1. Naoya Okada Asahikawa Medical college 4th year student
Pathway to the vagus through the sensory nerve with 5HT3-receptor in the colon
Naoya Okada
Asahikawa Medical college 4th year student

2. Backgrounds
stress
CRF
DMV
Stress induces colonic transit increasing, which is mediated by CRF through vagus.( Monnikes et Al, AJP G , 1992)
<serosa>
<Ach>
Colon activated
Smooth
Muscle
<mucosa>

3. GI transit accelerated!!
Background
2. Stress significantly increases gastorointestinal transit via the 5HT3-receptor (Miyata et al. JPET,1992 )
stress ?
5HT3 release
with 5HT3-receptor
GI transit accelerated!!
However, the involvement of 5HT3-receptor is not well established in way of CRF-induced acceleration of colonic transit.

4. Background
DMV
<with 5HT3-receptor>
5HT3
3. 5HT3 released from EC cells increase colonic transit via 5HT3-receptor through vagus. (Fukumoto et al. AJP 284 R , 2003)
<sensory nerve>
<with 5HT3-receptor>
<5HT3 >
However, there may be another pathway.
<serosa>
<Ach>
Smooth
Muscle
<mucosa>
ECcell

5. Aim Pathway to the vagus through the sensory nerve with 5HT3-receptor
stress
CRF
<sensory nerve>
<with 5HT3-receptor>
<Ach>
5HT3
DMV
Pathway to the vagus through the sensory nerve with 5HT3-receptor
<serosa>
<Ach>
Colon activated
Smooth
Muscle
<mucosa>
ECcell

6. Design
CRF
DMV
<sensory nerve>
<with 5HT3-receptor>
<Ach>
5HT3
block!
If 5HT3-receptor antagonist inhibits high colonic transit by CRF
<serosa>
block!
Colon activated
<Ach>
Smooth
Muscle
block!
<mucosa>
ECcell

7. Methods
1st. Alosetron (dose:10-5 M×0.5cc) or saline intraluminal injection
2nd. CRF (dose:1μg/5μl ) intracerebraventricular injection
3rd. 51Cr intraluminal injection
4th. Sacrifice->measurement of transit
Alosetron or
Saline
CRF
51Cr
Sacrifice
10m
10m
90m

8. How to inject intraluminally
Cannulation into the ascending colon

9. Methods
1st. Alosetron (dose:10-5 M×0.5cc) or saline intraluminal injection
2nd. CRF (dose:1μg/5μl ) intracistrnal injection
3rd. 51Cr intraluminal injection
4th. Sacrifice->measurement of transit
Alosetron or
Saline
CRF
51Cr
Sacrifice
10m
10m
90m

10. Results
CRF significantly increased G.C.

11. Results
A pathway via 5HT3-receptor through vagus exists.

12. Results
Alosetron siginificantly inhibited G.C. increase

13. Conclusion
Alosetron significantly inhibits the colonic transit which is activated by CRF I.C.
->sensory nerves with 5HT3-receptors mediate colonic response to CRF I.C.
There might be a pathway to the vagus through sensory nerves with 5HT3-receptors!?

14. THE END