NMDAR-mediated EPSCs are maintained and accelerate in time course during maturation of mouse and rat auditory brainstem in vitro.

摘要: NMDA receptors (NMDARs) mediate a slow EPSC at excitatory glutamatergic synapses throughout the brain. In many areas magnitude of NMDAR-mediated declines with development and is associated changes in subunit composition, but mature channel composition often unknown. We have employed calyx Held terminal its target, principal neuron medial nucleus trapezoid body (MNTB), to examine during synapse maturation from P10 P40. Our data show that has reached state by around P18. The amplitude (and dominant decay τ) fell 5 nA (τ: 40–50 ms) P10/11 0.3–0.5 10–15 NMDAR-EPSC showed no sensitivity ifenprodil, indicating lack NR2B subunits, block submicromolar concentrations zinc, consistent NR1-1b expression. Additionally, P11 P18 there was reduction voltage-dependent apparent dissociation constant for [Mg2+]o (Ko) changed 7.5 14 mm. Quantitative PCR relative expression NR2A NR2C increased, while immunohistochemistry confirmed presence NR2A, protein. Although small, it well coupled NO signalling, as indicated DAR-4M imaging. conclude native NMDAR channels fast time course reduced [Mg2+]o, dominance subunits functional exclusion subunits. pharmacology suggests single type we postulate NMDARs consist heterotrimers NR1-1b–NR2A–NR2C.