Relationship between remifentanil-induced hyperalgesia and function of nitrated glutamate transpor-tor-1 and glutamine synthetase in spinal cord of rats with incisional pain / 中华麻醉学杂志

ABSTRACT

Objective To investigate the relationship remifentanil-induced hyperalgesia and func-tion of nitrated glutamate transportor-1 ( GLT-1) and glutamine synthetase ( GS) in the spinal cord of rats with incisional pain. Methods Thirty-two male Sprague-Dawley rats, weighing 260-280 g, aged 2-3 months, in which caudal catheters were successfully implanted, were divided into 4 groups (n=8 each) u-sing a random number table method: control group ( group C) , incisional pain group ( group I) , remifen-tanil group ( group R) and remifentanil plus incisional pain group ( group RI) . Normal saline was intrave-nously infused for 60 min at 0. 1 ml · kg-1 · min-1 in group C. The model of incisional pain was estab-lished, and normal saline was simultaneously infused for 60 min via the tail vein at 0. 1 ml·kg-1 ·min-1 in group I. Remifentanil was infused for 60 min via the tail vein at 1. 0 μg· kg-1 ·min-1 in group R. The model of incisional pain was established, and remifentanil was infused for 60 min via the tail vein at 1. 0μg· kg-1 ·min-1 in group RI. The mechanical paw withdrawal threshold ( MWT) and thermal paw with-drawal latency ( TWL) were measured at 24 h before infusion of remifentanil or normal saline ( T0 ) and at 2, 6, 24 and 48 h after infusion ( T1-4 ) . The rats were sacrificed after the last measuremnet of pain thresh-old, and the L4-6 segment of the spinal cord was removed for determination of the expression of GLT-1 and GS (by Western blot) and expression of nitrated GLT-1 (nGLT-1) and nitrated GS (nGS) (by Western blot) . Ratios of nGLT-1∕GLT-1 and nGS∕GS were calculated. Results Compared with group C, the MWT was significantly decreased and TWL was shortened at T1-4 , the expression of GLT-1 and GS was down-regu-lated, the expression of nGLT-1 and nGS was up-regulated, and ratios of nGLT-1∕GLT-1 and nGS∕GS were increased in I, R and RI groups ( P<0. 05) . Compared with group I and group R, the MWT was signifi-cantly decreased and TWL was shortened at T1-4 , the expression of GLT-1 and GS was down-regulated, the expression of nGLT-1 and nGS was up-regulated, and ratios of nGLT-1∕GLT-1 and nGS∕GS were increased in group RI ( P<0. 05) . Conclusion The mechanism of remifentanil-induced hyperalgesia may be related to impaired function of GLT-1 and GS in the spinal cord of rats with incisional pain.