[Animal Modeling]-Long-term survival rat model of moderate to severe sepsis

  Objective: To establish a rat model of long-term survival of moderate to severe sepsis, observe the natural development of sepsis, and provide new ideas and methods for the study of sepsis.

   Method: 40 SD rats were divided into control group (sham group, 8) and cecal puncture group (brain ligation and puncture, CLP group, 32). All operations were performed under small animal anesthesia and sevoflurane inhalation. It is done under anesthesia. All rats have established arteriovenous access to the right neck. After recovery 24 hours after the operation, rats in the CLP group suffered from sepsis due to cecal ligation and perforation. After the operation, the rats were moved to the recovery room (room temperature 22-25°C) and kept in a cage. After the operation, intravenously hydrated 6% HEAS and 5% glucose at a ratio of 1:1 on the 1st and 2nd day, the hydration amount was 20 mL/kg/12h, and then hydrated until the rats started to eat. According to the survival rate of the rats, the rats in the CLP group are naturally divided into a survival group (survival group) and a death group (death group). Observe the rats 30 days after the operation, record symptoms, weight changes, IL-10 plasma concentration changes, and analyze changes in abdominal organs.

  Result: (1) In the CLP group, the survival rate was 75% within 24 hours, 62.5% within 72 hours, and 50% within 7 days. (2) According to the sepsis severity evaluation system, 32 rats in the CLP group reached moderate to severe sepsis 24 hours after surgery. (3) After the operation, the weight of the surviving group and the sham group decreased. The number of rats in the survival group decreased significantly from day 4 (P = 0.017). The surviving group had the lowest body weight 6 days after the operation, which was (8.51±2.23)% lower than the original body weight. The weight of the sham group was the lowest 4 days after operation, which was (2.73±1.82)% lower than the original weight. The difference between the groups was statistically significant (P = 0.026). At 30 days after surgery, the maximum weight gain rate between the two groups (sham group (16.16±2.39)% and survival group (13.03±3.74)%) was not significantly different between the two groups (P = 0.29). (4) Compared with the preoperative (0d), the plasma concentration of IL-10 in the three groups was increased, and the surviving group (P = 0.000) and the death group were significantly higher (P = 0.010). (5) For anatomy of the abdomen, please refer to the following: the death group had a lot of unpleasant bloody ascites, the ligated intestines were purple and black, there were no wraps, and no adhesions. In the surviving group, the abdominal cavity was widely adhered, the large uterus lost its original shape and luster, and tended to ligate the intestines, but did not enclose the abscess. The sham group had no abnormal anatomy. The rat spleen accounted for (2.64±0.37)‰ of body weight, and the ratio of spleen to body weight of rats in the sham group was (1.63±0.20)‰. The difference between the two was statistically significant (P = 0.032).

   Conclusion: This experiment establishes a CLP model for long-term survivors of moderate to severe sepsis, provides a reliable means for controlling CLP, and provides a method to screen the model, which is basically sepsis and abides by the law of development.