Development of a pattern in biochemical parameters in the core and penumbra during infarct evolution after transient MCAO in rats.

The period from stroke initiation to the cessation of penumbra damage spread represents a therapeutic window when expansion can be alleviated. In the present work, we studied some biochemical parameters helpful for the estimation of infarct progression and thus for the application of interventions. We designed four groups: the control group and three groups of animals after middle cerebral artery occlusion with reperfusion periods of 2h, 1day or 3days. In the ischaemic core and penumbra, fluorimetric and spectrophotometric methods for investigating total MnSOD and MAO-A/B activity as well as level of the glutamate were used. Protein synthesis was assessed by in vitro measurements of (14)C-leucine incorporation. Noticeable differences between core and penumbra biochemical parameters were shown. In the core, protein synthesis was transiently inhibited two hours and three days after ischaemia (36%). Glutamate and total SOD activity peaked on the first day, but on the third day after MCAO, rapidly decreased by about 44% and 33.6%, respectively. In the penumbra, ischaemia led to higher protein synthesis (78%), elevations in glutamate and rapid activation of MnSOD (by about 884%) one day after insult. On the third day, protein synthesis and MnSOD were still significantly elevated (36% and 388%, respectively), while glutamate levels returned to baseline. In addition, the impact of ischaemia on MAO-A/B activity in the penumbra was confirmed. In conclusion, biochemical parameter screening could be helpful to assess cell damage progress and the possibility of rescue. These regions reflect different biochemical patterns that seem to be clearly established on the first day after transient MCAO. Moreover, the first day of post-ischaemic reperfusion in the present model of stroke seems to be the breakpoint, i.e. the time at which expanding cell death from the infarct core to the penumbra can be at least partially eliminated.