title: Acute and chronic efficacy of bumetanide in an in vitro model of posttraumatic epileptogenesis.
abstract: BACKGROUND
  Seizures triggered by acute injuries to the developing brain respond poorly to first-line medications that target the inhibitory chloride-permeable GABAA receptor. Neuronal injury is associated with profound increases in cytoplasmic chloride ([Cl(-)]i) resulting in depolarizing GABA signaling, higher seizure propensity and limited efficacy of GABAergic anticonvulsants. The Na(+)-K(+)-2Cl(-) (NKCC1) cotransporter blocker bumetanide reduces [Cl(-)]i and causes more negative GABA equilibrium potential in injured neurons. We therefore tested both the acute and chronic efficacy of bumetanide on early posttraumatic ictal-like epileptiform discharges and epileptogenesis.
  
  
  METHODS
  Acute hippocampal slices were used as a model of severe traumatic brain injury and posttraumatic epileptogenesis. Hippocampal slices were then incubated for 3 weeks. After a 1-week latent period, slice cultures developed chronic spontaneous ictal-like discharges. The anticonvulsant and anti-epileptogenic efficacy of bumetanide, phenobarbital, and the combination of these drugs was studied.
  
  
  RESULTS
  Bumetanide reduced the frequency and power of early posttraumatic ictal-like discharges in vitro and enhanced the anticonvulsant efficacy of phenobarbital. Continuous 2-3 weeks administration of bumetanide as well as phenobarbital in combination with bumetanide failed to prevent posttraumatic ictal-like discharges and epileptogenesis.
  
  
  CONCLUSIONS
  Our data demonstrate a persistent contribution of NKCC1 cotransport in posttraumatic ictal-like activity, presumably as a consequence of chronic alterations in neuronal chloride homeostasis and GABA-mediated inhibition. New strategies for more effective reduction in posttraumatic and seizure-induced [Cl(-)]i accumulation could provide the basis for effective treatments for posttraumatic epileptogenesis and the resultant seizures.
authors.affiliation: Neurology Department, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Volodymyr
authors.initials: V
authors.lastname: Dzhala
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Staley
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000235:genetics; D000704:Analysis of Variance; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology*; D002712:Chlorides / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics; D009924:Organ Culture Techniques; D010634:Phenobarbital / Q000494:pharmacology; D011971:Receptors, Immunologic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000927:Anticonvulsants; C482560:CLM-1 protein, mouse; D002712:Chlorides; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins; D049994:Sodium Potassium Chloride Symporter Inhibitors; C415371:clomeleon; D002034:Bumetanide; D010634:Phenobarbital
keywords: Bumetanide; NKCC1; Trauma; phenobarbital; posttraumatic seizures