Distribution of somatostatin receptor type 2 in the rat: immunohistochemical study

Somatostatin receptor type 2 (SSTR-2) was identified immunohistochemically in the rat tissues using specific antipeptide antiserum raised in New Zealand white rabbits immunized with a conjugate of synthetic SSTR-2 peptide (31-41) with bovine serum albumin. Immunohistochemical analysis was performed by avidin-biotin complex method. SSTR-2 immunoreactivity was visualized in the central nervous system and anterior pituitary thus supporting previous investigations of SSTR-2 distribution using in vitro autoradiographic ligand binding. Significant stain was detected in neural perikarya, axons and dendrites as well as in many cells of retina, adrenal medulla, gastric and duodenal mucosa, Auerbach's nervous branch and Meíssner's nervous branch of the stomach, small intestine and colon. When using antiserum preincubated with synthetic SSTR-2 peptide (31- 41) or rat anterior pituitary homogenate which contains SSTR-2 peptide, no significant stain of the anterior pituitary or neurons in the hypothalamus was detected. These findings suggest that SSTR-2 is widely distributed and that the method used is valuable in studying the distribution of SSTR-2 in rats.