Characterization of somatostatin-like immunoreactivity in vertebrate retinas.

Large differences in retinal concentration of somatostatin-like immunoreactivity (SLI) were observed even among closely related species. Hog and chicken retinas, like those of goldfish and frog described previously, contained roughly equal amounts of SLI coeluting with somatostatin tetradecapeptide (S14) and octacosapeptide (S28) on Sephadex G 50 chromatography. In contrast, virtually all of the SLI from rat retina coeluted with S14, and nearly all of the bovine retinal SLI coeluted with S28. These species differences may reflect differences in post-translational processing of the various molecular forms of retinal SLI.