SOMATOSTATIN-28(1-12)-LIKE IMMUNOREACTIVITY IN THE RAT

The distribution of the newly characterized peptide somatostatin-28(1-12) was determined in rat tissues using a radioimmunoassay in which the immune plasma is directed against the C-terminus of the dodecapeptide. In the CNS, somatostatin-28(1-12)-like immunoreactivity is highly concentrated in the hypothalamus and the amygdala. In the digestive system, the highest levels of immunoreactivity are found in the stomach, the pancreas and the colon. The immunoreactive material measured in different tissues is heterogenous; in addition to the dodecapeptide, 2 N-terminally extended somatostatin-28(1-12) peptides of 4400 and 8000 MW are also detected by the immune plasma. The dodecapeptide itself usually accounts for the majority (66-75%) of the total somatostatin-28(1-12)-like immunoreactivity present in those tissues.