右美托咪定对大鼠海马神经元缺氧损伤时胞膜含NR1亚基的NMDA受体和含GluR2亚基的AMPA受体表达的影响

Effect of dexmedetomidine on expression of NR1 subunit-containing NMDA receptors and GluR2 subunit-containing AMPA receptors during hypoxic injury to rat hippocampal neurons

目的 评价右美托咪定对大鼠海马神经元缺氧损伤时胞膜含NR1亚基的NMDA受体和含GluR2亚基的AMPA受体表达的影响.方法 原代培养出生24h内的健康Wistar大鼠的海马神经元,接种于培养板中,采用随机数字表法分为3组（n=24）：对照组（C组）、缺氧组（H组）和右美托咪定组（D组）.H组和D组采用缺氧6h的方法制备神经元缺氧损伤模型;D组缺氧6h时加入0.1μmol/L右美托咪定孵育3h,随后更换正常培养基进行培养24h.采用CCK-8法检测神经元活力,检测LDH漏出率,Western blot法检测胞膜含NR1亚基的NMDA受体和含GluR2亚基的AMPA受体的表达水平,Fluo-3AM法检测胞浆钙离子浓度.结果 与C组比较,H组和D组神经元活力降低,LDH漏出率升高,胞膜含NR1亚基的NMDA受体表达上调,含GluR2亚基的AMPA受体表达下调,胞浆钙离子浓度升高（P＜0.05）;与H组比较,D组神经元活力升高,LDH漏出率降低,胞膜含NR1亚基的NMDA受体表达下调,含GluR2亚基的AMPA受体表达上调,胞浆钙离子浓度降低（P＜0.05）.结论 右美托咪定减轻大鼠海马神经元缺氧损伤的机制可能与抑制胞膜含NR1亚基的NM-DA受体表达上调和含GluR2亚基的AMPA受体表达下调有关.

Objective To evaluate the effect of dexmedetomidine on the expression of NR1 subunit-containing NMDA receptors and GIuR2 subunit-containing AMPA receptors during hypoxic injury to rat hippocampal neurons.Methods The hippocampal neurons were isolated from Wistar rats within 24 h after birth and divided into 3 groups （n=24 each） using a random number table：control group （group C）,hypoxia group （group H） and dexmedetomidine group （group D）.The cells were subjected to hypoxia for 6 h to establish the model of neuronal hypoxic injury in H and D groups.In group D,0.1 μmol/L dexmedetomidine was added at 6 h of hypoxia and neurons were incubated for 3 h,and then the culture medium was replaced with a normal medium and neurons were incubated for 24 h.The neuronal viability was measured by CCK-8 assay,the leakage of LDH was detected,and the leakage rate was calculated.The expression of NR1 subunits-containing NMDA receptors and GluR2 subunits-containing AMPA receptors was detected by Western blot.The concentration of calcium ion in cytoplasm was measured using Fluo-3AM.Results Compared with group C,the neuronal viability was significantly decreased,the LDH leakage rate was increased,the expression of NR1 subunits-containing NMDA receptors in the membrane was up-regulated,the expression of GluR2 subunits-containing AMPA receptors was down-regulated,and the concentration of calcium ion in cytoplasm was increased in H and D groups （P〈0.05）.Compared with group H,the neuronal viability was significantly increased,the LDH leakage rate was decreased,the expression of NR1 subunits-containing NMDA receptors in the membrane was down-regulated,the expression of GluR2 subunitscontaining AMPA receptors was up-regulated,and the concentration of calcium ion in cytoplasm was decreased in group D （P〈0.05）.Conclusion The mechanism by which dexmedetomidine reduces hypoxic injury to rat hippocampal neurons may be related to inhibiting up-regulation of the expression of NR1 subunits-containing NMDA receptors in the membrane and down-regulation of the expression of GluR2 subunitscontaining AMPA receptors.