Application Research Of A Novel Septic Rat Model Design By Cecal Ligation And Puncture

Objective: The optimal animal model to mimic clinical sepsis is cecal ligation and puncture(CLP) model in rodents now. The major methods for manipulating the motility of subjected animal depends on controlling the needle size, puncture number and the length of cecum ligated, but the experimental results are difficult to reproduce in practical application. The study aimed to further control the severity of infection and motility. The CLP model based on mapping the volume of cecum was establish to contrast with the CLP design based on mapping the length of cecum reported in previous reference for exploring the feasible design to improve the stability of the model.Methods: Male Sprague-Dawley rats were rendered to establish the cecal ligation and puncture model. Tow groups were divided for ligation by mapping the length and volume of the cecum. The group mapping the length of the cecum was further divided into different subgroups according to the percentage of total cecum length that was measured from ileocecal valve to the top of cecum by silk suture(50% and 75% of full cecum length). The group mapping the volume of the cecum was further divided into different subgroups according to the various cecal volumes(0.5ml,1.0ml, 1.5ml, 2.0ml and 2.5ml). Methylene blue was used to mark the volume of cecum. Then single through-and-through cecal puncture was performed with a 21-gauge needle. Blood and peritoneal cavity secretions cultures were assessed at 6 h after cecal ligation and puncture. Then 7 days motility was observed. Results: The motility of 50% and 75% subgroup in the group mapping the length of cecum were 90% and 100%, respectively. No significant difference was obseved between two groups (n=10, p =0.661). The increase of motility followed with the increases of cecal ligation volumes in the group mapping the volume of cecum. The 7 days lethality were 40%, 50%, 60%, 80% and 100% respectively paired with the groups of 0.5ml, 1.0ml, 1.5ml, 2.0ml and 2.5ml. Significant differences were demonstrated among groups (n=10, p = 0.002) while the rats of sham group were all survival. Mean survival times about 50% and 75% subgroup in the group mapping the length of cecum were 1.621±0.605 days and 1.150±0.099 days while the group of mapping the volume of cecum ranged from 4.708±0.893 days for 0.5ml ligation to 1.175±0.240 days for 2.5ml of the cecum ligated. The blood and peritoneal cavity secretions cultures which were assessed at 6 h after cecal ligation and puncture were all positive except the group of sham.Conclusions: The procedure of operation and experimental data demonstrate that the cecal volume ligation and puncture was a CLP model design that the procedure was easier to be standardized and reproduced. It is a better model design to establish the repeatable experimental results and suit for the application for sepsis mechanisms research and evaluation of therapeutic agent.