Gastrin stimulates gastric mast cells in rabbits

In a previous study we demonstrated that in human gastric mucosa tryptase was localized only in mast cells and that its levels were correlated with serum gastrin, suggesting a link between gastrin action and mucosal mast cell function. The aim of the present study was to discover whether pentagastrin injection could stimulate gastric mucosal mast cells in rabbits. Ten female rabbits (group S) were injected s.c. with pentagastrin (10 mu g/kg); another group of ten animals (group C) was injected s.c. with an equal volume of saline solution. One hour after the injection the rabbits were sacrificed and their stomachs removed. Antrum (A), corpus (C) and fundus (F) mucosal homogenates were assayed for total protein, tryptase, pepsinogen A (PGA), histamine and gastrin. Histamine tissue levels were significantly lower in group S than in group C in the antrum (Mann-Whitney test: U = 82, P < 0.01) and in the corpus (U = 83, P < 0.005). Tryptase levels were significantly higher in group S than in group C in all gastric areas (antrum: U = 95, P < 0.001; corpus: U = 85, P < 0.005 and fundus: U = 75, P < 0.05). Total protein, PGA and gastrin did not vary significantly between groups. In group C, no significant correlations were found among the five parameters. In group S, corpus tryptase was correlated with fundus tryptase (Spearman's r = 0.831, P < 0.01). The same relationship was observed for histamine (r = 0.672, P < 0.05). In group S, antrum gastrin was inversely correlated with antrum tryptase (r = -0.903, P < 0.001), and with corpus PGA (r = -0.806, P < 0.05). This study demonstrates that bolus pentagastrin administration stimulates gastric mucosal mast cells in the rabbit.