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
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。
