| [Objective] With the intensifying aging of the population, the incidence of cerebral vascular disease is rising in China. Cerebral vascular disease has deep influence on people’s health and life, and brought the heavy burden to family and the society because of its high morbidity and high mortality.Cerebral ischemia is the most common type of cerebral vascular disease and acquire more concern for the public and physician. Cathepsin L (cathepsin L, CTSL) in the form of the proenzyme was widely exists in animal cell primary lysosomes. Cerebral ischemia breaks stability of lysosome membrane and results in its permeability higher. A lot of CTSL are released into the cytoplasm and activated and degrade blood brain barrier (BBB). Hyperthermia or body temperature increase is a common complication occurring in the initial phase of an ischemic stroke.Clinical studies have shown that hyperthermia in stroke patients can worsen the outcome.But the reasons are not fully elucidated.In the present study, we have examined the changing of CTSL with the time after hyperthermia and its possible role on the brain edema and cerebral infarction.[Methods] Middle cerebral artery occlusion (MCAo) was induced according to Longa way in adult male Sprague-Dawley rats.100male SD rats were randomly divided into a sham group (n=20); normothermia ischemic (No+Is)3h(n=10),6h(n=10) and24h(n=20) groups; hyperthermia ischemia(Hp+Is)3h(n=10),6h(n=10) and24h group(n=10).After focal cerebral ischemia was successfully established, rats in Hp+Is group received hyperthermia treatment for3hours, whose rectal temperature was kept at39.0℃by a multifunctional small pet electric blanket.Rats in No+Is group received normothermia treatment for3hours, whose rectal temperature was kept at37.5℃by multifunctional small pet electric blanket. Neurologic score and infract size were evaluated at24h after the MCAo. The cerebral infarction volume was evaluated byTTC (2,3,5triphenylter-trazolium chloride) staining method at24h after ischemic/r-eperfusion. Brain edema was measured by wet and dry weight method. CTSL expression was detected by immunohistochemistry and western blot.[Results]1. Neurologic score also increased at6h and24h compared with3h in norothmer-mia ischemia group (P<0.05), reached to the peak at24h, but there is no difference between24h and6h. Neurologic score raised in hyperthermia ischemia group with the prolongation of time of ischemia/reperfusio(P<0.001).The neurologic score is much more higher at24h in hyperthermia ischemia group than the one at the same time in normothermia ischemia group(P<0.001). However there is no statistical difference at3h and6h within the two groups.2Infarct volumes of hyperthermia ischemia group increased compared with that of normothermia ischemia group (P<0.05).3. Ischemia increased the water content of the brain in normothermia ischemia group compared to the sham group at24h after ischemic/reperfusion(P<0.05). The water content of the brain in the hyperthermia ischemia group was higher than that of normothermia ischemia group (P<0.001).4. The amount of glial cells which expressed CTSL augmented and reached the peak at6h after ischemia/reperfusion in normothermia ischemia group compared with the Sham group, and they decreased to the bottom at24h which was even lower than the one of Sham group in normothermia ischemia group. The amount of glial cells which expressed CTSLin hyperthermia ischemia group fluctuated was similar to the ones in normothermia ischemia group. A-t6h, the amout of glial cells expressed CTSL in hyperthermia ischemia group increased compared to normothermia ischemia group(P<0.05).5The sum of neuron cells which expressed CTSL increased significantly and climbed to the summit at6h in normothermia ischemia group compared with Sham group, they inclined to normal level at24h. After ischemia/reperfusion, the variance of the sum of neuron cells which expressed CTSL in hyperthermia ischemia group is similar to those in normothermia ischemia group. The sum of neuron cells which expressed CTSL at6h in hyperthermia ischemia group was higher than the ones in normothermia ischemia group at the same time, which was statistically different.6We found that the The total number of glial cells expressed CTSL was much more than the sum of neuron cells expressed CTSL in Sham group, normothermia ischemia group and hyperthermia ischemia group by an optical microscope.And we have the similar finding by the Image Pro Plus analysis software which can automatically count the number of cells.7. The OD value of postive glial cells in normothermia ischemia group at3h and6h is no difference compared with Sham group, but it was below normal level at24h. The variation of the OD value of postive glial cells in hyperther-mia ischemia group is similar to normothermia ischemia group.The OD value of postive glial cells was not statistically different at24h between normothermia ischemia group and hyperthermia ischemia group.The OD of postive neuron cells increased significantly at6h after ischemic/reperfusion(P<0.001) compared with sham group, and it dropped slightly at24h, but was still higher than that one at3h in normothermia ischemia group (P<0.05). The OD of postive neuron cells began to rise at3h in hyperthermia ischemia group after schemic/reperfusion, and climed to the peak at6h, then slightly decreased, while it was still higher than that one at3h (P<0.05). The OD of At the time of3h,6h and24h after schemic/reperfusion, the OD of neuron cells in hypertherma ischemia group was higher than that in normothermia ischemia group at each same time point (P<0.05).8. The expression of CTSL initiately rised at3h after ischemia/reperfusion by western blot, and it reached the summit at6h. But The expression of CTSL slightly decreased at24h, while it was still higher than that one at3h. Hyperthermia upregulated CTSL expression at each time point compared to normothermia.[Conclusions]1. Hyperthermia increases can obviously increase the neurological score after brain ischemia/reperfusion.2. Hyperthermia aggravates brain edema and increases infract size after the onset of ischemia/reperfusion within24h.3CTSL distributions are different in brain cells. CTSL in the glial cells is very..rich, but is relatively less in neuron cells. The sum of postive glial cells and neuron cells which express CTSL increase at6h after ischemia/reperfusion, and they drop at24h.4. CTSL expression rises initiately at3h after ischemia/reperfusion. It reaches the peak at6h time point and drops at24h time point.5. Hyperthermia upregulates CTSL expression which exists in glial cells and neuron cells, and aggravates brain edema and increases infract size. |
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