AMPA Receptors in Cultured Vestibular Ganglion Neurons: Detection and Activation
AMPA Receptors in Cultured Vestibular Ganglion Neurons: Detection and Activation
复制标题
培养的前庭神经节神经元中的 AMPA 受体：检测和激活
DOI：
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发表时间：
1997
影响因子：
3.4
通讯作者：
J. Raymond
中科院分区：
文献类型：
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作者：
Denis Rabejac;G. Devau;J. Raymond
The presence and the activity of α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionic acid (AMPA) glutamate receptors were investigated in mouse cultured vestibular ganglion neurons using immunocytochemistry and measurement of intracellular calcium concentration ([Ca2+],) by spectrofluorimetry. Cultures of dissociated vestibular ganglia from 18 gestation day mouse embryos were grown in vitro for 3–4 days. lmmunocytochemical labelling of AMPA receptor subunits GluR2/R3 and GluR4 was detected in neuron cell bodies and proximal neurites and more lightly in glial cells. There was no clear selective subcellular localization of the different subunits. For the GluR1 subunit a signal was observed only in some neurons and neurites and was weak. Vestibular ganglion neurons responded to fast application of 1 mM glutamate and 10 mM aspartate through unknown receptors by a transient increase in [Ca2+]i. The mean amplitude of this rapid increase was about nine times the resting level and recovery was complete within 30–45 s after the application. If separated by an interval of at least 10 min, consecutive applications produced similar calcium responses. AMPA (1 mM) application induced the same type of responses. Five minutes prior to the AMPA exposure, the application of a specific AMPA antagonist, 6, 7‐dinitroquinoxaline‐2, 3‐dione (DNQX, 1.5 mM), in the external medium inhibited the response to AMPA. Chelation of external calcium by EGTA (1.5 mM) abolished the responses to drug applications, indicating that an influx of external calcium is involved in the [Ca2+]i increase. These observations suggest that heteromeric AMPA receptors are expressed in vestibular ganglion neurons in culture and play a functional role in their glutamate‐induced depolarization. Experiments are in progress using specific AMPA and NMDA antagonists to characterize the participation of the two types of ionotropic glutamate receptors in the glutarnate/aspartate‐induced intracellular calcium response.
