Ultrastructural lmmunolabeling Shows Prominent Presynaptic ...
Action potential propagation into the presynaptic dendrites of rat mitral cells
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Transcript of Action potential propagation into the presynaptic dendrites of rat mitral cells
![Page 1: Action potential propagation into the presynaptic dendrites of rat mitral cells](https://reader035.fdocuments.net/reader035/viewer/2022081511/5592e5951a28ab40698b4616/html5/thumbnails/1.jpg)
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Department of Neuroscience and Pharmacology
Copenhagen, 19th of June, 2013
Cellular Neuroscience examine
Rune RasmussenBSc. Student, Sport and Exercise Sciences
Action potential propagation into the presynaptic dendrites of rat mitral cells
(Bischofberger and Jonas, 1997)
![Page 2: Action potential propagation into the presynaptic dendrites of rat mitral cells](https://reader035.fdocuments.net/reader035/viewer/2022081511/5592e5951a28ab40698b4616/html5/thumbnails/2.jpg)
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Mitral cells (MC)
Pre-synaptic neurotransmitter release to interneurons (glutamate)
Principal projection neurons
Dendrodendritic synapses contain L- and N-type Ca2+ channels
Department of Neuroscience and Pharmacology
(Illustration from Neuroscience, fifth edition, 2011)
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Mitral cells (MC)
(Illustration from S. Cajal, 1894: La fine structures des centres nerveux)
Department of Neuroscience and Pharmacology
Large soma
Primary dendrite
![Page 4: Action potential propagation into the presynaptic dendrites of rat mitral cells](https://reader035.fdocuments.net/reader035/viewer/2022081511/5592e5951a28ab40698b4616/html5/thumbnails/4.jpg)
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Aim of study
Department of Neuroscience and Pharmacology
Examine directly the presynaptic voltage signal thattriggers transmitter release at dendrodendritic synapse in MC
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Evoked action potential (AP) – fast time course
Whole-cell current-clampSomatic current injection
(Illustration from Neuroscience, fifth edition, 2011)
Department of Neuroscience and Pharmacology
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Where is the AP initiated?
Evoked AP - fast time course
Department of Neuroscience and Pharmacology
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APs initiated near soma
Whole-cell current-clampSomatic current injection
Department of Neuroscience and Pharmacology
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APs initiated near soma
Whole-cell current-clampDendritic current injection
Department of Neuroscience and Pharmacology
![Page 9: Action potential propagation into the presynaptic dendrites of rat mitral cells](https://reader035.fdocuments.net/reader035/viewer/2022081511/5592e5951a28ab40698b4616/html5/thumbnails/9.jpg)
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APs amplitude conserved
Amplitude and time course maintained during back-propagationWhich channels mediates this?
Department of Neuroscience and Pharmacology
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Voltage-gated Na+ channels present in dendrites
Dendritic outside-out voltage clamp
(Illustration from Neuroscience, fifth edition, 2011)
Department of Neuroscience and Pharmacology
K+ replaced by Cs+
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Department of Neuroscience and Pharmacology
• Fast voltage-dependent activation• Rapid inactivation• Sensitive to TTX
Voltage-gated Na+ channels present in dendrites
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Na+ channels support AP back-propagation
Somatic current injection
Somatic AP-like voltage commandCurrent clamp dendrite
Department of Neuroscience and Pharmacology
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Small HD, which channels mediates this?
Half-duration (HD)* from baseline, not lowest value
½ height
*Half-duration defined in: Nature Reviews Neuroscience 8, 451-465 (June 2007)
Department of Neuroscience and Pharmacology
Fast repolarization phase
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Voltage-gated K+ channels present in dendrites
Dendritic outside-out voltage clamp from -60 to 30 mV
Department of Neuroscience and Pharmacology
Glutathione added
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Department of Neuroscience and Pharmacology
• Voltage-dependent activation• No inactivation• Sensitive to TEA
Voltage-gated K+ channels present in dendrites
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Department of Neuroscience and Pharmacology
K+ channels mediate repolarization phase
Somatic current injection
Somatic AP-like voltage commandCurrent clamp dendrite
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Summary
Amplitude and time course of somatic AP maintained during AP back-propagation in MC
Voltage-gated Na+ channels support this back-propagation into MC dendrites
Voltage-gated K+ channels mediate AP repolarization in MC dendrites
Department of Neuroscience and Pharmacology
![Page 18: Action potential propagation into the presynaptic dendrites of rat mitral cells](https://reader035.fdocuments.net/reader035/viewer/2022081511/5592e5951a28ab40698b4616/html5/thumbnails/18.jpg)
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Department of Neuroscience and Pharmacology
Copenhagen, 19th of June, 2013
Cellular Neuroscience examine
Rune RasmussenBSc. Student, Sport and Exercise Sciences
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Additional diagrams
Department of Neuroscience and Pharmacology
MC filled with biocytinand rhodamine stained.
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Additional diagrams
Department of Neuroscience and Pharmacology
Primary dendrite – Cell attached configuration
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Additional diagrams
Department of Neuroscience and Pharmacology
Soma – Before seal formation
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Additional diagrams
Department of Neuroscience and Pharmacology
Sodium current vs. distance Slope = pA/um
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Additional diagrams
Department of Neuroscience and Pharmacology
Amplitude of AP
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Additional diagrams
Department of Neuroscience and Pharmacology
Potassium current vs. distance Slope = pA/um
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Additional diagrams
Department of Neuroscience and Pharmacology
Half-duration of AP