Comparisons of repetitive-and single-insult ischaemia: effects on regional brain damage and behaviour.

Single- and repetitive-insult ischaemia have been used with the gerbil to model human stroke and the impact of anti-ischaemic agents. It is currently not well-established whether the duration of an ischaemic insult, or single vs repetitive insults may have different behavioural consequences. In this study, groups of gerbils were given either single- or repetitive-insult ischaemia of either 3, 6 or 9 min cumulative duration. As the cumulative duration of ischaemia was increased, the degree of brain damage correspondingly increased and performance in a water maze task was progressively more impaired. However, no behavioural or brain-damage differences were found between groups of animals which received comparable durations of single- or repetitive-insult ischaemia. Significant mortality was observed in the group receiving three 3 min ischaemic insults, suggesting that the repetitive ischaemia technique may be limited to brief periods of occlusion. We conclude that there are no grounds for distinguishing between the single- and repetitive-ischaemia paradigms when employing cumulative durations up to 9 min.