抄録
AMPA type glutamate receptor (AMPA-R) trafficking is thought to be one of the underlying bases of synaptic plasticity in cerebellum, however, detailed characteristics of AMPA-R trafficking has not yet been revealed. We have reported several characteristics of constitutive endocytosis of AMPA receptors in parallel fiber (PF) synapse in cerebellar Purkinje cell (PC) by means of Tetanus Toxin (TeTX) infusion. Recent studies have reported that activity of PF-PC synapse shows bidirectional plasticity, LTP or LTD, through the postsynaptic Ca2+ concentration, and that Nitric oxide (NO) produces induction for LTP in PF-PC synapse postsynaptically, through cGMP-PKG independent pathways. We therefore examined the role of NO on constitutive trafficking of AMPA-R in cerebellar Purkinje cell. Whole-cell voltage clamp recordings were made from a Purkinje cell held at -70 mV in cerebellar sagittal slice (300 μm). Bath-application of NO donor, both NOC-7 (5 μM, half life = 5 min) and NOR3 (30 μM, half life = 30 min), induced 50-60% potentiation of PF-evoked EPSCs amplitude. Intracellular infusion of TeTX suppressed this potentiation of PF-evoked EPSCs amplitude. These results suggest that NO-induced potentiation of PF-evoked EPSCs amplitude is caused by enhancement of surface-expressed AMPA-R number through exocytosis. [Jpn J Physiol 55 Suppl:S152 (2005)]
