Effect of cisplatin on analgesia with morphine in rats with incisional pain / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of cisplatin on analgesia with morphine in rats with incisional pain.Methods Forty-two adult male Sprague-Dawley rats,weighing 180-220 g,were randomly divided into 6 groups (n =7 each) using a random number tablenormal saline group (group C),normal saline + Pglycoprotein inhibitor LY335979 group (group CL),normal saline + morphine group (group CM),cisplatin group (group S),cisplatin + morphine group (group SM) and cisplatin + morphine + LY335979 group (group SML).Cisplatin 2 mg/kg was injected intraperitoneally once every two days for 5 times in S,SM and SML groups,while the equal volume of normal saline was injected intraperitoneally in C,CL and CM groups.At 2 days after the end of administration,the incisional pain models were established.At 10 min after establishing the model,normal saline 2 ml was injected subcutaneously in C and S groups; LY335979 20 mg/kg was injected via the caudal vein and normal saline 2 ml was injected subcutaneously in group CL; morphine 2 mg/kg was injected subcutaneously in CM and SM groups; LY335979 20 mg/kg was injected via the caudal vein and morphine 2 mg/kg was injected subcutaneously in group SML.Cumulative pain score was used to evaluate analgesia.Results Compared with group C,cumulative pain scores were significantly decreased in group CM,and no significant change was found in cumulative pain scores in CL and S groups.Compared with group CM,cumulative pain scores were significantly increased in group SM,and no significant change was found in cumulative pain scores in group SML.Cumulative pain scores were significantly lower in group SML than in group SM.Conclusion Cisplatin can weaken analgesia induced by morphine in rats with incisional pain through enhancing P-glycoprotein function in the blood-brain barrier.