Increased postsynaptic Ca<sup>2+</sup> reduces mini frequency at the <i>Drosophila</i> larval NMJ

Powers, Andrew S.; Grizzaffi, Jeffrey; Lnenicka, Gregory A.

doi:10.1002/syn.21971

Cited by 3 publications

(1 citation statement)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Increases in evoked release have been reported to be accompanied by an increase in spontaneous release (Cheung, Shayan, Boulianne, & Atwood, 1999;Stewart, Schuster, Goodman, & Atwood, 1996). However, evoked and spontaneous release are not always correlated and can be differentially regulated, arise from different synaptic sites and involve different molecular mechanisms (Kaeser & Regehr, 2014;Melom, Akbergenova, Gavornik, & Littleton, 2013;Powers et al, 2017;Ramirez & Kavalali, 2011). The increase in evoked transmitter release compensated for the decrease in facilitation and partially restored the EPSP amplitude during trains of APs.…”

Section: Pv Expression Produces An Increase In Transmitter Releasementioning

confidence: 99%

Parvalbumin expression affects synaptic development and physiology at the Drosophila larval NMJ

Nitabach

Lnenicka

2018

Journal of Neurogenetics

Self Cite

View full text Add to dashboard Cite

Presynaptic Ca appears to play multiple roles in synaptic development and physiology. We examined the effect of buffering presynaptic Ca by expressing parvalbumin (PV) in Drosophila neurons, which do not normally express PV. The studies were performed on the identified Ib terminal that innervates muscle fiber 5. The volume-averaged, residual Ca resulting from single action potentials (APs) and AP trains was measured using the fluorescent Ca indicator, OGB-1. PV reduced the amplitude and decay time constant (τ) for single-AP Ca transients. For AP trains, there was a reduction in the rate of rise and decay of [Ca] but the plateau [Ca] was not affected. Electrophysiological recordings from muscle fiber 5 showed a reduction in paired-pulse facilitation, particularly the F component; this was likely due to the reduction in residual Ca. These synapses also showed reduced synaptic enhancement during AP trains, presumably due to less buildup of synaptic facilitation. The transmitter release for single APs was increased for the PV-expressing terminals and this may have been a homeostatic response to the decrease in facilitation. Confocal microscopy was used to examine the structure of the motor terminals and PV expression resulted in smaller motor terminals with fewer synaptic boutons and active zones. This result supports earlier proposals that increased AP activity promotes motor terminal growth through increases in presynaptic [Ca].

show abstract

Section: Pv Expression Produces An Increase In Transmitter Releasementioning

confidence: 99%

Parvalbumin expression affects synaptic development and physiology at the Drosophila larval NMJ

Nitabach

Lnenicka

2018

Journal of Neurogenetics

Self Cite

View full text Add to dashboard Cite

show abstract

Novel Compensatory Mechanisms Enable the Mutant KCNT1 Channels to Induce Seizures

Ehaideb

Decker

Smith

et al. 2017

Preprint

View full text Add to dashboard Cite

Mutations in the sodium-activated potassium channel (KCNT1) gene are linked to epilepsy. Surprisingly, all KCNT1 mutations examined to date increase K+ current amplitude. These findings present a major neurophysiological paradox: how do gain-of-function KCNT1 mutations expected to silence neurons cause epilepsy? Here, we use Drosophila to show that expressing mutant KCNT1 in GABAergic neurons leads to seizures, consistent with the notion that silencing inhibitory neurons tips the balance towards hyperexcitation. Unexpectedly, mutant KCNT1 expressed in motoneurons also causes seizures. One striking observation is that mutant KCNT1 causes abnormally large and spontaneous EJPs (sEJPs). Our data suggest that these sEJPs result from local depolarization of synaptic terminals due to a reduction in Shaker channel levels and more active Na+ channels. Hence, we provide the first in vivo evidence that both disinhibition of inhibitory neurons and compensatory plasticity in motoneurons can account for the paradoxical effects of gain-of-function mutant KCNT1 in epilepsy.

show abstract

Allostatic Compensatory Mechanisms Enable the Mutant KCNT1 Channels to Induce Seizures and Hyperexcitability

et al. 2018

View full text Add to dashboard Cite

Increased postsynaptic Ca²⁺ reduces mini frequency at the Drosophila larval NMJ

Abstract: Repetitive stimulation of the Drosophila larval NMJ can produce a reduction in the frequency of miniature excitatory postsynaptic currents. By buffering postsynaptic Ca , it was shown that the decrease in "mini" frequency was due to an increase in postsynaptic Ca .

Cited by 3 publications

References 28 publications

Parvalbumin expression affects synaptic development and physiology at the Drosophila larval NMJ

Parvalbumin expression affects synaptic development and physiology at the Drosophila larval NMJ

Novel Compensatory Mechanisms Enable the Mutant KCNT1 Channels to Induce Seizures

Allostatic Compensatory Mechanisms Enable the Mutant KCNT1 Channels to Induce Seizures and Hyperexcitability

Contact Info

Product

Resources

About

Increased postsynaptic Ca2+ reduces mini frequency at the Drosophila larval NMJ

Abstract: Repetitive stimulation of the Drosophila larval NMJ can produce a reduction in the frequency of miniature excitatory postsynaptic currents. By buffering postsynaptic Ca , it was shown that the decrease in "mini" frequency was due to an increase in postsynaptic Ca .

Cited by 3 publications

References 28 publications

Parvalbumin expression affects synaptic development and physiology at the Drosophila larval NMJ

Parvalbumin expression affects synaptic development and physiology at the Drosophila larval NMJ

Novel Compensatory Mechanisms Enable the Mutant KCNT1 Channels to Induce Seizures

Allostatic Compensatory Mechanisms Enable the Mutant KCNT1 Channels to Induce Seizures and Hyperexcitability

Contact Info

Product

Resources

About

Increased postsynaptic Ca²⁺ reduces mini frequency at the Drosophila larval NMJ