Abstract
Application of either AMPA or Quisqualic acid (QA), agonists for AMPA-receptor, induces inward current response in the CA1 pyramidal neuron in rat hippocampal slice under whole-cell patch clamp. The responses to AMPA and QA were almost completely blocked by 30 μM NBQX and GYKI52466, antagonists for AMPA-receptor, and the response reversed at +10 mV, showing opening of the cationic channel. When one of these agonists was applied repeatedly, the second response to AMPA or QA was occluded at the shorter interval of the agonist application. However, there was no sign of the desensitization in the response, although GABA-induced Cl–-current response examined in the same type of cell exhibited strong desensitization. Furthermore, perfusion of cyclothiazide (CTZ), a reagent that relief the desensitization of AMPA-receptor, markedly augmented the AMPA- and QA-induced response without affecting the time course of the respopnse. Dose-response curve obtained in the presence of CTZ showed upward shift without the significant charge in KD value. These results suggested that the AMPA-receptor of the pyramidal neuron in the rat hippocampal slice may be lacking a nature of the desensitization or may be under suppression of the desensitization. [Jpn J Physiol 54 Suppl:S152 (2004)]
