Focal Cerebral Ischemia-reperfusion In Rats Research Articles

Effects of isoflurane preconditioning on expression of TLR4 and MyD88 during focal cerebral ischemiareperfusion in rats

Objectiye To investgate the effects of isoflurane preconditioning on expression of Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88) during focal cerebral ischemia-reperfusion (IR) in rats. Methods Thirty male SD rats weighing 250-300 g were randomly divided into 3 groups ( n = 10 each):sham operation group (group S);focal cerebral IR group and isoflurane preconditioning group (group IP). The animals were anesthetized with intraperitoneal pentobarbital 40 mg/kg. In group IR and IP a nylon thread with rounded tip was inserted into right internal jugular vein and threaded cranially until resistance was met. Mid-cerebral artery was occluded (MCAO) for 2 h followed by 24 h reperfusion. In group IP the animals inhaled 2% isoflurane98 % O2 for 1 h once a day for 5 consecutive days at 24 h before MCAO. Neurologic function was assessed and scored and cerebral infarct volume was measured at 24 h of reperfusion. The animals were sacrificed at 24, 48 and 72 h of reperfusion respectively. The right ischemic frontal lobes were removed for determination of TLR4, MyD88and NF-κB expression by Western blot analysis. Results MCAO significantly worsened neurologic function. The neurologic function deficit scores were significantly increased and the TLR4, MyD88 and NF-κB expression were significantly up-regulated in group IR as compared with group S (P ＜ 0.05). Isoflurane preconditioning significantly decreased cerebral infarct volumes and neurologic function deficit scores and down-regulated the expression of TLR4, MyD88 and NF-κB in group IP as compared with group IR ( P ＜ 0.05). Conclusion Isoflurane preconditioning can reduce inflammatory response and focal cerebral IR injury by down-regulating the expression of TLR4and Myd88. Key words: Isoflurane; Ischemic preconditioning; Toll-like receptor 4; Myeloid differentiation factor 88; Reperfusion injury; Brain

Effect of propolis flavonoids on the apoptosis of neuron and expression of caspase-3，bcl-2 and bax following focal cerebral ischemia-reperfusion in rats

Objective To observe the effect of propolis flavonoids on the apoptosis of neuron and expression of caspase-3，bcl-2 and bax following focal cerebral ischemia/reperfusion in rats and explore the protection mechanism of propolis flavonoids on the cerebral ischemia reperfusion injury.Methods 36 rats were randomly divided into sham operative，ischemia reperfusion model，propolis flavonoids group.Each group rats were further randomly divided into 1 d and 3 d group.Immunohistochemistry method was used to analyze the expression of caspase-3，bcl-2 and bax protein，and TUNEL method was used to evaluate the apoptosis of neuron.Results Compared with model group，bcl-2 protein positive cells in propolis flavonoids group were increased，and the apoptosis index of neuron，the caspase-3 and bax protein positive cells in propolis flavonoids group were reduced (P<0.01).Conclusions Propolis flavonoids can decrease the apoptosis of neuron through inhibiting the expression of caspase-3 and bax，increasing the expression of bcl-2，so propolis flavonoids may play some protective role during cerebral ischemia/reperfusion injury.

Effect of electroacupuncture on brain cells apoptosis and nerve function recovery after focal cerebral ischemia-reperfusion in rats

Objective To investigate the influence of acpuncture on free calcium in rat brain cells after focal cerebral ischemia reperfusion.Methods 145 adult male SD rats were randomly divided into control group,simple ischemia reperfusion group and acupuncture with ischemia reperfusion group.The middle cerebral artery occlusion/reperfusion (MCAO/R) rat model was established by the modified Longa occlusion method. ①The part of free calcium in rat brain cells,focal cevebral ischemia model of rats were made by thread locking up the blood vessel for 15 min.30 min later after reperfusion, the Baihui and Shuigou Point in Du meridian were acupunctured electrically 30 min.After 3h, 6h and 12h, the rat was killed and its brain cells were made into single cell suspension,marked by Fluo-3/AM.The fluorescence optical density was recorded by laser confocal microscopy.②The part of nerve functional reconstruction, focal cevebral ischemia model of rats were made by thread locking up the blood vessel for 12 hours.30 min later after reperfusion, the Baihui and Shuigou Point in Du meridian were acupunctured electrically 30 min.After 7 d, 14 d,30 d,60 d and 90 d, the rat was forced to detect it's strength of the dog.Results ①Free calcium in rats of acupuncture therapy group(6h:10.96±1.18;2h:20.9±4.37) was significantly less than that in control group in 6 h and 12 h after reperfusion (6 h: 16.87 ± 3.56,12 h: 34.10 ±1.06)(P<0.05).②The dog in rats of acupuncture therapy group was significantly more than that in control group in 7 d, 14 d after reperfusion (P＜ 0.05 ).No difference of the dog was detected in 30 d ,60 d and 90 d after reperfusion between the two groups.Conclusion Acupunture could decreases the concentration of free calcium and the expression of Caspase-3 mRNA in rat brain cells after focal cerebral ischemia reperfusion, and it can facilitate the recovery of nerve function. Key words: Cerebral ischemia reperfusion; Electro-acupuncture; Free calcium; Caspase-3 mRNA; Nerve function

Effect of lipoxin A4 on permeability of blood-brain barrier after focal cerebral ischemia-reperfusion in rats

Objective To investigate the effect of lipoxin A4 ( LXA4 ) on the permeability of blood-brain barrier (BBB) after focal cerebral ischemia-repeffnsion (I/R) in rats. Methods Fifty-four adult male SD rats weighing 200-250 g were randomly divided into 3 groups ( n = 18 each): group Ⅰ sham operation (group S); group Ⅱ focal cerebral I/R ( group I/R) and group Ⅲ LXA4 ( group L). Focal cerebral I/R was produced by middle cerebral artery occlusion (MCAO) with a 4-0 nylon thread with rounded tip inserted into right internal jugular vein and threaded cranially in group Ⅱ and Ⅲ . In group Ⅲ LXA4 100 ng was injected into right lateral ventricle of the brain after MCA was successfully occluded. MCAO was maintained for 2 h. The neurological deficit was evaluated and scored (0 = no deficit, 5 = death) at 24 h of reperfusion. 2% Evans blue 4 ml/kg was injected via femoral vein at 1 h before the animals were sacrificed. The animals were killed and their brains were immediately removed for determination of brain water content, Evans blue content and expression of matrix metalloproteinase-9 (MMP-9)in the ischemic cortex. Results The neurologic deficit scores, the brain water and Evans blue content and MMP-9 protein expression in the cortex were significantly higher in I/R group than in S group. The cerebral I/R-induced changes were significantly attenuated in LXA4 group. Conclusion LXA4 can protect blood-brain barrier against cerebral I/R injury by inhibiting MMP-9 protein expression in the brain tissue. Key words: Lipoxins; Reperfusion injury; Blood-brain barrier; Matrix metalloproteinase 9

Longitudinal changes of defensive and offensive factors in focal cerebral ischemia-reperfusion in rats

The cerebral ischemia-reperfusion injury remains a major medical problem due to the lack of effective treatment. The mechanism of brain injury is still unknown. The defensive and offensive factors, such as platelet-derived growth factor-BB (PDGF-BB), 5-lipoxygenase (5-LO), aquaporin-4 (AQP-4) and insulin-like growth factor-1 (IGF-1) may play important roles. So far, only individual factors were reported. What are the relationships among them in brain ischemia-reperfusion injury remains obscure. The present study is to investigate simultaneously the expression of PDGF-BB, 5-LO, AQP-4 and IGF-1 in middle cerebral artery occlusion/reperfusion (MCAO/R) in rats. We found that 5-LO and IGF-1 reached the peak level at 24 h after reperfusion, AQP-4 at 72 h and PDGF-BB at 7 days. With these results we inferred that both defensive factors, such as PDGF-BB, AQP-4 and IGF-1, and offensive factor, like 5-LO, play some roles in the ischemia-reperfusion injury.

Electro-stimulation of cerebellar fastigial nucleus (FNS) improves axonal regeneration

This study focused on the effect of electro-stimulation of fastigial nucleus on the expression of NgR and on axonal regeneration after focal cerebral ischemia-reperfusion in rats. Cerebral ischemia and reperfusion was induced by nylon monofilament. Ninety-six male SD rats were randomly divided into sham group and ischemic insult groups at 12 hours, 24 hours, and 1 to 3 weeks after cerebral ischemia-reperfusion. Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the changes of NgR mRNA expression. Immunohistochemistry was used to detect the expression of NgR protein and the state of axonal regeneration. Fastigial nucleus stimulation was applied at 2 hours after ischemia for one hour. The results demonstrated that NgR mRNA and protein in the infarcted cortex and hippocampus were significantly increased (p&lt;0.01). The axons were grossly damaged at 24h after cerebral ischemia-reperfusion when compared to the sham group. Fastigial nucleus stimulation decreased NgR mRNA and protein levels in the infarcted cortex and hippocampus (p&lt;0.01) and improved axonal growth at 24 hours and 2 weeks after ischemia-reperfusion (p&lt;0.05). These results suggest that electrostimulation of fastigial nucleus might provide a new strategy to promote CNS axonal regeneration.