Time-dependent changes of glial fibriliary acidic protein and cytosolic phospholipase A2 in hippocampal area of focal cerebral ischemia/reperfusion in rats

BACKGROUND： Interaction between astrocyte and neuron may two-dimensionally influence on ischemic injury; however, glial fibriliary acidic protein （GFAP） and cytosolic phospholipase A2 （cPLA2） are both important markers to reflect changes of astrocyte and neuron after cerebral ischemia, respectively. OBJECTIVE： To observe the changes of GFAP and positive cPLA2 cells in hippocampal area of model rats with focal cerebral ischemia in various phases of cerebral ischemia/reperfusion. DESIGN ： Randomized contrast observation SETTING： Department of Basic Medical Science of Human Anatomy and Histology ＆ Embryology, Medical College of Wuhan Polytechnic University; Faculty Medical College of Wuhan University. MATERIALS： The experiment was carried out in the Department of Basic Medical Science, Medical College of Wuhan Industry College from May to June 2004. A total of 28 healthy SD rats of either gender and weighing 200-250 g were provided by Animal Department of Medical College of Jianghan University. METHODS： All 28 rats were randomly divided into 7 groups, including sham operation group, 2-, 6-, 12-, 24- and 48-reperfusion groups, and triphenyltetrazolium chloride （TTC） group, with 4 in each group. Two hours after ischemia, ischemia/reperfusion models were established in left middle cerebral artery （MCA）; common carotid artery was ligated and line cork was inserted into it with the depth of （1.8±0.5） cm. Rats in sham operation group were inserted with the depth of 1.0 cm, and other operations were as the same as those in 2-hour ischemia/reperfusion groups. Models in TTC group were established as the same as those in 2-hour ischemia/24-hour reperfusion group, and they were used to evaluate the therapeutic effect. Changes of GFAP and cPLA2 in hippocampal area in various phases were detected with immunohisto- chemical method. MAIN OUTCOME MEASURES ： Changes of GFAP and positive cPLA2 cells in hippocampal area of rats with focal cerebral ischemia in various phases of ischemia/reperfusion. RESULTS： All 28 rats were involved in the final analysis without any loss. （1） Animal models successfully showed the effect of focal cerebral ischemia. （2） Changes of GFAP and cPLA2 in hippocampal area in various phases： Two hours after ischemia/reperfusion, changes of GFAP and cPLA2 were increased gradually, reached at peak at 24 hours, and decreased gradually. CONCLUSION ： Courses of GFAP and cPLA2 are changed at the onset of focal cerebral ischemia, and this suggests that both of them participate in injury or protection of brain tissue of focal cerebral ischemia.

Influence of rotating magnetic field on cerebral infarction volume, cerebral edema and free radicals metabolism after cerebral ischemia/reperfusion injury in rats

BACKGROUND: It has shown that magnetic field can improve blood circulation, decrease blood viscosity, inhibit free radicals, affect Ca2+ flow in nerve cells, control inflammatory and immunological reaction, and accelerate nerve cell regeneration. In addition, protective effect of magnetic field, which acts as an iatrophysics, on ischemic brain tissues has been understood gradually. OBJECTIVE: To investigate the effects of rotating magnetic field (RMF) on volume of cerebral infarction, cerebral edema and metabolism of free radicals in rats after cerebral ischemia/reperfusion injury. DESIGN: Randomized controlled animal study. SETTING: Rehabilitation Center of disabled children, Liaoniang; Department of Rehabilitation, the Second Affiliated Hospital, China Medical University; Department of Rehabilitation Physiotherapy, the First Affiliated Hospital, China Medical University. MATERIALS: A total of 70 healthy Wistar rats aged 18-20 weeks of both genders were selected and randomly divided into 3 groups: sham operation group with 12 rats, control group with 20 rats and treatment group with 38 rats. The treatment group included 4 time points: immediate reperfusion with 6 ones, 6-hour reperfusion with 20 ones, 12-hour reperfusion with 6 ones and 18-hour reperfusion with 6 rats. Main instruments were detailed as follows: magnetic head of rotating magnetic device was 6 cm in diameter; magnetic induction intensity at the surface of magnetic head was 0.25 T in silence; the maximal magnetic induction intensity was 0.09 T at the phase of rotation; the average rotating speed was 2500 r per minute. METHODS: The experiment was carried out in the China Medical University in March 2003. Focal cerebral ischemic animal models were established with modified Longa’s method. Operation was the same in the sham operation, but the thread was inserted as 10 mm. Neurologic impairment was assessed with 5-rating method to screen out cases. Those survivals with grade 1 and grade 2 after ischemia for 2 hours and reperfusion for 24 hours were included in the control group and treatment group. Those in the sham operation group and control group were not treated with RMF. Magnetic head was directed towards the head of rats of the treatment group, and the magnetic head was about 7 mm from skin, treated for 15 minutes. The rats were decapitated to take out brains at 24 hours after reperfusion in each group. Water content of brain and volume of cerebral infarction were assessed with wet-dry weight method and TTC staining, respectively. Activity of superoxide dismutase (SOD), content of malondialdehyde (MDA) and change of brain histomorphology in brain tissue of ischemic side were analyzed. MAIN OUTCOME MEASURES: ① Volume of cerebral infarction and changes of water content in brain; ② measurements of SOD and MDA contents in brain tissue of rats in all groups. RESULTS: A total of 70 qualified animals were involved in the final analysis after rejecting the death and unqualified animal models. ① Water content of brain: Water content of brain in the treatment was less than that in the control group at any time point except the immediate time point, and cerebral edema was relieved [(2.48±0.22)%, (2.32±0.19)%, (2.23±0.36)%, (2.91±0.44)%, P < 0.05]. In addition, there were no significant differences among 6-hour, 12-hour and 18-hour reperfusion groups (P > 0.05). ② Volume of cerebral infarction: The absolute volume of cerebral infarction in the treatment group was smaller than that in the control group [(128.21±15.05), (171.22±40.50) mm3, t =2.438, P < 0.05], and the relative volume of cerebral infarction was smaller than that in the control group [(20.22±1.44)%, (25.17±3.85)%, t =2.95, P < 0.05]. ③ Contents of SOD and MDA in brain tissues: Compared with the control group, the SOD content in the brain tissue in the treatment group increased [(54.54±3.85), (69.52±5.88) kNU/g, t =5.568, P < 0.05], while the MDA content decreased [(0.85±0.06), (1.03±0.09) μmol/g, t =4.076, P < 0.05]. ④ General morphological observation: General morphology manifested that the edema was distinct in the right cerebral hemisphere in the control group, showing fat-like white, shallow anfractuosity, flat gyria, brittle tissue and easy to break up. The edema of right cerebral hemisphere was light and surface was hyperaemia in the treatment group. CONCLUSION: RMF may improve anti-oxidative ability of brain tissue of rats with acute focal cerebral ischemia/reperfusion injury and reduce volume of cerebral infarction and degrees of cerebral edema.