Abstract: ［Abstract］〓Objective〖HTSS〗〓To observe the protective effect of ulinastatin on the postoperative cognitive dysfunction(POCD) impairment and to explore its specific mechanism of action in the pathogenesis of disease.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓Wistar rats were randomly divided into control group, POCD group, ulinastatin group, preoperative 5 days of space acquired experimental study. The control group was injected with normal saline; the POCD group was injected with normal saline after splenectomy under general anesthesia; and the ulinastatin group was injected with ulinastatin before and after the preparation of POCD model. The behavioral changes of rats in each group were evaluated 3 and 7 days after operation. The contents of malondialdehyde(MDA), superoxide dismutase(SOD), tumor necrosis factorα(TNFα), interleukin1β(IL1β) and nuclear factorκB(NFκB) in hippocampus and prefrontal cortex were measured.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓Three days after operation, the rats in POCD group had longer residence time, fewer times to cross the platform, longer working memory latency,  higher MDA content and lower SOD content than those in the control group. The levels of TNFa, IL1β and NFκB in POCD group were higher than those in the control group（P＜0.05）. The retention time of rats in ulinastatin group was shorter than that in control group and longer than that in POCD group. The rats in ulinastatin group had more times of perforation, longer working memory latency, shorter working memory latency than POCD group. The rats in ulinastatin group had higher MDA content than control group, lower SOD content than control group, higher SOD content than POCD group. The rats in ulinastatin group had higher TNFa, IL1β and NFκB levels than control group, had lower those than POCD group(P＜005). At 7 days after surgery, the residence time of the control group and the ulinastatin group was shorter than that at the 3 days after surgery, and the working memory latency was longer than that at the 3 days after surgery. At 7 days after surgery, the MDA content in the control group and ulinastatin group was higher than that in the 3 days after surgery，the MDA content in the POCD group was lower than that at the 3 days after surgery. At 7 days after surgery, the SOD content of the control group was lower than that at the 3 days after surgery， the MDA content in the ulinastatin group of the POCD group was higher than that of the postoperative 3 days. At 7 days after surgery, the levels of TNFα in the POCD group and ulinastatin group were lower than those at 3 days after surgery，the levels of IL1β and NFκB in the three groups were lower than those in the 3 days after surgery(P＜005).The residence time of the rats in the POCD group was shorter than that of the control group, and the latency of working memory was longer than that of the control group. The residence time of the rats in the ulinastatin group was shorter than that of the control group and longer than that of the POCD group. The working memory latency was longer than that of the control group and shorter than the POCD group. The MDA content in the POCD group was higher than that in the control group, and the SOD content was lower than that in the control group. The MDA content in the ulinastatin group was higher than that in the control group, and the SOD content was lower than that in the control group, which was higher than the POCD group. The levels of TNFα, IL1β and NFκB in the POCD group were higher than those in the control group. The level of IL1β in the ulinastatin group was lower than that in the POCD group(P＜005).
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓Ulinastatin has a positive effect on improving postoperative cognitive dysfunction by scavenging oxygen free radicals and inhibiting inflammatory responses.

Key words: cognition disorders； ulinastatin, postoperative complications； rats