PUBLICATION
Heterogeneity of postsynaptic receptor occupancy fluctuations among glycinergic inhibitory synapses in the zebrafish hindbrain
- Authors
- Rigo, J.M., Badiu, C., and Legendre, P.
- ID
- ZDB-PUB-030924-7
- Date
- 2003
- Source
- The Journal of physiology 553(3): 819-832 (Journal)
- Registered Authors
- Legendre, Pascal
- Keywords
- none
- MeSH Terms
-
- Animals
- Electric Stimulation
- Electrophysiology/methods
- Evoked Potentials/drug effects*
- In Vitro Techniques
- Kinetics
- Neurons/drug effects
- Neurons/physiology*
- Patch-Clamp Techniques
- Receptors, Glycine/physiology*
- Rhombencephalon/physiology*
- Spider Venoms/pharmacology
- Synapses/drug effects
- Synapses/physiology*
- Zebrafish
- PubMed
- 14500774 Full text @ J. Physiol.
Citation
Rigo, J.M., Badiu, C., and Legendre, P. (2003) Heterogeneity of postsynaptic receptor occupancy fluctuations among glycinergic inhibitory synapses in the zebrafish hindbrain. The Journal of physiology. 553(3):819-832.
Abstract
The amplitude of glycinergic miniature inhibitory postsynaptic currents (mIPSCs) strongly varies in neurons recorded in the isolated hindbrain of 50 hour- old zebrafish larvae. At this age, glycinergic synapses are functionally mature. In order to measure the occupancy level of postsynaptic glycine receptors (GlyRs) and to determine the pre- and/or postsynaptic origin of its variability, we analyzed mIPSCs within bursts evoked by alpha-latrotoxin (0.1-1 nM). Two types of burst were observed according to their mIPSC frequencies: 'slow' bursts with clearly spaced mIPSCs and 'fast' bursts characterized by superimposed events. Non-stationary noise analysis of mIPSCs in some 'slow' bursts recorded in the presence or in the absence of calcium denoted that mIPSC amplitude variance did not depend on the quantity of neurotransmitters released (presynaptic origin), but rather on intrinsic stochastic behaviour of the same group of GlyR (postsynaptic origin). In these bursts, the open probability measured at the peak of the mIPSCs was close to 0.5 while the maximum open probability is close to 0.9 for the synaptic isoform of GlyRs (heteromeric alpha1/beta GlyRs). In 'fast' bursts with superimposed events, a correlation was found between the amplitude of mIPSCs and the basal current level measured at their onset, which could suggest that the same group of GlyRs is activated during such bursts. Altogether, our results indicate that glycine synapses can display different release modes in the presence of alpha-latrotoxin. They also indicate that, in our model, postsynaptic GlyRs cannot be saturated by the release of a single vesicle.
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