Effect Of Nitro Oxide Synthase Inhibitor On Mitochondria Injury In Focal Cerebral Ischemia Rats

Cerebral ischemia is one of the diseases that severelyimpair people's heath, and one of the key factors that bringabout death and frequently remain sequelae. So far there is noextremely effective medicine. Therefore it is very profitablework to study the pathophysiology of cerebral ischemia andresearch and produce effective druges for cerebral ischemia. Inrecent years, the mechanisms of cerebral ischemic injury havebeen gradually elucidated. Excitotoxicity, calcium overload,inflammation, Nitric oxide, free radicals and dysfunction ofmitochondria have been included.Nitric oxide (NO) is synthesized from L-arginine by aconstitutive nitric oxide synthase (NOS) in the brain. NO is asmall, light molecule and the first gas known to act as abiological messenger. In recent years, many studies haveshowed that the role of NO might induce "dual effects"duringfocal cerebral ischemic injury, namely neuroprotective andneurotoxic effects. Our past experiment revealed that nitro oxidesynthase inhibitor had beneficial therapeutical effect on focalcerebral ischemic injury. It could improve neurological recoveryand reduce the infarcted volume, obviously decrease the injuryarea of brain and the quantity of degenerative neuron, markedlydiminish the stromal swelling, reduce the contents of MDA andincrease the activities of SOD in the focal ischemia brain tissue.In this experiment, the middle cerebral artery occlusion (MCAO)model was prepared. Ultrastructure changes of neuronalmitochondria were examined after ischemia by Electronicmicroscope. The isolated mitochondria of brain tissue wereobtained by differential centrifugation. The present experimentsare conducted to determine the therapeutical effects of NOSinhibitor on focal cerebral ischemic injury.Objective: To examine the effect of selective inducilenitro oxide synthase inhibitor, aminoguanidine(AG), onmitochondria injury in focal cerebral ischemia rats.Methods: The rats were randomly devided into sham,ischemia (control) and AG treatment group.The model of focalcerebral ischemia in rats were prepared with thread embolism.AG was administered respectively at 2h, 6h, 12h after MCAO.Rats were killed and mitochondria of cerebral tissue wereisolated by differential centrifugation 3 days after AG treatment.The swelling and the activity of mitochondria, the activities ofATPase, SOD, GSH-Px in mitochondria and the contents of NOand MDA in mitochondria were measured. Ultrastructurechanges of neuronal mitochondria were examined by Electronicmicroscope after ischemia and AG treatment.Results: 1 The OD values at 540nm decreased, theswelling of mitochondria markedly increased and the activity ofmitochondria decreased in ischemia 2h, 6h, 12h group (P<0.01).Compared with ischemia group, the swelling of mitochondriadecreased and the activity of mitochondria increased after AGadministered (P<0.05).2 The contents of mitochondria NO markedly increased inischemia 2h, 6h, 12h group (P<0.01). Compared with ischemiagroup, the contents of NO decreased after AG administered(P<0.05).3 The activities of ATPase, SOD and GSH-Px inmitochondria markedly decreased in MCAO rats(P<0.01), thecontents of MDA in mitochondria markedly increased (P<0.05).Compared with ischemia group, the activities of ATPase, SOD,GSH-Px in mitochondria enhanced(P<0.01) and the contents ofMDA in mitochondria decreased (P<0.05) in ischemia 2h, 6h,12h group administered by AG.4 This study showed the neuronal cytoplasm and themitochondria swelled, the cristae were disrupted, dissolved ordisappeared in MCAO rats. AG could ameliorate these injuryinduced by cerebral ischemia in rats.Conclusion: It could be concluded that AG could inhibitthe activity of NOS and the production of NO, beneficiallyimprove the energy pump of mitochondria, increase theactivity of mitochondria, and ameliorate oxidative injury aftercerebra ischemia, and then can effectively protect brain damageinduced by focal cerebral ischemia.Objective: To examine the effect of nonselective inducilenitro oxide synthase inhibitor NG-nitro-L-arginine(L-NA)onmitochondria injury in focal cerebral ischemia rats.Methods: The rats were randomly devided into sham,ischemia (control) and L-NA treatment group. The model offocal cerebral ischemia in rats were prepared with threadembolism. L-NA was administered respectively at 2h, 6h, 12hafter MCAO. Rats were killed and the mitochondria of cerebraltissue were isolated by differential centrifugation 3 days afterL-NA treatment. The activities of ATPase, SOD, GSH-Px inmitochondria and the contents of NO, MDA in mitochondriawere measured. Ultrastructure changes of neuronalmitochondria were examined by electronic microscope inischemia and L-NA treatment group.Results: 1 The swelling of mitochondria markedlyincreased and the activity of mitochondria decreased in ischemia2h, 6h, 12h group (P<0.01). Compared with ischemia group, theswelling of mitochondria decreased and the activity ofmitochondria increased in group of administration of L-NA afterischemia 12h(P<0.05). However, there was no significantdefference in ischemia 2h, 6h group compared with ischemiacontrol group.2 The contents of NO in mitochondria markedly increasedin ischemia 2h, 6h, 12h group(P<0.01). Compared withischemia group, the contents of NO decreased in ischemia 2h,6h, 12h group administered by L-NA (P<0.05).3 The activities of ATPase, SOD and GSH-Px inmitochondria decreased significantly after MCAO(P<0.01), thecontents of MDA in mitochondria markedly increased (P<0.05).Compared with ischemia group, the activities of ATPase, SOD,GSH-Px in mitochondria enhanced(P<0.01) and the contents ofMDA in mitochondria decreased(P<0.05) in ischemia 12h groupadministered by L-NA. There were no signigicantly defferenceon the activities of ATPase, SOD, GSH-Px and the contents ofMDA in mitochondria between ischemia 2h, 6h groupadministered by L-NA and ischemia 2h, 6h group.4 The studies we have performed showed the neuronalcytoplasm and the mitochondria swelled, the cristae weredisrupted, dissolved or disappeared in MCAO rats. L-NA couldameliorate these injury induced by cerebral ischemia in rats.Conclusion: Above researches lead us to conclude thatL-NA can beneficially inhibit the activity of NOS and theproduction of NO in mitochondria, decrease the swelling ofmitochondria, improve the energy pump of mitochondria,increase the activity of mitochondria and ameliorate oxidative...