Johnson J, Rickman D W, Brecha N C
Department of Ophthalmology, UCSF, San Francisco, California, USA.
Microsc Res Tech. 2000 Jul 15;50(2):103-11. doi: 10.1002/1097-0029(20000715)50:2<103::AID-JEMT2>3.0.CO;2-X.
This review discusses the expression and cellular localization of the neuropeptide somatostatin (SRIF) and one of the SRIF subtype (sst) receptors, sst(2A) in the mammalian retina. SRIF immunoreactivity is predominantly localized to a sparse population of amacrine and displaced amacrine cells in the ganglion cell layer in several mammalian retinas including the rat, rabbit, cat, and primate. These cells, characterized by multiple processes, form a sparse network in the inner plexiform layer (IPL) in all retinal regions. Very few processes are also in the outer plexiform layer. In contrast to the predominant distribution of SRIF processes to the IPL, there is a widespread distribution of sst(2A) immunoreactivity to both the inner and outer retina in all mammalian retinas studied to date. In rabbit retina, sst(2A) immunoreactivity is predominant in rod bipolar cells and in sparse wide-field amacrine cells. In the rat retina, sst(2A) immunoreactivity is localized to several neuronal cell types-cone photoreceptors, horizontal cells, rod and cone bipolar cells, and amacrine cells. Reverse-transcriptase-polymerase chain reaction analysis found that sst(2A) mRNA is expressed in the rat retina, while sst(2B) mRNA is not detected. Finally, in the primate retina sst(2) immunoreactivity is predominant in cone photoreceptors, with additional immunostained cell bodies and processes in the inner retina. These findings indicate that SRIF may modulate several neuronal cell types in the retina, and that it has a broad influence on both scotopic and photopic visual pathways.
本综述讨论了神经肽生长抑素（SRIF）及其亚型之一的生长抑素（sst）受体sst(2A)在哺乳动物视网膜中的表达和细胞定位。在包括大鼠、兔子、猫和灵长类动物在内的几种哺乳动物视网膜中，SRIF免疫反应性主要定位于神经节细胞层中稀疏的无长突细胞和移位无长突细胞群体。这些细胞具有多个突起，在所有视网膜区域的内网状层（IPL）中形成稀疏网络。在外网状层中也有极少的突起。与SRIF突起主要分布于IPL不同，迄今为止在所有研究的哺乳动物视网膜中，sst(2A)免疫反应性在内视网膜和外视网膜中均有广泛分布。在兔视网膜中，sst(2A)免疫反应性在视杆双极细胞和稀疏的宽视野无长突细胞中占主导。在大鼠视网膜中，sst(2A)免疫反应性定位于几种神经元细胞类型——视锥光感受器、水平细胞、视杆和视锥双极细胞以及无长突细胞。逆转录-聚合酶链反应分析发现大鼠视网膜中表达sst(2A) mRNA，而未检测到sst(2B) mRNA。最后，在灵长类动物视网膜中，sst(2)免疫反应性在视锥光感受器中占主导，在内视网膜中还有额外的免疫染色细胞体和突起。这些发现表明SRIF可能调节视网膜中的几种神经元细胞类型，并且对暗视觉和明视觉通路都有广泛影响。
