Abstract
In the central neuronal system, the synaptic strength changes dynamically, thereby playing pivotal roles in switching neuronal circuits. Despite a wealth of information accumulating on postsynaptic regulatory mechanisms, much less is known on the presynaptic mechanism, primarily because of small nerve terminal structures preventing direct electrophysiological approaches. The calyx of Held is a giant glutamatergic nerve terminal, which is visible in auditory brainstem slices, and allows one to address various questions on mechanisms operating in the presynaptic nerve terminal. In this talk, I'd like to present our recent results obtained using this preparation, with a particular focus upon presynaptic voltage-gated calcium channels (VGCCs). Facilitation and inactivation of presynaptic VGCCs contribute to dynamic changes in synaptic strength during high-frequency transmission, via modulating the probability of transmitter release. In addition, our results have revealed an unexpected role of the presynaptic VGCC, anchoring synaptic proteins involved in clathrin-coated synaptic vesicle endocytosis. Disruption of this interaction blocked endocytosis, as deduced from capacitance measurements. Thus, presynaptic VGCCs seem to play critical roles in both exocytosis and endocytosis of synaptic vesicles at the mammalian central synapse. [J Physiol Sci. 2007;57 Suppl:S3]
