Impact of single-site axonal GABAergic synaptic events on cerebellar interneuron activity
| العنوان: | Impact of single-site axonal GABAergic synaptic events on cerebellar interneuron activity |
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| المؤلفون: | Abdelali Jalil, Federico F. Trigo, Javier Zorrilla de San Martin |
| المصدر: | The Journal of General Physiology |
| بيانات النشر: | Rockefeller University Press, 2015. |
| سنة النشر: | 2015 |
| مصطلحات موضوعية: | Male, Interneuron, Physiology, Voltage-Gated Sodium Channels, Biology, gamma-Aminobutyric acid, Rats, Sprague-Dawley, Synapse, Interneurons, Postsynaptic potential, Cerebellum, medicine, Animals, GABAergic Neurons, Axon, Research Articles, gamma-Aminobutyric Acid, GABAA receptor, musculoskeletal, neural, and ocular physiology, Cell Biology, Synaptic Potentials, Receptors, GABA-A, Axon initial segment, Axons, Rats, medicine.anatomical_structure, nervous system, Synapses, GABAergic, Calcium, Female, Neuroscience, medicine.drug |
| الوصف: | Presynaptic GABAA receptors have a greater influence than previously known. Axonal ionotropic receptors are present in a variety of neuronal types, and their function has largely been associated with the modulation of axonal activity and synaptic release. It is usually assumed that activation of axonal GABAARs comes from spillover, but in cerebellar molecular layer interneurons (MLIs) the GABA source is different: in these cells, GABA release activates presynaptic GABAA autoreceptors (autoRs) together with postsynaptic targets, producing an autoR-mediated synaptic event. The frequency of presynaptic, autoR-mediated miniature currents is twice that of their somatodendritic counterparts, suggesting that autoR-mediated responses have an important effect on interneuron activity. Here, we used local Ca2+ photolysis in MLI axons of juvenile rats to evoke GABA release from individual varicosities to study the activation of axonal autoRs in single release sites. Our data show that single-site autoR conductances are similar to postsynaptic dendritic conductances. In conditions of high [Cl−]i, autoR-mediated conductances range from 1 to 5 nS; this corresponds to ∼30–150 GABAA channels per presynaptic varicosity, a value close to the number of channels in postsynaptic densities. Voltage responses produced by the activation of autoRs in single varicosities are amplified by a Nav-dependent mechanism and propagate along the axon with a length constant of 91 µm. Immunolabeling determination of synapse location shows that on average, one third of the synapses produce autoR-mediated signals that are large enough to reach the axon initial segment. Finally, we show that single-site activation of presynaptic GABAA autoRs leads to an increase in MLI excitability and thus conveys a strong feedback signal that contributes to spiking activity. |
| تدمد: | 1540-7748 0022-1295 |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::9eb52dfa83d7e121d914a1efea1bcf81Test https://doi.org/10.1085/jgp.201511506Test |
| حقوق: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....9eb52dfa83d7e121d914a1efea1bcf81 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 15407748 00221295 |
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