Objective  To investigate the protective effect and mechanism of serum containing Euonymus fortunei on the rat pancreatic islet cells.

  Methods  Forty male SD rats were randomly divided into 5 groups (n=8 in each group), including the control group (normal rat islet cells were cultured with normal rat serum), ischemic preconditioning group (abdominal aorta was blocked first and then re-opened before the pancreas was obtained, and the pancreatic islet cells were cultured with normal rat serum), Euonymus fortunei treatment group (normal rat islet cells were cultured with rat serum containing Euonymus fortunei), Euonymus fortunei group and blank group (normal rats were administered orally with Euonymus fortunei extract or distilled water for the preparation of rat serum). Diphenylthiocarbazone (DTZ) staining was utilized to observe and calculate the quantity of islets. Acridine orange (AO)/propidium iodide (PI) staining was adopted to calculate the survival rate of islet cells. The insulin release experiment was performed to calculate the stimulation index (SI) and evaluate islet cell function. The concentration of glutathione (GSH) and nitric oxide (NO) in islet cells was detected using GSH and NO kits. The expression level of inducible nitric oxide synthase (iNOS) messenger RNA (mRNA) was quantitatively measured by reverse transcription polymerase chain reaction (RT-PCR).

  Results  Islet cells were observed in specifically scarlet color after DTZ staining. The quantity of islet cells did not significantly differ among different groups (all P > 0.05). Along with the prolongation of culture time, the activity of islet cells in each group was gradually decreased. At 72 h after isolation and culture, compared with the control group, the survival rate of the cells was significantly higher in the Euonymus fortunei treatment group (P < 0.05). The insulin release test results demonstrated that compared with the control group, the SI of the ischemic preconditioning and Euonymus fortunei treatment groups was significantly increased (both P < 0.05). Compared with the control group, the GSH contents of pancreatic islet cells in the ischemic preconditioning and Euonymus fortunei treatment groups were considerably enhanced, the NO content was significantly decreased, and the expression level of iNOS mRNA was significantly down-regulated (all P < 0.05).

  Conclusions  Euonymus fortunei can increase the survival rate of islet cells and enhance the function of pancreatic islets by increasing the level of GSH, down-regulating the expression of iNOS and decreasing the NO production.