Cerebral cortical contusion in rat, 1 and 4 dpi

Traumatic brain injury (TBI) initiates a complex sequence of destructive and neuroprotective cellular responses. The initial mechanical injury is followed by an extended time period of secondary brain damage. Due to the complicated pathological picture a better understanding of the molecular events occurring during this secondary phase of injury is needed. This study was aimed at analysing gene expression patterns following cerebral cortical contusion in rat using high throughput microarray technology with the goal of identifying genes involved in an early and in a more delayed phase of trauma, as genomic responses behind secondary mechanisms likely are time-dependent. Keywords: Traumatic brain injury, genomic response Cerebral cortical contusions by weight drop were made on male rats. Cortex from individual animals were analysed in comparative hybridisation with the corresponding uninjured side. Two time points were compared 1 dpi (n=3, ie 3 replicates) and 4 dpi (n=4, i.e 4 replicates). Individual animals were analysed and total RNA from injured ipsilateral cortex and uninjured contralateral cortex were labelled with Cy5 and Cy3 dyes, then hybridised onto a 6240 cDNA probe microarray. Expression ratios were calculated using injured/ un-injured cortex. Dye swaps were used.