The antibody has a proven strong indirect immunofluorescent staining at a 1/400-1/800 dilution and strong Biotin-Streptavidin/HRP staining at a 1/1000-1/2000 dilution in rat hypothalamus (median eminence). The specificity of the antiserum was examined by soluble pre-adsorption with the peptides in question at a final concentration of 106M. Somatostatin immunolabeling was completely abolished by pre-adsorption with somatostatin, somatostatin 25, and somatostatin 28. Pre-adsorption with the following peptides resulted in no reduction of immunostaining: substance P, amylin, glucagon, insulin, neuropeptide Y, and VIP.