| BackgroundStroke is an acute cerebrovascular event associated with brain tissue injury.Stroke is one of the most important diseases that threaten human health and is one of the foremost contributors to functional disability.Each year,795,000 people experience a new or recurrent stroke.Approximately 610,000 of these are first attacks,and 185,000 are recurrent attacks,On average,every 40 seconds,someone in the United States has a stroke.Ischemic stroke accounts for about 85%and the rest is hemorrhagic stroke.With the aging of the social population,the incidence of ischemic stroke is increasing year by year.Thrombolysis and recanalization are the primary treatment for ischemic stroke.At present,Treatment time window of thrombolysis by intravenous application of recombinant plasminogen activator(rtPA)is narrow.Moreover,According to stroke treatment guidelines,Application of rtPA has strict indications and contraindications which making only 2%-5%of the stroke Patients have access to this treatment.About 50%of patients accepted the treatment will experience cerebral ischemia-reperfusion injury.pathophysiological mechanisms of cerebral ischemia reperfusion injury are extremely complex which involve multiple cascade reactions,such as ion imbalance,ATP depletion,massive release of excitatory neurotransmitters,extensive production of oxygen free radicals,inflammatory cascades and apoptosis,and so on.To seek multi-target neuroprotective drugs to reduce cerebral ischemia reperfusion injury has become an important subject of clinical medicine research.Although some anti-inflammatory agents,antioxidants or other agents have shown efficacy in animal experiments of stroke,many clinical trials have failed to show the desired effect of the drugs.In recent years,People pay more and more attention to active ingredients of natural plant with a variety of biological activity because of their multi-target,multiple ways in treatment of stroke and little toxic side effects.Therefore,To seek new neuroprotective agents from nature plants has become a hot spot for.And it will provide a broader idea for exploitation and development of new drugs.Sesamol(5-hydroxy-1,3-benzodioxole or 3,4-methylenedioxyphenol)is a major predominant aroma component of sesame seed oil obtained from natural Sesamum indicum L.Sesamol is water-soluble and possesses a variety of biological activity.Sesame products,have been known as traditional health supplement in Southeast Asian countries such as China and India.Compared with other dietary oils such as peanut oil,corn oil and sunflower oil,sesame oil can provide better antihypertensive,mediation of lipid,anti-fatigue and anti-aging Effect.At this stage,Sesame seeds have been accepted by Western pharmacists and used for various therapeutic purposes.It has been found that sesamol has a strong anti-inflammatory,anti-oxidation,anti-apoptotic and immune regulation characteristics.It was proved that antioxidant properties and anti-tumor properties of sesamol is stronger than resveratrol and derivatives from sunflower oil.It is effective to treat important organ damage caused by drugs and physical and chemical factors.At present,some clinical studies have also found that derivatives of sesame possess anti-fatigue,anti-aging,anti-cancer,Regulating cholesterolhe,anti-hypertension,Reducing diabetic complications and so on.In recent years,people have found that sesamol has neuroprotective function.The level of nerve growth factor and cannabinoid signal in the brain tissue of the diabetic rats will be affected if these rats were fed sesamol for long time and sesamol make effect on antidepressant performance due to the change.Antidepressant efficacy of sesamol is similar to classic antidepressant amitriptyline and the side effects are even smaller.In vitro,Sesamol can reduce the production of nitric oxide,hydrogen peroxide and reduce the activity of monoamine oxidase in glial cells.In conclusion,Sesamol has an effect on the inflammatory response,oxidative stress,and neuronal apoptosis cascade that are the important pathogenesis of stroke.Meanwhile,It is proved that sesamol inhibit effectively.risk factors for stroke such as hypertension,diabetes,hyperlipidemia,etc.It has a very important significance If we can prove that sesamol is ideal neuroprotective agent which make effect on treatment of stroke through multi-target,multi-dimensional.In the first part of this study,the rat model of cerebral ischemia-reperfusion was used to investigate the effect of sesamol on neurological deficit score,cerebral infarction volume,cerebral edema and brain histopathological changes and neuronal apoptosis.In the second part,We evaluated effect of sesamol on the oxidative stress,apoptosis cascade and inflammatory response of cerebral ischemia-reperfusion injury to understand the neuroprotective mechanism of sesamol.PART I Effects of sesamol on brain protection in rats with focal cerebral ischemia reperfusion injuryObjective:The present study aimed to evaluate the efficacy of sesamol in alleviating cerebral ischemic injury in a rat model of middle cerebral artery occlusion(MCAO).Methods:Adult SD rats were randomly divided into sham group,MCAO group,MCAO+sesamol group A and MCAO+sesamol group B.Rats were only exposed and isolated middle cerebral artery,without experiencing ischemia and reperfusion process in sham group.Rats exposed to 2 h ischemia and 24 h reperfusion in other groups.Sesamol at dose of 15mg·kg-1·d-1 and 25 mg·kg-1·d-1 was administered respectively via intraperitoneal injection for seven consecutive days prior to the induction of MCAO in the MCAO+sesamol A group and the MCAO+sesamol B group.Rats in sham group and MCAO group were injected via intraperitoneal with the same dose of solvent as control.The vital signs of heart rate,respiration,oxygen saturation and body temperature were observed before and after cerebral ischemia reperfusion.After 2 h ischemia and 24 h reperfusion,rats were given neurological deficiency tests,overdosed with general anesthesia,and then their brains were excised for infarct volume by TTC method,Degree of cerebral edema by dry and wet weight method by dry and wet weight method,and pathological changes were evaluation and analysis by HE staining of section.In addition,TdT-mediatedd UTP nick-end labeling(TUNEL)was used to observe the expression of neuronal apoptosis and apoptotic index was calculated.At last,SABC immunohistochemical staining method was used to the expression of caspase-3 in Ischemic brain tissue of rats.Results:Firstly,Compared with sham group,the neurological deficit score of MCAO group was significantly decreased(P<0.05).secondly,Compared with MCAO group,The scores were significantly improved in group MCAO+sesamol A and group MCAO+sesamol B(P<0.05)and the dose dependency of sesamol was presented.Thirdly,sesamol can reduce signifecantly cerebral infarction volume and brain water content compared with group MCAO(P<0.05).Fourthly,The morphological structure of the neurons and tissue capillaries was normal in sham group.Neuronal cells of MCAO group shrink,the nucleus staining deep,some showing a triangle,nucleolus disappeared,accompanied by vacuolization,twigs broken While the morphological changes of MCAO+sesamol A and MCAO+sesamol B group were significantly improved.The results of Tunel staining showed that only a small number of apoptotic cells were found in sham group.Compared with sham,MCAO group showed a large number of apoptotic cells under light microscope.Compared with MCAO group,MCAO +Sesamol A and MCAO+sesamol B group had lower apoptotic index and the number of wicked cells in the high dose group decreased more significantly.At last,Immunohistochemical staining after cerebral ischemia 2 h reperfusion 24 showed that compared with sham,caspase-3 positive cells in MCAO group were significantly increased(P<0.01).Compared with the MACO group,the number of caspase-3 positive cells in the two sesamol-treated groups decreased significantly,and MCAO+sesamol B was more significant than MCAO+sesamol A.Conclusions:Our results suggest that prophylactic administration of sesamol can improve neurological deficits caused by cerebral ischemia-reperfusion injury,reduce cerebral infarction volume,reduce cerebral edema,improve the pathological changes of nerve cells,and reduce apoptosis.PART ? Effects of Sesamol on Oxidative Stress Response,Apoptosis and Inflammatory Reaction in Cerebral Ischemia Reperfusion InjuryObjective:The aim of the study was to investigate the protective mechanisms of sesamol treatment on focal ischemia/reperfusion(I/R)injury at acute phase in the rat brain.Methods:SD rats were randomly divided into 3 groups:Sham group(sham operation group),MCAO group(middle cerebral artery occlusion,MCAO),sesamol group(25mg·kg-1·d-1 sesamol).We made middle cerebral artery occlusion model,Rats were exposed to 2 h ischemia and followed by 24 h reperfusion.Rats in sesamol group were given sesamol by Intraperitoneal injection daily a week before ischemia.Rats in the sham group didn't experience the process of ischemia-reperfusion.Rats in MCAO group and Sham group were injected saline by Intraperitoneal injection under the same conditions.After 24h reperfusion,The malondialdehyde content and The levels of antioxidant levels oxidative stress(superoxide dismutase,glutathione and glutatione peroxidase)were assessed.Furthermore,levels of B cell lymphoma-2(Bcl-2),B cell lymphoma-2-associated X protein(Bax)and caspase-3 were assayed by western blot.Finally,Inflammatory cytokines IL-1?,TNF-? and IL-8 in the brain tissues were analyzed by reverse transcription-quantitative polymerase chain reaction.Results:Compared with sham group,The brain level of MDA in rats from the MCAO group was significantly higher(4.15±0.36 vs.2.20±0.25,P<0.05),while the levels of SOD(65.15±7.57 vs.115.25± 10.24,P<0.05),GSH(3.55±0.52 vs.4.93±0.75,P<0.05)and GPx(3.21 ±0.96 vs.5.79±1.02,P<0.05)were significantly increased.The levels of proinflammatory mediators IL-6(1.17±0.85 vs.0.20±0.07,P<0.05)and TNF-? mRNA(1.40±0.16 vs.0.32±0.06,P<0.05)were increased.The levels of Bax(1.10±0.08 vs.1.80±0.25,P<0.05)and caspase-3(1.13±0.26 vs.0.36±0.05,P<0.05)were increased and the brain level of Bcl-2 decreased(0.50±0.03 vs.1.60±0.09,P<0.05).Compared with the MCAO group,pretreatment with sesamol seven days prior to focal cerebral I/R injury had significant positive effects,including a reduction in malondialdehyde content(2.45±0.44 Vs.4.15±0.36,P<0.05)and elevation of antioxidant superoxide dismutase(92.15±8.82 vs.65.15±7.57,P<0.05),glutathione(4.45±0.55 vs.3.55±0.52,P<0.05)and glutatione peroxidase(5.25±1.07 vs.3.21±0.96,P<0.05).Furthermore,the mRNA expression of proinflammatory cytokines IL-6(0.38±0.04 vs.1.40±0.11,P<0.05)and TNF-? mRNA(0.33±0.08 vs.1.17±0.35,P<0.05)were significantly reduced in focal cerebral I/R injury rats upon sesamol intervention.At last,B cell lymphoma-2-associated X protein(1.10±0.08 vs.1.80±0.25,P<0.05)and caspase-3(0.70±0.06 vs.1.13±0.26,P<0.05)were significantly down regulated,whereas the level of Bcl-2 was effectively increased(1.20±0.09 vs.0.50±0.03,P<0.05).Conclusions:Our results suggestted that the beneficial effects of sesamol on cerebral I/R injury may be due to the reduction of oxidative stress,inhibition of apoptosis and inflammation. |
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