Changes in CaMK Ⅱ α expression in spinal cord and dorsal root ganglia during remifentanil-induced hyperalgesia in a rat model of incisional pain / 中华麻醉学杂志

ABSTRACT

Objective To investigate the changes in the expression of Ca2+/calmodulin-dependent protein kinase Ⅱ α (CaMK Ⅱ α) in the spinal cord and dorsal root ganglia (DRG) during remifentanil-induced hyperalgesia in a rat model of incisional pain (IP).Methods Thirty-two male Sprague-Dawley rats in which caudal vein catheter was successfully placed,aged 260-280 g,were divided into 4 groups (n=8 each) using a random number table method:control group (group C),IP group,remifentanil group (group R) and remifentanil plus IP group (group RIP).Normal saline was infused via the caudal vein for 60 min at a rate of 0.1 ml · kg-1 · min-1 in group C.Normal saline was infused via the caudal vein for 60 min at a rate of 0.1 ml · kg-1 · min-1,and the model of IP was simultaneously established in group IP.Remifentanil was infused via the caudal vein for 60 min at a rate of 1.0 μg · kg-1 · min-1 in group R.Remifentanil was infused via the caudal vein for 60 min at a rate of 1.0 μg · kg-1 · min-1,and the model of IP was simultaneously established in group RIP.Mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 24 h before infusion and 2,6,24 and 48 h after infusion (T0-4).The rats were sacrificed after the last behavioral test,and L4-6 segment of the spinal cord and DRGs were removed for determination of the expression of total and phosphorylated CaMK Ⅱ α (tCaMK Ⅱ α,pCaMK Ⅱ α) by Western blot.The ratio of pCaMK Ⅱ /tCaMK Ⅱ α was calculated.Results Compared with group C,MWT was significantly decreased,TWL was shortened,the expression of tCaMK Ⅱ α and pCaMK Ⅱ α in the spinal cord and DRGs was up-regulated,and the ratio of pCaMK Ⅱ α/tCaMK Ⅱ α was increased in I,R and RIP groups (P＜0.05 or 0.01).Compared with group IP and group R,MWT was significantly decreased,TWL was shortened,the expression of tCaMK Ⅱ α and pCaMK Ⅱ α in the spinal cord and DRGs was up-regulated,and the ratio of pCaMK Ⅱ α/tCaMK Ⅱ α was increased in group RIP (P＜0.05 or 0.01).Conclusion The mechanism by which remifentanil induces hyperalgesia may be related to upregulated expression of CaMK Ⅱ α in the spinal cord and DRGs in a rat model of IP.