Objective: To investigate the effects of dexmedetomidine(DEX) on postoperative cognitive function, plasma microRNA-206(miR-206) and brain derived neurotrophic factor(BDNF) levels in elderly patients with colorectal cancer. Methods: One hundred and sixty elderly patients undergoing elective colorectal cancer surgery under general anesthesia in our hospital from January 2018 to December 2019 were selected. The patients were divided into study group and control group according to the random number table method, with 80 patients in each. Patients in the study group were given DEX 1 mg·kg-1 10 min before anesthesia, and 0.3 mg·(kg·h)-1 intraoperatively until 30 min before the end of surgery. The patients in the control group were given the same amount of normal saline instead of DEX. The incidence of postoperative cognitive dysfunction(POCD) and the plasma miR-206, BDNF levels and adverse reactions at postoperative 1, 3 and 7 days were compared between the two groups. According to the occurrence of POCD at postoperative 7 days, patients were divided into POCD group and non-POCD group. Results: The incidence of POCD in the study group was lower than that in the control group, and on postoperative 1, 3 and 7 days, the plasma BDNF level in the study group was higher than that in the control group, meanwhile, the relative transcript level of plasma miR-206 in the study group was lower than that in the control group(P<0.05). The plasma BDNF level of POCD patients was significantly higher than that of the non-POCD group at postoperative 1, 3 and 7 days(P<0.05), and the relative transcript level of plasma miR-206 was also higher than that of the non-POCD group(P<0.05). The areas under the curve of miR-206 in plasma at postoperative day 1 for predicting the occurrence of POCD at postoperative 3 and 7 days were 0.78(95%CI 0.67-0.84, P<0.001) and 0.82(95%CI 0.71-0.89, P<0.001) respectively. Moreover, miR-206 in plasma at postoperative 1 day >4.10 was an independent risk factor for POCD in elderly colorectal cancer patients at postoperative 7 days(P<0.05). Conclusion: DEX can reduce the risk of POCD in elderly patients under general anesthesia with colorectal cancer surgery, which may be related to the decreased miR-206 expression and increased BDNF level in plasma.
 童朝阳, 黄成娅, 朱宏伟, 等.老年患者围手术期脑功能评估与术后认知功能障碍的研究现状[J]. 国际麻醉学与复苏杂志, 2019, 40(1):67-71.
 WANG W X, WU Q, LIANG S S, et al. Dexmedetomidine promotes the recovery of neurogenesis in aged mouse with postoperative cognitive dysfunction[J]. Neurosci Lett, 2018, 677(6):110-116.
 FRIEDMAN R C, FARH K K, BURGE C B, et al. Most mammalian mRNAs are conserved targets of microRNAs[J]. Genome Res, 2009, 19(1):92-105.
 SOLOMON M G, GRIFFIN W C, LOPEZ M F, et al. Brain regional and temporal changes in BDNF mRNA and microRNA-206 expression in mice exposed to repeated cycles of chronic intermittent ethanol and forced swim stress[J]. Neuroscience, 2019, 406(5):617-625.
 RASMUSSEN L S, O'BRIEN J T, SILVERSTEIN J H, et al. Is peri-operative cortisol secretion related to post-operative cognitive dysfunction?[J]. Acta Anaesthesiol Scand, 2005, 49(9):1225-1231.
 贺娜, 解雅英, 于建设, 等.术后认知功能障碍的研究进展[J]. 国际麻醉学与复苏杂志, 2014, 35(3):250-253, 267.
 HOU B J, DU Y, GU S X, et al. General anesthesia combined with epidural anesthesia maintaining appropriate anesthesia depth may protect excessive production of inflammatory cytokines and stress hormones in colon cancer patients during and after surgery[J]. Medicine(Baltimore), 2019, 98(30):e16610.
 梁敏运, 屠佳慧.右美托咪定对老年全身麻醉患者术后苏醒期躁动及术后认知功能的影响[J]. 中国老年学杂志, 2018, 38(14):3403-3405.
 吴剑平, 路建, 周清河, 等.帕瑞昔布钠预先给药联合右美托咪定对老年脊柱手术患者炎性反应和术后早期认知功能的影响[J]. 上海医学, 2019, 42(7):418-423.
 ZHANG H, WU Z, ZHAO X, et al. Role of dexmedetomidine in reducing the incidence of postoperative cognitive dysfunction caused by sevoflurane inhalation anesthesia in elderly patients with esophageal carcinoma[J]. J Cancer Res Ther, 2018, 14(7):1497-1502.
 闫小强, 安静, 高学超, 等.卵巢癌手术后右美托咪定复合舒芬太尼术镇痛对患者睡眠及血清BDNF水平影响[J]. 中国计划生育学杂志, 2020, 28(3):357-361.
 DENG F L, OUYANG M W, WANG X F, et al. Differential role of intravenous anesthetics in colorectal cancer progression:implications for clinical application[J]. Oncotarget, 2016, 7(47):77087-77095.
 ZHANG J, LIU G, ZHANG F, et al. Analysis of postoperative cognitive dysfunction and influencing factors of dexmedetomidine anesthesia in elderly patients with colorectal cancer[J]. Oncol Lett, 2019, 18(3):3058-3064.
 WEI L, YAO M, ZHAO Z, et al. High-fat diet aggravates postoperative cognitive dysfunction in aged mice[J]. BMC Anesthesiol, 2018, 18(1):20.
 JEONG H, CHUNG J Y, KO I G, et al. Effect of polydeoxyribonucleotide on lipopolysaccharide and sevoflurane-induced postoperative cognitive dysfunction in human neuronal SH-SY5Y cells[J]. Int Neurourol J, 2019, 23(Suppl 2):S93-S101.
 Lü J, OU W, ZOU X H, et al. Effect of dexmedetomidine on hippocampal neuron development and BDNF-TrkB signal expression in neonatal rats[J]. Neuropsychiatr Dis Treat, 2016, 12(12):3153-3159.
 DONG Y, HONG W, TANG Z, et al. Dexmedetomidine attenuates neurotoxicity in developing rats induced by sevoflurane through upregulating BDNF-TrkB-CREB and downregulating proBDNF-P75NRT-RhoA signaling pathway[J]. Mediators Inflamm, 2020, 2020(6):5458061.
 XING T, DU L, ZHUANG X, et al. Upregulation of microRNA-206 induces apoptosis of vascular smooth muscle cells and decreases risk of atherosclerosis through modulating FOXP1[J]. Exp Ther Med, 2017, 14(5):4097-4103.