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The M1 Muscarinic Receptor Antagonist VU0255035 Delays the Development of Status Epilepticus after Organophosphate Exposure and Prevents Hyperexcitability in the Basolateral Amygdala.

Authors :
Miller SL
Aroniadou-Anderjaska V
Pidoplichko VI
Figueiredo TH
Apland JP
Krishnan JK
Braga MF
Source :
The Journal of pharmacology and experimental therapeutics [J Pharmacol Exp Ther] 2017 Jan; Vol. 360 (1), pp. 23-32. Date of Electronic Publication: 2016 Oct 31.
Publication Year :
2017

Abstract

Exposure to organophosphorus toxins induces seizures that progress to status epilepticus (SE), which can cause brain damage or death. Seizures are generated by hyperstimulation of muscarinic receptors, subsequent to inhibition of acetylcholinesterase; this is followed by glutamatergic hyperactivity, which sustains and reinforces seizure activity. It has been unclear which muscarinic receptor subtypes are involved in seizure initiation and the development of SE in the early phases after exposure. Here, we show that pretreatment of rats with the selective M <subscript>1</subscript> receptor antagonist, VU0255035 [N-(3-oxo-3-(4-(pyridine-4-yl)piperazin-1-yl)propyl)-benzo[c][1,2,5]thiadiazole-4 sulfonamide], significantly suppressed seizure severity and prevented the development of SE for about 40 minutes after exposure to paraoxon or soman, suggesting an important role of the M <subscript>1</subscript> receptor in the early phases of seizure generation. In addition, in in vitro brain slices of the basolateral amygdala (a brain region that plays a key role in seizure initiation after nerve agent exposure), VU0255035 blocked the effects produced by bath application of paraoxon-namely, a brief barrage of spontaneous inhibitory postsynaptic currents, followed by a significant increase in the ratio of the total charge transferred by spontaneous excitatory postsynaptic currents over that of the inhibitory postsynaptic currents. Furthermore, paraoxon enhanced the hyperpolarization-activated cation current I <subscript>h</subscript> in basolateral amygdala principal cells, which could be one of the mechanisms underlying the increased glutamatergic activity, an effect that was also blocked in the presence of VU0255035. Thus, selective M <subscript>1</subscript> antagonists may be an efficacious pretreatment in contexts in which there is risk for exposure to organophosphates, as these antagonists will delay the development of SE long enough for medical assistance to arrive.<br /> (Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.)

Details

Language :
English
ISSN :
1521-0103
Volume :
360
Issue :
1
Database :
MEDLINE
Journal :
The Journal of pharmacology and experimental therapeutics
Publication Type :
Academic Journal
Accession number :
27799295
Full Text :
https://doi.org/10.1124/jpet.116.236125