DISTRIBUTION OF SOMATOSTATIN RECEPTOR MESSENGER-RNAS IN THE RAT GASTROINTESTINAL-TRACT

Background & Aims: The gastrointestinal (Gl) tract is a major source a nd target of somatostatin (SRIF), Recently, five pharmacologically dif ferent SRIF receptors (sst1-5) were cloned. The cellular and tissue di stribution of the sst1-5 messenger RNAs (mRNAs) were studied in the ra t Gl tract using in situ hybridization histochemistry (ISHH). Methods: Two sets of S-35-Uridine triphosphate (UTP)-labeled antisense and sen se riboprobes were prepared for each sst. ISHH was conducted on frozen tissue samples from rat stomach, duodenum, jejunum, ileum, colon, and pancreas, Results: mRNAs of all five sst-s are widely expressed in th e rat Gl tract. The distribution pattern for each sst mRNA was identic al with both antisense probes, No specific signal was found with any o f the sense probes. Each layer of the different parts of the gut expre ssed mRNAs of multiple sst subtypes, All organs expressed sst3 mRNA ve ry intensely, The lowest levels of mRNA expression for all five subtyp es within the GI tract were found in the pancreas, Conclusions: The wi despread expression of sst mRNAs suggests a significant: role for SRIF in the regulation of Gl function.