Inhibitory effect of acteoside on melittin-induced catecholamine exocytosis through inhibition of Ca2+-dependent phospholipase A(2) and extracellular Ca2+ influx in PC12 cells

Abstract

To investigate the inhibitory effect of acteoside on the process of exocytosis induced by melittin, we measured Ca2+ mobilization, arachidonic acid (AA) release and catecholamine exocytosis in PC12 chromaffin cells. Melittin significantly increased the intracellular Ca2+ mobilization via receptor-operated calcium channel but not the intracellular Ca2+ release. It caused AA release via activation of Ca2+-dependent phospholipase A(2) (PLA(2)) and catecholamine secretion in a dose-dependent manner. Acteoside dose-dependently inhibited the release of AA and intracellular Ca2+ mobilization induced by melittin. Acteoside reduced the catecholamine release and raised the amount of intracellular chromogranin A which is co-released with catecholamine from melittin-stimulated PC12 cells. Taken together, our results suggest that acteoside could suppress the exocytosis via inhibition of Ca2+-dependent PLA(2) and extracellular Ca2+ influx in PC12 cells stimulated by melittin.