In normal rat forebrain, the NR1/NR2A and NR1/NR2B dimmers are the main constitutional forms of NMDA receptors. The present study was carried out to determine the functional properties of the heteromeric NMDA receptor...In normal rat forebrain, the NR1/NR2A and NR1/NR2B dimmers are the main constitutional forms of NMDA receptors. The present study was carried out to determine the functional properties of the heteromeric NMDA receptor subunits and their inhibition by bis(7)-tacrine (B7T). Rat NR1, NR2A and NR2B cDNAs were transfected into human embryonic kidney 293 cells (HEK-293).The inhibition of NMDA-activated currents by B7T was detected in HEK-293 cell expressing NR1/NR2A or NR1/NR2B receptors by using whole-cell patch-clamp techniques. The results showed that in HEK-293 cells expressing NR1/NR2A receptor, 1μmol/L B7T inhibited 30μmol/L NMDA- and 1000μmol/L NMDA-activated steady-state currents by 46% and 40%, respectively (P>0.05; n=5), suggesting that the inhibition of B7T on NR1/NR2A receptor doesn’t depend on NMDA concentration, which is consistent with a non-competitive mechanism of inhibition. But for the NR1/NR2B receptor, 1μmol/L B7T inhibited 30μmol/L NMDA- and 1000 μmol/L NMDA-activated steady-state currents by 61% and 13%, re-spectively (P<0.05; n=6), showing that B7T appears to be competitive with NMDA. In addition, simultaneous application of 1μmol/L B7T and 1000μmol/L NMDA produced a moderate inhibition of peak NMDA-activated current, followed by a gradual decline of the current to a steady state. However, the gradual onset of inhibition produced by B7T applied simultaneously with NMDA was eliminated when B7T was given 5s before NMDA. These results suggested that B7T inhibition of NMDA current mediated by NR1/NR2B receptor was slow onset, and it did not depend on the presence of the agonist. With holding potentials ranging from -50 to +50 mV, the B7T inhibition rate of NMDA currents didn’t change significantly, and neither did the reversal potential. We are led to conclude that the NR1/NR2B recombinant receptor can serve as a very useful model for studying the molecular mechanism of NMDA receptor inhibition by B7T.展开更多
目的:观察滋补脾阴方药对脾阴虚痴呆大鼠脑内N-甲基-D-天冬氨酸受体(NMDAR)亚单位NR1、NR2A、NR2B m RNA表达的影响。方法:运用逆转录聚合酶链反应(RT-PCR)技术,对NMDAR亚单位NR1、NR2A、NR2B m RNA在各脑区的表达状况作相应的检测。结...目的:观察滋补脾阴方药对脾阴虚痴呆大鼠脑内N-甲基-D-天冬氨酸受体(NMDAR)亚单位NR1、NR2A、NR2B m RNA表达的影响。方法:运用逆转录聚合酶链反应(RT-PCR)技术,对NMDAR亚单位NR1、NR2A、NR2B m RNA在各脑区的表达状况作相应的检测。结果:痴呆组以及脾阴虚痴呆组大鼠NMDAR亚单位NR1、NR2A、NR2B m RNA在各脑区表达均明显减弱下调(P<0.05);ZBPYR治疗组NMDAR亚单位NR1、NR2A、NR2B m RNA均明显上调(P<0.05)。结论:使用ZBPYR治疗的大鼠NMDAR m RNA的表达水平在各脑区均明显上调,这表明ZBPYR以提升NMDAR m RNA的方式,使得NMDAR蛋白的含量显著增多,而发挥其抗痴呆作用。展开更多
目的:探讨低氧和运动训练对大鼠学习记忆的作用和交互作用及其与海马突触传递功能之间的关系。方法:采用交互设计的研究方案对SD大鼠进行8周14.2%的低氧暴露或/和60 min的无负重游泳训练后,通过Morris水迷宫检测大鼠的学习和记忆能力,...目的:探讨低氧和运动训练对大鼠学习记忆的作用和交互作用及其与海马突触传递功能之间的关系。方法:采用交互设计的研究方案对SD大鼠进行8周14.2%的低氧暴露或/和60 min的无负重游泳训练后,通过Morris水迷宫检测大鼠的学习和记忆能力,并测定海马组织中γ-氨基丁酸(GABA)含量和N-甲基-D-天门冬氨酸受体(NMDAR)亚基NR1、NR2B的m RNA表达量。结果:1长期的低氧暴露可使大鼠的潜伏期显著增加(P<0.05),穿越平台的次数显著减少(P<0.05),运动训练能使大鼠的潜伏期显著缩短(P<0.05),穿越平台的次数显著增加(P<0.05),低氧联合运动训练对缩短大鼠潜伏期、提高大鼠穿越平台次数没有显著的交互作用(P>0.05)。2慢性低氧暴露能显著降低海马组织中NR1和NR2B m RNA的表达(P<0.05),运动训练能显著提高海马组织中NR1和NR2B的m RNA表达和降低GABA含量(P<0.05),低氧联合运动训练对海马组织中NR1、NR2B m RNA表达的提高和GABA含量的降低没有显著的交互作用(P>0.05)。结论:1长期的低氧暴露可抑制学习记忆能力,而运动训练能够增加学习记忆能力,虽然运动训练在一定程度上可以改善低氧暴露大鼠的学习记忆能力,但是并不能完全逆转低氧暴露所造成的学习能力下降。2长期的低氧暴露或运动训练可下调或上调海马NR1和NR2B m RNA表达,抑制或增强海马突触功能可塑性,这可能是影响学习记忆能力的重要机制。展开更多
基金supported by grants from the National Natural Science Foundation of China(No. 30970927)the Natural Science Foundation of Hubei Province, China(No.2008CDA053)the Wuhan Science and Technology Foundation(Nos.200970634270,201250499145-27 and 20115069-9189-23)
文摘In normal rat forebrain, the NR1/NR2A and NR1/NR2B dimmers are the main constitutional forms of NMDA receptors. The present study was carried out to determine the functional properties of the heteromeric NMDA receptor subunits and their inhibition by bis(7)-tacrine (B7T). Rat NR1, NR2A and NR2B cDNAs were transfected into human embryonic kidney 293 cells (HEK-293).The inhibition of NMDA-activated currents by B7T was detected in HEK-293 cell expressing NR1/NR2A or NR1/NR2B receptors by using whole-cell patch-clamp techniques. The results showed that in HEK-293 cells expressing NR1/NR2A receptor, 1μmol/L B7T inhibited 30μmol/L NMDA- and 1000μmol/L NMDA-activated steady-state currents by 46% and 40%, respectively (P>0.05; n=5), suggesting that the inhibition of B7T on NR1/NR2A receptor doesn’t depend on NMDA concentration, which is consistent with a non-competitive mechanism of inhibition. But for the NR1/NR2B receptor, 1μmol/L B7T inhibited 30μmol/L NMDA- and 1000 μmol/L NMDA-activated steady-state currents by 61% and 13%, re-spectively (P<0.05; n=6), showing that B7T appears to be competitive with NMDA. In addition, simultaneous application of 1μmol/L B7T and 1000μmol/L NMDA produced a moderate inhibition of peak NMDA-activated current, followed by a gradual decline of the current to a steady state. However, the gradual onset of inhibition produced by B7T applied simultaneously with NMDA was eliminated when B7T was given 5s before NMDA. These results suggested that B7T inhibition of NMDA current mediated by NR1/NR2B receptor was slow onset, and it did not depend on the presence of the agonist. With holding potentials ranging from -50 to +50 mV, the B7T inhibition rate of NMDA currents didn’t change significantly, and neither did the reversal potential. We are led to conclude that the NR1/NR2B recombinant receptor can serve as a very useful model for studying the molecular mechanism of NMDA receptor inhibition by B7T.
文摘目的:观察滋补脾阴方药对脾阴虚痴呆大鼠脑内N-甲基-D-天冬氨酸受体(NMDAR)亚单位NR1、NR2A、NR2B m RNA表达的影响。方法:运用逆转录聚合酶链反应(RT-PCR)技术,对NMDAR亚单位NR1、NR2A、NR2B m RNA在各脑区的表达状况作相应的检测。结果:痴呆组以及脾阴虚痴呆组大鼠NMDAR亚单位NR1、NR2A、NR2B m RNA在各脑区表达均明显减弱下调(P<0.05);ZBPYR治疗组NMDAR亚单位NR1、NR2A、NR2B m RNA均明显上调(P<0.05)。结论:使用ZBPYR治疗的大鼠NMDAR m RNA的表达水平在各脑区均明显上调,这表明ZBPYR以提升NMDAR m RNA的方式,使得NMDAR蛋白的含量显著增多,而发挥其抗痴呆作用。
文摘目的:探讨低氧和运动训练对大鼠学习记忆的作用和交互作用及其与海马突触传递功能之间的关系。方法:采用交互设计的研究方案对SD大鼠进行8周14.2%的低氧暴露或/和60 min的无负重游泳训练后,通过Morris水迷宫检测大鼠的学习和记忆能力,并测定海马组织中γ-氨基丁酸(GABA)含量和N-甲基-D-天门冬氨酸受体(NMDAR)亚基NR1、NR2B的m RNA表达量。结果:1长期的低氧暴露可使大鼠的潜伏期显著增加(P<0.05),穿越平台的次数显著减少(P<0.05),运动训练能使大鼠的潜伏期显著缩短(P<0.05),穿越平台的次数显著增加(P<0.05),低氧联合运动训练对缩短大鼠潜伏期、提高大鼠穿越平台次数没有显著的交互作用(P>0.05)。2慢性低氧暴露能显著降低海马组织中NR1和NR2B m RNA的表达(P<0.05),运动训练能显著提高海马组织中NR1和NR2B的m RNA表达和降低GABA含量(P<0.05),低氧联合运动训练对海马组织中NR1、NR2B m RNA表达的提高和GABA含量的降低没有显著的交互作用(P>0.05)。结论:1长期的低氧暴露可抑制学习记忆能力,而运动训练能够增加学习记忆能力,虽然运动训练在一定程度上可以改善低氧暴露大鼠的学习记忆能力,但是并不能完全逆转低氧暴露所造成的学习能力下降。2长期的低氧暴露或运动训练可下调或上调海马NR1和NR2B m RNA表达,抑制或增强海马突触功能可塑性,这可能是影响学习记忆能力的重要机制。
