Midazolam and isoflurane combination reduces late brain damage in the paraoxon-induced status epilepticus rat model

Evyatar Swissa, Guy Bar-Klein, Yonatan Serlin, Itai Weissberg, Lyna Kamintsky, Arik Eisenkraft, Liran Statlender, Shai Shrot, Yossi Rosman, Ofer Prager, Alon Friedman

Research output: Contribution to journalArticlepeer-review


Organophosphates (OPs) are widely used as pesticides and have been employed as warfare agents. OPs inhibit acetylcholinesterase, leading to over-stimulation of cholinergic synapses and can cause status epilepticus (SE). OPs poisoning can result in irreversible brain damage and death. Despite termination of SE, recurrent seizures and abnormal brain activity remain common sequelae often associated with long-term neural damage and cognitive dysfunction. Therefore, early treatment for prevention of seizures is of high interest. Using a rat model of paraoxon poisoning, we tested the efficacy of different neuroprotective and anti-epileptic drugs (AEDs) in suppressing early seizures and preventing brain damage. Electrocorticographic recordings were performed prior, during and after injection of 4.5 LD50 paraoxon, followed by injections of atropine and toxogonin (obidoxime) to prevent death. Thirty minutes later, rats were injected with midazolam alone or in combination with different AEDs (lorazepam, valproic acid, phenytoin) or neuroprotective drugs (losartan, isoflurane). Outcome measures included SE duration, early seizures frequency and epileptiform activity duration in the first 24 -hs after poisoning. To assess delayed brain damage, we performed T2-weighted magnetic resonance imaging one month after poisoning. SE duration and the number of recurrent seizures were not affected by the addition of any of the drugs tested. Delayed brain injury was most prominent in the septum, striatum, amygdala and piriform network. Only isoflurane anesthesia significantly reduced brain damage. We show that acute treatment with isoflurane, but not AEDs, reduces brain damage following SE. This may offer a new therapeutic approach for exposed individuals.

Original languageAmerican English
Pages (from-to)99-105
Number of pages7
StatePublished - 1 May 2020


  • Acetylcholinesterase
  • Anesthesia
  • Anti-epileptic drugs
  • Organophosphates
  • Recurrent seizures
  • Status epilepticus

All Science Journal Classification (ASJC) codes

  • General Neuroscience
  • Toxicology


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