The Effects of Serotonin Receptor Antagonists on Contraction and Relaxation Responses Induced by Electrical Stimulation in the Rat Small Intestine

Farzaneh Farajian Mashhadi, Robert J. Naylor, Farideh A. Javid

Research output: Contribution to journalArticle

Abstract

Background: The main source of 5-HT in body is in enterchromafin cells of intestine, different studies mentioned different roles for endogenous 5-HT and receptors involved and it is not clearified the mechanism of action of endogenous 5-HT. Objectives: To study the role of endogenous 5-HT on modulation of contraction and relaxation responses induced by electrical field stimulation (EFS) in different regions of the rat intestine. Materials and Methods: Segments taken from the rat duodenum, jejunum, mid and terminal ileum were vertically mounted, connected to a transducer and exposed to EFS with different frequencies in the absence and presence of various inhibitors of enteric mediators i. e. specific 5-HT receptor antagonists. Results: EFS-induced responses were sensitive to TTX and partly to atropine, indicating a major neuronal involvement and a cholinergic system. Pre-treatment with WAY100635 (a 5-HT1A receptor antagonist) and granisetron up to 10.0 ?M, GR113808 (a 5-HT4 receptor antagonist), methysergide and ritanserin up to 1.0 ?M, failed to modify responses to EFS inall examined tissues. In the presence of SB258585 1.0 ?M (a 5-HT6 receptor antagonist) there was a trend to enhance contraction in the proximal part of the intestine and reduce contraction in the distal part. Pre-treatment with SB269970A 1.0 ?M (5-HT7 receptor antagonist) induced a greater contractile response to EFS at 0.4 Hz only in the duodenum. Conclusions: The application of 5-HT1A, 5-HT2, 5-HT3, 5-HT4, 5-HT6 and 5-HT7 receptor antagonists, applied at concentrations lower than 1.0 ?M did not modify the EFS-induced contraction and relaxation responses, whichsuggests the unlikely involvement of endogenous 5-HT in mediating responses to EFS in the described test conditions. Keywords: Electric Stimulation Therapy; Serotonin 5-HT1 Receptor Antagonists; Intestine, Small
LanguageEnglish
Pagese18311
JournalGene Cell Tissue
Volume1
Issue number1
Publication statusPublished - 1 Apr 2014

Fingerprint

Serotonin Antagonists
Electric Stimulation
Small Intestine
Serotonin
Serotonin 5-HT1 Receptor Antagonists
Intestines
Serotonin Receptors
Duodenum
Serotonin 5-HT4 Receptor Antagonists
Receptors, Serotonin, 5-HT4
Ritanserin
Granisetron
Electric Stimulation Therapy
Methysergide
Receptor, Serotonin, 5-HT1A
Jejunum
Transducers
Atropine
Ileum
Cholinergic Agents

Cite this

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title = "The Effects of Serotonin Receptor Antagonists on Contraction and Relaxation Responses Induced by Electrical Stimulation in the Rat Small Intestine",
abstract = "Background: The main source of 5-HT in body is in enterchromafin cells of intestine, different studies mentioned different roles for endogenous 5-HT and receptors involved and it is not clearified the mechanism of action of endogenous 5-HT. Objectives: To study the role of endogenous 5-HT on modulation of contraction and relaxation responses induced by electrical field stimulation (EFS) in different regions of the rat intestine. Materials and Methods: Segments taken from the rat duodenum, jejunum, mid and terminal ileum were vertically mounted, connected to a transducer and exposed to EFS with different frequencies in the absence and presence of various inhibitors of enteric mediators i. e. specific 5-HT receptor antagonists. Results: EFS-induced responses were sensitive to TTX and partly to atropine, indicating a major neuronal involvement and a cholinergic system. Pre-treatment with WAY100635 (a 5-HT1A receptor antagonist) and granisetron up to 10.0 ?M, GR113808 (a 5-HT4 receptor antagonist), methysergide and ritanserin up to 1.0 ?M, failed to modify responses to EFS inall examined tissues. In the presence of SB258585 1.0 ?M (a 5-HT6 receptor antagonist) there was a trend to enhance contraction in the proximal part of the intestine and reduce contraction in the distal part. Pre-treatment with SB269970A 1.0 ?M (5-HT7 receptor antagonist) induced a greater contractile response to EFS at 0.4 Hz only in the duodenum. Conclusions: The application of 5-HT1A, 5-HT2, 5-HT3, 5-HT4, 5-HT6 and 5-HT7 receptor antagonists, applied at concentrations lower than 1.0 ?M did not modify the EFS-induced contraction and relaxation responses, whichsuggests the unlikely involvement of endogenous 5-HT in mediating responses to EFS in the described test conditions. Keywords: Electric Stimulation Therapy; Serotonin 5-HT1 Receptor Antagonists; Intestine, Small",
author = "Mashhadi, {Farzaneh Farajian} and Naylor, {Robert J.} and Javid, {Farideh A.}",
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The Effects of Serotonin Receptor Antagonists on Contraction and Relaxation Responses Induced by Electrical Stimulation in the Rat Small Intestine. / Mashhadi, Farzaneh Farajian; Naylor, Robert J.; Javid, Farideh A.

In: Gene Cell Tissue, Vol. 1, No. 1, 01.04.2014, p. e18311.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The Effects of Serotonin Receptor Antagonists on Contraction and Relaxation Responses Induced by Electrical Stimulation in the Rat Small Intestine

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AU - Naylor, Robert J.

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N2 - Background: The main source of 5-HT in body is in enterchromafin cells of intestine, different studies mentioned different roles for endogenous 5-HT and receptors involved and it is not clearified the mechanism of action of endogenous 5-HT. Objectives: To study the role of endogenous 5-HT on modulation of contraction and relaxation responses induced by electrical field stimulation (EFS) in different regions of the rat intestine. Materials and Methods: Segments taken from the rat duodenum, jejunum, mid and terminal ileum were vertically mounted, connected to a transducer and exposed to EFS with different frequencies in the absence and presence of various inhibitors of enteric mediators i. e. specific 5-HT receptor antagonists. Results: EFS-induced responses were sensitive to TTX and partly to atropine, indicating a major neuronal involvement and a cholinergic system. Pre-treatment with WAY100635 (a 5-HT1A receptor antagonist) and granisetron up to 10.0 ?M, GR113808 (a 5-HT4 receptor antagonist), methysergide and ritanserin up to 1.0 ?M, failed to modify responses to EFS inall examined tissues. In the presence of SB258585 1.0 ?M (a 5-HT6 receptor antagonist) there was a trend to enhance contraction in the proximal part of the intestine and reduce contraction in the distal part. Pre-treatment with SB269970A 1.0 ?M (5-HT7 receptor antagonist) induced a greater contractile response to EFS at 0.4 Hz only in the duodenum. Conclusions: The application of 5-HT1A, 5-HT2, 5-HT3, 5-HT4, 5-HT6 and 5-HT7 receptor antagonists, applied at concentrations lower than 1.0 ?M did not modify the EFS-induced contraction and relaxation responses, whichsuggests the unlikely involvement of endogenous 5-HT in mediating responses to EFS in the described test conditions. Keywords: Electric Stimulation Therapy; Serotonin 5-HT1 Receptor Antagonists; Intestine, Small

AB - Background: The main source of 5-HT in body is in enterchromafin cells of intestine, different studies mentioned different roles for endogenous 5-HT and receptors involved and it is not clearified the mechanism of action of endogenous 5-HT. Objectives: To study the role of endogenous 5-HT on modulation of contraction and relaxation responses induced by electrical field stimulation (EFS) in different regions of the rat intestine. Materials and Methods: Segments taken from the rat duodenum, jejunum, mid and terminal ileum were vertically mounted, connected to a transducer and exposed to EFS with different frequencies in the absence and presence of various inhibitors of enteric mediators i. e. specific 5-HT receptor antagonists. Results: EFS-induced responses were sensitive to TTX and partly to atropine, indicating a major neuronal involvement and a cholinergic system. Pre-treatment with WAY100635 (a 5-HT1A receptor antagonist) and granisetron up to 10.0 ?M, GR113808 (a 5-HT4 receptor antagonist), methysergide and ritanserin up to 1.0 ?M, failed to modify responses to EFS inall examined tissues. In the presence of SB258585 1.0 ?M (a 5-HT6 receptor antagonist) there was a trend to enhance contraction in the proximal part of the intestine and reduce contraction in the distal part. Pre-treatment with SB269970A 1.0 ?M (5-HT7 receptor antagonist) induced a greater contractile response to EFS at 0.4 Hz only in the duodenum. Conclusions: The application of 5-HT1A, 5-HT2, 5-HT3, 5-HT4, 5-HT6 and 5-HT7 receptor antagonists, applied at concentrations lower than 1.0 ?M did not modify the EFS-induced contraction and relaxation responses, whichsuggests the unlikely involvement of endogenous 5-HT in mediating responses to EFS in the described test conditions. Keywords: Electric Stimulation Therapy; Serotonin 5-HT1 Receptor Antagonists; Intestine, Small

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