Effect of NMDA receptor ligands on mast cell histamine release, a reappraisal

Natural polyamines have been proposed to induce histamine release from mast cells through a direct interaction with G proteins. Alternatively, the pol yamine binding site of ionotropic N-methyl-D-aspartate (NMDA) receptors has been suggested as a target for spermine on mast cells. We reexamined both hypotheses. Incubation of Int peritoneal mast cells with spermine resulted in a concentration-dependent histamine release (EC50 270 mu M). Incubation with NMDA receptor agonists. glutamate or NMDA, associated to the co-agonis t glycine. did not induce secretion. Western blot experiments did not revea l NMDA R1, R2a, R2b or R2c subunit expression in rat peritoneal mast cell m embranes. The NMDA receptor antagonist at the glycine site, L-689,560, did not modify, at relevant concentrations, the spermine-induced secretion. The NMDA receptor antagonists, ifenprodil and LY 235959, and the NMDA channel blocker, MK801, slightly inhibited, at high concentrations, the secretory e ffect of spermine. The polyamine arcaine, an antagonist of the NMDA recepto r polyamine binding site, induced histamine secretion (EC50 350 mu M). Both spermine- and arcaine-induced effects were independent upon extracellular calcium and were largely inhibited by treatment of mast cells with pertussi s toxin or benzalkonium chloride. The response to spermine and arcaine was prevented by the hydrolysis of sialic acid residues of the cell surface by neuraminidase, and was restored by permeabilization of the plasma membrane with streptolysine-O, indicating that polyamines act intracellularly. These results confirm the involvement of pertussis toxin-sensitive G proteins in the secretory effect of polyamines and demonstrate the absence of NMDA rec eptors on rat peritoneal mast cells. Nonselective effects of some NMDA rece ptor ligands on mast cells cannot be excluded.