Somatostatin and somatostatin subtype 2A expression in the mammalian retina

✍ Scribed by Juliette Johnson; Dennis W. Rickman; Nicholas C. Brecha

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 467 KB
• Volume: 50
• Category: Article
• ISSN: 1059-910X
• DOI: 10.1002/1097-0029(20000715)50:2<103::aid-jemt2>3.0.co;2-x

✦ Synopsis

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.