Williams K, Dichter M A, Molinoff P B
Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104-6084.
Mol Pharmacol. 1992 Jul;42(1):147-51.
The density of N-methyl-D-aspartate (NMDA) receptors on membranes prepared from cultured cortical neurons was determined using binding assays with [125I]I-MK-801 after exposure of cultures to antagonists of the NMDA receptor complex. The density of binding sites for [125I]I-MK-801 was increased by 40-80% after exposure to D-2-amino-5-phosphonopentanoic acid (D-AP5), with no change in the number or viability of neurons. The effect of D-AP5 was concentration dependent, with an EC50 of 10 microM. Up-regulation of NMDA receptors was observed after 2-7 days but not after 1 day of exposure to 100 microM D-AP5. The density of NMDA receptors was also increased after exposure of cells to CGS 19755 and MK-801 but not after exposure to the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. The binding of [3H]AMPA was unaltered after exposure to D-AP5. These results demonstrate that the density of NMDA receptors on cultured neurons can be selectively up-regulated by exposure to NMDA receptor antagonists. Increases in the density of NMDA receptors occurring in vivo could complicate therapeutic approaches to the treatment of neurological disorders.
在用NMDA受体复合物拮抗剂处理培养的皮层神经元后，通过[125I]I-MK-801结合试验测定了从培养的皮层神经元制备的膜上N-甲基-D-天冬氨酸（NMDA）受体的密度。暴露于D-2-氨基-5-膦酰基戊酸（D-AP5）后，[125I]I-MK-801的结合位点密度增加了40%-80%，而神经元数量或活力没有变化。D-AP5的作用呈浓度依赖性，半数有效浓度（EC50）为10微摩尔。暴露于100微摩尔D-AP5 2-7天后观察到NMDA受体上调，但暴露1天后未观察到上调。细胞暴露于CGS 19755和MK-801后，NMDA受体密度也增加，但暴露于α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）/海人藻酸受体拮抗剂6-氰基-7-硝基喹喔啉-2,3-二酮后未增加。暴露于D-AP5后，[3H]AMPA的结合未改变。这些结果表明，暴露于NMDA受体拮抗剂可选择性地上调培养神经元上NMDA受体的密度。体内发生的NMDA受体密度增加可能会使神经疾病的治疗方法复杂化。
