GlyT2+ neurons in the lateral cerebellar nucleus.
The deep cerebellar nuclei (DCN) are a major hub in the cerebellar circuitry but the functional classification of their neurons is incomplete. We have previously characterized three cell groups in the lateral cerebellar nucleus: large non-GABAergic neurons and two groups of smaller neurons, one of which express green fluorescence protein (GFP) in a GAD67/GFP mouse line and is therefore GABAergic. However, as a substantial number of glycinergic and glycine/GABA co-expressing neurons have been described in the DCN, this classification needed to be refined by considering glycinergic neurons. To this end we took advantage of a glycine transporter isoform 2 (GlyT2)-eGFP mouse line that allows identification of GlyT2-expressing, presumably glycinergic neurons in living cerebellar slices and compared their electrophysiological properties with previously described DCN neuron populations. We found two electrophysiologically and morphologically distinct sets of GlyT2-expressing neurons in the lateral cerebellar nucleus. One of them showed electrophysiological similarity to the previously characterized GABAergic cell group. The second GlyT2+ cell population, however, differed from all other so far described neuron types in DCN in that the cells (1) are intrinsically silent in slices and only fire action potentials upon depolarizing current injection and (2) have a projecting axon that was often seen to leave the DCN and project in the direction of the cerebellar cortex. Presence of this so far undescribed DCN neuron population in the lateral nucleus suggests a direct inhibitory pathway from the DCN to the cerebellar cortex.
Uusisaari
Marylka
M
Laboratory for Neuronal Circuit Dynamics, Brain Science Institute, RIKEN, Wako-shi, Saitama, Japan.
Knöpfel
Thomas
T
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D015415:Biomarkers; D048430:Cell Shape / Q000502:physiology; D048429:Cell Size; D002525:Cerebellar Cortex / Q000166:cytology / Q000502:physiology; D002529:Cerebellar Nuclei / Q000166:cytology / Q000378:metabolism*; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D005998:Glycine / Q000378:metabolism*; D050487:Glycine Plasma Membrane Transport Proteins / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000235:genetics; D008239:Lysine / Q000031:analogs & derivatives; D051379:Mice; D008822:Mice, Transgenic; D009433:Neural Inhibition / Q000502:physiology*; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D013194:Staining and Labeling; D009435:Synaptic Transmission / Q000502:physiology
D015415:Biomarkers; D050487:Glycine Plasma Membrane Transport Proteins; C493270:Slc6a5 protein, mouse; D049452:Green Fluorescent Proteins; C013411:biocytin; D008239:Lysine; D005998:Glycine