Expression of galanin receptor messenger RNAs in different regions of the rat gastrointestinal tract.

Galanin effects are mediated by three G-protein-coupled receptors: galanin receptor 1 (GalR1), GalR2 and GalR3. We quantified mRNA levels of GalR1, GalR2 and GalR3 in the rat stomach, small and large intestine using real-time RT-PCR. All three GalR mRNAs were detected throughout the gut at different levels. GalR1 and GalR2 mRNA levels were higher in the large than in the small intestine. GalR2 mRNA was most abundant in the stomach. GalR3 mRNA levels were generally quite low. The differential regional distribution of GalRs suggests that the complex effects of galanin in the gut are the result of activating multiple receptor subtypes, whose density, subtype and signaling vary along the gastrointestinal tract.