瑞芬太尼诱发切口痛大鼠痛觉过敏时脊髓δ受体与糖原合成酶激酶-3β活性的关系

Relationship between delta opioid receptors and activity of glycogen synthase kinase-3β in spinal cord during hyperaigesia induced by remifentanil in a rat model of incisional pain

目的评价瑞芬太尼诱发切口痛大鼠痛觉过敏时脊髓δ受体与糖原合成酶激酶-3β（GSK-3B）活性的关系。方法取尾静脉置管成功的雄性SD大鼠24只，体重240—260g，2—3月龄，采用随机数字表法，将其分为3组（n=8）：对照组（C组）腹腔注射等容量生理盐水，静脉输注等速率生理盐水60min；瑞芬太尼＋切口痛组（R＋I组）腹腔注射等容量生理盐水，静脉输注瑞芬太尼1．2μg·kg^-1·min^-160min，于输注即刻制备切口痛模型；8受体拮抗剂组（N组）腹腔注射那曲吲哚0．1mg／kg，静脉输注瑞芬太尼1．2μg·kg^-1·min^-160min，于输注即刻制备切口痛模型。于静脉输注生理盐水或瑞芬太尼前24h、静脉给药后2、6、24和48h（T0-4）时测定机械缩足反应阈（MWT）和热缩足潜伏期（TWL）。最后一次痛阈测定结束后处死大鼠，取脊髓L4-6节段，采用Westernblot法测定GSK-3β及磷酸化GSK-3β（pGSK-3β）的表达水平，计算pGSK-3β／GSK-3β比值，采用RT—PCR法测定GSK-3βmRNA表达水平。结果与C组比较，R＋I组和N组T1-4时MWT降低，TWL缩短，脊髓组织GSK-3β、pGSK-3β和GSK-3pmRNA的表达上调，pGSK-3β／GSK-3β比值降低（P〈0．05）；与R＋I组比较，N组T1-4时MWT升高，TWL延长，脊髓组织GSK-3β、pGSK-3β和GSK-3βmRNA的表达下调，pGSK-3β／GSK-3β比值升高（P〈0．05）。结论瑞芬太尼诱发切口痛大鼠痛觉过敏时脊髓GSK-3β的活性增强与8受体的激活有关。

Objective To evaluate the relationship between delta opioid receptors （DORs） and activity of glycogen synthase kinase-3β （GSK-3β） in the spinal cord during hyperalgesia induced by remifentanil in a rat model of ineisional pain （ IP）. Methods Twenty-four male Sprague-Dawley rats, aged 240-260 g, weighing 2-3 months, were randomly divided into 3 groups （n = 8 each） using a random number table： control group （group C） , remifentanil＋IP group （group R＋I） and DOR antagonist nahrindole group （group N）. A 1-cm longitudinal incision was made in the plantar surface of the left hindpaw in anesthetized rats. In group C, the equal volume of normal saline was injected intraperitoneally, and normal saline was then infused for 60 min at the same rate. In group R＋I, the equal volume of normal saline was injected intraperitoneally, remifentanil was infused for 60 rain at 1.2μg· kg^-1·min^-1 , and IP was produced immediately after onset of remifentanil infusion. In group N, naltrindole 0.1 mg/kg was injected intraperitoneally, remifentanil was infused for 60min at 1.2 μg ·kg^-1·min^-1 , and IP was produced immediately after onset of remifentanil infusion. At 24 h before infusion of normal saline or remifentanil and 2, 6, 24 and 48 h after iv administration （T0-4） , the mechanical paw withdrawal threshold （MWT） and thermal paw withdrawal latency （TWL） were measured. The rats were sacrificed after the last measurement of pain threshold, the lumbar segment （ L4-6 ） of the spinal cord was removed for determination of the expression of GSK-3β, phosphor-GSK-3β （pGSK-3β） （by Western blot） and GSK-3β mRNA （real- time PCR）. The ratio of pGSK-3β/GSK-3β was calculated. Results Compared with group C, the MWT was significantly decreased, and the TWL was shortened at T1-4 , the expression of GSK-3β, pGSK-3β and GSK-3β mRNA was up-regulated, and pGSK-3β/GSK-3β ratio was decreased in R＋I and N groups. Compared with group R ＋ I, the MWT was significantly increased, and the TWL was prolonged at T1-4, the expression of GSK-3β, pGSK-3β and GSK-3β mRNA was down-regulated, and pGSK-3β/GSK-3β ratio was increased in group N. Conclusion Activation of DOR is involved in enhancement of activity of GSK-3β in the spinal cord during hyperalgesia induced by remifentanil in a rat model of IP.