ABSTRACT
FS390, a novel microbial metabolite from Streptomyces spp. was identified as a small molecular substance and shown a inhibition activities for the release of neurotransmitter from rat hippocampal neuron and PC12 cells. FS390 is an inhibitor of trifiated norepinephrine ([3H]-NE) release in high K+ buffer solution containing ionomycin, indicating that FS390 inhibits neurotransmitter release after the influx of Ca2+ ions. When examined the effect of FS390 on beta-glucuronidase release from guinea pig neurophils, FS390 inhibited beta-glucuronidas release: when treated with 5 microgram/mL of FS390, which was not induced cellular cytotoxicity. The fact that the beta-glucuronidase release in neutrophil and norepinephrine release in neuron was inhibited suggests the similarity in the locations and the mechanisms of FS390 action targets. When treated with 5 microgram/mL of FS390, [3H]-NE release and neurite extension for both rat hippocampal neurons and PC12 cells were prevented. These observations of FS390 functioning as an inhibitor of neurotransmitter release suggest that FS390 has an important role in synaptic transmission in neuron.