A dual role of 5-hydroxytryptamine receptor 3 in serotonin induced ion transport in rat distal colon.
5-hydroxytryptamine (5-HT)-evoked intestinal secretion can be divided into neural and non-neural pathway. Recently, 5-HT(3) receptor in neural pathway received much attention as a possible target in bowel diseases. The present study aims to investigate the effects of 5-HT(3) receptor in different enteric neural plexus (myenteric plexus and submucosal plexus) on rat colonic ion transport by using rat intact colon and mucosa/submucosa preparations. Ussing chamber and real-time PCR techniques were performed in our present study. Surprisingly, we found that in mucosa/submucosa preparations, 5-HT-induced DeltaI(SC) (change in short-circuit current) was not inhibited, but further increased by pretreatment with 5-HT(3) receptor antagonists, MDL72222 and Tropanyl-3, 5-dimethylbenzoate. And this response was significantly attenuated in the presence of tetrodotoxin (TTX). Conversely, in rat intact colon, 5-HT(3) receptor antagonists significantly inhibited 5-HT-induced DeltaI(SC). The results from real-time PCR proved the existence of 5-HT(3) receptor in muscularis externa and submucosa. Taken together, 5-HT(3) receptors possess a role of dual regulation on electrolyte secretion in rat distal colon, the neural stimulatory effect of 5-HT(3) receptor in myenteric plexus and the inhibitory effect of 5-HT(3) receptor in submucosal plexus.
Yang
Ning
N
Department of Physiology, School of Basic Medical Sciences, Capital Medical University, Beijing (100069), People's Republic of China.
Tian
Yue-Min
YM
Zhang
Xiao-Hui
XH
Zheng
Li-Fei
LF
Xue
Hong
H
Chen
Xin
X
Zhu
Lin
L
Zhu
Jin-Xia
JX
D000818:Animals; D003106:Colon / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D017615:Enteric Nervous System / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D007419:Intestinal Secretions / Q000378:metabolism*; D017136:Ion Transport / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044406:Receptors, Serotonin, 5-HT3 / Q000235:genetics / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D058831:Serotonin 5-HT3 Receptor Antagonists; D012702:Serotonin Antagonists / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors; D014326:Tropanes / Q000494:pharmacology
D012333:RNA, Messenger; D044406:Receptors, Serotonin, 5-HT3; D058831:Serotonin 5-HT3 Receptor Antagonists; D012702:Serotonin Antagonists; D014326:Tropanes; D012701:Serotonin; D013779:Tetrodotoxin; C042253:bemesetron