Identification method and electrophysiological evaluation of cerebellum-projecting anteromedial nucleus neurons by retrograded fluorescence probe

Objective To explore sufficient ways to identify the anteromedial nucleus (MVNs) neurons that project to the cerebellum and evaluate their activity. Methods Retrograde fluorescence probe injection techniques were in vivo applicated to MVNs neurons that project to the cerebellum, neutral red staining was used to determine cell survival time, electrophysiological characteristics by whole cell patch clamp technique were recorded between retrograde labeled anteromedial nucleus neurons projecting to the cerebellum (CPMVNs) and unlabeled MVNs. Results Typical electrophysiological characteristics of retrograde labeled CPMVNs, including spontaneous firing frequency, membrane potential, excitatory presynaptic glutamate afferent and inhibitory postsynaptic gamma aminobutyric acid (GABA) ergic afferent showed no statistical significance, compared with unlabeled MVNs. The amplitudes of monosynaptically evoked excitatory postsynaptic currents (eEPSCs) were respectively (267.100±7.563) pA (n=18), (266.900±6.730) pA (n=25), P=0.962. The current amplitude and frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) were respectively(19.320±1.768)pA and (2.936±0.512) Hz (n=21), (18.360±1.700) pA and (2.871±0.454) Hz (n=27), with P values were 0.207, 0.755 separately, which showed no statistical significance. Conclusion Vivo application of retrograde fluorescence probe injection techniques helps to identify good CPMVNs, which are specific subjectsfor further study on synaptic transmission mechanism of vestibular-cerebellum pathway. Key words: Medial vestibular nucleus; Electrophysiology; Netrograde label; Brain slice; Synaptic transmission