Effect of pretreatment with a tyrosine kinase inhibitor (PP1) on brain oedema and neurological function in an automated cortical cryoinjury model in mice

Cortical Aquaporin-4 in relation to brain oedema and neurological function of cortical cryo-injured mice

To estimate the spatial and temporal expression of Aquaporin-4 (AQP-4) in a murine model of automated cerebral cryoinjury and correlate AQP-4 expression with development of brain oedema and neurological function. AQP-4 levels were determined quantitatively by Western blots at site of injury and at sites adjacent to and distant from injury in brains of cryoinjured (experimental) (n=18), sham injured (n=18) & normal mice at 24, 48, 72h post injury. AQP-4 expression was correlated with percentage water content of brain, Neurological Severity Score (NSS) and rotarod scores. We found a 1.4-fold increase in expression of AQP-4 at the site of injury and at sites distant from injury at 24h when compared to normal mice (p=0.05). The increase in expression of AQP-4 24h post injury was significantly higher in experimental group at the site of injury and at the site adjacent to the injury in the ipsilateral hemisphere when compared to the sham injured mice (p=0.05). At 24h post injury the median NSS score in the experimental group was 9 (interquartile range 7.25-10) and that in the sham group was 0.5 (interquartile range 0.0-1.0) (p<0.001). At 48 and 72h, AQP-4 expression remained elevated in the experimental group when compared to normal brain, but the levels were not significantly different from that in sham group. AQP-4 expression was significantly elevated in the ipsilateral hemisphere in the first 24h following cerebral cortical injury in mice and this could be correlated with worsening of neurological function. Over the next 48h, there was a trend towards decrease in AQP-4 expression that was associated with partial recovery of neurological function.

Targeting different pathophysiological events after traumatic brain injury in mice: Role of melatonin and memantine

The tissue damage that emerges during traumatic brain injury (TBI) is a consequence of a variety of pathophysiological events, including free radical generation and over-activation of N-methyl-d-aspartate-type glutamate receptors (NMDAR). Considering the complex pathophysiology of TBI, we hypothesized that combination of neuroprotective compounds, targeting different events which appear during injury, may be a more promising approach for patients. In this context, both NMDAR antagonist memantine and free radical scavenger melatonin are safe in humans and promising agents for the treatment of TBI. Herein, we examined the effects of melatonin administered alone or in combination with memantine on the activation of signaling pathways, injury development and DNA fragmentation. Both compounds reduced brain injury moderately and the density of DNA fragmentation significantly. Notably, melatonin/memantine combination decreased brain injury and DNA fragmentation significantly, which was associated with reduced p38 and ERK-1/2 phosphorylation. As compared with melatonin and memantine groups, SAPK/JNK-1/2 phosphorylation was also reduced in melatonin/memantine combined animals. In addition, melatonin, memantine and their combination decreased iNOS activity significantly. Here, we provide evidence that melatonin/memantine combination protects brain from traumatic injury, which was associated with decreased DNA fragmentation, p38 phosphorylation and iNOS activity.