Effect of mild hypothermia on the changes of cerebral blood flow, brain blood barrier and neuronal injuries following reperfusion of focal cerebral ischemia in rats.
OBJECTIVE
To compare the effects of mild hypothermia induced in different time courses on rats subjected to 3 hours (h) of ischemia followed by 3 h or 72 h of reperfusion.


METHODS
Eighty male Sprague-Dawley rats were divided into three mild hypothermic (MHT, 32 +/- 0.2 degrees C) groups, including intra-ischemia (MHTi), intra-reperfusion (MHTr), and intra-ischemia/reperfusion (MHTi + r) group, and one normothermic group (NT, 37 +/- 0.2 degrees C) as the control. Reversible focal ischemia was carried out in rats with suture model. The cortical blood flow was measured during 3 h of ischemia followed by 3 h of reperfusion. The permeability of brain blood barrier (BBB) was estimated after 3 h of reperfusion. The infarct volume was measured at 72 h after reperfusion to determine the effects of MHT.


RESULTS
The acute post-ischemic hyperperfusion and delayed hypoperfusion in ischemic perifocal region and sustained hypoperfusion in ischemic core were inhibited in MHTi + r and MHTi rats (P < 0.05). MHTi + r protection on post-ischemic progressive hypoperfusion in the perifocal region was more effective than that of MHTi (P < 0.05). The BBB disruption and the infarct volume were significantly reduced in both MHTi and MHTi + r groups (P < 0.05), especially in the MHTi + r rats.


CONCLUSIONS
This study demonstrates that MHTi + r has more substantial protective effects on reducing ischemia/reperfusion injury than MHTi. It may inhibit post-ischemic hyperperfusion and delayed or sustained hypoperfusion in ischemic perifocal regions, and reduce brain blood barrier disruption in the cortex region.
Huang
F
F
Department of Neurosurgery, Hua Shan Hospital, Shanghai Medical University, China.
Zhou
L
L
D000818:Animals; D001812:Blood-Brain Barrier; D002560:Cerebrovascular Circulation; D007036:Hypothermia, Induced; D002546:Ischemic Attack, Transient / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D009474:Neurons / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000503:physiopathology*; D013997:Time Factors