A simple novel technique to induce short-lasting local brain ischaemia in the rat

Brain ischaemia models are essential to study the pathomechanisms of stroke. Our aim was to investigate the reliability and reproducibility of our novel focal ischaemia-reperfusion model.

To induce a cortical transient ischaemic attack, we lifted the distal middle cerebral artery (MCA) with a special hook. The early changes after 2 × 15-min occlusion were observed in the somatosensory evoked responses (SERs). The histological responses to 2 × 15-min MCA occlusion and to 30-, 45- or 60-min ischaemia were examined after a 1-day survival period by 2,3,5-triphenyltetrazolium chloride (TTC) and Fluoro Jade C (FJC) staining. Another group, with 30-min ischaemia, was analysed histologically by FJC, S100 and CD11b labelling after a 5-day survival period.

The amplitudes of the SERs decreased immediately at the beginning of the ischaemic period, and remained at a reduced level during the ischaemia. Reperfusion resulted in increasing SER amplitudes, but they never regained the control level. The short-lasting ischaemia did not lead to brain infarction when evaluated with TTC, but intense labelling was found with FJC. The 30-min ischaemia did not result in FJC labelling after 1 day, but marked labelling was observed after 5 days with FJC, S100 and CD11b in the cortical area supplied by the MCA.

We present here a novel, readily reproducible method to induce focal brain ischaemia. The ischaemia-reperfusion results in noteworthy changes in the SERs and the appearance of conventional tissue damage markers. This method involves possibilities for precise blood flow regulation, and the setting of the required level of perfusion.