Protective function of extrinsic sensory neurons in acute rabbit experimental colitis.

BACKGROUND/AIMS: Sensory nerves appear to have a protective effect against acute injury in the gastric mucosa. Their function in the intestine is unclear.

METHODS

In this study an immune-complex model of colitis was used to induce inflammation in the distal colon with and without functional ablation of sensory neurons by capsaicin pretreatment.

RESULTS

Colitis was more severe in the capsaicin-pretreated group than in the vehicle group 48 and 96 hours after induction of colitis. Neutrophil infiltration, expressed as inflammatory index, was significantly increased to 4.25 +/- 0.4 vs. 1.83 +/- 0.5 at 48 hours and to 2.66 +/- 0.6 vs. 1.65 +/- 0.3 at 96 hours in the capsaicin group and the vehicle group, respectively. The microscopic ulcer index also was significantly increased in the capsaicin-pretreated group compared with the vehicle group (63.3 +/- 10.6 vs. 3.3 +/- 2.4 at 48 hours, 20.0 +/- 8.4 vs. 1.5 +/- 1.1 at 96 hours). Immunoreactive substance P (SP) and calcitonin gene-related peptide (CGRP) contents were decreased in extracts of inflamed compared with uninflamed colon.

CONCLUSIONS

These data suggest that sensory neurons have a protective role in an acute rabbit model of experimental colitis by release of sensory neuropeptides (SP, CGRP), which may modulate vascular tone and mucosal blood flow.