Effects of propofol on hippocampal GABAA and NMDA receptor expression in a rat model of inflammatory pain / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of propofol on the expression of hippocampal γ-aminobutyric acid (GABAA) and NMDA receptor in a rat model of inflammatory pain (IP).Methods A total of 32 female Sprague-Dawley rats,weighing 180-220 g,were randomly divided into 4 groups (n =8 each)control group (group C),group IP,and different doses of propofol groups (P1,2 groups).IP was induced by injection of formalin.In group C,normal saline and dimethyl sulfoxide (DMSO) 0.1 ml/kg were injected intraperitoneally.In group IP,normal saline and DMSO 0.1 ml/kg were injected intraperitoneally,and 5 min later formalin was injected.In P1,2 groups,propofol 30 and 100 mg/kg were intraperitoneally injected,respectively,and 5 min later formalin was injected.The pain behavior of rats was observed within 1 h after injection of formalin and pain intensity scoring (PIS) value was calculated.The animals were sacrificed at 1 h after injection of formalin and the hippocampi were isolated for determination of GABAA and NMDA receptor expression by immunohistochemisty.Results Compared with group C,PIS value was significantly increased,GABAA and NMDA receptor expression was up-regulated in IP and P1.2 groups.Compared with group IP,PIS value was significantly decreased,GABAA receptor expression was up-regulated,and NMDA receptor expression was down-regulated in P1,2 groups.PIS value was significantly lower,GABAA receptor expression was higher,and NMDA receptor expression was lower in group P2 than in group P1.Conclusion Intraperitoneal propofol can down-regulate NMDA receptor expression in hippocampi of rats with IP,thus inhibiting responses to pain sensitivity; intraperitoneal propofol can up-regulate hippocampal GABAA receptor expression,thus enhancing endogenous mechanism of analgesia.