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A 5-HT2 receptor mediates serotonin-induced electrolyte transport in rat left colon

A Siriwardena1, J M Kellum

  • 1Division of General & Trauma Surgery, Medical College of Virginia, Virginia Commonwealth University, Richmond 23284.

The Journal of Surgical Research
|September 1, 1993
PubMed

Insights

Serotonin (5-hydroxytryptamine, 5-HT) triggers intestinal secretion by acting on a specific mucosal receptor. This research identifies the 5-HT2 receptor as key in mediating serotonin

Area of Science:

  • Gastroenterology
  • Pharmacology
  • Molecular Biology

Background:

  • Serotonin (5-hydroxytryptamine, 5-HT) is a key mediator of diarrhea in carcinoid syndrome.
  • The precise mechanisms underlying serotonin-induced intestinal secretion are not fully understood.

Purpose of the Study:

  • To investigate if serotonin stimulates electrolyte transport via direct action on mucosal receptors.
  • To elucidate the specific serotonin receptor subtype involved in intestinal secretion.

Main Methods:

  • Utilized rat left colon flat sheet preparations in flux chambers to study serotonin-induced electrolyte transport.
  • Measured short-circuit current and ion movement (sodium and chloride) in response to serotonin.
  • Employed selective serotonin receptor antagonists (ketanserin for 5-HT2, and others for 5-HT1 and 5-HT3) to identify receptor involvement.

Main Results:

  • Serotonin induced a concentration-dependent increase in short-circuit current, indicating stimulated electrolyte transport.
  • The 5-HT2 antagonist ketanserin significantly inhibited serotonin's effect on electrolyte transport, with a pA2 value of 7.7.
  • Serotonin's action involved inhibiting both sodium and chloride movement from mucosa to serosa.
  • 5-HT1 and 5-HT3 antagonists did not affect serotonin-induced electrolyte transport.

Conclusions:

  • A 5-HT2 receptor located near the colonic mucosa plays a crucial role in regulating serotonin-stimulated intestinal electrolyte transport.
  • This finding provides insight into the pathophysiology of carcinoid syndrome-related diarrhea and potential therapeutic targets.

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