Objective To investigate the impact of hyperthermia on the expression of claudin-1 in focal cerebral ischemia-reperfusion injury in rats and its mechanism in ischemic cerebral injury.Methods A total of 100 male Sprague-Dawley rats were randomly divided into 3 groups:sham operation,normothermia and hyperthermia groups.Both the normothermia and hyperthermia groups were redivided into 3 time points:Ischemia (1 hour) and reperfusion for 3,6,and 24 h.A model of middle cerebral artery occlusion was induced by the intraluminal suture method.At 24 h after reperfusion,brain water content was measured by the wet and dry weight method.The volume of cerebral infarction was assessed by 2,3,5 triphenyl tetrazolium chloride staining.At 3,6,and 24 h after reperfusion,the claudin-1 expression in ischemic brain tissue was measured by Western blot and immunohistochemical staining Results At 24 h after reperfusion,the mean neurological function score in the normothermia group was significantly lower than that in the hyperthermia group (2.3 ± 0.48 vs.3.2 ± 0.63; t =3.576,P =0.002).The brain water content on the operated sides in the sham operation,normothermia and hyperthermia groups was 79.31％ ± 0.60％,81.13％ ± 0.12％,and 84.4％ ± 0.55％,respectively.There were significant differences (F=147.115,P=0.000).Western blot analysis showed that at 3,6,and 24 h after reperfusion,the expression levels of claudin-1 in the normothermia and hyperthermia groups were significantly lower than the sham operation group (all P =0.000),and the expression levels of claudin-1 progressively decreased with the extension of ischemia-reperfusion time (all P ＜ 0.05).At the same time point,the expression level of claudin-1 in the hyperthermia group was significantly lower than that in the normothermia group (all P ＜ 0.01).At 3 and 6 h after reperfusion,the positive expression of claudin-1 among the cerebrovascular endothelial cells was observed in the sham operation,normothermia and hyperthermia groups,while at 24 h after reperfusion,no claudin-1 positive cells were observed.Compared to the sham operation group,at 3 h after reperfusion,the numbers of claudin-1 positive cell and claudin-1 IOD/area (integrated optical density/accumulated positive cell area) in the normothermia and hyperthermia groups begin to decrease,they decreased significantly at 6 h and disappeared at 24 h (P=0.000).At 3 and 6 h after reperfusion,claudin-1 IOD/area in the hyperthermia group was significantly lower than that in the normothermia group (all P ＜ 0.01).Conclusions During cerebral ischemia-reperfusion,hyperthermia may aggravate ischemic brain edema and brain injury by down-regulating the expression of claudin-1 in blood-brain barrier.

Objective To investigate the effect of hyperthermia on expression of cathespin L (CTSL) in focal cerebral ischemia-reperfusion injury of rats and its mechanism in ischemia injury.Methods A total of 100 male Sprague-Dawley rats were randomly divided into sham-operated group (n=20),normothermia group (n=40) and hyperthermia group (giving constant temperature heating for 39 ℃,n=40);rats in the sham-operated group and normothermia group were given constant temperature heating for 37.5 ℃.Models of middle cerebral occlusion reperfusion in the later two groups were induced by intraluminal suture method.Both the normothermia and hyperthermia groups were sub-divided into 3 time point groups:ischemia for one h and reperfusion for 3,6 and 24 h (n=10,10 and 20).At 24 h after reperfusion,the neurological deficit scores,volume of infarction and brain water content were assessed.At 3,6,and 24 h after reperfusion,the expression of CTSL in ischemic brain tissues was measured by Western blotting and immunohistochemical staining.Results At 24 h after reperfusion,the mean neurological deficit scores,volume of infarction and brain water content in the hyperthermia groups were significantly higher than those in the normothermia groups (3 h:3.37±0.48 vs.2.20±0.42,6 h:59.08％±0.98％ vs.24 h:37.96％±0.16％ and 84.82％±1.79％ vs.82.18％±0.45％,P＜ 0.05).Western blotting showed that CTSL expression did not change at each time point in the normothermia group,while the CTSL expression in the hyperthermia group was significantly higher than that in the normothermia group at each time point,respectively (P＜0.05).CTSL expressed in neuron and glia of sham-operated group delected by immunohistochemistry,especially in glia.As compared with that in the sham-operated group,glia CTSL integrated optical density/accumulated positive cell area (IOD/area) began to decrease in the normothermia group at 24 h after reperfusion;neuron CTSL IOD/area began to increase at 3 h,reached to the summit at 6 h,and then,decreased at 24 h (P＜0.05).At each time point,neuron CTSL IOD/area in the hyperthermia group was significantly higher than that in the normothermia group (P＜0.05).Conclusion Hyperthermia can probably worsen the brain edema and damage by up-regulating CTSL expression after ischemia/reperfusion.