Effect of dexmedetomidine on postoperative pain in rats with preoperative sleep deprivation / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of dexmedetomidine on postoperative pain in rats with preoperative sleep deprivation. Methods Fifty healthy adult male Sprague-Dawley rats, aged 12 - 14 weeks, weighing 200-300 g, were divided into 5 groups ( n = 10 each) using a random number tablecontrol group (group C), sleep deprivation group (group SD), incisional pain group (group IP), sleep deprivation plus incisional pain group ( group SD + IP) and sleep deprivation plus incisional pain plus dexmedetomidine group (group SD+IP+DEX). Sleep deprivation was induced by the flower pot technique, and then the incisional pain model was carried out on first day after completion of sleep deprivation. Dexme-detomidine 50 μg∕kg was intraperitoneally injected for 3 consecutive days before establishing the model of in-cisional pain in group SD+IP+DEX, and the equal volume of normal saline was given in the other groups. The mechanical paw withdrawal threshold ( MWT) and thermal paw withdrawal threshold ( TWT) were measured before operation or at 1 day before sleep deprivation and after operation or at 12, 24 and 72 h af-ter sleep deprivation. Blood samples were collected and spinal cord tissues were removed after the end of be-havior test for determination of serum corticosterone concentrations (by enzyme-linked immunosorbent assay and content of 5-hydroxytryptamine (5-HT) in spinal dorsal horns (by high-performance liquid chromatogra-phy). Results Compared with group C, the MWT and TWT were significantly decreased, and the serum corticosterone concentrations and content of 5-HT in spinal dorsal horns were increased in the other 4 groups(P<0. 05). Compared with group IP, the MWT and TWT were significantly decreased, and the serum cor-ticosterone concentrations and content of 5-HT in spinal dorsal horns were increased in group SD+IP, and the MWT and TWT were significantly increased (P<0. 05), and no significant change was found in the ser-um corticosterone concentrations or content of 5-HT in spinal dorsal horns in group SD + IP + DEX ( P >0. 05). Compared with group SD+IP, the MWT and TWT were significantly increased, and the serum cor-ticosterone concentrations and content of 5-HT in spinal dorsal horns were decreased in group SD+IP+DEX (P<0. 05). Conclusion Dexmedetomidine can reduce postoperative pain in rats with preoperative sleep deprivation, and the mechanism may be related to inhibiting stress responses and levels of 5-HT in spinal dorsal horns.