Marshak David W
Department of Neurobiology and Anatomy,McGovern Medical School,University of Texas Health Science Center at Houston,Houston,TX 77225.
Vis Neurosci. 2016 Jan;33:E017. doi: 10.1017/S0952523816000146.
Amacrine cells are a diverse set of local circuit neurons of the inner retina, and they all release either GABA or glycine, amino acid neurotransmitters that are generally inhibitory. But some types of amacrine cells have another function besides inhibiting other neurons. One glycinergic amacrine cell, the Aii type, excites a subset of bipolar cells via extensive gap junctions while inhibiting others at chemical synapses. Many types of GABAergic amacrine cells also release monoamines, acetylcholine, or neuropeptides. There is now good evidence that another type of amacrine cell releases glycine at some of its synapses and releases the excitatory amino acid glutamate at others. The glutamatergic synapses are made onto a subset of retinal ganglion cells and amacrine cells and have the asymmetric postsynaptic densities characteristic of central excitatory synapses. The glycinergic synapses are made onto other types of ganglion cells and have the symmetric postsynaptic densities characteristic of central inhibitory synapses. These amacrine cells, which contain vesicular glutamate transporter 3, will be the focus of this brief review.
无长突细胞是视网膜内层多种类型的局部回路神经元，它们都释放γ-氨基丁酸（GABA）或甘氨酸，这两种氨基酸神经递质通常具有抑制作用。但某些类型的无长突细胞除了抑制其他神经元外还有其他功能。一种甘氨酸能无长突细胞，即Aii型，通过广泛的缝隙连接兴奋一部分双极细胞，同时在化学突触处抑制其他双极细胞。许多类型的GABA能无长突细胞还释放单胺、乙酰胆碱或神经肽。现在有充分的证据表明，另一种无长突细胞在其一些突触处释放甘氨酸，而在其他突触处释放兴奋性氨基酸谷氨酸。谷氨酸能突触形成于一部分视网膜神经节细胞和无长突细胞上，具有中枢兴奋性突触特有的不对称突触后致密物。甘氨酸能突触形成于其他类型的神经节细胞上，具有中枢抑制性突触特有的对称突触后致密物。这些含有囊泡谷氨酸转运体3的无长突细胞将是本简要综述的重点。
