Johnson J, Wong H, Walsh J H, Brecha N C
Department of Neurobiology, UCLA School of Medicine, Los Angeles, California 90095, USA.
J Comp Neurol. 1998 Mar 30;393(1):93-101. doi: 10.1002/(sici)1096-9861(19980330)393:1<93::aid-cne9>3.0.co;2-l.
In the retina, somatostatin influences neuronal activity likely by acting at one or more somatostatin subtype (sst) receptors. Somatostatin and somatostatin-binding sites are distributed predominantly to the inner retina. The present study has investigated the cellular expression of one of the sst receptors, the sst2A receptor isoform, in the rabbit retina. These studies have used a new polyclonal antibody directed to the predicted C-terminus of mouse sst2A(361-369) receptor. Antibody specificity was tested by preadsorption of the primary antibody with a peptide corresponding to sst2A(361-369). sst2A Receptor immunoreactivity was localized mainly to the plasma membrane of rod bipolar cells and to sparsely occurring, wide-field amacrine cells. Immunostaining in rod bipolar cells was strongest in the axon and axon terminals in lamina 5 of the inner plexiform layer (IPL) and was weakest in the cell body and dendrites. Double-labeling experiments using a monoclonal antibody against protein kinase C (PKC; alpha and beta), a rod bipolar cell-selective marker, showed complete colocalization. In horizontal sections of retina, immunostained bipolar cell bodies had a dense distribution, which is in agreement with the reported distribution of rod bipolar cell bodies. Immunoreactive amacrine cell bodies were located at the border of the inner nuclear layer and the IPL, and thin varicose processes ramified mainly in laminae 2 and 4 of the IPL. These observations indicate that somatostatin influences visual information processing in the retina 1) by acting presynaptically on rod bipolar cell axon terminals and b) by influencing the activity of sparsely occurring amacrine cells.
在视网膜中，生长抑素可能通过作用于一种或多种生长抑素亚型（sst）受体来影响神经元活动。生长抑素和生长抑素结合位点主要分布在内层视网膜。本研究调查了兔视网膜中一种sst受体——sst2A受体亚型的细胞表达情况。这些研究使用了一种针对小鼠sst2A(361 - 369)受体预测C末端的新型多克隆抗体。通过用与sst2A(361 - 369)对应的肽预吸附一抗来测试抗体特异性。sst2A受体免疫反应性主要定位于视杆双极细胞的质膜以及稀疏分布的广域无长突细胞。视杆双极细胞中的免疫染色在神经纤维层（IPL）第5层的轴突和轴突终末最强，在细胞体和树突中最弱。使用针对蛋白激酶C（PKC；α和β）的单克隆抗体进行的双重标记实验，PKC是视杆双极细胞的选择性标记物，结果显示完全共定位。在视网膜水平切片中，免疫染色的双极细胞体分布密集，这与报道的视杆双极细胞体分布一致。免疫反应性无长突细胞体位于内核层和IPL的边界，细的曲张突起主要在IPL的第2层和第4层分支。这些观察结果表明，生长抑素通过1）突触前作用于视杆双极细胞轴突终末以及2）影响稀疏分布的无长突细胞的活动来影响视网膜中的视觉信息处理。
