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Serotonin availability in rat colon is reduced during a Western diet model of obesity
- Source :
- American Journal of Physiology-Gastrointestinal and Liver Physiology. 303:G424-G434
- Publication Year :
- 2012
- Publisher :
- American Physiological Society, 2012.
-
Abstract
- Constipation and slowed transit are associated with diet-induced obesity, although the mechanisms by which this occurs are unclear. Enterochromaffin (EC) cells within the intestinal epithelium respond to mechanical stimulation with the release of serotonin [5-hydroxytryptamine (5-HT)], which promotes transit. Thus our aim was to characterize 5-HT availability in the rat colon of a physiologically relevant model of diet-induced obesity. EC cell numbers were determined immunohistochemically in chow-fed (CF) and Western diet-fed (WD) rats, while electrochemical methods were used to measure mechanically evoked (peak) and steady-state (SS) 5-HT levels. Fluoxetine was used to block the 5-HT reuptake transporter (SERT), and the levels of mRNA for tryptophan hydroxylase 1 and SERT were determined by quantitative PCR, and SERT protein was determined by Western blot. In WD rats, there was a significant decrease in the total number of EC cells per crypt (0.86 ± 0.06 and 0.71 ± 0.05 in CF and WD, respectively), which was supported by a reduction in the levels of 5-HT in WD rats (2.9 ± 1.0 and 10.5 ± 2.6 μM at SS and peak, respectively) compared with CF rats (7.3 ± 0.4 and 18.4 ± 3.4 μM at SS and peak, respectively). SERT-dependent uptake of 5-HT was unchanged, which was supported by a lack of change in SERT protein levels. In WD rats, there was no change in tryptophan hydroxylase 1 mRNA but an increase in SERT mRNA. In conclusion, our data show that foods typical of a WD are associated with decreased 5-HT availability in rat colon. Decreased 5-HT availability is driven primarily by a reduction in the numbers and/or 5-HT content of EC cells, which are likely to be associated with decreased intestinal motility in vivo. © 2012 the American Physiological Society.
- Subjects :
- Male
Serotonin
medicine.medical_specialty
Colon
Physiology
Crypt
Stimulation
Tryptophan Hydroxylase
Biology
Diet, High-Fat
Reuptake
Rats, Sprague-Dawley
Western blot
In vivo
Fluoxetine
Physiology (medical)
Internal medicine
Enterochromaffin Cells
medicine
Animals
Obesity
RNA, Messenger
Serotonin Plasma Membrane Transport Proteins
Gastroenterology & Hepatology
Hepatology
medicine.diagnostic_test
Gastroenterology
Intestinal epithelium
Rats
Diet
Endocrinology
Enterochromaffin cell
Gastrointestinal Motility
Constipation
5-hydroxytryptamine
constipation
electrochemistry
diet-induced obesity
serotonin reuptake transporter
Subjects
Details
- ISSN :
- 15221547 and 01931857
- Volume :
- 303
- Database :
- OpenAIRE
- Journal :
- American Journal of Physiology-Gastrointestinal and Liver Physiology
- Accession number :
- edsair.doi.dedup.....c6bb3d8a1fba8c9fec1b6db698faaef3