Document Detail


Electrophysiological, morphological, and topological properties of two histochemically distinct subpopulations of cerebellar unipolar brush cells.
MedLine Citation:
PMID:  22528965     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Unipolar brush cells (UBCs) are excitatory cerebellar granular layer interneurons whose brush-like dendrites receive one-to-one mossy fiber inputs. Subclasses of UBCs differ primarily by expressing metabotropic glutamate receptor (mGluR) 1α or calretinin. We used GENSAT Tg(Grp-EGFP) BAC transgenic mice, which selectively express enhanced green fluorescent protein (EGFP) in mGluR1α-positive UBCs to compare the functional properties of the two subclasses. Compared to EGFP-negative UBCs, which include the calretinin-positive cells, EGFP-positive UBCs had smaller somata (area 48 vs 63 μm(2)), lower specific membrane resistance (6.4 vs. 13.7 KΩ cm(2)), were less prone to intrinsic firing, and showed more irregular firing (in cell-attached ~49 % were firing vs. ~88 %, and the CV was 0.53 vs. 0.32 for EGFP-negative cells). Some of these differences are attributable to higher density of background K(+) currents in EGFP-positive cells (at -120 mV, the barium-sensitive current was 94 vs. 37 pA in EGFP-negative cells); Ih, on the contrary, was more abundantly expressed in EGFP-negative cells (at -140 mV, it was -122 vs. -54 pA in EGFP-positive neurons); furthermore, while group II mGluR modulation of the background potassium current in EGFP-negative UBCs was maintained after intracellular dialysis, mGluR modulation in EGFP-positive UBCs was lost in whole-cell recordings. Finally, cell-attached firing was reversibly abolished by the GABA(B) activation in EGFP-positive, but not in EGFP-negative UBCs. Immunohistochemistry showed that EGFP-negative UBCs express GIRK2 at high density, while mGluR1α UBCs are GIRK2 negative, suggesting that GIRK2 mediates the mGluR-sensitive current in EGFP-negative UBCs. These data suggest that the two subclasses perform different functions in the cerebellar microcircuits.
Authors:
Jin-Ah Kim; Gabriella Sekerková; Enrico Mugnaini; Marco Martina
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  Cerebellum (London, England)     Volume:  11     ISSN:  1473-4230     ISO Abbreviation:  Cerebellum     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-11-15     Completed Date:  2013-04-24     Revised Date:  2013-12-06    
Medline Journal Info:
Nlm Unique ID:  101089443     Medline TA:  Cerebellum     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1012-25     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Calbindin 2
Cerebellar Cortex / cytology*,  metabolism
Cerebellum / cytology*,  metabolism
Electrophysiological Phenomena / physiology*
G Protein-Coupled Inwardly-Rectifying Potassium Channels / genetics*,  metabolism
Green Fluorescent Proteins / metabolism
Histocytochemistry / methods
Interneurons / metabolism
Mice
Mice, Transgenic
Neurons / metabolism
Receptors, Metabotropic Glutamate / metabolism*
S100 Calcium Binding Protein G / genetics,  metabolism
Grant Support
ID/Acronym/Agency:
CA060553/CA/NCI NIH HHS; R01 NS009904/NS/NINDS NIH HHS; R0109904//PHS HHS
Chemical
Reg. No./Substance:
0/Calb2 protein, mouse; 0/Calbindin 2; 0/G Protein-Coupled Inwardly-Rectifying Potassium Channels; 0/Kcnj6 protein, mouse; 0/Receptors, Metabotropic Glutamate; 0/S100 Calcium Binding Protein G; 0/enhanced green fluorescent protein; 147336-22-9/Green Fluorescent Proteins
Comments/Corrections

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