Relationship between inflammatory responses induced by perioperative infection and surgical stress and postoperative cognitive dysfunction in mice / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the relationship between inflammatory responses induced by perioperative infection and surgical stress and postoperative cognitive dysfunction in mice. Methods One hundred forty?four healthy male C57BL∕6 mice, aged 8-12 weeks, weighing 20-25 g, were divided into 4 groups ( n=36 each) using a random number table control group ( group C) , surgery group ( group S) , infection group ( group I) , and infection+surgery group ( group I+S) . In group S, the open reduction and internal fixation was performed after tibial fracture was induced. Lipopolysaccharide ( LPS) 100 μg∕kg was injected intraperitoneally at the same time every day for 5 consecutive days starting from 1 day before surgery in group I. In group I+S, LPS 100 μg∕kg was injected intraperitoneally at the same time every day for 5 consecutive days starting from 1 day before surgery, and the open reduction and internal fixation was per?formed after tibial fracture was induced at 2 h after LPS injection on the day of surgery. Contextual fear con?ditioning test was performed on 1 and 3 days after surgery, and cognitive function was assessed. The rate of freezing time was calculated. The peripheral venous blood samples were collected for determination of plas?ma interleukin?6 ( IL?6) and IL?1β concentrations by enzyme?linked immunosorbent assay. The animals were then sacrificed, and the hippocampi were isolated for determination of IL?6, IL?1β and prostaglandin E2 ( PGE2 ) contents in hippocampal tissues by enzyme?linked immunosorbent assay. Results Compared with group C, the rate of freezing time was significantly decreased on 1 and 3 days after surgery, and the contents of IL?6, IL?1βand PGE2 in hippocampal tissues were significantly increased on 1 and 3 days after surgery in S and I+S groups, the concentrations of plasma IL?6 and IL?1βwere significantly increased on 1 day after surgery, and the concentration of plasma IL?1βwas significantly increased on 3 days after surgery in group S, the concentrations of plasma IL?6 and IL?1β were significantly increased on 1 and 3 days after surgery in I and I+S groups ( P0?05) . Compared with group S or group I, the rate of freezing time was significantly decreased on 1 and 3 days after surgery, and the concentrations of IL?6 and IL?1βin plasma and contents of IL?6, IL?1β and PGE2 in hippocampal tissues were significantly increased on 1 and 3 days after surgery in group I+S ( P<0?01) . Conclusion Inflammatory responses induced by periopera?tive infection and surgical stress can aggravate postoperative cognitive dysfunction in mice.