title: Peroxisome proliferator-activated receptors γ/mitochondrial uncoupling protein 2 signaling protects against seizure-induced neuronal cell death in the hippocampus following experimental status epilepticus.
abstract: BACKGROUND
  Status epilepticus induces subcellular changes that may lead to neuronal cell death in the hippocampus. However, the mechanism of seizure-induced neuronal cell death remains unclear. The mitochondrial uncoupling protein 2 (UCP2) is expressed in selected regions of the brain and is emerged as an endogenous neuroprotective molecule in many neurological disorders. We evaluated the neuroprotective role of UCP2 against seizure-induced hippocampal neuronal cell death under experimental status epilepticus.
  
  
  METHODS
  In Sprague-Dawley rats, kainic acid (KA) was microinjected unilaterally into the hippocampal CA3 subfield to induce prolonged bilateral seizure activity. Oxidized protein level, translocation of Bcl-2, Bax and cytochrome c between cytosol and mitochondria, and expression of peroxisome proliferator-activated receptors γ (PPARγ) and UCP2 were examined in the hippocampal CA3 subfield following KA-induced status epilepticus. The effects of microinjection bilaterally into CA3 area of a PPARγ agonist, rosiglitazone or a PPARγ antagonist, GW9662 on UCP2 expression, induced superoxide anion (O(·2)(-)) production, oxidized protein level, mitochondrial respiratory chain enzyme activities, translocation of Bcl-2, Bax and cytochrome c, and DNA fragmentation in bilateral CA3 subfields were examined.
  
  
  RESULTS
  Increased oxidized proteins and mitochondrial or cytosol translocation of Bax or cytochrome c in the hippocampal CA3 subfield was observed 3-48 h after experimental status epilepticus. Expression of PPARγ and UCP2 increased 12-48 h after KA-induced status epilepticus. Pretreatment with rosiglitazone increased UCP2 expression, reduced protein oxidation, O(·2)(-) overproduction and dysfunction of mitochondrial Complex I, hindered the translocation of Bax and cytochrome c, and reduced DNA fragmentation in the CA3 subfield. Pretreatment with GW9662 produced opposite effects.
  
  
  CONCLUSIONS
  Activation of PPARγ upregulated mitochondrial UCP2 expression, which decreased overproduction of reactive oxygen species, improved mitochondrial Complex I dysfunction, inhibited mitochondrial translocation of Bax and prevented cytosolic release of cytochrome c by stabilizing the mitochondrial transmembrane potential, leading to amelioration of apoptotic neuronal cell death in the hippocampus following status epilepticus.
authors: Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 83301, Taiwan. ycchuang@adm.cgmh.org.tw
authors: Yao-Chung
authors: YC
authors: Chuang
authors: Tsu-Kung
authors: TK
authors: Lin
authors: Hsuan-Ying
authors: HY
authors: Huang
authors: Wen-Neng
authors: WN
authors: Chang
authors: Chia-Wei
authors: CW
authors: Liou
authors: Shang-Der
authors: SD
authors: Chen
authors: Alice Y W
authors: AY
authors: Chang
authors: Samuel H H
authors: SH
authors: Chan
mesh_terms: D000818:Animals; D016923:Cell Death / Q000502:physiology; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology; D007473:Ion Channels / Q000502:physiology*; D008297:Male; D024101:Mitochondrial Proteins / Q000502:physiology*; D009474:Neurons / Q000378:metabolism / Q000473:pathology*; D047495:PPAR gamma / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species; D012640:Seizures / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D015398:Signal Transduction / Q000502:physiology*; D013226:Status Epilepticus / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D000071246:Uncoupling Protein 2
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; D047495:PPAR gamma; D017382:Reactive Oxygen Species; C000604391:Ucp2 protein, rat; D000071246:Uncoupling Protein 2