstrated that the S. borealis extract exerts its anti-hyperglycemic effect through activation of AMPK and enhancement of insulin signaling.

The Effects of Glucocorticoid and alpha-Lipoic Acid on Ischemia-Reperfusion Injury

During revascularization after ischemia, oxygen free radicals and cytotoxic enzymes are released and they have a role in pathogenesis of ischemia-reperfusion injury. Glucocorticoid decreases oxygen free radical formation by inhibition of arachidonic acid metabolism, and alpha-lipoic acid scavenges nitric oxide(NO) with inhibition of hydroxy radical formation. Author investigated the role of glucocorticoid and alpha-lipoic acid to decrease ischemia reperfusion injury in 24 anesthetized rats (normal saline-injected, n= 8; dexamethasone-injected, n=8; alpha-lipoic acid-injected, n= 8), subjecting a soleus muscle to 4 hours of tourniquet ischemia followed by 2 hours of reperfusion, and evaluated the concentration of NO, tissue edema, and neutrophil count of rat skeletal muscle as a indicator of tissue damage by ischemia- reperfusion injury. We obtained the results that glucocorticoid and alpha-lipoic acid treatment decreased the increase of NO concentration, tissue edema, and neutrophil count significantly. These results support that pretreatment with glucocorticoid or alpha-lipoic acid has a beneficial effect on the preventive management of ischemia-reperfusion injury.