Changes in duodenal mast cells in response to dehydroleucodine.

Dehydroleucodine (DhL), a sesquiterpene lactone isolated from Artemisia douglasiana Besser, prevents gastroduodenal damage elicited by necrosis-inducing agents such as absolute ethanol. Changes in the number of mast cells or evidence of activation of the cells for mediator release have been observed in a wide spectrum of disease processes involving the gastrointestinal tract. In the present study we examined the effects of DhL on duodenal mast cell population and their histamine content, with the goal of throwing more light on the mechanism of action of the drug. Male Rockland mice (n = 30) were divided into two groups and administered orally with 0.4% carboxymethylcellulose (CMC; control group) or DhL in 0.4% CMC, 40 mg/kg body weight (DhL group). The animals were killed 60 min after dosing and their duodena were removed. Mucosal and submucosal mast cells were studied by light and electron microscopy, and the duodenal histamine content was measured by high-performance liquid chromatography. DhL increased the number of mast cells in the submucosal layer. This was related to an increase in the tissue histamine levels (from 324 +/- 19.14 to 1,284 +/- 20 pg/mg tissue, in controls and DhL-treated, respectively). The mast cells in the submucosa from the control group showed a cytoplasm containing a predominant population of homogenously dense granules, and the DhL-treated group exhibited swollen granules showing different degrees of particulation. The mucosal mast cell population showed no modifications in response to the cytoprotective agent. DhL induces (1) a selective increase in the number of mast cells in the submucosal layer and (2) changes in the distribution and appearance of their secretory granules. These findings, probably associated with the higher histamine levels after DhL treatment, could be involved in the cytoprotective action of the lactone, previously reported by us.