N-甲基-D-天冬氨酸受体在大鼠术后疲劳综合征的中枢发生机制研究

Relationship between NMDA receptor and postoperative fatigue syndrome and its associated central mechanism

目的：探讨N-甲基-D-天冬氨酸（NMDA）受体在大鼠术后疲劳综合征（POFS）的中枢发生机制。方法将96只SD大鼠按体质量大小编号，完全随机分为对照组（开腹后仅翻动肠袢、腹腔注射1 ml／kg 0．9％氯化钠溶液1次）、POFS模型组（70％中段小肠切除、腹腔注射1 ml／kg 0．9％氯化钠溶液1次）和NMDA受体拮抗剂组（70％中段小肠切除、腹腔注射1 mg／kg MK801溶液），每组再按术后1、3、5及7 d 分为4小组，每小组8只。每小组大鼠在术后对应时间点进行旷场试验后对海马组织进行取材，实时荧光定量聚合酶链反应检测大鼠海马NMDA受体1及犬尿氨酸氨基转移酶Ⅲ（KATⅢ）的mRNA表达；Western blot检测NMDA受体1的蛋白表达；高效液相-荧光法检测色氨酸（TRP）、犬尿氨酸（KYN）及犬尿喹啉酸（KYNA）的浓度；电镜观察海马神经元超微结构变化。结果术后1 d和3 d，与对照组比较，模型组大鼠运动得分减少（P＜0．05），休息时间、中央格子停留时间及外周／中央格子比均增加（P＜0．05）；NMDA受体1 mRNA及蛋白表达增加（P＜0．05）， KATⅢ mRNA表达减少（P＜0．05）；KYN／TRP及KYN／KYNA比值增加（P＜0．05）；拮抗剂组与模型组比较，术后1 d大鼠中央格子停留时间以及外周／中央格子比均降低（P＜0．05）；术后1 d和3 d NMDA受体1mRNA及蛋白表达降低（均为P＜0．05）。电镜结果显示，模型组海马神经元超微结构受损，拮抗剂组得到相应改善。结论 POFS大鼠海马NMDA受体表达增加，神经元存在一定程度的损伤，NMDA受体拮抗剂能改善POFS的中枢疲劳。

Objective To explore the central mechanism of postoperative fatigue syndrome by detecting the expression of NMDA receptor and tryptophan metabolism. Methods After being numbered according to the weight, ninety-six male SD rats were randomly divided into control group （bowel loop was flipped after laparotomy and received intraperitoneal injection of saline at a dose of 1 ml/kg ）, POFS model （70% of the length of small intestine was resected and received intraperitoneal injection of saline at a dose of 1 ml/kg）, and NMDA antagonist groups （70% of the length of small intestine was resected and received intraperitoneal injection of MK801 at a dose of 1 ml/kg ）. Each group was divided into subgroups by postoperative 1, 3, 5 and 7 d, with 8 rats in each subgroup. The hippocampus was removed at each time point after open field test （OFT） to detect the mRNA expression levels of NMDA receptor 1 and kynurenine aminotransferase Ⅲ （KATⅢ） by real-time PCR. Protein level of NMDA receptor 1 was detected by Western blot. High performance liquid chromatography （HPLC） was used to measure the concentrations of tryptophan （TRP）, kynurenine （KYN） and kynurenic acid（KYNA）. Ultra-structural changes of hippocampal neurons were observed by transmission electron microscopy （TEM）.＆amp;nbsp;Results As compared to control group, exercise score decreased （P〈0.05）, rest time and central panel residence time prolonged, periphery/central panel ratio increased （all P〈0.05）, mRNA and protein expressions of NMDA receptor 1 increased （P〈0.05）, mRNA expression of KAT Ⅲ decreased （P〈0.05）, KYN/TRP ratio and KYN/KYNA ratio decreased （all P〈0.05） in POFS group on postoperative day 1 and 3. As compared to POFS group, central panel residence time and periphery/central panel ratio decreased on postoperative day 1 , and mRNA and protein expressions of NMDA receptor 1 decreased on postoperative day 1 and 3 （all P〈0.05） in antagonist group. TEM revealed that degenerated neuron was found in the hippocampus of POFS rats , while such damage was improved in antagonist group. Conclusion The increased expression level of NMDA receptor may play an important role in POFS. NMDA receptor antagonist MK801 may improve the POFS.