Related Experiment Videos
Sensory pathways and cyclooxygenase regulate mucus gel thickness in rat duodenum
Y Akiba1, O Furukawa, P H Guth
1CURE: Digestive Diseases Research Center, Department of Medicine, School of Medicine, University of California, Los Angeles, California 90073, USA.
American Journal of Physiology. Gastrointestinal and Liver Physiology
|February 15, 2001
Summary
Acid challenges trigger duodenal mucus thickening via capsaicin-sensitive nerves and prostaglandins. This pathway involves calcitonin gene-related peptide (CGRP) and nitric oxide, crucial for regulating duodenal mucus gel thickness.
Area of Science:
- Gastroenterology
- Neurogastroenterology
- Physiology
Background:
- The duodenal hyperemic response to acid involves capsaicin-sensitive nerves releasing calcitonin gene-related peptide (CGRP) and nitric oxide.
- The role of these neural pathways in regulating duodenal mucus gel thickness remains unclear.
Purpose of the Study:
- To investigate whether capsaicin-sensitive afferent nerves and associated vasodilatory substances regulate duodenal mucus gel thickness.
- To determine the role of cyclooxygenase (COX) activity in this process.
Main Methods:
- In vivo optical measurement of duodenal gel thickness in anesthetized rats.
- Administration of capsaicin, bradykinin, PGE(2), and acid (pH 2.2) with or without antagonists/inhibitors (capsazepine, CGRP-(8-37), N(G)-nitro-L-arginine methyl ester, indomethacin).
- Sensory deafferentation via capsaicin pretreatment.
Main Results:
- Acid, bradykinin, capsaicin, and PGE(2) all increased duodenal mucus gel thickness.
- Inhibition of vanilloid/CGRP receptors, nitric oxide synthase, or sensory deafferentation delayed gel thickening.
- Indomethacin abolished gel thickening induced by acid, bradykinin, and capsaicin, indicating essential cyclooxygenase activity.
Conclusions:
- Capsaicin-sensitive neural pathways, involving CGRP and nitric oxide, mediate an initial increase in duodenal mucus gel thickness.
- Cyclooxygenase activity is essential for the regulation of duodenal gel thickness by acid and other agonists.
- Duodenal afferent nerves modulate COX-mediated control of mucus gel thickness.