右美托咪定对痛觉过敏大鼠脊髓PKCγ、CaMKⅡα及pCaMKⅡα表达的影响

Influence of dexmedetomidine on expressions of PKCγ, Ca MKⅡα and p Ca MKⅡα in spinal cord in rats with hyperalgesia

目的探讨右美托咪定对切口痛-瑞芬太尼痛觉过敏大鼠脊髓蛋白激酶C（PKC）γ、钙/钙调素依赖性蛋白激酶（CaMK）Ⅱα及pCaMKⅡα表达的影响.方法雄性SD 大鼠40 只,体质量240-260 g,2-3 月龄,随机数字表法分为5 组（n=8）：空白对照组（C 组）、瑞芬太尼＋切口痛组（R＋I 组）、右美托咪定＋瑞芬太尼＋切口痛组（D＋R＋I 组）、右美托咪定＋瑞芬太尼＋切口痛＋佛波醇酯＋二甲基亚砜组（D＋R＋I＋P＋DMSO 组）、右美托咪定＋瑞芬太尼＋切口痛＋二甲基亚砜组（D＋R＋I＋DMSO 组）.采用足底切口的方法制备切口痛模型.瑞芬太尼以1.2 μg·kg^-1·min^-1 的速度经尾静脉输注90 min;右美托咪定以50 μg/kg 的剂量于术前30 min 皮下注射;佛波醇酯及二甲基亚砜均为鞘内注射10μL.分别于输注前24 h（T0）、输注后2、6、24 和48 h（T1-4）时测定热刺激缩足潜伏期（PWL）和机械刺激缩足阈值（PWT）.最后1 次行为学测试后处死大鼠,取脊髓L4-6 节段.采用Western blot 法测定脊髓背角PKCγ、CaMKⅡα及pCaMKⅡα的表达.结果除T0 外,与C 组比较,其余各组PWL 缩短、PWT 降低,PKCγ、CaMKⅡα及pCaMKⅡα表达上调.与R＋I 组比较,D＋R＋I 组、D＋R＋I＋DMSO 组PWL 延长、PWT 升高,PKCγ、CaMKⅡα及pCaMKⅡα表达下调.与D＋R＋I 组比较,D＋R＋I＋P＋DMSO 组PWL 缩短、PWT 降低,PKCγ、CaMKⅡα及pCaMKⅡα表达上调.与D＋R＋I＋P＋DMSO 组比较,D＋R＋I＋DMSO 组PWL 延长、PWT 升高,PKCγ、CaMKⅡα及pCaMKⅡα表达下调.结论右美托咪定可以减少切口痛-瑞芬太尼痛觉过敏大鼠脊髓PKCγ、CaMKⅡα及pCaMKⅡα的表达.

Objective To investigate the influence of dexmedetomidine on expressions of protein kinase c (PKC)γ, cal?cium/calmodulin-dependent protein kinase (CaMK)Ⅱαand pCaMKⅡαin spinal cord in rats with incisional pain (IP) and remifentanil-induced hyperalgesia. Methods Forty male Sprague-Dawley rats, aged 2-3 months, weighing 240-260 g, were randomly divided into 5 groups (n=8 each):blank control group (group C), remifentanil+incisional pain group (group R+I), dexmedetomidine + remifentanil + incisional pain group (group D+R+I), dexmedetomidine + remifentanil + incisional pain+phorbol myristate acetate+DMSO group (group D+R+I+P+DMSO) and dexmedetomidine+remifentanil+incisional pain+DMSO group (group D+R+I+DMSO). The incisional pain rat model was established by a plantar incision in left hind paw. Remifentanil was infused at a rate of 1.2μg·kg-1·min-1 for 90 min via the caudal vein. Dexmedetomidine was adminis?tered subcutaneously at a dose of 50μg/kg at 30 min before plantar incision. Phorbol myristate acetate and DMSO were intra?thecally injected at a dose of 10 μL. Paw withdrawal latency (PWL) to thermal stimulation and paw withdrawal threshold (PWT) to von Frey hair stimulation were measured 24 h before remifentanil infusion (T0) and at 2, 6, 24 and 48 h (T1-4) after intraveonus remifentanil injection. The rats were sacrificed after the last behavioral test and the L 4-6 segment of spinal cord was removed to determine the expressions of PKCγ, CaMKⅡαand pCaMKⅡαin spinal cord by Western blot analysis. Re? sults Compared with group C, the value of PWL was significantly shortened and PWT was significantly decreased except T0, and the expressions of PKCγ, CaMKⅡαand pCaMKⅡαwere up-regulated in other groups. Compared with group R+I, the value of PWL was significantly prolonged and PWT was significantly increased, the expressions of PKCγ, CaMKⅡαand pCaMKⅡαwere down-regulated in group D+R+I and group D+R+I+DMSO. Compared with group D+R+I, the value of PWL was significantly shortened and PWT was significantly decreased, the expressions of PKCγ, CaMKⅡαand pCaMKⅡαwere up-regulated in group D+R+I+P+DMSO. Compared with group D+R+I+P+DMSO, the value of PWL was significantly prolonged and PWT was significantly increased, the expressions of PKCγ, CaMKⅡαand pCaMKⅡαwere down-regulated in group D+R+I+DMSO. Conclusion Dexmedetomidine can reduce the expressions of PKCγ, CaMKⅡαand pCaMKⅡαin spinal cord in rats with IP and hyperalgesia induced by remifentanil.