Guinea pig 5-HT transporter: cloning, expression, distribution, and function in intestinal sensory reception.
Studies of the guinea pig small intestine have suggested that serotonin (5-HT) may be a mucosal transmitter that stimulates sensory nerves and initiates peristaltic and secretory reflexes. We tested the hypothesis that guinea pig villus epithelial cells are able to inactivate 5-HT because they express the same 5-HT transporter as serotonergic neurons. A full-length cDNA, encoding a 630-amino acid protein (89.2% and 90% identical, respectively, to the rat and human 5-HT transporters) was cloned from the guinea pig intestinal mucosa. Evidence demonstrating that this cDNA encodes the guinea pig 5-HT transporter included 1) hybridization with a single species of mRNA ( approximately 3.7 kb) in Northern blots of the guinea pig brain stem and mucosa and 2) uptake of [3H]5-HT by transfected HeLa cells via a saturable, high-affinity (Michaelis constant 618 nM, maximum velocity 2.4 x 10(-17) mol . cell-1 . min-1), Na+-dependent mechanism that was inhibited by chlorimipramine > imipramine > fluoxetine > desipramine > zimelidine. Expression of the 5-HT transporter in guinea pig raphe and enteric neurons and the epithelium of the entire crypt-villus axis was demonstrated by in situ hybridization and immunocytochemistry. Inhibition of mucosal 5-HT uptake potentiates responses of submucosal neurons to mucosal stimulation. The epithelial reuptake of 5-HT thus appears to be responsible for terminating mucosal actions of 5-HT.
Department of Anatomy and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
J X
JX
Chen
H
H
Pan
T P
TP
Rothman
P R
PR
Wade
M D
MD
Gershon
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport / Q000187:drug effects; D001933:Brain Stem / Q000378:metabolism / Q000502:physiology; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D002997:Clomipramine / Q000494:pharmacology; D003001:Cloning, Molecular; D018076:DNA, Complementary; D003891:Desipramine / Q000494:pharmacology; D005473:Fluoxetine / Q000494:pharmacology; D006168:Guinea Pigs; D006367:HeLa Cells; D006801:Humans; D007099:Imipramine / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism / Q000502:physiology*; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000378:metabolism; D010528:Peristalsis; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D012701:Serotonin / Q000378:metabolism; D050486:Serotonin Plasma Membrane Transport Proteins; D014158:Transcription, Genetic; D015031:Zimeldine / Q000494:pharmacology
D002352:Carrier Proteins; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; C493232:Slc6a4 protein, rat; D005473:Fluoxetine; D012701:Serotonin; D015031:Zimeldine; D002997:Clomipramine; D007099:Imipramine; D003891:Desipramine