Function, expression, and characterization of the serotonin transporter in the native human intestine

Ravinder K. Gill, Nitika Pant, Seema Saksena, Amika Singla, Talat M. Nazir, Lisa Vohwinkel, Jerrold R. Turner, Jay Goldstein, Waddah A. Alrefai, Pradeep K. Dudeja

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

The enteric serotonin transporter (SERT) plays a critical role in modulating serotonin availability and thus has been implicated in the pathogenesis of various intestinal disorders. To date, SERT expression and function in the human intestine have not been investigated. Current studies were designed to characterize the function, expression, distribution, and membrane localization of SERT in the native human intestine. Real-time PCR studies showed relatively higher SERT mRNA expression in the human small intestine compared with colon (ileum ≫ duodenum ≫ jejunum). Northern blot analysis revealed three mRNA hybridizing species encoding SERT (3.0, 4.9, and 6.8 kb) in the human ileum. Consistent with SERT mRNA expression, SERT immunostaining was mainly detected in the epithelial cells of human duodenal and ileal resected tissues. Notably, SERT expression was localized predominantly to the apical and intracellular compartments and was distributed throughout the crypt-villus axis. Immunoblotting studies detected a prominent protein band (∼70 kDa) in the ileal apical plasma membrane vesicles (AMVs) isolated from mucosa obtained from organ-donor intestine. Functional studies showed that uptake of [ 3H]serotonin (150 nM) in human ileal AMVs was 1) significantly increased in the presence of both Na+ and Cl-; 2) inhibited (∼50%) by the neuronal SERT inhibitor, fluoxetine (10 μM) and by unlabeled 5-HT; and 3) exhibited saturation kinetics indicating the presence of a carrier-mediated process. Our studies demonstrated differential expression of SERT across various regions of the human intestine and provide evidence for the existence of a functional SERT capable of removing intraluminal serotonin in human ileal epithelial cells.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume294
Issue number1
DOIs
StatePublished - Dec 1 2007

Fingerprint

Serotonin Plasma Membrane Transport Proteins
Population Groups
Intestines
Serotonin
Ileum
Messenger RNA
Epithelial Cells
Cell Membrane
Fluoxetine
Jejunum
Duodenum
Immunoblotting
Northern Blotting
Small Intestine
Real-Time Polymerase Chain Reaction
Colon
Mucous Membrane
Tissue Donors

Keywords

  • Serotonin transporter expression
  • Serotonin uptake

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

Cite this

Function, expression, and characterization of the serotonin transporter in the native human intestine. / Gill, Ravinder K.; Pant, Nitika; Saksena, Seema; Singla, Amika; Nazir, Talat M.; Vohwinkel, Lisa; Turner, Jerrold R.; Goldstein, Jay; Alrefai, Waddah A.; Dudeja, Pradeep K.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 294, No. 1, 01.12.2007.

Research output: Contribution to journalArticle

Gill, Ravinder K. ; Pant, Nitika ; Saksena, Seema ; Singla, Amika ; Nazir, Talat M. ; Vohwinkel, Lisa ; Turner, Jerrold R. ; Goldstein, Jay ; Alrefai, Waddah A. ; Dudeja, Pradeep K. / Function, expression, and characterization of the serotonin transporter in the native human intestine. In: American Journal of Physiology - Gastrointestinal and Liver Physiology. 2007 ; Vol. 294, No. 1.
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