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Endogenous adenosine differentially modulates 5-hydroxytryptamine release from a human enterochromaffin cell model
Fievos L Christofi1, Minsoo Kim, Jacqueline E Wunderlich
1Department of Anesthesiology, The Ohio State University, Columbus 43210, USA.
Gastroenterology
|July 6, 2004
Summary
Adenosine receptors influence serotonin release in carcinoid cells. Endogenous adenosine release is key for gut mechanosensory reflexes, impacting serotonin (5-HT) levels and calcium signaling.
Area of Science:
- Gastroenterology
- Neuroscience
- Cellular Biology
Background:
- Human carcinoid BON cells and tumors express adenosine receptors.
- Adenosine signaling plays a role in cellular functions within the gut.
Purpose of the Study:
- To investigate the role of adenosine receptors in modulating cAMP, intracellular calcium ([Ca(2+)](i)), and serotonin (5-HT) release in human carcinoid BON cells.
- To understand the impact of adenosine receptor activation and blockade on 5-HT release and calcium signaling.
Main Methods:
- Adenosine receptor (R) mRNA, proteins, and function were analyzed using Western blots and immunofluorescent labeling.
- Intracellular calcium ([Ca(2+)](i)) imaging was performed using Fluo-4/AM.
- Pharmacologic and physiologic techniques were employed to assess receptor function and 5-HT release.
Main Results:
- A1, A2, and A3 adenosine receptors were detected in BON cells and carcinoid tumors.
- Adenosine deaminase, A2R activation, and A3R inhibition increased baseline 5-HT, while A3R activation decreased it.
- A2R antagonists or blockade of adenosine reuptake reduced mechanically evoked 5-HT release; touch-evoked [Ca(2+)](i) responses were augmented by adenosine deaminase and A1/A3R antagonists.
Conclusions:
- Tonic and mechanically evoked release of endogenous adenosine are critical for differential adenosine receptor activation.
- Adenosine receptor modulation of 5-HT release and calcium signaling has significant implications for gut mechanosensory reflexes.
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