Article
Influence of intraischemic versus postischemic induced normobaric hyperoxia on neurobehavioral deficits in a focal mass lesion in rodents
Einfluss einer intraischämisch versus postischämisch induzierten normobaren Hyperoxie auf das Outcome nach fokaler zerebraler Hirnläsion
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Published: | April 11, 2007 |
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Objective: The effects of intra – versus postischemic arterial normobaric hyperoxia on a 2-week assessment of behavorial deficits were evaluated in a focal mass lesion model in rodents.
Methods: 58 Spraque Dawley rats were included in the study. Baseline measurement of ptiO2 and EEG was followed by induction of an epidural focal mass lesion. The endpoint of balloon inflation was defined by flattening of the EEG. Brain compression was prolonged over 60 min and followed by reperfusion (~60 min). Neurobehavior was assessed over 15 days by postural reflex (PR); open field (OF); beam balance (BB); beam walking (BW); Morris water maze (MWM). Study groups with arterial normoxia (paO2 ~100mmHg, n=25), intraischemic (n=13) and post-ischemic (n=8) arterial, normobaric hyperoxia (paO2 ~220mmHg) were compared to a sham group (n=12). The lesion was histologically evaluated by morphometric analysis.
Results: Sham-operated animals showed a normal EEG pattern, regular ptiO2 values and neurobehavior over time. All injured animals showed a significant worsening of EEG compared to the sham operated group (p<0.05), however no differences were found between treatment groups (p>0.05). PtiO2 increased to normal values under intraischemic and postischemic normobaric hyperoxia (p<0.05) while normoxic animals showed lower ptiO2 values. Neurobehavioral testing of injured animals showed a significant worsening (BB p<0.05, BW p<0.05, PR p<0.05, MWM p<0.05) compared to sham operated animals. Neurobehavioral deficits of animals treated with postischemic arterial hyperoxia were statistically not improved (BB, OF, BW, PR and WMT) compared to animals with intraischemic hyperoxia or normoxia, The histology showed no statistically significant difference in lesion size between injured study groups.
Conclusions: Induction of arterial hyperoxia increases oxygen delivery but did not improve outcome or structural damages.