Somatostatin mRNA and molecular forms during development of the rat retina

The developmental control of rat retinal somatostatin (SS) expression was determined by Northern blot hybridization. The amount of SS transcript is higher than adult levels at embryonic day 16 and declines during late prenatal development. This pattern parallels the developmental expression of somatostatin immunoreactivity. The expression of somatostatin-immunoreactive peptide products using gel filtration chromatography was determined over the same period. Three molecular weight forms occur during development: a high m.wt. product and two smaller peptides which migrate with somatostatin-28 (SS28) and somatostatin-14 (SS14). SS14 is the peptide that predominates at all developmental time points, and is the only form detectable in the adult retina. The transient prenatal increase of somatostatin message and peptide suggests a role for this peptide in the developing retina.