Distribution of somatostatin-28 (1-12) immunoreactivity in the diencephalon and the brainstem of the dog

The term somatostatin refers to a family of peptides, mainly somatostatin-1 4, somatostatin-28 and somatostatin-28 (1-12), which are the cleavage produ cts of a single 116 amino acid-long preprosomatostain molecule. The product ion of antibodies to these peptides allows their localization in a number o f neuronal populations throughout the entire neuroaxis in many mammals. The dog has been pointed out as an extremely useful animal model for studying age-related cognitive dysfunction and other neuronal changes associated wit h aging in which somatostatin appears to be involved. However, only very sc anty information is available with regard to the distribution of somatostat in in the brain of the dog. In the present work we have determined the patt ern of the distribution of somatostatin-28 (1-12) immunoreactivity in the d iencephalon and the brainstem of the dog, High to moderate densities of lab eled perikarya were: found in the anterior periventricular and arcuate hypo thalamic nuclei, the reticular thalamic nucleus, in delimited parts of the nucleus of the brachium inferior colliculus, the retrorubral area, the dors al raphe nucleus, the myelencephalic reticular formation and the dorsal mot or nucleus of the vagus. Less dense population of somatostatin cells were l ocalized in other diencephalic and brainstem nuclei. The distribution of la beled fibers was even broader as in addition to those above mentioned there were a number of areas that appeared devoid of labeled perikarya. Many of the findings were similar to those reported in earlier works while others u nderlined the existence of inconsistencies in the distribution pattern of t his peptide in the brain of mammals.