Accession Number:

ADA619862

Title:

Accelerated Intoxication of GABAergic Synapses by Botulinum Neurotoxin A Disinhibits Stem Cell-Derived Neuron Networks Prior to Network Silencing

Descriptive Note:

Journal article

Corporate Author:

ARMY MEDICAL RESEARCH INST OF CHEMICAL DEFENSE ABERDEEN PROVING GROUND MD

Report Date:

2015-04-23

Pagination or Media Count:

13.0

Abstract:

Botulinum neurotoxins BoNTs are extremely potent toxins that specifically cleave SNARE proteins in peripheral synapses, preventing neurotransmitter release. Neuronal responses to BoNT intoxication are traditionally studied by quantifying SNARE protein cleavage in vitro or monitoring physiological paralysis in vivo . Consequently, the dynamic effects of intoxication on synaptic behaviors are not well-understood. We have reported that mouse embryonic stem cell-derived neurons ESNs are highly sensitive to BoNT based on molecular readouts of intoxication. Here we study the time-dependent changes in synapse- and network-level behaviors following addition of BoNTA to spontaneously active networks of glutamatergic and GABAergic ESNs. Whole-cell patch-clamp recordings indicated that BoNTA rapidly blocked synaptic neurotransmission, confirming that ESNs replicate the functional pathophysiology responsible for clinical botulism. Quantitation of spontaneous neurotransmission in pharmacologically isolated synapses revealed accelerated silencing of GABAergic synapses compared to glutamatergic synapses, which was consistent with the selective accumulation of cleaved SNAP-25 at GAD1 pre-synaptic terminals at early timepoints. Different latencies of intoxication resulted in complex network responses to BoNTA addition, involving rapid disinhibition of stochastic firing followed by network silencing. Synaptic activity was found to be highly sensitive to SNAP-25 cleavage, reflecting the functional consequences of the localized cleavage of the small subpopulation of SNAP-25 that is engaged in neurotransmitter release in the nerve terminal. Collectively these findings illustrate that use of synaptic function assays in networked neurons cultures offers a novel and highly sensitive approach for mechanistic studies of toxinneuron interactions and synaptic response to BoNT.

Subject Categories:

  • Biochemistry
  • Anatomy and Physiology
  • Medicine and Medical Research
  • Pharmacology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE