Abstract
Galantamine has emerged as a potential antidote to prevent the acute toxicity of organophosphorus (OP) compounds. Changes in inhibitory GABAergic activity in different brain regions can contribute to both induction and maintenance of seizures in subjects exposed to the OP nerve agent soman. Here, we tested the hypothesis that galantamine can prevent immediate and delayed effects of soman on hippocampal inhibitory synaptic transmission. Spontaneous inhibitory postsynaptic currents (IPSCs) were recorded from CA1 pyramidal neurons in hippocampal slices obtained at 1 h, 24 h, or 6 to 9 days after the injection of guinea pigs with saline (0.5 ml/kg i.m.), 1×LD50 soman (26.3 μg/kg s.c.), galantamine (8 mg/kg i.m.), or galantamine at 30 min before soman. Soman-challenged animals that were not pretreated showed mild, moderate, or severe signs of acute intoxication. At 1 h after the soman injection, the mean IPSC amplitude recorded from slices of mildly intoxicated animals and the mean IPSC frequency recorded from slices of severely intoxicated animals were larger and lower, respectively, than those recorded from slices of control animals. Regardless of the severity of the acute toxicity, at 24 h after the soman challenge the mean IPSC frequency was lower than that recorded from slices of control animals. At 6 to 9 days after the challenge, the IPSC frequency had returned to control levels, whereas the mean IPSC amplitude became larger than control. Pretreatment with galantamine prevented soman-induced changes in IPSCs. Counteracting the effects of soman on inhibitory transmission can be an important determinant of the antidotal effectiveness of galantamine.
Footnotes
This work was supported in part by the National Institutes of Health National Institute of Neurological Disorders and Stroke CounterACT Program [Grant U01-NS059344]; and the National Institutes of Health National Institute of Environmental Health Sciences [Grant 5T32ES007263].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.167700.
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ABBREVIATIONS:
- OP
- organophosphorus
- ACh
- aceteylcholine
- AChE
- acetylcholinesterase
- IPSC
- inhibitory postsynaptic current
- IACUC
- Institutional Animal Care and Use Committee
- ANOVA
- analysis of variance
- nAChR
- nicotinic acetylcholine receptor
- mAChR
- muscarinic acetylcholine receptor
- ACSF
- artificial cerebrospinal fluid.
- Received March 2, 2010.
- Accepted June 15, 2010.
- Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
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