| Cerebrovascular disease has been one of the most curious diseases thatthreaten the health of human beings, which cause high morbidity, mutilationand death. A lot of pathological and biological changes will exist when thecerebral ischemia happen. The mechanisms of injury of cerebral ischemiainclude Ca2+overload,free radical,NO,cell apoptosis, cytokines and so on.Therefore, to explore the mechanisms of cerebral ischemia and anti-ischemiadrugs receive more and more attention. As the studies deepening, it wassuggested that H2S may be involved in many physiological and pathologicalprocesses. And now H2S is recognized as the third endogenous signalinggaso-transmitter, following nitric oxide (NO) and carbon monoxide (CO).Especially H2S as a novel neuro-transmitter of the central nervous systemfunction has an important regulatory role. It has been demonstrated that threeenzymes present in mammalian tissues:cystathionine-β-synthase (CBS), cyst-athionine-γ-lyase(CSE),and3-mercaptopyruvate sulfur transferase (3MST).3MST in conjunction with cysteine amino transferase (CAT) contributes signi-ficantly in generating H2S from L-cysteine in the presence of a-ketoglutaratein the brain and in the vascular endothelium of thoracic aorta. Study found thatH2S involved in the occurrence of focal cerebral ischemic injury. Somescholars have found that H2S could have the protection of nerve cells againstmitochondrial oxidative stress. Therefore the effect of H2S on focal cerebralischemia was investigated in rats.Part1Change of endogenous hydrogensulfide/3-mercaptopyruvat sulfurtransferase in focal cerebral ischemia ratsObjective: To observe the changes of H2S/3MST in focal cerebralischemia rats and to investigate the effect of H2S on focal cerebral ischemiarats. Methods:(Ninety six×2) male rats were randomly divided into sevengroups.①sham group×2;②ischemia1h group×2;③ischemia3h group×2;④ischemia6h group×2;⑤ischemia9h group×2;⑥ischemia12h group×2;⑦ischemia24h group×2.Focal cerebral ischemia model was reconstructed byreforming Longa method. Rats were anesthetized with10%chloral hydrate bythe dose of0.35ml/100g body weight. Left common carotid artery(CCA),external carotid artery(ECA),internal carotid artery(ICA)were separated.Left common carotid artery and internal carotid artery were tied with suture inorder to avoid the bleeding in process. The distal end of external artery wasburned out and cut a small hole before the beginning of bifurcation ofcommon carotid artery. The obstruction of the middle cerebral artery wasperformed by inserting0.2mm nylon suture in the left external carotid arteryvia internal carotid artery, it reach and occlude the beginning of the left middlecerebral artery. The rats of sham group were only suffered the operation butdo not insert the suture. All rats were sacrificed according to the scheduledtime.Brain were removed and stained by triphenyltetrazolium chloride(TTC).Then each slice was taken photo. Ischemic brain tissue volume wereobserved and calculated by image analysis system. The content of H2S and theactivity of3MST in brain tissue were respectively detected.Results:1Compared with those of sham group rats, the symptoms of neurologicalimpairment greatly appeared from3h to24h after ligation, such as semiparalyzed condition.2Compared with those of sham group rats, the infarcted volumes weregreatly increased from3h to24h after ligation.(P<0.01)。3The content of H2S and the activity of3MST in brain tissue were notaltered at1h after ischemia (P>0.05). The content of H2S and the activity of3MST in brain tissue were significantly decreased in ischemia3h,6h,9h,12hand24h groups compared with those of sham group (P<0.05, P <0.01).Conclusion: The content of H2S and the activity of3MST in brain tissuewere markedly decreased in focal cerebral ischemia3h,6h,9h,12h and24h groups. We could arrive at the conclusion that H2S/3MST may be play a role inthe physiopathologic process of focal cerebral ischemiaPart2Effects of hydrogen sulfide on the function of mitochondria infocal cerebral ischemia ratsObjective: To study the effect of H2S on focal cerebral ischemia andexplore its possible mechanisms from the function of mitochondria in rats.Methods:(Forty×2) male rats were randomly divided into five groups(n=8).①sham group×2;②ischemia group×2;③ischemia+NaHS High dosegroup×2;④ischemia+NaHS Middle dose group×2;⑤ischemia+NaHS Lowdose group×2. Focal cerebral ischemia model was reconstructed by reformingLonga method. The content of H2S and the activity of3MST in brain tissuewere respectively detected. The infarcted volume of each group were observedand calculated by image analysis system. Neuronal mitochondrial ultrastru-cture was observed by electron microscope. The mitochondria were preparedby differential centrifugation. The swelling and activity of mitochondria weredetermined. The activities of SOD, GSH-PX and ATPase, and the contents ofmalondialdehyde (MDA) in neuronal mitochondria were respectivedlymeasured.Results:1The infarcted volume greatly appeared in ischemia group comparedwith those of the sham group (P<0.01). Compared with those of ischemiagroup, the infarcted volumes were significantly decreased in ischemia+NaHSHigh, Middle dose group(P<0.01).2The content of H2S and the activity of3MST in brain tissue weresignificantly decreased in ischemia group rats compared with those of thesham group (P<0.01). Compared with those of the ischemia group, the contentof H2S and the activity of3MST in brain tissue were significantly increased inischemia+NaHS High, Middle dose groups (P<0.05,P<0.01).3The swelling of mitochondria and the activity of mitochondria weremarkedly decreased (P<0.01) and the activities of SOD, GSH-PX and ATPasewere significantly decreased and the content of malondialdehyde(MDA) in neuronal mitochondria was significantly increased in ischemia groupcompared with those of the sham group (P<0.01). Compared with those of theischemia group, the activities of SOD, GSH-Px and ATPase and the activity ofneuronal mitochondria were significantly enhanced and the swelling ofmitochondria was markedly ameliorated and the content of MDA wassignificantly decreased in ischemia+NaHS High, Middle dose groups,(P<0.05,P<0.01).4The structure of neuron were intact,neuron arranged in neat rows andcolored evenly in sham group. Compared with those of the sham group,neuron necrosis and astrocyte swelling, mitochondrial membranes swelling,mitochondrial cristae ruptured and disappeared in ischemia group. Comparedwith those of the ischemia group, the injury of the neuron was significantlyameliorated in ischemia+NaHS High, Middle dose group.Conclusion: It could be concluded that H2S has a beneficial focalcerebral ischemia tissue protection against the ischemia injury in rats byimproving the function of neuronal mitochondria,antagonizing oxidative stressin neuronal mitochondria and maintaining mitochondrial structure and redoxfunction, which may be one of the mechanisms of ameliorating cerebralischemia injury.Conclusion:1The content of H2S and the activity of3MST in brain tissue weremarkedly decreased in focal cerebral ischemia3h,6h,9h,12h and24h group.H2S/3MST may be play a role in the physiopathologic process of focalcerebral ischemia.2H2S has a beneficial protection against the ischemia injury in rats byimproving the function of neuronal mitochondria, and maintaining mito-chondrial structure. |
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