The role of 5-HT3 and 5-HT4 receptors in the adaptive mechanism of colonic transit following the parasympathetic denervation in rats.
BACKGROUND
Clinical studies show that disturbed colonic motility induced by extrinsic nerves damage is restored over time. We studied whether 5-HT3 and 5HT4 receptors are involved in mediating the adaptive mechanisms following parasympathetic denervation.


METHODS
Parasympathetic denervation of the entire colon was achieved by bilateral pelvic nerve transection and truncal vagotomy in rats. Colonic transit was measured by calculating the geometric center (GC) of 51Cr distribution. Expression of 5-HT3 and 5HT4 receptor mRNA was determined by real time RT-PCR.


RESULTS
Parasympathetic denervation caused a significant delay in colonic transit (GC=4.36) at postoperative day (POD) 1, compared with sham operation (GC=6.31). Delayed transit was gradually restored by POD 7 (GC=5.99) after the denervation. Restored colonic transit was antagonized by the administration of 5-HT3 and 5HT4 receptors antagonists at POD 7. 5-HT3 and 5HT4 receptors mRNA expression were significantly increased in the mucosal/submucosal layer at POD 3 or POD 7, whereas no significant difference was observed in the longitudinal muscle layers adherent with the myenteric plexus (LMMP).


CONCLUSIONS
It is suggested that up-regulation of 5-HT3 and 5-HT4 receptors expression in the mucosal/submucosal layer is involved to restore the delayed transit after the parasympathetic denervation in rats.
Tong
Weidong
W
Department of Surgery, Medical College of Wisconsin and Zablocki VA Medical Center, Milwaukee, Wisconsin 53295, USA.
Kamiyama
Yoichi
Y
Ridolfi
Tim J
TJ
Zietlow
Aaron
A
Zheng
Jun
J
Kosinski
Lauren
L
Ludwig
Kirk
K
Takahashi
Toku
T
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D003106:Colon / Q000294:innervation* / Q000502:physiology; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D007413:Intestinal Mucosa / Q000294:innervation / Q000502:physiology; D008297:Male; D009197:Myenteric Plexus / Q000502:physiology; D009416:Nerve Regeneration / Q000502:physiology; D017764:Parasympathectomy; D010275:Parasympathetic Nervous System / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044406:Receptors, Serotonin, 5-HT3 / Q000235:genetics / Q000502:physiology*; D044422:Receptors, Serotonin, 5-HT4 / Q000235:genetics / Q000502:physiology*; D058831:Serotonin 5-HT3 Receptor Antagonists / Q000494:pharmacology; D058832:Serotonin 5-HT4 Receptor Antagonists / Q000494:pharmacology; D015854:Up-Regulation / Q000502:physiology
D012333:RNA, Messenger; D044406:Receptors, Serotonin, 5-HT3; D058831:Serotonin 5-HT3 Receptor Antagonists; D058832:Serotonin 5-HT4 Receptor Antagonists; D044422:Receptors, Serotonin, 5-HT4