The influence of bovine casein-derived exorphins on mast cells in rodents

Abstract

The secretagogue effects of α-casein (90–95) and β-casomorphin-7 on two populations of mast cells in rodents were investigated. Mast cells of “connective tissue type” were obtained from rat peritoneal cavity (PMC), and “mucosal-like type” mast cells (BMMC) were cultured from mouse bone marrow cells. β-Hexosaminidase activity was considered to be a marker of the cells’ secretory response. No reaction of BMMC on exorphins was found at up to millimolar concentrations. β-Casomorphin-7 and α-casein (90–95) exert secretagogue effect on PMC at milli- and micromolar concentrations, respectively. For this reason, further experiments were performed with α-casein (90–95) only. The PMC were activated in a non-cytotoxic, dose-, temperature-, and energy-dependent manner. Although PMC were responsive in a calcium and magnesium free buffer, the reaction was abolished when preincubation with EDTA was performed. Preincubation with opiate antagonist, naloxone, was effective only at millimolar concentration range. The significant decrease in PMC reactivity to α-casein (90–95) after preincubation with benzalkonium chloride suggests a peptidergic pathway of activation which involves a membrane-assisted but receptor-independent stimulation of G i-like proteins.