The study was to examine the effects of Sanguis draconis ethanol extract (SDEE) on streptozotocin (STZ)- and cytokine-induced β-cell damage. In vitro, SDEE did not cause cytotoxicity below 200 μg/ml, and can prevent STZ (5. mM)-induced cell death and apoptosis below 100 μg/ml on RIN-m5F cells. SDEE inhibits IL-1β/IFN-γ-stimulated NO, TNF-α release, and iNOS expression. Furthermore, SDEE suppressed the IL-1β/IFN-γ- or STZ-induced p65 expression of NF-κB, which is associated with inhibition of IκB-α degradation. In vivo, treatment of ICR mice with STZ (100. mg/kg, i.p. single injection) resulted in hyperglycemia and hypoinsulinemia, which was further evidenced by blood glucose and plasma insulin. The diabetogenic effects of STZ were completely prevented when mice were orally administered with SDEE for 3 weeks, however, the blood glucose and plasma insulin showed no significant change after SDEE administration alone. In addition, SDEE also can inhibit STZ-induced iNOS protein expression, pancreatic injury and lipid peroxidation. In conclusions, the molecular mechanism by which SDEE inhibits iNOS gene expression appears to involve the inhibition of NF-κB activation. These results suggest the possible therapeutic value of S. draconis and could be potentially developed into a novel drug for preventing the progression of diabetes mellitus.
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