Early expression of AMPA receptors and lack of NMDA receptors in developing rat climbing fibre synapses
Early expression of AMPA receptors and lack of NMDA receptors in developing rat climbing fibre synapses
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DOI：
10.1113/jphysiol.2005.084517
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发表时间：
2005-05-01
影响因子：
5.5
通讯作者：
Kessler, JP
中科院分区：
文献类型：
--
作者：
Lachamp, P;Balland, N;Kessler, JP
新生的谷氨酸能突触是结构性地获得AMPA受体，还是通过预先存在的NMDA受体激活触发的调节途径获得AMPA受体，仍然是一个悬而未决的问题。在这里，我们提供了一些谷氨酸能突触发育而不表达NMDA受体的证据。用免疫细胞化学方法证明，发育中的大鼠攀缘纤维与浦肯野细胞之间的突触在形成时(即胚胎第19天)就表达含有GluR2的AMPA受体，但从未携带可检测到的NMDA受体。电生理记录证实了这一点。早在PO时，浦肯野细胞就记录到兴奋性突触电流。然而，在自发或诱发的突触反应中都没有发现NMDA受体介导的成分。此外，我们排除了突触外NMDA受体的可能作用，因为我们证明了AMPA受体聚集在新生的攀缘纤维突触不会被宫内慢性NMDA受体阻断所改变。
Whether nascent glutamatergic synapses acquire their AMPA receptors constitutively or via a regulated pathway triggered by pre-existing NMDA receptor activation is still an open issue. Here, we provide evidence that some glutamatergic synapses develop without expressing NMDA receptors. Using immunocytochemistry, we showed that synapses between developing rat climbing fibres and Purkinje cells expressed GluR2-containing AMPA receptors as soon as they were formed (i.e. on embryonic day 19) but never carried detectable NMDA receptors. This was confirmed by electrophysiological recordings. Excitatory synaptic currents were recorded in Purkinje cells as early as PO. However, no NMDA receptor-mediated component was found in either spontaneous or evoked synaptic responses. In addition, we ruled out a possible role of extrasynaptic NMDA receptors by showing that AMPA receptor clustering at nascent climbing fibre synapses was not modified by chronic in utero NMDA receptor blockade.