Galanin receptors in the rat gastrointestinal tract

Abstract

Galanin functions are mediated by three distinct G-protein-coupled receptors, galanin receptor 1 (GalR1), GalR2 and GalR3, which activate different intracellular signaling pathways. Here, we quantified mRNA levels of GalR1, GalR2 and GalR3 in the gastrointestinal tract using real time RT-PCR. GalR1 and GalR2 mRNAs were detected in all segments with the highest levels in the large intestine and stomach, respectively. GalR3 mRNA levels were quite low and mostly confined to the colon. We also investigated the effect of galanin 1-16, which has high affinity for GalR1 and GalR2 and low affinity for GalR3 on depolarization-evoked Ca 2+ increases in rat cultured myenteric neurons using Ca 2+ -imaging. Intracellular Ca 2+ changes in myenteric neurons were monitored using the Ca 2+ sensitive dye, fluo-4, and confocal microscopy. Galanin 1-16 (1 µM) markedly inhibited the K + -evoked Ca 2+ increases in myenteric neurons. In summary, the differential distribution of GalRs supports the hypothesis that the complex effects of galanin in the gastrointestinal tract result from the activation of multiple receptor subtypes. Furthermore, this study confirms the presence of functional GalRs and suggests that galanin modulates transmitter release from myenteric neurons through inhibition of voltage-dependent calcium channels involving a G i/o -coupled GalR.

Common genetic variants in GAL, GAP43 and NRSN1 and interaction networks confer susceptibility to Hirschsprung disease

“…Galanin encoded by GAL is a neuroendocrine peptide, which is widely expressed in the central and peripheral nervous systems and also the gastrointestinal tract . Additionally, galanin modulates transmitter release from myenteric neurons via inhibition of voltage‐dependent calcium channels mediated by G‐protein‐coupled receptors . A recent genomewide study suggested GAL as a candidate for HSCR due to the reduced level of GAL expression in HSCR group compared with control group, and our results further supported this opinion.…”

Protective role of μ opioid receptor activation in intestinal inflammation induced by mesenteric ischemia/reperfusion in mice

“…Expression of β‐actin (an endogenous internal control gene) was measured in parallel for every sample, and the data obtained for μOR, TNF‐α, and IL‐10 were normalized to those of the β‐actin. Relative quantities (RQ) of mRNA were analyzed using the comparative threshold cycle (Ct) method (Livak and Schmittgen,2001; Anselmi et al,2005).…”

bHLH proneural genes as cell fate determinants of entero-endocrine cells, an evolutionarily conserved lineage sharing a common root with sensory neurons

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