NADPH-diaphorase colocalization with somatostatin receptor subtypes sst2A and sst2B in the retina

PURPOSE. TO investigate the differential localization of somatotropin relea se-inhibitory factor (SRIF) receptor subtypes (sst2A and sst2B) and their p ossible colocalization with reduced nicotinamide adenine dinucleotide phosp hate (NADPH)-diaphorase in the rat and rabbit retina. METHODS. Polyclonal antibodies raised against sst2A and sst2B receptors wer e applied to 10- to 14-mum cryostat sections of rat and rabbit retinas fixe d in paraformaldehyde. NADPH-diaphorase reactivity was assessed histochemic ally. Double labeling was performed for sst2A or sst2B receptors with NADPH -diaphorase, and with markers for the cell types present in the retina (pro tein kinase C [PKC], tyrosine hydroxylase; [TH], calbindin, and recoverin). RESULTS. SSt2A immunoreactivity was detected in rod bipolar cells and coloc alized with NADPH-diaphorase in the rabbit, but not the rat, retina, sst2B was present only in photoreceptor cells of the rat and colocalized with NAD PH-diaphorase. CONCLUSIONS. These results suggest that SRIF, acting through sst2A receptor s in bipolar cells and sst2B receptors in photoreceptor cells, may affect n itric oxide function in the rabbit and rat retina.