The functional analyses of Cbln-GluD1 signaling

尽管已经证明delta 2谷氨酸受体（GluD 2）通过与Cbln 1相互作用在突触形成/维持和突触可塑性中起关键作用，但GluD 1的功能仍然是难以捉摸的。使用GluD 1基因敲除小鼠，我们研究了内嗅皮层神经元直接投射的陷窝-分子层中海马CA 1区神经元突触的电生理特性。我们发现GluD 1在调节NMDA/AMPA比值和突触可塑性阈值中起着重要作用。此外，GluD 1基因敲除小鼠表现出微量恐惧条件反射障碍，其中CA 1区腔隙分子层中的突触传递是必不可少的。值得注意的是，这项研究首次揭示了GluD 1在突触可塑性中的生物学功能。

Although it was demonstrated that the delta2 glutamate receptor (GluD2) played crucial roles in synapse formation/maintenance and synaptic plasticity through interactions with Cbln1, function of GluD1 remains still elusive. Using GluD1-null mice, we investigated electrophysiological characteristics of the hippocampal CA1 neuron synapses in stratum lacunosum-moleculare where the entorhinal cortical neurons directly project. We found that GluD1 was critically involved in tuning NMDA/AMPA ratio and the threshold of synaptic plasticity. Furthermore, GluD1-null mice showed impairment in trace fear conditioning in which synaptic transmission in the stratum lacunosum-moleculare of the CA1 region is essential. It should be noted that this study, for the first time, revealed biological function of GluD1 in synaptic plasticity.