Cinnamon extracts exert intrapancreatic cytoprotection against streptozotocin in vivo

In the current study, we aimed to investigate the potential hypoglycemic bioactivity of cinnamon extracts (CES) on streptozotocin (STZ)-induced hyperglycemia in mice. In biological methods, glucose metabolic ability of all mice was evaluated by glucose tolerance testing (GTT). Blood levels of pancreas-produced insulin, glucagon, inflammation-associated interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) were determined via enzyme linked immunosorbent assay (ELISA). In gene level, intrapancreatic mRNA expressions of insulin, TNF-alpha and nuclear-factor kappa B (NF-kappa B) were assayed by reverse transcription polymerase chain reaction (RT-PCR). Meanwhile, intracellular insulin-immunoactive cells in the pancreas were analyzed by using immunohistochemical staining. In addition, the protein levels of intrapancreatic NF-kappa B, I kappa B (p-I kappa B) and IKK were tested by western blotting. As a result, CES-treated mice showed increased body weight, blood glucose and insulin, reduced IL-6 and TNF-alpha contents in sera. Further, the TNF-alpha and NF-kappa B mRNA expressions in the CES-treated pancreas were down-regulated at a dose-dependent manner, while insulin mRNA was elevated. Moreover, the reduced intrapancreatic NF-kappa B, I kappa B (p-I kappa B) and IKK expression were observed in CES-treated pancreas, respectively. Taken together, our current findings indicate that CES-mediated intrapancreatic cytoprotection is linked to the molecular mechanism that may be through inhibiting inflammatory stress and promoting insulin secretion in the pancreas.