P2X4受体在瑞芬太尼诱发大鼠术后痛觉过敏中的作用

目的：探究P2X4受体在阿片类药物诱导的痛觉过敏中的作用。方法：成年雄性Sprague-Dawley(SD)大鼠随机分为尾静脉泵注生理盐水组(N0组)、瑞芬太尼0.5 μg/(kg.min)组(R1组)、瑞芬太尼1.0 μg/(kg.min)组(R2组)、瑞芬太尼1.5 μg/(kg.min)组(R3组)、瑞芬太尼5.0 μg/(kg.min)组(R4组)。于处理前1 d(T1)，尾静脉置管后30 min(T2)，停药后30 min(T3)，1 h(T4)，2 h(T5)，24 h(T6)测量大鼠机械缩足阈值(paw withdrawal mechanical threshold，PWMT)和热缩足潜伏期(paw withdrawal thermal latency，PWTL)，获得诱导痛觉过敏最佳的瑞芬太尼输注速度；随后取成年雄性SD大鼠，分为尾静脉置管后泵入生理盐水组(N组)、尾静脉置管后泵入瑞芬太尼1.0 μg/(kg.min)组(R组)。于上述处理时间点T1，T2，T4测量大鼠PWMT和PWTL，并于停药后1 h选取大鼠脊髓腰膨大检测P2X4受体的mRNA和蛋白表达。另取成年雄性SD大鼠，并将其分为切口痛模型并尾静脉置管后泵入生理盐水组(I+N组)和切口痛模型并尾静脉置管后泵入瑞芬太尼1.0 μg/(kg.min)组(I+R组)。于上述处理时间点T1，T2，T3，T4，T5，T6以及8 h(T7)和72 h(T8)测量大鼠PWMT和PWTL，于停药后1 h取大鼠脊髓腰膨大组织检测P2X4受体的mRNA和蛋白表达，免疫荧光检测小胶质细胞激活的状态。结果：T3和T5时间点PWMT和PWTL的趋势均为R4组0.05)。与I+N组相比，I+R组大鼠在T4，T5，T6时间点的PWMT和PWTL明显降低，差异均有统计学意义(均P<0.05)，同时I+R组大鼠脊髓P2X4受体mRNA和蛋白表达水平均明显上调，差异均有统计学意义(均P<0.05)。此外，I+R组大鼠脊髓背角的小胶质细胞的活化较I+N组明显增强。结论：静脉注射瑞芬太尼可致大鼠痛觉过敏，单纯静脉注射瑞芬太尼导致的痛觉过敏可能与P2X4受体无关；瑞芬太尼可导致切口痛大鼠出现更明显的痛觉过敏，其中小胶质细胞活化及P2X4受体可能参与瑞芬太尼诱发术后痛觉过敏的形成机制。

Role of spinal P2X4 receptor in remifentanil-induced postoperative hyperalgesia

Objective: To explore the role of P2X4 receptor in opioid-induced hyperalgesia (OIH).Methods: A total of 30 Sprague-Dawley (SD) male rats were randomly divided into 5 groups: asaline (N0) group, a remifentanil at 0.5 μg/(kg.min) (R1) group, a remifentanil at 1.0 μg/(kg.min)(R2) group, a remifentanil at 1.5 μg/(kg.min) (R3) group, and a remifentanil at 5.0 μg/(kg.min)(R4) group. The paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermallatency (PWTL) were measured at follow time points to optimize the dosages: the day beforetreatment (T1), 30 min after tail intravenous catheterization (T2), and 30 min (T3), 1 h (T4), 2h (T5), 24 h (T6) after withdrawal from remifentanil. Then, the rats were randomly divided into 2groups: a saline group (N group), a remifentanil at 1.0 μg/(kg.min) group (R group). The PWMTand PWTL were measured at follow time points: T1, T2, and T4. The lumbar enlargement of spinewas selected at 1 h after withdrawal from remifentanil, and the expression of P2X4 receptor mRNAand protein was examined in OIH. Additional male rats were selected and randomly divided into2 groups: a plantar incision surgery followed by saline treatment group (I+N group), a plantarincision surgery followed by remifentanil treatment group (I+R group). The PWMT and PWTLwere measured at follow time points: T1, T2, T3, T4, T5, T6, 48 h (T7) and 72 h (T8) afterwithdrawal from remifentanil. The lumbar enlargement of spine was selected at 1 h after withdrawalfrom remifentanil, the expression of P2X4 receptor mRNA and protein was examined by PCR andWestern blotting, and the microglial activation in spine 1 h after withdrawal from remifentanil wereassessed by immunofluorescence.Results: The pain thresholds including PWMT and PWTL in different groups were as follows: R4group