Li H S, Niedzielski A S, Beisel K W, Hiel H, Wenthold R J, Morley B J
Boys Town National Research Hospital, Omaha, NE 68131.
Hear Res. 1994 Aug;78(2):235-42. doi: 10.1016/0378-5955(94)90029-9.
The neurotransmitter at the synapses between hair cells and spiral ganglion cells in the cochlea is probably L-glutamate or a similar excitatory amino acid. Glutamate uptake by nerve terminals and glial cells is an important component of neurotransmission at glutamatergic synapses of the central nervous system, for providing a reservoir of transmitter or transmitter precursors and the termination of the released glutamate. Hair cell synapses are not surrounded by glial cells, therefore, the uptake mechanism for glutamate in the cochlea may be unique. cDNA was synthesized from total RNA isolated separately from the rat organ of Corti, spiral ganglia, and lateral wall tissues. The expression of a glutamate/aspartate transporter (GLAST) was detected by DNA amplification with the polymerase chain reaction. The other two members of glutamate transporters in this family were not detected by this method. A partial cDNA encoding to GLAST was identified by sequence analysis in a rat cochlear cDNA library. Data concerning the expression and the molecular structure of the glutamate transporter GLAST in the cochlea may provide important information regarding the neurotransmission process at the hair cell-afferent synapses.
耳蜗中毛细胞与螺旋神经节细胞之间突触的神经递质可能是L-谷氨酸或类似的兴奋性氨基酸。神经末梢和神经胶质细胞对谷氨酸的摄取是中枢神经系统谷氨酸能突触神经传递的重要组成部分，用于提供递质或递质前体的储存库以及终止释放的谷氨酸。毛细胞突触未被神经胶质细胞包围，因此，耳蜗中谷氨酸的摄取机制可能是独特的。从分别从大鼠柯蒂氏器、螺旋神经节和侧壁组织分离的总RNA合成cDNA。通过聚合酶链反应进行DNA扩增检测谷氨酸/天冬氨酸转运体（GLAST）的表达。该家族中谷氨酸转运体的其他两个成员未通过该方法检测到。通过对大鼠耳蜗cDNA文库进行序列分析，鉴定出一个编码GLAST的部分cDNA。关于耳蜗中谷氨酸转运体GLAST的表达和分子结构的数据可能为毛细胞-传入突触的神经传递过程提供重要信息。
