INVESTIGATING the release mechanism of nerve growth factor (NGF) the possible cooperation of SNAREs (target (t)-and vesicular (v)-soluble NSF attachment protein receptors) which form a fusion core during docking of synaptic vesicles at the plasma membrane was examined. Cleavage of those proteins by clostridium toxins shows that SNAP-25 (synaptic vesicle associated protein) and syntaxin are involved but not synaptobrevin 2. α-Latrotoxin, which effects the release of neurotransmitters by acting on the fusion core, also induces Ca2+-independent NGF release. Taken together, the results indicate the formation of a fusion core during regulated NGF release and implicate the existence of NGF vesicles.