Jusuf Patricia R, Haverkamp Silke, Grünert Ulrike
The National Vision Research Institute of Australia, Carlton, Victoria 3053, Australia.
J Comp Neurol. 2005 Jul 25;488(2):113-28. doi: 10.1002/cne.20555.
The major inhibitory neurotransmitter glycine is used by about half of the amacrine cells in the retina. Amacrine cells provide synaptic output to bipolar, ganglion, and other amacrine cells. The present study investigated whether different bipolar and amacrine cell types in the primate retina differ with respect to the expression of glycine receptor (GlyR) subtypes. Antibodies specific for the alpha1, alpha2, and alpha3 subunits of the GlyR were combined with immunohistochemical markers for bipolar and amacrine cells and applied to vertical sections of macaque (Macaca fascicularis) and marmoset (Callithrix jacchus) retinae. For all subunits, punctate immunoreactivity was expressed in the inner plexiform layer. The GlyRalpha2 immunoreactive (IR) puncta occur at the highest density, followed by GlyR(alpha)3 and GlyR(alpha)1 IR puncta. Postembedding electron microscopy showed the postsynaptic location of all subunits. Double immunofluorescence demonstrated that the three alpha subunits are clustered at different postsynaptic sites. Two OFF cone bipolar cell types (flat midget and diffuse bipolar DB3), are predominantly associated with the alpha1 subunit. Two ON bipolar cell types, the DB6 and the rod bipolar cell, are predominantly associated with the alpha2 subunit. The glycinergic AII amacrine cell is presynaptic to the alpha1 subunit in the OFF-sublamina, and postsynaptic to the alpha2 subunit in the ON-sublamina. Another putative glycinergic cell, the vesicular glutamate transporter 3 cell, is predominantly presynaptic to the alpha2 subunit. The dopaminergic amacrine cell expresses the alpha3 subunit at a low density.
主要抑制性神经递质甘氨酸被视网膜中约一半的无长突细胞所利用。无长突细胞向双极细胞、神经节细胞和其他无长突细胞提供突触输出。本研究调查了灵长类动物视网膜中不同类型的双极细胞和无长突细胞在甘氨酸受体（GlyR）亚型表达方面是否存在差异。针对GlyR的α1、α2和α3亚基的特异性抗体与双极细胞和无长突细胞的免疫组织化学标记物相结合，并应用于猕猴（食蟹猴）和狨猴（绢毛猴）视网膜的垂直切片。对于所有亚基，在内网状层均有斑点状免疫反应性表达。GlyRα2免疫反应性（IR）斑点的密度最高，其次是GlyR（α）3和GlyR（α）1 IR斑点。包埋后电子显微镜显示所有亚基的突触后位置。双重免疫荧光表明这三个α亚基聚集在不同的突触后位点。两种OFF型视锥双极细胞类型（扁平侏儒双极细胞和弥散双极细胞DB3）主要与α1亚基相关。两种ON型双极细胞类型，即DB6和视杆双极细胞，主要与α2亚基相关。甘氨酸能AII无长突细胞在OFF亚层中是α1亚基的突触前细胞，在ON亚层中是α2亚基的突触后细胞。另一种假定的甘氨酸能细胞，即囊泡谷氨酸转运体3细胞，主要是α2亚基的突触前细胞。多巴胺能无长突细胞低密度表达α3亚基。
