Objective To evaluate the effect of hypothermia on the expression of dynamin?related protein 1 ( Drp1) in brain tissues during global cerebral ischemia?reperfusion ( I∕R) in rats. Methods Thirty?six healthy male Sprague?Dawley rats, weighing 280-320 g, were divided into 3 groups ( n=12 each) using a random number table: sham operation group ( group Sham ) , global cerebral I∕R group ( group I∕R) and hypothermia group ( group H) . Cardiac arrest was induced by transoesophageal cardiac pacing followed by cardiopulmonary resuscitation to establish the global cerebral I∕R model in anesthetized rats in I∕R and H groups. In group H, the body temperature ( rectal temperature) was cooled down to 32-34 ℃ within 15 min starting from the beginning of reperfusion, and maintained at this level for 6 h. At 72 h of reperfusion, neurological deficit was scored, and the rats were sacrificed, and the whole brain was removed for examination of the pathological changes in hippocampal CA1 region and for determination of nor?mal pyramidal cell count and neuronal apoptosis in hippocampal CA1 region and expression of Drp1 and cy?tochrome c (Cyt c) in hippocampal tissues (by Western blot). The apoptosis rate was calculated. Re?sults Compared with group S, the neurological deficit score and apoptosis rate were significantly in?creased, and the number of normal pyramidal cells was decreased in I∕R and H groups, the expression of Drp1 and Cyt c in hippocampal tissues was significantly up?regulated in group I∕R ( P<0.05) , and no sig?nificant change was found in the expression of Drp1 and Cyt c in hippocampal tissues in group H ( P>0.05) . Compared with group I∕R, the neurological deficit score and apoptosis rate were significantly de?creased, the number of normal pyramidal cells was increased, and the expression of Drp1 and Cyt c in hip?pocampal tissues was down?regulated in group H ( P<0.05) . Conclusion The mechanism by which hypo?thermia inhibits cell apoptosis during global cerebral I∕R may be related to down?regulation of Drp1 expres?sion in rats.

Objective To investigate the effect of mild hypothermia combined with mitochondrial divison inhibitor 1 in mitochondrial after cerebral ischemia-reperfusion (IR).Methods Fourty male healthy Sprague-Dawley (SD) rats, weighing 280-320 g, were randomly divided into 5 groups (n=8 each): group Sham, group IR, hypothermia group (group H), Mdivi-1 group (group M) and hypothermia+Mdivi-1 group (group HM).Animal models of global cerebral IR were established by transoesophageal cardiac pacing inducing cardiac arrest followed by cardiopulmonary resuscitation (ischemia 4 min and reperfusion 6 h).The group Sham was similarly treated to group IR except the cardiac arrest and cardiopulmonary resuscitation.In groups H and HM, the core temperature was cooled down to 32-34℃ within 15 min starting from the beginning of reperfusion, and maintained for 6 h.In the other groups, the core temperature was maintained at the normal temperature.In groups M and HM, the animals were given Mdivi-1 (1.2 mg/kg) intravenously at the beginning of the reperfusion and the other groups were given the same Volume of dimethylsnlfone (DMSO).After 6 h of reperfusion, the rats were sacrificed, and bilateral hippocampi were immediately removed for determination the protein level of dynamin-related proten 1 (Drp1) and cytochrome C (Cyt-C) expression by Western blot and obsevation of the mitochondrial structure of pyramidal cell in hippocampal CA1 under electronic microscope.Results Compared with group Sham, the expression of Drp1 and Cyt-C was up-regulated in groups IR, H, M and HM (P＜0.05).Compared with group IR, the expression of Drp1 and Cyt-C was down-regulated in groups H, M and HM (P＜0.05).Compared with groups H and M, the expression of Drp1 and Cyt-C was down-regulated in group HM (P＜0.05).There was no significant difference in the expression of Drp1 and Cyt-C between groups H and M.The mitochondria were rod-shaped with clear and sound structure in group Sham, while mitochondria showed various degree of fission, swollen structures, matrix deposit, vacuoles formation and cristae collapse in other groups.The changes of group HM were relatively slight.Conclusion Mild hypothermia combined with mitochondrial divison inhibitor 1 alleviate mitochondrial damage after global cerebral IR of rats.The combined effect is better than that of any individual application.

Objective To explore the effects of complement C1q on postsynaptic density protein 95(PSD95)and motor function of rats with cerebral ischemia-reperfusion injury.Methods Thirty-six clean male SD rats,aged 6-8 weeks,weighing 220-250 g,were randomly divided into three groups:sham group(group S),middle cerebral artery occlusion(MCAO)group(group M),and MCAO+C1q neutralization group(group A),12 rats in each group.Group S only received anatomical separation of common carotid ar-tery without insertion of monofilament,group M established the MCAO model was prepared by insertion of monofilament,and group A received C1q neutralizing antibody 10 μl injected into the lateral ventricle on the first day after establishing MCAO model.Three days after modeling,the adhesion removal experiment was used to record the adhesion stimulus removal time,and the balance beam experiment was used to evaluate the limb motor function of the rats.After the rats were sacrificed,the ELISA method was used to detect the C1q and C3 levels in the hippocampus tissue,the Western blot method was used to detect the C1q subcom-ponent subunit A(C1qa)and PSD95 protein levels in the hippocampus tissue,and the Nissl staining was used to record the number of Nissl bodies.Results Compared with group S,group M exhibited a signifi-cantly longer adhesion removal time,significantly elevated balance beam experiment score,significantly higher levels of C1q,C3,and C1qa in the hippocampus,and significantly lower levels of PSD95 and Nissl's body count in the hippocampus(P＜0.05).Compared with group M,group A exhibited significantly shor-ter adhesion removals,a significantly lower balance beam experiment score,significantly lower levels of C1q,C3,and C1qa in the hippocampus,significantly higher PSD95 content,and a significantly higher Nissl's body count in the hippocampus(P＜0.05).Conclusion Cerebral ischemia-reperfusion injury in rats can induce extensive activation of the complement system and aggravate the loss of synaptic protein PSD95 and motor dysfunction in rat hippocampal tissue through complement protein C1q.Neutralizing com-plement therapy can effectively improve cerebral ischemia-reperfusion injury in rats.

Objective To evaluate the effect of hydrogen sulfide on hippocampal endoplasmic reticulum stress during global cerebral ischemia-reperfusion (I/R) in rats.Methods Seventy-two pathogen-free healthy male Sprague-Dawley rats,weighing 280-320 g,aged 8-10 weeks,were divided into 3 groups (n=24 each) using a random number table:sham operation group (group Sham),global cerebral I/R group (group I/R) and global cerebral I/R plus sodium hydrosulfide group (group I/R+NaHS).Cardiac arrest was induced with transoesophageal cardiac pacing followed by cardiopulmonary resuscitation to establish the global cerebral I/R model.Immediately after recovery of spontaneous circulation,sodium hydrosulfide 2.5 mg/kg was intraperitoneally injected in group I/R+NaHS,and normal saline 5 ml/kg was given in group I/R.The hippocampi were immediately removed at 24 h of reperfusion for determination of the expression of glucose-regulated protein 78 (GRP78),C/EBP-homologous protein (CHOP) and caspase-12 in hippocampal tissues (by Western blot).At 1,3 and 7 days of reperfusion,the hippocampal tissues were obtained and stained with haematoxylin and eosin for examination of the pathological changes in hippocampal CA1 region (under a light microscope) and for determination of apoptosis in hippocampal cells (using TUNEL staining),and the apoptosis rate was calculated.Results Compared with group Sham,the apoptosis rate of hippocampal tissues at 1,3 and 7 days of reperfusion in group I/R and at 3 and 7 days of reperfusion in group I/R+NaHS were significantly increased,and the expression of GRP78,CHOP and caspase-12 in hippocampal tissues was significantly up-regulated in I/R and I/R+NaHS groups (P＜0.05).Compared with group I/R,the apoptosis rate of hippocampal tissues was significantly decreased,and the expression of GRP78,CHOP and caspase-12 was down-regulated at 1,3 and 7 days of reperfusion (P＜0.05),and the pathological changes were significantly attenuated in group I/R+NaHS.Conclusion The mechanism by which hydrogen sulfide reduces apoptosis in hippocampal cells is related to inhibition of endoplasmic reticulum stress during global cerebral I/R in rats.