The enteric nervous system plays an integral role in the gastrointestinal tract. Within this intricate network, enteric glia are crucial in the maintenance of normal bowel function, yet their signaling mechanisms are poorly understood. Enteric glia, and not enteric neurons, selectively responded to lysophosphatidic acid (LPA), a product of phosphatidylcholine metabolism, with dose-dependent calcium (Ca2+) signaling over a range from 100 pM to 10 μM. The elicited calcium transients involved both the mobilization of intracellular Ca2+ stores and the influx of extracellular Ca 2+ as LPA signals were obliterated following the depletion of intracellular Ca2+ and attenuated by the removal of Ca2+ from the perfusion buffer. Pretreatment with pertussis toxin (100 ng/ml) reduced the magnitude of LPA Ca2+ transients (95±20 nM vs 168±17 nM for controls). Repetitive exposure yielded diminished responsiveness, with a 25% reduction in [Ca2+]i between first and second exposures. Inhibition of the inositol 1,4,5-trisphosphate (IP3) receptor with 200 μM 2-aminoethoxydiphenylborate (2APB) abolished LPA signals. RT-PCR analysis demonstrated the presence of two LPA-coupled endothelial differentiation gene (EDG) receptor mRNAs (EDG-2 and EDG-7) in myenteric plexus primary cultures. EDG-2 expression in glial cells of the ENS was confirmed immunocytochemically.
|Original language||English (US)|
|Number of pages||7|
|State||Published - 2004|
Bibliographical noteFunding Information:
This research was supported by the National Institutes of Health (DK41204 and accompanying Minority Supplemental Grant, and Systems & Integrative Biology training grant GM08322-11) and by a pre-doctoral fellowship from the Horace Rackham School of Graduate Studies, University of Michigan.
- EDG receptors
- Enteric nervous system