Development and sequels of intestinal inflammation in nematode-infected rats: Role of mast cells and capsaicin-sensitive afferents

Objectives: To determine whether intestinal mast cells and capsaicin-sensit ive afferent nerves are involved in the development and sequels of Nippostr ongylus brasiliensis-induced intestinal inflammation in rats. Methods: Two series of experiments were performed. In the first series, six groups of 8 rats were used to study the effects of mast cell stabilization by ketotifen . In the second series, six groups of 6 rats were used to study the effects of gut extrinsic sensory neuron depletion by capsaicin, For each series, f our groups of rats were infected with N. brasiliensis and two groups were n ot infected. Results: Infection with N. brasiliensis resulted in an increas e of myeloperoxidase (MPO) activity and mast cell numbers at day 12 postinf ection; MPO returned to preinfection levels by day 35 while mast cell numbe rs remained elevated at that time. In ketotifen-treated infected rats, the increase of MPO at day 12 was less pronounced, but MPO activity remained el evated and mast cell numbers were increased at day 35. In capsaicin-treated infected rats, the MPO increase at day 12 was augmented, and MPO was still not returned to preinfection values by day 35; in contrast, the increase o f mast cell numbers at days 12 and 35 was not modified by afferent nerve de pletion. Conclusion: Mast cell stabilization decreased jejunal inflammation during the acute stage (day 12), but prolonged the inflammatory process un til at least day 35 postinfection. The data also confirmed the protective r ole of gut extrinsic sensory neurons against intestinal inflammation in a m odel of nematode infection and revealed that these afferent nerves do not s eem crucial for the development of nematode-induced hypermastocytosis. Copy right (C) 2001 S. Karger AG, Basel.