TY - JOUR
T1 - Axonal GABAA receptors increase cerebellar granule cell excitability and synaptic activity
AU - Pugh, Jason R.
AU - Jahr, Craig E.
PY - 2011/1/12
Y1 - 2011/1/12
N2 - We report that activation of GABAAreceptors on cerebellar granule cell axons modulates both transmitter release and the excitability of the axon and soma. Axonal GABAAreceptors depolarize the axon, increasing its excitability and causing calcium influx at axonal varicosities. GABA-mediated subthreshold depolarizations in the axon spread electrotonically to the soma, promoting orthodromic action potential initiation. When chloride concentrations are unperturbed, GABA iontophoresis elicits spikes and increases excitability of parallel fibers, indicating that GABAAreceptor- mediated responses are normally depolarizing. GABA release from molecular layer interneurons activates parallel fiber GABAAreceptors, and this, in turn, increases release probability at synapses between parallel fibers and molecular layer interneurons. These results describe a positive feedback mechanism whereby transmission from granule cells to Purkinje cells and molecular layer interneurons will be strengthened during granule cell spike bursts evoked by sensory stimulation.
AB - We report that activation of GABAAreceptors on cerebellar granule cell axons modulates both transmitter release and the excitability of the axon and soma. Axonal GABAAreceptors depolarize the axon, increasing its excitability and causing calcium influx at axonal varicosities. GABA-mediated subthreshold depolarizations in the axon spread electrotonically to the soma, promoting orthodromic action potential initiation. When chloride concentrations are unperturbed, GABA iontophoresis elicits spikes and increases excitability of parallel fibers, indicating that GABAAreceptor- mediated responses are normally depolarizing. GABA release from molecular layer interneurons activates parallel fiber GABAAreceptors, and this, in turn, increases release probability at synapses between parallel fibers and molecular layer interneurons. These results describe a positive feedback mechanism whereby transmission from granule cells to Purkinje cells and molecular layer interneurons will be strengthened during granule cell spike bursts evoked by sensory stimulation.
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U2 - 10.1523/JNEUROSCI.4506-10.2011
DO - 10.1523/JNEUROSCI.4506-10.2011
M3 - Article
C2 - 21228165
AN - SCOPUS:78651482612
SN - 0270-6474
VL - 31
SP - 565
EP - 574
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 2
ER -