Hájos N, Freund T F, Mody I
Department of Functional Neuroanatomy, Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1450 Budapest, Hungary.
Acta Biol Hung. 2002;53(4):465-72. doi: 10.1556/ABiol.53.2002.4.7.
NMDA receptors participate in the glutamatergic excitation of both principal cells and GABAergic interneurons. The features of NMDA channels on specific interneurons, however, are not known. Therefore, we obtained direct measurements of single NMDA receptor channels on anatomically identified oriens/alveus interneurons projecting to stratum lacunosum-moleculare (O-LM cells) and compared them to those found on hippocampal principal cells using cell-attached recordings in in vitro slice preparations. The recorded channels could be blocked by ketamine, a membrane-permeable NMDA channel inhibitor. In the absence of Mg(2+), all O-LM cells had NMDA channels with a comparable slope conductance (approximately 60pS) to those measured on CA1 pyramidal cells or dentate granule cells. In addition, NMDA channels with smaller conductance (43-45 pS) were also found on two O-LM cells but not on principal cells. These results suggest that at least two types of NMDA channels are expressed on O-LM cells likely reflecting distinct subunit composition.
N-甲基-D-天冬氨酸（NMDA）受体参与了对主细胞和γ-氨基丁酸（GABA）能中间神经元的谷氨酸能兴奋作用。然而，特定中间神经元上NMDA通道的特性尚不清楚。因此，我们对投射至腔隙-分子层的解剖学上已确定的海马伞/槽带中间神经元（O-LM细胞）上的单个NMDA受体通道进行了直接测量，并在体外脑片制备中使用细胞贴附式记录将其与海马主细胞上的通道进行了比较。所记录的通道可被氯胺酮（一种可透过膜的NMDA通道抑制剂）阻断。在没有镁离子（Mg²⁺）的情况下，所有O-LM细胞都具有与在CA1锥体细胞或齿状颗粒细胞上测得的通道斜率电导相当（约60皮西门子）的NMDA通道。此外，在两个O-LM细胞上还发现了电导较小（43 - 45皮西门子）的NMDA通道，但在主细胞上未发现。这些结果表明，O-LM细胞上表达了至少两种类型的NMDA通道，这可能反映了不同的亚基组成。
