摘要目的:评价膝关节炎慢性痛老龄大鼠术后神经认知障碍时海马受体相互作用蛋白激酶1(RIPK1)与NOD样受体热蛋白结构域相关蛋白3(NLRP3)炎症小体的关系。方法:健康雄性SD大鼠64只，18月龄，体质量500～550 g，采用随机数字表法分为4组( n＝16)：膝关节炎慢性痛组(P组)、膝关节炎慢性痛＋手术组(PS组)、RIPK1抑制剂Necrostatin-1 ＋膝关节炎慢性痛＋手术组(NPS组)和二甲基亚砜(DMSO)＋膝关节炎慢性痛＋手术组(DPS组)。采用左膝关节腔内注射碘乙酸盐(MIA)1 mg的方法制备膝关节炎模型并于12周后行七氟烷麻醉下剖腹探查术。NPS组和DPS组分别于术前1 h腹腔注射Necrostatin-1 6.25 mg/kg或等剂量DMSO。于关节腔内注射MIA前1周、注射后6和12周时测定热痛阈。于术后7 d时，采用Morris水迷宫实验评估认知功能；取海马组织，HE染色后光镜下观察病理学结果，采用Western blot法测定RIPK1、磷酸化RIPK1(p-RIPK1)、NLRP3、活化的半胱氨酸天冬氨酸蛋白酶1(cl-caspase-1)、凋亡相关斑点样蛋白(ASC)的表达，采用ELISA法测定IL-1β和IL-18的含量。 结果:4组大鼠MIA注射后6和12周时热痛阈较注射前降低( P<0.05)，4组大鼠各时点热痛阈比较差异无统计学意义( P>0.05)。与P组比较，PS组、DPS组和NPS组逃避潜伏期延长，原平台象限停留时间缩短，穿越原平台位置次数减少，海马组织RIPK1、p-RIPK1、NLRP3、cl-caspase-1和ASC表达上调，IL-1β和IL-18含量升高( P<0.05)，海马神经元发生明显病理损伤；与PS组和DPS组比较，NPS组逃避潜伏期缩短，原平台象限停留时间延长，穿越原平台位置次数增加，海马组织RIPK1、p-RIPK1、NLRP3、cl-caspase-1和ASC表达下调，IL-1β和IL-18含量降低( P<0.05)，海马神经元病理损伤减轻。 结论:膝关节炎慢性痛老龄大鼠术后海马RIPK1功能增强，进而激活NLRP3炎症小体，诱发神经炎症，可能参与术后神经认知障碍的发生机制。

abstractsObjective:To evaluate the relationship between hippocampal receptor-interacting protein kinase-1 (RIPK1) and nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasomes in postoperative neurocognitive dysfunction of aged rats with chronic knee arthritis pain.Methods:Sixty-four healthy male Sprague-Dawley rats, aged 18 months, weighing 500-550 g, were divided into 4 groups ( n=16 each) using a random number table method: chronic knee arthritis pain group (group P), chronic knee arthritis pain+ operation group (group PS), RIPK1 inhibitor necrostatin-1+ chronic knee arthritis pain+ operation group (group NPS), and DMSO+ chronic knee arthritis pain+ operation group (group DPS). The knee arthritis model was prepared by intra-articular injection of monosodium iodoacetate (MIA) 1 mg into the left knee joint, and 12 weeks later exploratory laparotomy was performed under sevoflurane anesthesia. Necrostatin-1 6.25 mg/kg and the equal volume of DMSO were intraperitoneally injected at 1 h before operation in NPS group and DPS group, respectively. Thermal pain threshold was measured at 1 week before MIA injection and 6 and 12 weeks after MIA injection. Morris water maze test was used to evaluate the cognitive function at 7 days after surgery. Hippocampal tissues were obtained for microscopic examination of the pathological changes (after HE staining) and for determination of the expression of RIPK1, phosphorylated RIPK1 (p-RIPK1), NLRP3, activated cysteine-aspartic protease caspase-1 (cl-caspase-1), apoptosis-associated speck-like protein containing a CARD (ASC) (by Western blot) and contents of interleukin-1beta (IL-1β) and IL-18 (by enzyme-linked immunosorbent assay). Results:Thermal pain threshold was significantly decreased at 6 and 12 weeks after MIA injection as compared with that before injection ( P<0.05), and there was no significant difference in thermal pain threshold among the four groups ( P>0.05). Compared with P group, the escape latency was significantly prolonged, the time of staying at the original platform quadrant was shortened, the number of crossing the original platform was reduced, the expression of RIPK1, p-RIPK1, NLRP3, cl-caspase-1 and ASC was up-regulated, and the contents of IL-1β and IL-18 were increased ( P<0.05), and pathological changes of hippocampal neurons were marked in PS group, DPS group and NPS group. Compared with PS group and DPS group, the escape latency was significantly shortened, the time of staying at the original platform quadrant was prolonged, the number of crossing the original platform was increased, the expression of RIPK1, p-RIPK1, NLRP3, cl-caspase-1 and ASC was down-regulated, the contents of IL-1β and IL-18 were decreased ( P<0.05), and pathological changes of hippocampal neurons were significantly attenuated in NPS group. Conclusions:Postoperative hippocampal RIPK1 function is enhanced in aged rats with chronic knee arthritis pain, which then activates NLRP3 inflammasomes, triggering neuroinflammation, and this process may be involved in the mechanism of postoperative neurocognitive dysfunction.