sst1 mRNA is the prominent somatostatin receptor mRNA in the rat gastrointestinal tract: reverse transcription polymerase chain reaction and in situ-hybridization study

The inhibitory peptide hormone somatostatin and its receptors (sst1-sst5) r egulate many physiological functions in the gastrointestinal tract. In an a ttempt to correlate the various effects of somatostatin in gastrointestinal physiology to individual sst subtypes sst1-sst5, mRNAs have been localized by semiquantitative reverse transcription polymerase chain reaction amplif ication and in situ hybridization of sst1 and sst3 in the rat alimentary tr act. sst1-sst4 mRNAs were found throughout the gastrointestinal tract, sst1 mRNA being more abundant than sst2 and much more abundant than sst3 and ss t4 mRNAs. sst5 transcripts were at the detection threshold, sst1 and sst3 m RNAs are present in enterocytes and enteric neurons suggesting a role of th ese subtypes in the somatostatin-mediated inhibition of acetylcholine relea se from myenteric neurons and of secretomotor neuron activity in the submuc ous plexus. The presence of sst3 mRNA in smooth muscle cells points to an a dditional role of this receptor in regulating gut motility. (C) 1999 Harcou rt Publishers Ltd.