Chen Z, Ito K, Fujii S, Miura M, Furuse H, Sasaki H, Kaneko K, Kato H, Miyakawa H
Department of Physiology, Yamagata University School of Medicine, Japan.
Recept Channels. 1996;4(1):1-8.
The effects of both the activation and the blockade of D1 or D2 dopamine receptors on long-term depression (LTD) of synaptic transmission, and the involvement of NMDA and GABA receptors in LTD, were investigated in CA1 neurons of rat hippocampal slices. Low-frequency stimulation (LFS, 450 pulses at 1 Hz) produced LTD of the slope of field EPSPs (-14.3%, mean, n = 10). The induction of LTD was blocked by the NMDA receptor antagonist, AP5 (1.4%, n = 7), by the D1 receptor antagonist, SCH-23390 (3.5%, n = 8), or by the D2 receptor agonist, LY-171555 (4.4%, n = 8). Either the activation of D1 receptors by SKF-38393 or the blockade of D2 receptors by sulpiride produced significantly larger LTD than the control LTD (-31.1%, n = 11; -30.6%, n = 9, respectively). Although LTD was blocked by picrotoxin, a GABAA receptor/Cl- channel antagonist (4.9%, n = 8), LTD was produced by LFS in the medium containing both SKF-38393 and picrotoxin (-27.3%, n = 7). These results indicate that: (1) the induction of LTD by LFS in hippocampal CA1 neurons is under the influence of both NMDA and GABA receptors; (2) both D1 and D2 receptors are involved in the modulation of LTD in that the activation of D1 receptors enhances LTD, while that of D2 receptors inhibits LTD, and (3) while the induction of LTD is blocked by picrotoxin, this effect is superseded by SKF-38393.
研究了多巴胺D1或D2受体的激活和阻断对大鼠海马脑片CA1神经元突触传递长时程抑制（LTD）的影响，以及NMDA和GABA受体在LTD中的作用。低频刺激（LFS，1Hz，450个脉冲）可使场兴奋性突触后电位（fEPSP）斜率产生LTD（-14.3%，平均值，n = 10）。NMDA受体拮抗剂AP5（1.4%，n = 7）、D1受体拮抗剂SCH-23390（3.5%，n = 8）或D2受体激动剂LY-171555（4.4%，n = 8）均可阻断LTD的诱导。SKF-38393激活D1受体或舒必利阻断D2受体所产生的LTD均显著大于对照LTD（分别为-31.1%，n = 11；-30.6%，n = 9）。虽然LTD可被GABAA受体/Cl-通道拮抗剂印防己毒素阻断（4.9%，n = 8），但在同时含有SKF-38393和印防己毒素的培养基中，LFS仍可产生LTD（-27.3%，n = 7）。这些结果表明：（1）海马CA1神经元中LFS诱导的LTD受NMDA和GABA受体的影响；（2）D1和D2受体均参与LTD的调节，其中D1受体的激活增强LTD，而D2受体的激活则抑制LTD；（3）虽然印防己毒素可阻断LTD的诱导，但SKF-38393可取代这种作用。
