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N Brecha, A Vila, J Allen; Somatostatin Subtype Receptor 4 Expression in Mouse and Rat Retina . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2768.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Somatostatin (SRIF) in the rat and mouse retina is expressed by sparsely occurring amacrine and displaced amacrine cells. Their processes are mainly distributed to laminae 1 and 5 of the inner plexiform layer (IPL). SRIF influences neuronal activity by interacting with five somatostatin receptors, which are G-protein-coupled receptors. We characterized the expression and cellular localization of the somatostatin subtype receptor 4 (sst4) in mouse and rat retina. Methods: Rat and mouse retinas were fixed with 4% paraformaldehyde and processed for immunohistochemistry using an affinity-purified antibody to the C-terminus of sst4. Antibody specificity was evaluated by immunostaining with the sst4 antibody preabsorbed with 10-6M C-terminus sst4 peptide fragment and by immunostaining of retinas from mice with a homozygous deletion of the sst4 gene. Results: Specific sst4 immunoreactivity was localized to numerous multistratified processes in all regions of the IPL and processes in the axon layer and to medium and large cell bodies in the ganglion cell layer. Immunoreactivity was localized to the plasma membrane and cytoplasm. Immunostaining was not observed in the optic nerve or central nervous system nuclei that receive retinal ganglion cell projections. Immunostaining was not observed in sections incubated with sst4 antibodies preabsorbed with sst4 C-terminus peptide and in homozygous mice lacking sst4. Conclusion: These findings show that the sst4 is mainly localized to the dendrosomatic compartment of multistratified ganglion cells. These observations are consistent with an earlier report of sst4 mRNA in cells located in the ganglion cell layer. The difference in the distribution of SRIF- and sst4-immunoreactive processes supports the hypothesis that this peptide acts in a paracrine manner to influence multiple cell types distributed throughout the retina.
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