title: Minocycline neuroprotection in a rat model of asphyxial cardiac arrest is limited.
abstract: OBJECTIVE
  The study investigated a possible neuroprotective potency of minocycline in an experimental asphyxial cardiac arrest (ACA) rat model. Clinically important survival times were evaluated thus broadening common experimental approaches.
  
  
  METHODS
  Adult rats were subjected to 5 min of ACA followed by resuscitation. There were two main treatment groups: ACA and sham operated. Relating to minocycline treatment each group consisted of three sub-groups: pre-, post-, and sans-mino, with three different survival times: 4, 7, and 21 days. Neurodegeneration and microgliosis were monitored by immunohistochemistry. Alterations of microglia-associated gene expression were analyzed by quantitative RT-PCR.
  
  
  RESULTS
  ACA induced massive nerve cell loss and activation of microglia/macrophages in hippocampal CA1 cell layer intensifying with survival time. After 7 days, minocycline significantly decreased both, neuronal degeneration and microglia response in dependence on the application pattern; application post ACA was most effective. After 21 days, neuroprotective effects of minocycline were lost. ACA significantly induced expression of the microglia-associated factors Ccl2, CD45, Mac-1, F4-80, and Tnfa. Independent on survival time, minocycline affected these parameters not significantly. Expression of iNOS was unaffected by both, ACA and minocycline.
  
  
  CONCLUSIONS
  In adult rat hippocampus microglia was significantly activated by ACA. Minocycline positive affected neuronal survival and microglial response temporary, even when applied up to 18 h after ACA, thus defining a therapeutically-relevant time window. As ACA-induced neuronal cell death involves acute and delayed events, longer minocycline intervention targeting also secondary injury cascades should manifest neuroprotective potency, a question to be answered by further experiments.
authors.affiliation: Institute of Biochemistry and Cell Biology, University of Magdeburg, Leipziger Strasse 44, Magdeburg, Germany. gerburg.keilhoff@med.ovgu.de
authors.forename: Gerburg
authors.initials: G
authors.lastname: Keilhoff
authors.forename: Hannes
authors.initials: H
authors.lastname: Schweizer
authors.forename: Robin
authors.initials: R
authors.lastname: John
authors.forename: Kristina
authors.initials: K
authors.lastname: Langnaese
authors.forename: Uwe
authors.initials: U
authors.lastname: Ebmeyer
mesh_terms: D000818:Animals; D001237:Asphyxia / Q000188:drug therapy / Q000209:etiology / Q000473:pathology*; D015415:Biomarkers / Q000032:analysis; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000188:drug therapy; D016923:Cell Death; D004195:Disease Models, Animal; D006323:Heart Arrest / Q000150:complications*; D006624:Hippocampus / Q000473:pathology*; D007150:Immunohistochemistry; D017628:Microglia / Q000473:pathology; D008911:Minocycline / Q000494:pharmacology / Q000627:therapeutic use*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D012151:Resuscitation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger; D008911:Minocycline