Canatoxin triggers histamine secretion from rat peritoneal mast cells

Canatoxin, a toxic protein present in the seeds ofCanavalia ensiformis, induces the secretion of serotonin, dopamine and insulin through activation of the lipoxygenase pathway. The purpose of the present study was to verify if canatoxin causes histamine release from rat peritoneal mast cells and to perform a detailed study of this phenomenon. Our results indicate that canatoxin is capable of activating mast cells to release histamine. The process is time- and concentration-dependent, occurs without cell damage and requires metabolic energy as well as the presence of divalent cations (Ca²⁺ and Mg²⁺). Optimal release occurs at 37°C and at physiological pH. Extremes of temperature (0°C and 45°C) inhibit the process. We conclude that canatoxin induces histamine release from rat peritoneal mast cells by an active secretory process.