Effect of Auricularia auricular polysaccharide on ischemia myocardial injury

AIM: To investigate the protective effect of auricularia auricular polysaccharide (AAP) on the myocardial injury induced by ischemia and its underlying mechanism. METHODS: AAP was orally administrated to rats at the does of 50, 100 or 200 mg·kg-1·d-1 for 20 d. Myocardial injury was induced in anesthetized Sprague-Dawley rats by left anterior descending coronary artery ligation. Myocardial infarct size, the level of lactate dehydrogenase (LDH), the activity of superoxide dismutase (SOD), the production of lipid peroxidation malondialdehyde (MDA) and protein level of myocardial collagen of the heart were measured. RESULTS: The average myocardial infarct size in AAP groups was significantly smaller than that in ischemia group. The level of serum LDH induced by regional myocardial ischemia was significantly decreased in AAP group compared to ischemia group (P<0.01). AAP inhibited the production of MDA and increased the activity of SOD. Furthermore, AAP reduced the protein level of myocardial collagen after ischemia (P<0.01). CONCLUSION: AAP prevents myocardium from ischemia injury as an antioxidant.     

Evaluation of rat MCAO model by laser Doppler flowmetry

AIM: To investigate the feasibility and reliability of using laser Doppler flowmetry (LDF) to evaluate the animal model of cerebral ischemia and reperfusion injury in vivo. METHODS: Ten Sprague-Dawley (SD) male rats, weighing 280-310 g, were subject to unilateral middle cerebral artery occlusion (MCAO) with the routine method of line-embolism, and the cortical blood flow was continuously monitored by LDF during ischemia and reperfusion in the rats. Meanwhile, the degree of injury induced by cerebral ischemia and reperfusion was evaluated after MCAO by the nervous scoring of rat criteria. Brain slices were obtained by the method of neck end breaking and brain autopsy at the time point of ischemia for 2 h and reperfusion for 24 h. The volumes of infarction in the brain slices were determined by TTC staining. RESULTS: (1) In the successful MCAO rats, the average local blood flow remarkably decreased from the baseline value of (224.99±75.00) PU to (67.23±6.90) PU in the ischemic period. The mean difference was 157.76 PU and decreasing amplitude of local blood flow was more than 70% by MCAO. In the reperfusion period, the average local blood flow was rapidly recovered to (216.01±7.30) PU after the embolus was pulled out, which was only slightly lower than that of the baseline level without statistical significance. However, the mean difference of 148.78 PU between the local blood flow of reperfusion and local blood flow of cerebral ischemia for 2 h was found (P<0.01). The average local nervous score was 10.35 at 24 h after cerebral ischemia and reperfusion,higher than that of the baseline (0 point). The infracted evidence with remarkable brain edema in the brain slices was clearly observed with TTC staining. (2) In the unsuccessful MCAO rats, the decrease in local blood flow was less than 50%. The local nervous score was 0 point at 24 h, which was equal to the baseline value. No local infraction and brain edema was observed in the brain slices. CONCLUSION: Besides using the local nervous functional scoring, continuously monitoring of blood flow by LDF in vivo is a reliable and useful method to confirm the successful establishment of rat MCAO model.     

Effects of nitric oxide synthase inhibitors on focal cerebral ischemic injury in rats

AIM:To observe the effects of nitric oxide and different isoforms of nitric oxide synthase inhibitors on the focal cerebral ischemic injury in rats. METHODS:After the rat model of focal cerebral ischemia were established with middle cerebral artery occlusion (MCAO), aminoguanidine(AG)and N^G-nitro-L-arginine(L-NA )were administrated and the cerebral infarct size, NO production,MDA content, nitric oxide synthase(NOS) and SOD activities in the focal ischemic brain tissues were examined. RESULTS:AG could significantly attenuate the focal cerebral ischemic injury, and L-NA had a protective effect when it was administrated at 1 h,6 h but not at 3 h after surgery.CONCLUSION:Cerebral ischemic injury could be attenuated by both selective and nonselective inhibition of NOS.     

Effects of Salvia miltiorrhiza Bunge.f.alba. on mitochondrial damage and apoptosis induced by cerebral ischemia and reperfusion

AIM: To observe the effects of Salvia miltiorrhiza Bunge.f.alba. (Sal) on the mitochondrial ultra-structure, oxidative stress and apoptosis induced by ischemia injury in a rat model of focal cerebral ischemia and reperfusion.METHODS: The middle cerebral artery occlusion/reperfusion (MCAO/R) rat model was established by a modified Longa occlusion method. Adult male SD rats were randomly divided into control group, simple ischemia reperfusion group, Sal with ischemia reperfusion group and butylphthalide with ischemia reperfusion group. To study the protective effects of Sal and its mechanism, the intervention of Sal was given and the ultra-structure of mitochondria, functions of mitochondria under oxidative stress and the incidence of apoptosis of brain cells were determined.RESULTS: Many electron dense toxic granulation and vacuolus in mitochondria were observed in the rat brain of focal cerebral ischemia and reperfusion. Under the condition of ischemia and reperfusion, the mitochondria membrane was disaggregative, and the tubular cristae of mitochondrion disappeared. MDA content was obviously increased and the activity of glutathione peroxidase decreased significantly. The apoptosis of brain cells were observed in a great quantity. The changes of ultra-structure of mitochondria and the activity of GSH-Pxase were significantly improved by the treatment of Sal. Furthermore, treatment with Sal delayed the decrease of GSH-Pxase activity, and inhibited the increase in MDA content in brain tissue after ischemia and reperfusion. The incidence of apoptosis of brain cells was also decreased.CONCLUSION: Sal protects the brain tissue from ischemia injury.     

Effects of ghrelin on brain edema and aquaporin 4 expression after cerebral ischemia/reperfusion in rats

AIM: To explore the effects of ghrelin on the brain edema, the permeability of blood-brain barrier (BBB) and the expression of aquaporin 4 (AQP4) after cerebral ischemia/reperfusion in rats. METHODS: Adult male Sprague-Dawley rats were randomly divided into sham operation group, middle cerebral artery occlusion (MCAO) group and ghrelin treatment group. The MCAO model was made with nylon thread for 2 h of occlusion following 22 h of reperfusion. Ghrelin at a dose of 10 nmol/kg was injected via femoral vein at the beginning of reperfusion. The cerebral infarct volume was measured by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Brain functional deficits were evaluated by determining the neurological scores. The changes of brain swelling and water content were analyzed through volume calculation and dry/wet weight measurement. The permeability of BBB was detected by collecting extravascular Evans blue (EB) in the brain cortex. The changes of AQP4 expression were assessed by the methods of immunohistochemistry and Western blotting. RESULTS: Compared with MCAO group, the rats in ghrelin treatment group had smaller brain infarct volume, lower EB exudation content and neurological scores. The percentage of brain swelling, water content and AQP4 expression were lower in ghrelin treatment group than those in MCAO group. CONCLUSION: Ghrelin reduces the injury of cerebral ischemia/reperfusion, and lightens the brain edema and BBB damage in rats. Ghrelin also inhibits the expression of AQP4 in brain tissue.     

Protective effect of magnesium on brain with acute ischemia and reperfusion injury

AIM: To dynamically observe the protective effect of magnesium on the brain with ischemia and reperfusion injury in the middle cerebral artery occlusion (MCAO) rat model using the device of laser Doppler flowmetry (LDF) .METHODS: Twenty-four Sprague-Dawley male rats (280-300 g) were used to establish MCAO model with the conventional line-embolism method.The rats were divided into 4 groups according to the initial time of peritoneal injection of magnesium sulfate (MgSO₄).The rats in MgSO₄ groups were treated with 25% MgSO₄ at 160 mg/kg at time points of 20 min, 30 min and 40 min after ischemia.The rats in control group were treated with the same volume of normal saline.The real-time fluctuation of the local cerebral blood flow (CBF) was dynamically monitored by LDF.The degree of nervous functional defect was evaluated by calculating the neurological impairment score of the rats after suffered from 2 h ischemia and followed with 24 h reperfusion.All the rats were killed with an end breaking method, and the volumes of brain infarction were evaluated by TTC staining at the brain slices obtained by autopsy.RESULTS: The fluctuating features in 3 MgSO₄ treatment groups were as follows: when reperfusion began, the local CBF appeared and increased smoothly, then approached to its baseline step by step, and kept at the stable level in the whole reperfusion period.The CBF in control group fluctuated sharply in the whole reperfusion period associated with the heart beating, which was significantly different from those in MgSO₄ treatment groups.The average volume of brain infarction in MgSO₄ treatment groups was 26.5%, 36.5% and 24.5%, respectively, and was 54.0% in control group.The local nervous defect scores in MgSO₄ treatment groups were 5.670±1.003, 8.670±1.211 and 7.170±1.472, respectively, and was 11.170±0.983 in control group.CONCLUSION: Vasomotor functional improvement might be one of the protective mechanisms of magnesium on the brain with cerebral ischemia and reperfusion injury in acute ischemic stroke.     

Protective effect of spermine on rats with acute cerebral ischemia/reperfusion injury

AIM: To study the effects and the possible mechanisms of exogenous spermine on the rats with acute transient focal cerebral ischemia/reperfusion (I/R) injury.METHODS: The rat model of focal cerebral ischemia/reperfusion was established by middle cerebral artery occlusion (2 h) and reperfusion (2 h). Healthy adult SD rats were divided into 5 groups;sham group,I/R group and spermine(4,20 and 40 mmol/L)groups.The degree of cerebral injury was evaluated by neurological deficit score, infracted volume, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content. The morphological changes of the brain were observed by HE staining and electron microscopy. RESULTS: Compared with I/R group, the neurological deficit score, infracted volume and the content of MDA were decreased, the SOD activity was increased and the ultrastructural changes were improved in spermine-treated groups. CONCLUSION: Exogenous spermine has a protective effect against acute focal cerebral ischemia/reperfusion injury. The mechanisms may be related to scavenging free radical by spermine.     

Sivelestat sodium reduces cerebral ischemia-reperfusion injury in rats

AIM: To investigate the protective effect of neutrophil elastase inhibitor sivelestat sodium hydrate (ONO-5046) on the global brain ischemia-reperfusion injury in rats.METHODS: The global brain ischemia model in rats was induced by occlusion both sides of arteria carotis communis with hypotension for 20 min, followed by 24 h reperfusion. The brain water ratio was detected. The levels of malondialdehyde (MDA), the activities of superoxide dismutase (SOD) and myeloperoxidase (MPO) in brain were measured by spectrophotometer. Immunohistochemistry was employed to assess the expression of nuclear factor κB (NF-κB) and tumor necrosis factor α (TNF-α). The histopathological change was observed with HE staining. RESULTS: Pretreatment with ONO-5046 markedly reduced brain water ratio by global brain ischemia, decreased MDA levels, increased SOD activity, inhibited MPO activity and decreased expression of NF-κB and TNF-α. ONO-5046 also improved the brain from histopathological injury. CONCLUSION: NE inhibitor ONO-5046 has a protective effect on global brain ischemia-reperfusion injury and NE provides a new target for treatment of cerebral ischemia-reperfusion injury.     

Stability of cerebral focal ischemia/reperfusion model induced by monofilament in Kunming mice

AIM: To study the stability of mouse cerebral ischemia/reperfusion model induced by the method of monofilament. METHODS: Sixty male Kunming mice were divided into 3 groups according to the body weight: group A (18-21 g), group B (22-28 g) and group C (30-35 g). Ischemia/reperfusion (I/R) model was made by middle cerebral artery occlusion (MCAO) with nylon monofilament. To evaluate the mouse MCAO model, the method of PRM2 laser Doppler was used to detect the cerebral blood flow, the neurological deficit scores were determined by Longa standard and infarction volume was detected with TTC staining. The content of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) were also measured by ELISA. RESULTS: The successful rates of model establishment in both group A and group B were higher than that in group C (P＜0.05), especially the highest in group B . The mortality in group A was significantly higher than that in group B and group C (P＜0.05). The behavior scores and cerebral infarct volume in group A and group B were significantly higher than those in group C (P＜0.05). Obvious brain injury and neurological deficits were also observed in group A and group B with the higher content of MDA and the lower activity of SOD in the cerebral cortex of the injury side. CONCLUSION: There are three important factors to ensure the success and stability of MCAO mouse model induced by monofilament, i.e. the diameter of monofilament matching the body weight of the mice, the suitable length of monofilament within the blood vessel, as well as the maintaining of proper room temperature during experiment. The MDA content and SOD activity are also effective indexes for evaluating the cerebral I/R injury.     

Role of oxytocin in neonatal rat hippocampal neurons after hypoxic-ischemic injury

AIM: To investigate whether oxytocin has neuroprotective effects on hippocampal CA1 pyramidal neurons from neonatal rats exposed to hypoxic-ischemic brain injury and the underlying mechanisms. METHODS: An in vitro model of hypoxic-ischemic injury was used by exposing the brain slices to oxygen-glucose deprivation (OGD) solution. Acute dissociated brain slices (6~8 slices per rat) from 8 Sprague-Dawely rats of 7~10 d old were used. The slices were randomly divided into 4 groups:control group, OGD 20 min group, OGD 40 min group and OGD+oxytocin group. The effect of oxytocin on neuronal death was evaluated by TO-PRO-3 staining. Fresh brain slices from other 20 neonatal rats were divided into OGD group, OGD+oxytocin group, OGD+dVOT (oxytocin receptor antagonist)+oxytocin group, and OGD+bicucuclline (GABA_A receptor antagonist)+oxytocin group. The onset of anoxic depolarization in the hippocampal neurons treated with different drugs was recorded by whole-cell patch-clamp techniques. RESULTS: The results of TO-PRO-3 staining showed that neuronal deaths in hippocampal CA1 area were increased over the prolonged OGD time. Oxytocin significantly reduced the hypoxic-ischemic deaths. Oxytocin dramatically prolonged the onset time of anoxic depolarization after the application of OGD solution. Both dVOT and bicuculline blocked this effect. CONCLUSION: Oxytocin plays a neuroprotective role in neonatal rat hippocampal CA1 pyramidal neurons by enhancing the inhibitory synaptic transmission via oxytocin receptors. Therefore, oxytocin is useful as a candidate for neuroprotective treatment after neonatal hypoxic-ischemic brain injury.     

Allicin inhibits hippocampal neuronal apoptosis induced by global cerebral ischemia-reperfusion

AIM: To explore the effect of allicin on hippocampal neuronal apoptosis induced by global cerebral ischemia-reperfusion and its mechanisms. METHODS: Wistar rats were subjected to 15 min global cerebral ischemia followed by 72 h reperfusion. Flow cytometry (FCM) was used to evaluate the rate of hippocampal neuronal apoptosis and colorimetric method was used for the measurement of nitric oxide (NO), malondialdehyde (MDA) contents and superoxide dismutase (SOD) activity in hippocampal tissue. RESULTS: Neuronal apoptotic rate, nitric oxide and malondialdehyde contents in hippocampal tissues of rats in I-R group were significantly higher than those in sham group. However, superoxide dismutase activity in hippocampal tissues of rats in I-R group was obviously lower than that in sham group. Allicin pretreatment inhibited the above changes in a dose-dependent manner. CONCLUSION: Allicin hihibits hippocampal neuronal apoptosis induced by global ischemia-reperfusion insult through anti-oxidation. The anti-oxidation action of allicin may be one of the mechanisms of inhibitory effects on hippocampal neuronal apoptosis.     

Combination of taurine and diazepam has neuroprotective effect on focal cerebral ischemia-reperfusion in rats

AIM: To observe the neuroprotective effect of combined treatment with taurine and diazepam against focal cerebral ischemia-reperfusion in rats. METHODS: Sixty male Sprague-Dawley rats were randomly divided into five groups: sham-operation group, vehicle group, taurine group (200 mg/kg, ip), diazepam group (10 mg/kg, ip) and combined treatment group (taurine 100 mg/kg+diazepam 5 mg/kg). Focal cerebral ischemia was induced by the method of middle cerebral artery occlusion (MCAO) in rats, and reperfusion was emerged by removing the thread 2 h later. The drugs were administered respectively at the time of reperfusion, and subsequently repeated once 12 h later. The animals in vehicle group were intraperitoneally injected with isodose normal saline. The neurological deficit score, the brain water content and cerebral infarction were measured 48 h after MCAO. Other 5 group animals of focal cerebral ischemia-reperfusion (n=16 in each group) were set up as mentioned above and accepted treatments 10 h after reperfusion, likewise repeated once 12 h later. Twelve animals in each group were adopted the same management as the previous 5 groups at 48 h after MCAO. The remained 4 animals in each group were sacrificed until two weeks after MCAO to observe the histopathological changes by nissl staining. RESULTS: Compared to vehicle group, the animals in combined treatment group at 2 h or 12 h after MCAO both decreased the neurological deficit score, reduced the brain water content and infarct volume (P<0.01 or P<0.05). The combined treatment significantly alleviated the neurological necrosis as well. The neuroprotective effect of the combined treatment was superior to that of using taurine or diazepam alone. CONCLUSION: These results suggest that combination of taurine and diazepam treatment has a coordinate neuroprotective effect on both the acute and chronic brain damage of focal cerebral ischemia-reperfusion.     

Changes and significance of ATPase and free radical in aged rats with brain ischemia-reperfusion

AIM: To study the mechanism of brain ischemia-reperfusion injury from ATPase activity and free radical metabolism in aged rats. METHODS: The young rats (5 months) and the aged rats (more than 20 months) were divided into young control group(YCG), young model group(YMG), aged control group(ACG) and aged model group(AMG). The ATPase and SOD activities and the contents of MDA, Ca^2＋, Na^＋ and K^＋ were measured in the rats with 30 min brain ischemia followed by 60 min reperfusion. RESULTS: The Ca^2＋content in the AMG was higher than that in the YMG and the ACG. The Na^＋-K^＋-ATPase activity in the ACG was lower than that in the YCG,was lower in the AMG than that in the YMG. The Ca^2＋-ATPase activities in the YCG was higher than that in the ACG, was lower in the AMG than that in the YMG and was higher than the ACG's. The serum and brain tissue SOD activities in the ACG was lower than that in the YCG, was lower in the AMG than YMG 's. The serum and brain tissue MDA/SOD ratio in the AMG was higher than that in the ACG.CONCLUSION:The brain tissue ischemia-reperfusion injury was related with calcium overload and free radical injury.The pathological changes were obvious and had some characteristics in the aged rats compared with the young rats because of the brain t issue aging changes in ATPase,calcium content and free radical metabolism in the aged rats.     

Effect of peurarin pretreatment on endothelial nitric oxide synthase in rat brain tissues at the early stage of cerebral ischemia in rats

AIM: To investigate the neuroprotective effect of puerarin on the expression of endothelial nitric oxide synthase (eNOS) in rat brain tissues at the early stage of cerebral ischemia.METHODS: Forty-five rats were randomized into 3 groups: 5 in sham-operated group (S group), 20 in cerebral ischemia group (M group) and 20 in puerarin pretreatment group (P group).The rats in M group and P group were further divided into 4 subgroups to apply cerebral ischemia for 0.5 h, 1 h, 2 h and 4 h,respectively.The rats were subject to middle cerebral artery occlusion (MCAO) except those in S group.Puerarin was administered with intraperitoneal injection (100 mg/kg, ip) in P group 10 min before MCAO.The equal volume of the vehicle was administered in M groups and S group at the same time.Neurological deficit scores were determined to evaluate the functional changes of the central nervous system.The pathological changes of the brain tissues were observed under microscope with neuron nissl body staining.The protein expression and distribution of eNOS in the brain tissues were evaluated by the methods of immunohistochemistry and Western blotting.RESULTS: Neurological deficit scores of the rats in all subgroups of P groups were significantly lower than those in the corresponding subgroups of M groups (P<0.05).The dissolution extent of neuron nissl body in P groups was lower than that in M groups.The protein expression of eNOS in the brain tissues in all subgroups of P groups was higher than that in the corresponding subgroups of M groups.CONCLUSION: Pretreatment with puerarin protects brain tissues from injury of cerebral ischemia at the early stage by up-regulating the protein expression of eNOS in the brain tissues.     

Protective effect of Auricularia auricular-judae polysaccharide on pulmonary tissues of rats with LPS-induced acute lung injury

AIM: To investigate the effects of Auricularia auricular-judae polysaccharide(AAP) on pulmonary tissues of rats with LPS-induced acute lung injury(ALI) and its mechanisms.METHODS: Adult Sprague-Dawley rats were randomly divided into control group, LPS group,low-dose AAP group, middle-dose AAP group, high-dose APP group, and dexamethasone group. The rats were injected with LPS(8 mg/kg, ip) to induce ALI. The rats in the AAP groups were treated with AAP for 7 d before the induction of ALI. The protein concentration in the bronchoalveolar lavage fluid(BALF) was measured. The lung edema degree was measured by detecting the wet/dry weight ratio. The myeloper-oxidase(MPO), total antioxidant capacity(T-AOC), total superoxide dismutase(T-SOD), nitric oxide synthase(NOS) and malondialdehyde(MDA) levels were determined. The pathological changes of the lung tissues were evaluated by HE staining.RESULTS: Treatment with AAP significantly improved LPS-induced lung pathological changes, attenuated the protein concentration in the BALF and wet/dry weight ratio, inhibited the activities of MPO and NOS, reduced MDA level and increased the activities of T-AOC and T-SOD.CONCLUSION: AAP protects against LPS-induced acute lung injury in rats.     

Effect of transplantation of hMSCs modified by BDNF and GDNF gene on injured brain in rat MCAO model

AIM：To study the therapeutic effect of human mesenchymal stem cells (hMSCs) modified by brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) gene transfer with liposome on middle cerebral artery occlusion (MCAO) model rats. METHODS：The nonviral expression vector was constructed and transfected into the hMSCs by liposomal method. The rat brain injury model was established by the method of MCAO. The gene-modified hMSCs, control hMSCs or PBS was transplanted into the rats 24 h after MCAO by femoral venous injection. The neurological function score, the change of the body weight and the behavior test were used to evaluate the damage of the brain in the rats. The degree of the damage and the migration of the cells 15 d after transplantation were analyzed by observing the histological changes of the brain tissues. RESULTS：The expression levels of BDNF and GDNF in gene-modified hMSCs were much higher than those in control hMSCs. The transplantation of BDNF and GDNF gene-modified hMSCs promoted the functional recovery and reduced the infarct size in the rats after MCAO. A few exogenesis cells only survived in the infarct area of the brain in the MCAO rats, and the cells showed no differentiation. CONCLUSION：Transplantation of BDNF and GDNF gene-modified hMSCs by nonviral expression vector is effective in treating cerebral ischemia. The effect may result from the action of the cytokines secreted by these cells, reducing the injuries induced by the brain ischemia and accelerating the nerve repair following the injury.     

All-trans retinoic acid attenuates blood-brain barrier injury induced by cerebral ischemia-reperfusion in rats through JNK/P38 MAPK signaling pathway

AIM: To investigate the effect of all-trans retinoic acid (ATRA) on blood-brain barrier after cerebral ischemia-reperfusion (CIR) injury in rats and its possible role mechanism.METHODS: Male SD rats were randomly divided into sham group, model (CIR) group and CIR+ATRA (10, 30 and 90 mg/kg) groups. The rat model of CIR injury was established by MCAO thread occlusion method. After ischemia for 1.5 h and reperfusion for 24 h, the neurological functional behavioral score, cerebral infarction volume, brain water content and Evans blue content were determined. The activity of matrix metalloprotein-9 (MMP-9) was measured by gelatin zymography. The protein levels of claudin-5, occludin, ZO-1, JNK, p-JNK, P38, p-P38 and MMP-9 in the brain tissues were determined by Western blot.RESULTS: Compared with CIR model group, ATRA at 30 mg/kg significantly improved neurological function, and decreased cerebral infarction volume, brain water content, Evans blue content and the degradation of tight junction proteins in ischemic area (P<0.01). The activity and protein expression of MMP-9 in ischemic brain tissue were decreased (P<0.01). The phosphorylation of JNK and P38 was inhibited and the protein levels of p-JNK and p-P38 were decreased (P<0.01).CONCLUSION: ATRA reduces the damage of brain tissue and the destruction of blood-brain barrier induced by CIR in rats. The protective effect may be related to inhibiting the activation of JNK/P38 MAPK signaling pathway and MMP-9.     

Effect of ginsenoside Rg1 on activity and protein expression of NOS in rats with cerebral ischemic reperfusion injury

AIM: To observe the neuroprotective effects of ginsenoside Rg1 on focal cerebral ischemia reperfusion (I/R) injury in rats. METHODS: SD rats were applied to right middle cerebral artery occlusion (MCAO) for 2 h followed by 24 h of reperfusion. The rats were randomly divided into sham-operation group, I/R group and ginsenoside Rg1 pretreatment groups. The rats in ginsenoside Rg1 pretreatment groups were pretreated with ginsenoside Rg1 at doses of 10, 20 or 40 mg/kg once a day for 7 days and then subject to MCAO. The neurological deficit score was measured by Longa's method. The neurons were observed with Nissel staining. The nitric oxide (NO) content, the activity of nitric oxide synthase (NOS) and inducible NOS (iNOS) in the brain tissues were determined. The expression of neuronal NOS(nNOS) and iNOS was detected by Western blotting. RESULTS: Compared with sham-operation group, ginsenoside Rg1 significantly reduced the neurological deficit score and increased the neuron number in the hippocampus. The activity of NOS and iNOS, and NO content were decreased. Ginsenoside Rg1 also down-regulated the expression of nNOS and iNOS. CONCLUSION: Ginsenoside Rg1 has protective effect on the brain during cerebral I/R injury in rats. The mechanism may be related to reducing the content of NO and the activiy of NOS dose-dependently.     

Effect of cyclooxygenase 2 on hippocampal neuronal damage induced by aluminum in rats

AIM:To study the relationship between cyclooxygenase 2(COX-2) and the damage of hippocampal neurons by aluminum overload in rats. METHODS:Newborn SD rats(less than 24 h) were used to establish the model of primary culture of hippocampal neurons. The neurons were treated with aluminum at concentration of 200 μmol/L. The techniques of RNA interference(RNAi) and cell transfection were used to study the role of COX-2 in hippocampal neuron. Following RNAi by cell transfection, Western blotting analysis was used to determine the protein expression of COX-2. Cell growth was assayed by the method of MTT. The pathological changes of the neurons were observed by fluorescence labeling. The activity of superoxide dismutase(SOD) and lactate dehydrogenase(LDH), and the content of malondialdehyde(MDA) were detected for evaluating cell damage. RESULTS:COX-2 RNAi by cell transfection significantly decreased the protein expression of COX-2 without changing the neuronal pathomorphology, cell viability, SOD activity and MDA content. However, it obviously improved livability and SOD activity of the hippocampal neurons, which were aluminum-overloaded. Inhibition of COX-2 expression also reduced the leakage of LDH and the content of MDA, and ameliorated the pathological changes in neurons. CONCLUSION:Moderate silence of COX-2 expression not only significantly affects the morphological changes and physiological functions of hippocampal neurons, but also prevents the neurons from aluminum-induced damages.