The miR-9-5p/CXCL11 pathway is a key target of hydrogen sulfide-mediated inhibition of neuroinflammation in hypoxic ischemic brain injury

We previously showed that hydrogen sulfide(H2S)has a neuroprotective effect in the context of hypoxic ischemic brain injury in neonatal mice.However,the precise mechanism underlying the role of H2S in this situation remains unclear.In this study,we used a neonatal mouse model of hypoxic ischemic brain injury and a lipopolysaccharide-stimulated BV2 cell model and found that treatment with L-cysteine,a H2S precursor,attenuated the cerebral infarction and cerebral atrophy induced by hypoxia and ischemia and increased the expression of miR-9-5p and cystathionineβsynthase(a major H2S synthetase in the brain)in the prefrontal cortex.We also found that an miR-9-5p inhibitor blocked the expression of cystathionineβsynthase in the prefrontal cortex in mice with brain injury caused by hypoxia and ischemia.Furthermore,miR-9-5p overexpression increased cystathionine-β-synthase and H2S expression in the injured prefrontal cortex of mice with hypoxic ischemic brain injury.L-cysteine decreased the expression of CXCL11,an miR-9-5p target gene,in the prefrontal cortex of the mouse model and in lipopolysaccharide-stimulated BV-2 cells and increased the levels of proinflammatory cytokines BNIP3,FSTL1,SOCS2 and SOCS5,while treatment with an miR-9-5p inhibitor reversed these changes.These findings suggest that H2S can reduce neuroinflammation in a neonatal mouse model of hypoxic ischemic brain injury through regulating the miR-9-5p/CXCL11 axis and restoringβ-synthase expression,thereby playing a role in reducing neuroinflammation in hypoxic ischemic brain injury.

Effect of Qingre Huayu Decoction on Autophagy and Apoptosis of Neurons in Rats with Ischemic Brain Injury by Regulating Ca^(2+)/CaMKKβ-AMPK-mTOR Pathway

[Objectives]To explore the neuroprotective mechanism of Qingre Huayu Decoction on rats with acute cerebral ischemia injury.[Methods]SD rats were divided into sham operation group,ischemia model group,low,medium and high dose groups of Qingre Huayu De-coction,with 10 rats in each group.Referring to the MCAO operation model,both the sham operation group and the model group were given normal saline by gavage,and the Qingre Huayu Decoction group was given different doses of Qingre Huayu Decoction by gavage.After the op-eration,the rats were scored for neurological deficit,neurons were stained with HE,apoptotic cells were detected with TUNEL,and the levels of autophagy and apoptotic proteins in the Ca^(2+)/CaMKKβ-AMPK-mTORpathway in brain tissue were detected with Western-blot.[Results]Compared with the model group,the neurological function score of Qingre Huayu Decoction Group decreased significantly(P<0.05),the pathological damage of neurons in Qingre Huavu Decoction Group decreased.the proportion of apoptosis-positive cells detected by TUNEL de-creased(P<0.05),and the expression of CaMKKβand AMPK increased,expression of mTOR decreased,expression of Beclin-1 and LC3 increased,and expression of Caspase-3decreased in Qingre Huayu Decoction Group(P<0.05).[Conclusions]Qingre Huayu Decoction may play a neuroprotective role by activating Ca^(2+)/CaMKKβ-AMPK-mTOR pathway and regulating the level of apoptosis and autophagy.

TianmaGouteng yin attenuates ischemic stroke-induced brain injury by inhibiting the AGE/RAGE pathway

Background:Ischemic stroke is characterized by permanent or transient obstruction of blood flow,leading to a growing risk factor and health burden.Tianmagouteng yin(TMG)is commonly used in Chinese medicine to treat cerebral ischemia.The aim of this study was to investigate the neuroprotective effects of TMG against ischemic stroke.Methods:Either permanent middle cerebral artery occlusion(pMCAO)or sham operation was performed on anesthetized Wistar male rats(n=36).Results:Results demonstrated that TMG administration reduced the infarction volume and mitigated the neurobehavioral deficits.Hematoxylin and eosin(HE)staining and Prussian blue staining revealed that TMG attenuated tissue disruption and microbleeds in hippocampus tissues.In addition,TMG down-regulated the receptor of advanced glycation end products(RAGE)and p-JAK2.It also inhibited the concentrations of advanced glycation end products(AGEs),ferritin,malondialdehyde(MDA),and reactive oxygen species(ROS).Conclusion:As repetitive clinical trials of neuroprotectants targeting stroke have failed previously,our results suggested that the natural product,TMG,can probably help in the vicious cycles of ischemic stroke pathology.

Reduction of epinephrine in the lumbar spinal cord following repetitive blast-induced traumatic brain injury in rats

Traumatic brain inju ry-induced unfavorable outcomes in human patients have independently been associated with dysregulated levels of monoamines,especially epinephrine,although few preclinical studies have examined the epinephrine level in the central nervous system after traumatic brain injury.Epinephrine has been shown to regulate the activities of spinal motoneurons as well as increase the heart rate,blood pressure,and blood flow to the hindlimb muscles.Therefore,the purpose of the present study was to determine the impact of repeated blast-induced traumatic brain injury on the epinephrine levels in seve ral function-s pecific central nervous system regions in rats.Following three repeated blast injuries at 3-day intervals,the hippocampus,motor cortex,locus coeruleus,vestibular nuclei,and lumbar spinal cord were harvested at post-injury day eight and processed for epinephrine assays using a high-sensitive electrochemical detector cou pled with high-performance liquid chromatography.Our results showed that the epinephrine levels were significantly decreased in the lumbar spinal cord tissues of blast-induced traumatic brain injury animals compared to the levels detected in age-and sex-matched sham controls.In other function-specific central nervous system regions,although the epinephrine levels were slightly altered following blast-induced tra u matic brain injury,they were not statistically significant.These results suggest that blast injury-induced significant downregulation of epinephrine in the lumbar spinal cord could negatively impact the motor and cardiovascular function.This is the first repo rt to show altered epinephrine levels in the spinal cord following repetitive mild blast-induced traumatic brain injury.

Dabrafenib,an inhibitor of RIP3 kinase-dependent necroptosis,reduces ischemic brain injury

Ischemic brain injury triggers neuronal cell death by apoptosis via caspase activation and by necroptosis through activation of the receptor-interacting protein kinases （RIPK） associated with the tumor necrosis factor-alpha （TNF-a）/death receptor. Recent evidence shows RIPK inhibitors are neuroprotective and al- leviate ischemic brain injury in a number of animal models, however, most have not yet undergone clinical trials and safety in humans remains in question. Dabrafenib, originally identified as a B-raf inhibitor that is currently used to treat melanoma, was later revealed to be a potent RIPK3 inhibitor at micromolar con- centrations. Here, we investigated whether Dabrafenib would show a similar neuroprotective effect in mice subjected to ischemic brain injury by photothrombosis. Dabrafenib administered intraperitoneally at 10 mg/ kg one hour after photothrombosis-induced focal ischemic injury significantly reduced infarct lesion size in C57BL6 mice the following day, accompanied by a markedly attenuated upregulation of TNF-u. However, subsequent lower doses （5 mg/kg/day） failed to sustain this neuroprotective effect after 4 days. Dabrafenib bl ocked lipopolysaccharides-induced activation of TNF-ct in bone marrow-derived macrophages, suggesting that Dabrafenib may attenuate TNF-ct-induced necroptotic pathway after ischemic brain injury. Since Dab- rafenib is already in clinical use for the treatment of melanoma, it might be repurposed for stroke therapy.

Acupuncture activates signal transduction pathways related to brain-tissue restoration after ischemic injury

A middle cerebral artery occlusion-model was established in rats using the improved thread embolism method.Rats were treated with acupuncture at either Dazhui（DU14）,Renzhong（DU26）, Baihui（DU20）,or a non-meridian point.Detection with protein-chip technology showed that the level of protein phosphorylation in both groups was upregulated or downregulated depending on the signaling pathway compared with the model group that did not receive acupuncture.Analysis of proteins showing downregulated phosphorylation revealed that five signaling pathways were activated in the acupuncture-treatment group,while only two were activated in the acupuncture-control group.In contrast,analysis of proteins showing upregulated phosphorylation revealed only one pathway was activated in the acupuncture-treatment group,whereas four pathways were activated in the acupuncture-control group.Furthermore,the number of activated proteins in the acupuncture-treatment group was not only higher than the acupuncture-control group,but unlike the acupuncture-control group,the majority of activated proteins were key proteins in the signaling pathways.Our findings indicate that acupuncture at specific points can activate multiple signaling pathways to promote the restoration of brain tissue following ischemic injury,and that this is based on a combination of effects resulting from multiple pathways,targets,and means.

Ischemic preconditioning protects against ischemic brain injury

In this study, we hypothesized that an increase in integrin αβand its co-activator vascular endothelial growth factor play important neuroprotective roles in ischemic injury. We performed ischemic preconditioning with bilateral common carotid artery occlusion for 5 minutes in C57BL/6J mice. This was followed by ischemic injury with bilateral common carotid artery occlusion for 30 minutes. The time interval between ischemic preconditioning and lethal ischemia was 48 hours. Histopathological analysis showed that ischemic preconditioning substantially diminished damage to neurons in the hippocampus 7 days after ischemia. Evans Blue dye assay showed that ischemic preconditioning reduced damage to the blood-brain barrier 24 hours after ischemia. This demonstrates the neuroprotective effect of ischemic preconditioning. Western blot assay revealed a significant reduction in protein levels of integrin αβ, vascular endothelial growth factor and its receptor in mice given ischemic preconditioning compared with mice not given ischemic preconditioning 24 hours after ischemia. These findings suggest that the neuroprotective effect of ischemic preconditioning is associated with lower integrin αβand vascular endothelial growth factor levels in the brain following ischemia.

The superiority and feasibility of 2,3,5-triphenyltetrazolium chloride-stained brain tissues for molecular biology experiments based on microglial properties

Background:TTC(2,3,5-triphenyltetrazolium chloride)staining is the most commonly used method in identifying and assessing cerebral infarct volumes in the transient middle cerebral artery occlusion model.Given that microglia exhibit different morphologies in different regions after ischemic stroke,we demonstrate the superiority and necessity of using TTC-stained brain tissue to analyze the expression of various proteins or genes in different regions based on microglia character.Methods:We compared brain tissue(left for 10 min on ice)from the improved TTC staining method with penumbra from the traditional sampling method.We identified the feasibility and necessity of the improved staining method using real time(RT)-PCR,Western blot,and immunofluorescence analysis.Results:There was no protein and RNA degradation in the TTC-stained brain tissue group.However,the TREM2 specifically expressed on the microglia showed a significant difference between two groups in the penumbra region.Conclusions:TTC-stained brain tissue can be used for molecular biology experiments without any restrictions.In addition,TTC-stained brain tissue shows greater superiority due to its precise positioning.

Vascular endothelial growth factor: an attractive target in the treatment of hypoxic/ischemic brain injury

Cerebral hypoxia or ischemia results in cell death and cerebral edema, as well as other cellular reactions such as angiogenesis and the reestablishment of functional microvasculature to promote recovery from brain injury. Vascular endothelial growth factor is expressed in the central nervous system after hypoxic/ischemic brain injury, and is involved in the process of brain repair via the regulation of angiogenesis, neurogenesis, neurite outgrowth, and cerebral edema, which all require vascular endothelial growth factor signaling. In this review, we focus on the role of the vascular endothelial growth factor signaling pathway in the response to hypoxic/ischemic brain injury, and discuss potential therapeutic interventions.

Ischemic postconditioning protects against ischemic brain injury by up-regulation of acid-sensing ion channel 2a

Ischemic postconditioning renders brain tissue tolerant to brain ischemia,thereby alleviating ischemic brain injury.However,the exact mechanism of action is still unclear.In this study,a rat model of global brain ischemia was subjected to ischemic postconditioning treatment using the vessel occlusion method.After 2 hours of ischemia,the bilateral common carotid arteries were blocked immediately for 10 seconds and then perfused for 10 seconds.This procedure was repeated six times.Ischemic postconditioning was found to mitigate hippocampal CA1 neuronal damage in rats with brain ischemia,and up-regulate acid-sensing ion channel 2a expression at the m RNA and protein level.These findings suggest that ischemic postconditioning up-regulates acid-sensing ion channel 2a expression in the rat hippocampus after global brain ischemia,which promotes neuronal tolerance to ischemic brain injury.

Mechanisms and status of research on the protective effects of traditional Chinese medicine against ischemic brain injury

Ischemic brain injury occurs when the metabolic needs of brain tissue cannot be met due to insufficient blood supply to the brain.It is one of the main causes of death and adult disability worldwide.The recurrence rate of ischemic brain injury is high.It places a heavy economic burden on families and society,and seriously affects human health and quality of life.In traditional Chinese medicine,ischemic stroke belongs to the category of“stroke”.The use of traditional Chinese medicine to treat stroke has a long history.After years of experimental research,a large amount of theoretical knowledge and practical experience have been accumulated.Promoting blood circulation and removing blood stasis is the basis of traditional Chinese medicine theory on the treatment of ischemic stroke.Commonly used single Chinese medicines include Chuangxiong(Ligusticum chuanxiong hort),Danggui(Angelica sinensis),Danshen(Salvia miltiorrhiza Bunge),Honghua(Carthamus tinctorius L.),Mudanpi(Moutan Cortex),and Huangqi(Astragali Radix).Buyang Huanwu decoction,Xinglou Chengqi decoction,Taohong Siwu decoction,and other traditional Chinese medicine prescriptions are believed to have a protective effect against brain damage caused by ischemic stroke.With the development of modern medical technology,the mechanism of traditional Chinese medicine treatments for ischemic brain injury has gradually been explored.This article reviews the mechanisms of traditional Chinese medicine’s protection against ischemic brain injury and its current clinical application.

Repair and regeneration properties of Ginkgo biloba after ischemic brain injury

The irretrievable fate of neurons rhetoric for the first half of this dominated the neuroscience century, a position that was fiercely contested and recently debunked by extensive studies carried out in the field of neuroregeneration research. The turning point came in the year 1928, when Ramon Y. Cajal＇s （Lobato, 2008） work suggested that the regenerative capacity of neurons, though limited, could exist beyond their physical be- ing and depended on the environment surrounding them. That the manipulation of the restrictive environment surrounding the neuron could aid the regenerative process was conclusively established by Aguayo and colleagues （Richardson et al., 1980）. Since then, various strategies have been employed to target the different phases of regeneration which include： cell-replacement and augmenting endogenous neurogenesis, the use of trophic factors, reversal of the inhibitory cues, and induction of signal- ing pathways that stimulate axon growth and guidance （Horner and Gage. 2000）.

Altered protein markers related to neural plasticity and motor function following electro-acupuncture treatment in a rat model of ischemic-hypoxic brain injury

BACKGROUND：Previous studies have demonstrated that acupuncture treatment could ameliorate impaired motor function,and these positive effects might be due to neural plasticity.OBJECTIVE：Myelin basic protein（MBP）,microtubule-associated protein 2（MAP2）,growth-associated protein-43（GAP-43）,and synaptophysin（SYN） were selected as markers of neural remodeling,and expression of these markers was evaluated with regard to altered motor function following brain injury and acupuncture treatment.DESIGN,TIME AND SETTING：A completely randomized experiment was performed at the Central Laboratory of Peking University First Hospital from November 2006 to May 2007.MATERIALS：Twenty-four Sprague Dawley rat pups,aged 7 days,were selected for the present experiment.The left common carotid artery was ligated to establish a rat model of ischemic-hypoxic brain injury.METHODS：All animals were randomly divided into three groups：sham operation,model,and electro-acupuncture treatment,with 8 rats in each group.Rats in the model and electro-acupuncture treatment group underwent establishment of ischemic-hypoxic brain injury.Upon model established,rats underwent hypobaric oxygen intervention for 24 hours.Only the left common carotid artery was exposed in rats of the sham operation group,without model establishment or oxygen intervention.The rats in the electro-acupuncture treatment group were treated with electro-acupuncture.One acupuncture needle electrode was inserted into the subcutaneous layer at the Baihui and Dazhui acupoint.The stimulation condition of the electro-acupuncture simulator was set to an amplitude-modulated wave of 0-100% and alternative frequency of 100 cycles/second,as well as frequency-modulated wave of 2-100 Hz and an alternative frequency of 3 cycles/second.Maximal current through the two electrodes was limited to 3-5 mA.The stimulation lasted for 30 minutes per day for 2 weeks.Rats in the sham operation and model groups were not treated with electro-acupuncture,but only fixed to the table for the same time period.MAIN OUTCOME MEASURES：After 2 weeks stimulation,expression of MBP,MAP2,GAP-43,and SYN were detected in the brain by immunohistochemistry.Motor function was evaluated in the three groups.RESULTS：In the sham operation group,MBP was abundant in the myelinated nerve fibers.In the electro-acupuncture treatment group,however,the corpus callosum exhibited more MBP staining than the model group.MAP2 expression was increased in the model group,and increased further in the electro-acupuncture treatment group compared with the sham operation group.GAP-43 expression in the cerebral cortex was less in model group than in sham operation,but present in abundance in the electro-acupuncture treatment group.SYN expression in the cerebral cortex was less in the model and electro-acupuncture treatment group compared with the sham operation group.There was no significant difference in SYN expression and distribution between the model and electro-acupuncture treatment groups.Motor function of rats in the electro-acupuncture treatment group was significantly better than the model group（P 〈 0.05）,although function remained lower than the sham operation group（P 〈 0.05）.CONCLUSION：Two weeks of electro-acupuncture treatment improved motor function in rats,and protein markers related to neural plasticity also changed,which may be a mechanism for improved motor function in rats with ischemic-hypoxic brain injury.

Diffusion tensor imaging of neural tract injury in a patient with hypoxic-ischemic brain injury

Hypoxic-ischemic brain injury （HI-BI） is one of the most common causes of severe neurological disability, Some studies have reported diffusion tensor imaging （DTI） findings of neonatal patients with HI-BI. However, very little is known about DTI in the adult brain. The present study reports on a 15-year-old male patient with HI-BI, who exhibited no specific focal lesions on conventional brain MRI at 5 weeks. However, neural tract injuries were revealed by DTI. Seven control subjects were also evaluated. The patient suffered from cardiac arrest due to ventricular fibrillation for a period of 10 15 minutes. At 4 weeks after onset of cardiac arrest, although he was conscious and alert, he exhibited mild quadriparesis and severe cognitive dysfunction. DTI was acquired at 5 weeks after HI-BI onset. Decreased fractional anisotropy or voxel number of neural tracts suggested partial injury of the corticospinal tract, fornix, and cingulum. Disruptions of the fornix and cingulum on DTI confirmed neural tract injury. DTI could serve as a useful tool for evaluating the state of neural tracts in patients with HI-BI.

T cell interactions with microglia in immune-inflammatory processes of ischemic stroke

The primary mechanism of secondary injury after cerebral ischemia may be the brain inflammation that emerges after an ischemic stroke,which promotes neuronal death and inhibits nerve tissue regeneration.As the first immune cells to be activated after an ischemic stroke,microglia play an important immunomodulatory role in the progression of the condition.After an ischemic stroke,peripheral blood immune cells(mainly T cells)are recruited to the central nervous system by chemokines secreted by immune cells in the brain,where they interact with central nervous system cells(mainly microglia)to trigger a secondary neuroimmune response.This review summarizes the interactions between T cells and microglia in the immune-inflammatory processes of ischemic stroke.We found that,during ischemic stroke,T cells and microglia demonstrate a more pronounced synergistic effect.Th1,Th17,and M1 microglia can co-secrete proinflammatory factors,such as interferon-γ,tumor necrosis factor-α,and interleukin-1β,to promote neuroinflammation and exacerbate brain injury.Th2,Treg,and M2 microglia jointly secrete anti-inflammatory factors,such as interleukin-4,interleukin-10,and transforming growth factor-β,to inhibit the progression of neuroinflammation,as well as growth factors such as brain-derived neurotrophic factor to promote nerve regeneration and repair brain injury.Immune interactions between microglia and T cells influence the direction of the subsequent neuroinflammation,which in turn determines the prognosis of ischemic stroke patients.Clinical trials have been conducted on the ways to modulate the interactions between T cells and microglia toward anti-inflammatory communication using the immunosuppressant fingolimod or overdosing with Treg cells to promote neural tissue repair and reduce the damage caused by ischemic stroke.However,such studies have been relatively infrequent,and clinical experience is still insufficient.In summary,in ischemic stroke,T cell subsets and activated microglia act synergistically to regulate inflammatory progression,mainly by secreting inflammatory factors.In the future,a key research direction for ischemic stroke treatment could be rooted in the enhancement of anti-inflammatory factor secretion by promoting the generation of Th2 and Treg cells,along with the activation of M2-type microglia.These approaches may alleviate neuroinflammation and facilitate the repair of neural tissues.

Versatile strategies for adult neurogenesis:avenues to repair the injured brain

Brain injuries due to trauma or stroke are major causes of adult death and disability.Unfortunately,few interventions are effective for post-injury repair of brain tissue.After a long debate on whether endogenous neurogenesis actually happens in the adult human brain,there is now substantial evidence to support its occurrence.Although neurogenesis is usually significantly stimulated by injury,the reparative potential of endogenous differentiation from neural stem/progenitor cells is usually insufficient.Alternatively,exogenous stem cell transplantation has shown promising results in animal models,but limitations such as poor long-term survival and inefficient neuronal differentiation make it still challenging for clinical use.Recently,a high focus was placed on glia-to-neuron conversion under single-factor regulation.Despite some inspiring results,the validity of this strategy is still controversial.In this review,we summarize historical findings and recent advances on neurogenesis strategies for neurorepair after brain injury.We also discuss their advantages and drawbacks,as to provide a comprehensive account of their potentials for further studies.

Ischemic preconditioning reduces ischemic brain injury by suppressing nuclear factor kappa B expression and neuronal apoptosis

Ischemic stroke induces a series of complex pathophysiological events including blood-brain barrier disruption, inflammatory response and neuronal apoptosis. Previous studies demonstrate that ischemic preconditioning attenuates ischemic brain damage via inhibiting blood-brain barrier disruption and the inflammatory response. Rats underwent transient （15 minutes） occlusion of the bilateral common carotid artery with 48 hours of reperfusion, and were subjected to permanent middle cerebral artey occlusion. This study explored whether ischemic preconditioning could reduce ischemic brain injury and relevant molecular mechanisms by inhibiting neuronal apoptosis. Results found that at 72 hours following cerebral ischemia, myeloperoxidase activity was enhanced, malondialdehyde levels increased, and neurological function was obviously damaged. Simultaneously, neuronal apoptosis increased, and nuclear factor-KB and cleaved caspase-3 expression was significantly increased in ischemic brain tissues. Ischemic preconditioning reduced the cerebral ischemia-induced inflammatory response, lipid peroxidation, and neurological function injury. In addition, ischemic preconditioning decreased nuclear factor-KB p65 and cleaved caspase-3 expression. These results suggested that ischemic preconditioning plays a protective effect against ischemic brain injury by suppressing the inflammatory response, reducing lipid peroxidation, and neuronal apoptosis via inhibition of nuclear factor-KB and cleaved caspase-3 expression.

Fetal Head Compression: Its Possible Role in Neurologic Injury

It is widely assumed that fetal ischemic brain injury during labor derives almost exclusively from severe, systemic hypoxemia with marked neonatal depression and acidemia. Severe asphyxia, however, is one of several causes of perinatal neurological injury and may not be the most common;most neonates diagnosed with hypoxic-ischemic encephalopathy do not have evidence of severe asphyxia. Sepsis, direct brain trauma, and drug or toxin exposure account for some cases, while mechanical forces of labor and delivery that increase fetal intracranial pressure sufficiently to impair brain perfusion may also contribute. Because of bony compliance and mobile suture lines, the fetal skull changes shape and redistributes cerebrospinal fluid during labor according to constraints imposed by contractions, and bony and soft tissue elements of the birth canal as the head descends. These accommodations, including the increase in intracranial pressure, are adaptive and necessary for efficient descent of the head while safeguarding cerebral blood flow. Autonomic reflexes mediated through central receptors normally provide ample protection of the brain from the considerable pressure exerted on the skull. On occasion, those forces, which are transmitted intracranially, may overcome the various adaptive anatomical, cardiovascular, metabolic, and neurological mechanisms that maintain cerebral perfusion and oxygen availability, resulting in ischemic brain injury. Accepting the notion of a potentially adverse impact of fetal head compression suggests that avoidance of excessive uterine activity and of relentless pushing without steady progress in descent may offer protection for the fetal brain during parturition. Excessive head compression should be considered in the differential diagnosis of ischemic encephalopathy.

Possible divergence of serum-and glucocorticoid-inducible kinase function in ischemic brain injury

As recent medical progress decreases the incidence of certain diseases, ischemic brain injury remains one of the major dis- eases that threaten human lives, especially in western countries. Ischemic brain injury occurs as a result of lack of oxygen and nutrients due to obstruction of blood flow in the brain, and often leads to neurological disorders such as cerebral palsy, depression, and ultimately, death. Around 800,000 Americans suffer a new or recurrent stroke, and more than 130,000 people die annually in the United States （Goldstein et al., 2011）. Despite much effort in searching for an effective treatment, at most a few reagents are approved for therapeutic medication in many countries.

Interventional effect of laser acupoint radiation on the expression of Nissl body and brain-derived neurotrophic factor in newborn rat models with ischemic/hypoxic cerebral injury

BACKGROUND： Some researches report that He-Ne laser can activate function of erythrocytes and increase content of blood and oxygen via bio-stimulating effect; therefore, it suspects that laser radiation at Baihui and Dazhui can partially increase blood circulation for oxygen-supplying content of brain and improve functional status of neurons. OBJECTIVE： To verify the effects of laser radiation at Baihui and Dazhui on the expression of Nissl body of brain tissue neurons and brain-derived neurotrophic factor （BDNF） in newborn rats with ischemic/hypoxic cerebral injury. DESIGN： Randomized controlled animal study. SETTING： Department of Neurological Histochemistry, Xianning University. MATERIALS： Forty Wistar rats of 7 - 8 days old, weighing 15 - 20 g and of both genders, were selected from Wuhan Experimental Animal Center. All the rats were randomly divided into sham operation group （n =8）, model group （n =16） and radiation group （n = 16）. The experimental animals were disposed according to ethical criteria. BDNF kit was provided by Wuhan Boster Bioengineering Co., Ltd. METHODS： The experiment was carried out in the Department of Neurological Histochemistry, Xianning University from April 2005 to October 2006. Rats in the radiation group and model group were performed with ligation of left common carotid artery, recovered at room temperature for 1 - 6 days, maintained in self-made hypoxic cabin under normal pressure and injected mixture gas （0.05 volume fraction of 02 and 0.92 volume fraction of N2） for 2 hours. In addition, rats in the sham operation group were treated with separation of left common carotid artery but not ligation and hypoxia. Rats in the model group were not given any treatment; while, rats in the radiation group were exposed with He-Ne laser of 63.28 nm in the wave length at Baihui and Dazhui acupoints on the second day after ischemia-hypoxia. The radiation was given for 10 minutes per day and once a day. Ten days were regarded as a course and the rats were exposed for 2 courses in total. At 20 days after routine breeding, left hemisphere tissues of rats in the three groups were collected for staining of Nissl body and immunohistochemistry of BDNF. MAIN OUTCOME MEASURES： Nissl body staining in left hemisphere tissue and expression of immune positive cells of BDNF. RESULTS： All 40 rats were involved in the final analysis. （1） Nissl body staining： Neuronal cytoplasm of brain tissue was full of blue granule Nissl bodies in the sham operation group; while, Nissl body in neuronal cytoplasm in the model group was stained slightly and had a certain degree of degeneration; meanwhile, there were a lot of blank area in ischemic region. Nissl body in neuron cytoplasm was gradually recovered in the radiation group and relieved as compared with that in the model group. （2） Positive cells of BDNF： Number of immune positive cells of BDNF which were ligated in lateral cerebral hemisphere of rats in the model group was higher than that in the sham operation group （P 〈 0.05）; while, BDNF expression in the radiation group was increased as compared with that in the model group （P 〈 0.05）. CONCLUSION： After laser acupoint radiation, Nissl body is increased and BDNF expression is also increased. This suggests that laser acupoint radiation has neuroprotective effect on brain tissue after ischemia-hypoxia injury.