NMDA and AMPA receptors contribute similarly to temporal processing in mammalian retinal ganglion cells.
NMDA and AMPA receptors contribute similarly to temporal processing in mammalian retinal ganglion cells.
复制标题
NMDA 和 AMPA 受体对哺乳动物视网膜神经节细胞的时间处理有类似的贡献。
DOI：
10.1113/jphysiol.2014.276543
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Demb,JonathanB
中科院分区：
文献类型：
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作者：
Stafford,BenjaminK;Manookin,MichaelB;Singer,JoshuaH;Demb,JonathanB
在大脑的大多数区域，NMDA型谷氨酸受体（NMDAR）表现出比AMPA型受体（AMPAR）更慢的动力学。大多数视网膜神经节细胞表达AMPAR和NMDAR的组合，但NMDAR动力学是否限制光刺激的时间编码还不清楚。在这项研究中，我们在两种类型的豚鼠视网膜神经节细胞中测量了由视觉刺激引起的AMPAR和NMDAR介导的电导。在这两种细胞类型中，AMPAR和NMDAR介导的反应在生理范围内编码快速变化的对比度调制在视网膜神经节细胞中，NMDARs和AMPARs共同作用编码广泛的时间频率，这表明在某些感觉神经元中NMDARs具有相对较快的动力学.（AMPAR，NMDAR）通常在相同的突触处表达。AMPAR被认为介导大部分快速兴奋性神经传递，而NMDAR，其相对较慢的动力学和较高的Ca 2+渗透性，被认为介导突触可塑性，特别是在专门用于学习和记忆的神经回路中。然而，在感觉神经元中，AMPAR和NMDAR的作用还不太清楚。在这里，我们在离体豚鼠视网膜测试AMPAR和NMDAR是否差异支持两种神经节细胞类型的时间对比度编码。在OFF α和δ神经节细胞中，对比刺激诱发了具有特征性J形I-V关系的NMDAR介导的反应。在OFF Delta细胞中，AMPAR和NMDAR介导的反应可以在低频率下调制，但在10 Hz刺激期间受到抑制，此时反应由突触抑制形成。在抑制被阻断的情况下，AMPAR和NMDAR介导的反应都可以在10 Hz下调节，表明NMDAR动力学不限制时间编码。在OFF Alpha细胞中，NMDAR介导的反应遵循频率高达18 Hz的刺激。在这两种细胞类型中，NMDAR介导的对9-18 Hz对比度调制的反应相对于AMPAR介导的反应显示出<10 ms的延迟。因此，NMDAR联合收割机与AMPAR组合以编码快速调节的谷氨酸释放，并且NMDAR动力学基本上不限制OFF α和δ神经节细胞的时间编码。此外，双极细胞通路中的突触能传递受到不同的调节：在某些情况下，突触前抑制在高时间频率下抑制释放。
Key pointsIn most areas of the brain, NMDA‐type glutamate receptors (NMDARs) exhibit slower kinetics than do AMPA‐type receptors (AMPARs).Most retinal ganglion cells express a combination of AMPARs and NMDARs, but whether NMDAR kinetics limit temporal encoding of light stimulation is not well understood.In this study, we measured AMPAR‐ and NMDAR‐mediated conductances evoked by visual stimulation in two types of guinea pig retinal ganglion cell.In both cell types, AMPAR‐ and NMDAR‐mediated responses encoded rapidly varying contrast modulation within the physiological range (up to 18 temporal cycles s–1).In retinal ganglion cells, NMDARs and AMPARs act together to encode a wide range of temporal frequencies, suggesting that NMDARs in some sensory neurons have relatively fast kinetics.AbstractPostsynaptic AMPA‐ and NMDA‐type glutamate receptors (AMPARs, NMDARs) are commonly expressed at the same synapses. AMPARs are thought to mediate the majority of fast excitatory neurotransmission whereas NMDARs, with their relatively slower kinetics and higher Ca2+permeability, are thought to mediate synaptic plasticity, especially in neural circuits devoted to learning and memory. In sensory neurons, however, the roles of AMPARs and NMDARs are less well understood. Here, we tested in thein vitroguinea pig retina whether AMPARs and NMDARs differentially support temporal contrast encoding by two ganglion cell types. In both OFF Alpha and Delta ganglion cells, contrast stimulation evoked an NMDAR‐mediated response with a characteristic J‐shapedI–Vrelationship. In OFF Delta cells, AMPAR‐ and NMDAR‐mediated responses could be modulated at low frequencies but were suppressed during 10 Hz stimulation, when responses were instead shaped by synaptic inhibition. With inhibition blocked, both AMPAR‐ and NMDAR‐mediated responses could be modulated at 10 Hz, indicating that NMDAR kinetics do not limit temporal encoding. In OFF Alpha cells, NMDAR‐mediated responses followed stimuli at frequencies up to ∼18 Hz. In both cell types, NMDAR‐mediated responses to contrast modulation at 9–18 Hz showed delays of <10 ms relative to AMPAR‐mediated responses. Thus, NMDARs combine with AMPARs to encode rapidly modulated glutamate release, and NMDAR kinetics do not limit temporal coding by OFF Alpha and Delta ganglion cells substantially. Furthermore, glutamatergic transmission is differentially regulated across bipolar cell pathways: in some, release is suppressed at high temporal frequencies by presynaptic inhibition.