J Neurogastroenterol Motil.  2010 Jul;16(3):281-290.

The Role of Peripheral Cannabinoid Receptors Type 1 in Rats With Visceral Hypersensitivity Induced by Chronic Restraint Stress

• Shen L
• Yang XJ
• Qian W
• Hou XH

Abstract

BACKGROUND/AIMS
This study was designed to investigate the possibility that the enhanced nociceptive responsiveness associated with canabonoid type 1 receptors (CB1Rs) and identify its role in mediating visceral hypersensitivity induced by chronic restraint stress.
METHODS
Rats were exposed to daily partial restraint stress or sham partial restraint stress with intraperitoneal injection of the vehicle, CB1R agonist or antagonist for 4 consecutive days. We tested the visceromotor reflex to colorectal distention at day 0 and 5. Reverse-transcription polymerase chain reaction and Western blot were used to assess the expression of CB1Rs.
RESULTS
Intraperitoneal CB1 agonist (ACEA) injection significantly diminished (p < 0.05) the enhanced visceromotor reflex to colorectal distention at day 5 in stressed rats. Change in electromyogram response after ACEA over baseline, at pressure of 40 mmHg (+13.3 +/- 2.2), 60 mmHg (+15.3 +/- 2.8) and 80 mmHg (+17.0 +/- 4.0) were much lower than in the control animals, which were +35.9 +/- 5.1, +41.1 +/- 6.3 and +54.1 +/- 9.6, respectively. Whereas, CB1 antagonist (SR141716A) had an opposite effect. Compared with control group, the change in electromyogram response after SR141716A over baseline was significantly enhanced (p < 0.05) for the distending pressure of 40 mmHg (+56.0 +/- 10.3), 60 mmHg (+74.6 +/- 12.3) and 80 mmHg (+82.9 +/- 11.0), respectively. Reverse-transcription polymerase chain reaction and Western blotting demonstrated the stress-induced up-regulation of colon CB1Rs (p < 0.05).
CONCLUSIONS
Our results suggest there is a key contribution of peripheral CB1Rs involved in the maintenance of visceral hyperalgesia after repeated restraint stress, providing a novel mechanism for development of peripheral visceral sensitization.

Keyword

Irritable bowel syndrome; Receptor, Cannabinoid, CB1; Stress disorders; Hyperalgesia

MeSH Terms

Animals
Blotting, Western
Colon
Hyperalgesia
Hypersensitivity
Injections, Intraperitoneal
Irritable Bowel Syndrome
Negotiating
Piperidines
Polymerase Chain Reaction
Pyrazoles
Rats
Receptor, Cannabinoid, CB1
Receptors, Cannabinoid
Reflex
Salicylamides
Up-Regulation
Piperidines
Pyrazoles
Receptor, Cannabinoid, CB1
Receptors, Cannabinoid
Salicylamides