Glutamate Uncaging: Difference between revisions

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===RuBi-Glutamate===
===RuBi-Glutamate===


- caged-glutamate compound
* caged-glutamate compound
- based on ruthenium photochemistry
* based on ruthenium photochemistry
- excited with visible wavelengths
* excited with visible wavelengths
- releases glutamate after 1-photon or 2-photon excitation.
* releases glutamate after 1-photon or 2-photon excitation.
- high quantum efficiency
* high quantum efficiency
- can be used at low concentrations,
* can be used at low concentrations,
- partly avoids blockade of GABAergic transmission
* partly avoids blockade of GABAergic transmission
- 2-photon uncaging of RuBi-Glutamate has a high spatial resolution and generates excitatory responses in individual dendritic spines with physiological kinetics.
* 2-photon uncaging of RuBi-Glutamate has a high spatial resolution and generates excitatory responses in individual dendritic spines with physiological kinetics.
- With laser beam multiplexing, two-photon RuBi-Glutamate uncaging can also be used to depolarize and fire pyramidal neurons with single-cell resolution.
* With laser beam multiplexing, two-photon RuBi-Glutamate uncaging can also be used to depolarize and fire pyramidal neurons with single-cell resolution.
- RuBi-Glutamate enables the photoactivation of neuronal dendrites and circuits with visible or two-photon light sources, achieving single cell, or even single spine, precision.
* RuBi-Glutamate enables the photoactivation of neuronal dendrites and circuits with visible or two-photon light sources, achieving single cell, or even single spine, precision.


ruthenium-bipyridine complexes can be used as caging compounds
ruthenium-bipyridine complexes can be used as caging compounds. ruthenium is a transition metal with versatile chemistry. polypyridines of ruthenium photorelease entire ligands in a heterolytic fashion, by means of a widely known mechanism in which the initial photoexcited state quickly evolves into a dissociative state, so the photorelease is therefore clean and fast.
ruthenium is a transition metal with versatile chemistry
 
polypyridines of ruthenium photorelease entire ligands in a heterolytic fashion, by means of a widely known mechanism in which the initial photoexcited state quickly evolves into a dissociative state, so the photorelease is therefore clean and fast.
 
: '''Pros: RuBi-Glutamate'''
* minimal antagonistic effects on GABAergic transmission
 
 
: '''Cons: RuBi-Glutamate'''
* not much prior literature to demo the effects




Line 26: Line 32:
===MNI-Glutamate===
===MNI-Glutamate===
2-photon uncaging of MNI-glutamate has been used successfully to functionally map synaptic receptors <ref name="Araya2006"></ref><ref name="Carter2004"></ref><ref name="Gasparini2006"></ref><ref name="Matsuzaki2004"></ref><ref name="Sobczyk2005"></ref>, activate individual spines, and individual neurons.
2-photon uncaging of MNI-glutamate has been used successfully to functionally map synaptic receptors <ref name="Araya2006"></ref><ref name="Carter2004"></ref><ref name="Gasparini2006"></ref><ref name="Matsuzaki2004"></ref><ref name="Sobczyk2005"></ref>, activate individual spines, and individual neurons.
* needs to be applied to the tissue at relatively high (mM) concentrations for effective two-photon uncaging.
 
* at high concentrations, MNI-glutamate, like other caged compounds, is a very effective antagonist of GABAergic transmission.
 
: '''Pros: MNI-glutamate'''
* lots of prior literature to demo the effects
* antagonist of GABAergic transmission at high concentrations
 
 
: '''Cons: MNI-glutamate'''
* needs to be applied to the tissue at relatively high (mM) concentrations for effective 2-photon uncaging.
* antagonist to GABAergic transmission so can't be used to study GABAergic neurons




Revision as of 21:10, 28 November 2015

One of the first experiments uncaging glutamate on dendrites was done by Kandler on CA1 pyramidal neurons in slices. They reported the long-term depression of glutamate responses after the pairing of uncaging with depolarization of the neuron. A similar result was obtained with bursts of uncaging by Dodt; these authors used an infrared-guided laser stimulation system to uncage glutamate on the apical dendrites of layer 5 neocortical pyramidal neurons.


Uncaging Compounds

RuBi-Glutamate

  • caged-glutamate compound
  • based on ruthenium photochemistry
  • excited with visible wavelengths
  • releases glutamate after 1-photon or 2-photon excitation.
  • high quantum efficiency
  • can be used at low concentrations,
  • partly avoids blockade of GABAergic transmission
  • 2-photon uncaging of RuBi-Glutamate has a high spatial resolution and generates excitatory responses in individual dendritic spines with physiological kinetics.
  • With laser beam multiplexing, two-photon RuBi-Glutamate uncaging can also be used to depolarize and fire pyramidal neurons with single-cell resolution.
  • RuBi-Glutamate enables the photoactivation of neuronal dendrites and circuits with visible or two-photon light sources, achieving single cell, or even single spine, precision.

ruthenium-bipyridine complexes can be used as caging compounds. ruthenium is a transition metal with versatile chemistry. polypyridines of ruthenium photorelease entire ligands in a heterolytic fashion, by means of a widely known mechanism in which the initial photoexcited state quickly evolves into a dissociative state, so the photorelease is therefore clean and fast.


Pros: RuBi-Glutamate
  • minimal antagonistic effects on GABAergic transmission


Cons: RuBi-Glutamate
  • not much prior literature to demo the effects


MNI-Glutamate

2-photon uncaging of MNI-glutamate has been used successfully to functionally map synaptic receptors [1][2][3][4][5], activate individual spines, and individual neurons.


Pros: MNI-glutamate
  • lots of prior literature to demo the effects
  • antagonist of GABAergic transmission at high concentrations


Cons: MNI-glutamate
  • needs to be applied to the tissue at relatively high (mM) concentrations for effective 2-photon uncaging.
  • antagonist to GABAergic transmission so can't be used to study GABAergic neurons


CNB-glutamate

CNB-glutamate


L-glutamic acid

L-glutamic acid α(4,5-dimethoxy-2-nitrobenzyl) ester (Callaway, Katz, 1993)



REFERENCES

<references>

[1]


[2]


[3]


[4]


[5]


  1. ↑ 1.0 1.1 Araya Yuste 2006 The spine neck filters membrane potentials
  2. ↑ 2.0 2.1 Carter Sabatini 2004 State-dependent calcium signaling in dendritic spines of striatal medium spiny neurons
  3. ↑ 3.0 3.1 Gasparini Magee 2006 State dependent dendritic computation in hippocampal CA1 pyramidal neurons
  4. ↑ 4.0 4.1 Matsuzaki Kasai 2001 Dendritic spine geometry is critical for AMPA receptor expression in hippocampal CA1 pyramidal neurons
  5. ↑ 5.0 5.1 Sobczyk Svoboda 2005 NMDA receptor subunitdependent Ca2 signaling in individual hippocampal dendritic spines


  • Salierno Marceca Peterka Yuste Etchenique 2010 fast ruthenium polypyridine cage complex photoreleases glutamate with visible or IR light in one and two photon regimes J Inorg Biochem
  • Callaway Katz 1993 Photostimulation using caged glutamate reveals functional circuitry in living brain slices
  • Callaway Yuste 2002 Stimulating neurons with light
  • Frick Dodt 2001 Glutamate receptors form hot spots on apical dendrites of neocortical pyramidal neurons
  • Pettit Augustine 1997 Chemical twophoton uncaging: a novel approach to mapping glutamate receptors
  • Shepherd Svoboda 2003 Circuit analysis of experience-dependent plasticity in the developing rat barrel cortex
  • Wieboldt Hess 1994 Photolabile precursors of glutamate: synthesis, photochemical properties, and activation of glutamate receptors on a microsecond time scale.
  • Yoshimura Callaway 2005 Excitatory cortical neurons form fine-scale functional networks.
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