REDUCED MORTALITY AND BRAIN-DAMAGE AFTER LOCOMOTOR-ACTIVITY IN GERBILFOREBRAIN ISCHEMIA

Background and Purpose Preischemic spontaneous locomotor activity was distinguished in this laboratory as a factor influencing outcome after 15 and 20 minutes of forebrain ischemia in gerbils. Histological inve stigations were carried out to analyze potential relations between pos tischemic survival and a reduction of cerebral damage by spontaneous l ocomotor activity. Methods Male Mongolian gerbils were divided into tw o groups, one with access to running wheels (''runners'') and one kept in conventional cages (''nonrunners'') for 2 weeks preceding forebrai n ischemia of 15 or 20 minutes. A total of 99 gerbils were divided in subgroups and were allowed to recover for 2 weeks for assessment of su rvival. Other subgroups (n=7 to 9) were killed at day 4 for quantitati ve histology of selectively vulnerable areas such as hippocampus, cort ex, striatum, and thalamus. Results Two weeks after 15-minute ischemia , 44% of nonrunners had survived compared with 90% of runners (P<.01). With 20-minute ischemia all runners survived compared with 21% of non runners. Quantitative histology (15-minute ischemia) revealed selectiv e nerve cell injury in various cerebral regions in both groups. In run ners, however, with the exception of the CA1 sector, damage was attenu ated in cortex, striatum, and hippocampus. Furthermore, the extent of thalamic infarction was reduced (P<.05). Conclusions Locomotor activit y before global cerebral ischemia is highly efficient in protecting th e brain as demonstrated by enhanced survival and a reduction of tissue damage in Mongolian gerbils. The mechanisms underlying this protectio n are currently unclear. However, further understanding of this intrig uing phenomenon should enhance the understanding of ischemia pathophys iology and lead to the development of new treatment strategies.