抄録
In the literature, synaptic vesicle endocytosis has been attributed to three pathways: (1) kiss-and-run, (2) rapid endocytosis and (3) classical (clathrin-mediated) endocytosis. To examine endocytic pathways of superior cervical ganglion (SCG) neurons in long-term culture, we tested effects of endocytic inhibitors on synaptic transmission induced by various synaptic activities. QVPSRPNRAP (P4), a peptide of dynamin interacting with amphiphysin 1 inhibits clathrin-mediated endocytosis. Dynasore inhibits not only clathrin-mediated endocytosis but also other compensatory synaptic vesicle endocytosis. P4 introduced into the presynaptic neuron showed no change in the EPSP amplitudes evoked by paired action potentials (APs) with the interval of 20-2000 ms. However, P4 reduced EPSP amplitudes during repetitive firing at 5, 10, 20 and 30 Hz for 2 sec and slowed down the recovery after a train of APs at 5 Hz for 5 min. P4 gradually reduced the amplitude of EPSPs evoked by longer repetitive firing, even low frequency at 0.2 Hz for 60 min. Control scrambled peptide showed no reduction. Dynasore remarkably reduced EPSP amplitudes with various pattern of stimulation. These findings suggest that use-dependent endocytic pathways are induced in cultured presynaptic SCG neurons. [J Physiol Sci. 2008;58 Suppl:S123]
