期刊
SYNAPSE
卷 65, 期 11, 页码 1222-1230出版社
WILEY
DOI: 10.1002/syn.20962
关键词
Gray synapses; symmetry; excitation; inhibition; postsynaptic density
On the basis of ultrastructural parameters, the concept was formulated that asymmetric Type I and symmetric Type II synapses are excitatory and inhibitory, respectively. This functional Gray synapses concept received strong support from the demonstration of the excitatory neurotransmitter glutamate in Type I synapses and of the inhibitory neurotransmitter g-aminobutyric acid in Type II synapses, and is still frequently used in modern literature. However, morphological and functional evidence has accumulated that the concept is less tenable. Typical features of synapses like shape and size of presynaptic vesicles and synaptic cleft and presence of a postsynaptic density (PsD) do not always fit the postulated (excitatory/inhibitory) function of Gray's synapses. Furthermore, synapse function depends on postsynaptic receptors and associated signal transduction mechanisms rather than on presynaptic morphology and neurotransmitter type. Moreover, the notion that many synapses are difficult to classify as either asymmetric or symmetric has cast doubt on the assumption that the presence of a PsD is a sign of excitatory synaptic transmission. In view of the morphological similarities of the PsD in asymmetric synapses with membrane junctional structures such as the zonula adherens and the desmosome, asymmetric synapses may play a role as links between the postsynaptic and presynaptic membrane, thus ensuring long-term maintenance of interneuronal communication. Symmetric synapses, on the other hand, might be sites of transient communication as takes place during development, learning, memory formation, and pathogenesis of brain disorders. Confirmation of this idea might help to return the functional Gray synapse concept its central place in neuroscience. Synapse 65:1222-1230, 2011. (C) 2011 Wiley-Liss, Inc.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据