Duration-Dependent Neuroprotective Effect of Post-Ischemic Mild Hypothermia in the Gerbil Global Ischemic-Reperfusion Model

ABSTRACT

BACKGROUND: The present study was performed in order to evaluate the duration-dependent neuroprotective effect of post-ischemic mild hypothermia against delayed neuronal damage following transient global ischemia and to estimate the optimal duration of brief post-ischemic mild hypothermia. METHODS: Post-ischemic mild hypothermia of different duration(1 hour, 3 hours, and 6 hours) was performed immediately after 10-minute global ischemia in gerbils, and the hippocampal CA1 cell loss after 3 days was evaluated. The duration-dependent neuroprotective effect of post-ischemic mild(33-34degrees C) hypothermia of each duration was compared to the normothermic control by using histopathological methods. RESULTS: 1, 3 and 6 hours of mild hypothermia immediately following reperfusion resulted in progressively increased protection from ischemic damage, 10.0+/-8.2%, 33.7+/-21.9%, and 75.9+/-13.4%, respectively. The 3-hour and the 6-hour post-ischemic mild hypothermia groups revealed significant decreases in hippocampal CA1 area cell loss compared to the normothermic control group(9.0+/-7.7%, p<0.05), and the 6-hour group had a greater preservation than the 3-hour group(p<0.05). CONCLUSION: The results suggest that post-ischemic mild hypothermia protects against delayed neuronal damage in the hippocampal CA1 area following 10-minute transient global ischemia: 3-hour post-ischemic mild hypothermia provides a potential reduction of neuronal damage, but a 6-hour treatment is more effective in preventing neuronal damage than a 3-hour one.