Adenosine is an endogenous nucleoside in the central nervous system that acts on adenosine receptors. These are G protein-coupled receptors that have four known subtypes: A1, A2A, A2B, and A3 receptors. In the present study, we aimed to map the location of the adenosine receptor subtypes in adult wild-type zebrafish retina using in situ hybridization and immunohistochemistry. A1R, A2AR, and A2BR mRNA were detected in the ganglion cell layer (GCL), the inner nuclear layer (INL), the outer nuclear layer (ONL), and the outer segment (OS). A3R mRNA was detected in the GCL, ONL, and OS. A1R-immunoreactivity was expressed as puncta in the INL and in the outer plexiform layer (OPL). A1Rs were located within the cone pedicle and contiguous to horizontal cell tips in the OPL. A2AR-immunoreactivity was expressed as puncta in the GCL, inner plexiform layer (IPL), INL, and outer retina. A2AR puncta in the outer retina were situated around the ellipsoids and nuclei of cones, and weakly around the rod nuclei. A1Rs and A2ARs were clustered around ON cone bipolar cell terminals and present in the OFF lamina of the INL but were not expressed on mixed rod/cone response bipolar cell terminals. A2BR-immunoreactivity was mainly localized to the Müller cells, while A3Rs were found to be expressed in retinal ganglion cells of the GCL, INL, ONL, and OS. In summary, all four adenosine receptor subtypes were localized in the zebrafish retina and are in agreement with expression patterns shown in retinas from other species.

中文翻译：

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成年斑马鱼视网膜中腺苷受体的表达。

腺苷是中枢神经系统中作用于腺苷受体的内源性核苷。这些是G蛋白偶联受体，具有四个已知的亚型：A1，A2A，A2B和A3受体。在本研究中，我们旨在使用原位杂交和免疫组织化学技术绘制成年野生型斑马鱼视网膜中腺苷受体亚型的位置。在神经节细胞层（GCL），内核层（INL），外核层（ONL）和外段（OS）中检测到A1R，A2AR和A2BR mRNA。在GCL，ONL和OS中检测到A3R mRNA。A1R免疫反应性在INL和外丛状层（OPL）中以点表示。A1R位于圆锥形椎弓根内，并与OPL中的水平细胞尖端相邻。A2AR免疫反应性在GCL中表示为点 内部网状层（IPL），INL和外部视网膜。视网膜外侧的A2AR突点位于椭球和视锥核周围，而在视杆核周围较弱。A1R和A2ARs聚集在ON锥双极细胞末端周围，并存在于INL的OFF层中，但在混合的杆/锥应答双极细胞末端上不表达。A2BR免疫反应性主要位于Müller细胞，而A3Rs在GCL，INL，ONL和OS的视网膜神经节细胞中表达。总之，所有四个腺苷受体亚型都位于斑马鱼的视网膜中，并且与其他物种的视网膜中显示的表达模式一致。A1R和A2ARs聚集在ON锥双极细胞末端周围，并存在于INL的OFF层中，但在混合的杆/锥响应双极细胞末端上不表达。A2BR免疫反应性主要位于Müller细胞，而A3Rs在GCL，INL，ONL和OS的视网膜神经节细胞中表达。总之，所有四个腺苷受体亚型都位于斑马鱼的视网膜中，并且与其他物种的视网膜中显示的表达模式一致。A1R和A2ARs聚集在ON锥双极细胞末端周围，并存在于INL的OFF层中，但在混合的杆/锥应答双极细胞末端上不表达。A2BR免疫反应性主要位于Müller细胞，而A3Rs在GCL，INL，ONL和OS的视网膜神经节细胞中表达。总之，所有四个腺苷受体亚型都位于斑马鱼的视网膜中，并且与其他物种的视网膜中显示的表达模式一致。