Effects of sericin on heme oxygenase-1 expression in the hippocampus and cerebral cortex of type 2 diabetes mellitus rats

Previous studies have demonstrated that sericin effectively reduces blood glucose, and protects islet cells, as well as the gonads and kidneys. However, whether sericin improves diabetes mellitus-induced structural and functional problems in the central nervous system remains poorly understood. Rat models of type 2 diabetes mellitus were established by intraperitoneal injection of streptozotocin. The present study observed histological changes in the hippocampus and cerebral cortex, as well as heme oxygenase-1 expression, and explored sericin effects on the central nervous system in diabetic rats. Pathological damage to neural cells in the rat hippocampus and cerebral cortex was relieved following intragastric administration of sericin at a dose of 2.4 g/kg for 35 consecutive days. Heme oxygenase-1 protein and mRNA expressions were decreased in the hippocampus and cerebral cortex of diabetes mellitus rats after sericin treatment. The results suggest that sericin plays a protective effect on the nervous system by decreasing the high expression of heme oxygenase-1 following diabetes mellitus.

Pine pollen inhibits cell apoptosis-related protein expression in the cerebral cortex of mice with arsenic poisoning

Previous studies have demonstrated that pine pollen can inhibit cerebral cortical cell apoptosis in mice with arsenic poisoning. The present study sought to detect the influence of pine pollen on apoptosis-related proteins. Immunohistochemistry, western blotting and enzyme-linked immunosorbent assays were used to measure the levels of apoptosis-related proteins in the cerebral cortex of mice with arsenic poisoning. Results indicated that pine pollen suppressed cell apoptosis in the cerebral cortex of arsenic-poisoned mice by reducing Bax, Bcl-2 protein expression and increasing p53 protein expression.

Edema and neuronal apoptosis in the hippocampus and cortex of elderly rats following transient cerebral ischemia/reperfusion injury

BACKGROUND： Previous studies of cerebral ischemia have used young animals, with an ischemic time greater than 5 minutes （safe time limit）. Despite an increased understanding of neuronal apoptosis, it remains uncertain whether brief cerebral ischemic events of 5 minutes or less damage brain tissue in elderly rodents. OBJECTIVE： To investigate the effects of transient cerebral ischemia （5 minutes）/reperfusion injury on brain cortical and hippocampal edema, aquaporin-4 （AQP-4） expression, and neuronal apoptosis in aged rats, and to compare ischemic sensitivity between cortex and hippocampus. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Institute of Cerebrovascular Disease, Qingdao University Medical School from April 2008 to March 2009. MATERIALS： Rabbit anti-AQP-4 polyclonal antibody, TUNEL kit, and SABC immunohistochemistry kit were purchased from Wuhan Boster Bioengineering, China. METHODS： A total of 160 healthy, male, aged 19-21 months, Wistar rats were randomly assigned to 4 groups： sham-surgery, and ischemia 1-, 3-, and 5-minute groups, with 40 rats in each group. The global cerebral ischemia model was established using the Pusinelli four-vessel occlusion, and the three cerebral ischemia groups were subdivided into reperfusion 12-hour, 1-, 2-, 3-, and 7-day subgroups, with 8 rats in each subgroup. The sham-surgery group was subjected to exposure of the first cervical bilateral alar foramina and bilateral common carotid arteries. MAIN OUTCOME MEASURES： The dry-wet weight assay was used to measure brain water content and histopathology of the cortex and hippocampus was observed following hematoxylin-eosin staining. In addition, cortical and hippocampal AQP-4 expression was detected by streptavidin-biotin complex immunohistochemistry, and neuronal apoptosis was detected by the TUNEL method. RESULTS： There was no significant difference in brain water content or AQP-4 expression in the cortex and hippocampus between ischemia 1- and 3-minute groups and the sham-surgery group or brain water content or AQP-4 expression in the cortex between ischemia 5-minute group and sham-surgery group （P 〉 0.05）. However, brain water content and AQP-4 expression in the hippocampus after 5 minutes of cerebral ischemia were significantly increased compared with the sham-surgery group （P 〈 0.05 or P 〈 0.01）. Several TUNEL-positive cells were observed in the cortex and hippocampus of the sham-surgery group and ischemia 1-minute group, as well as in the cortex of the ischemia 3-minute group. In addition, the number of apoptotic neurons in the hippocampus of ischemia 3-minute group and in the cortex and hippocampus of ischemia 5-minute group was significantly increased （P 〈 0.05 or P 〈 0.01 ）. Neuronal apoptosis was increased after 12 hours of ischemia/reperfusion, and it reached a peak by 2 days （P 〈 0.01）. CONCLUSION： Transient cerebral ischemia （5 minutes） resulted in increased hippocampal edema, AQP-4 expression, and neuronal apoptosis. Moreover, cerebral ischemia had a greater effect on neuronal apoptosis than brain edema or AQP-4 expression, and the hippocampus was more sensitive than the cortex.

Activin A maintains cerebral cortex neuronal survival and increases voltage-gated Na^+ neuronal current

Activin A, which was first described in 1986, has been shown to maintain hippocampal neuronal survival. Activin A increases intracellular free Ca2＋ via L-type Ca2＋ channels. Our previous study showed that activin A promotes neurite growth of dorsal root ganglia in embryonic chickens and inhibits nitric oxide secretion. The present study demonstrated for the first time that activin A could maintain cerebral cortex neuronal survival in vitro for a long period, and that activin A was shown to increase voltage-gated Na＋ current （/Na） in Neuro-2a cells, which was recorded by patch clamp technique. The present study revealed a novel mechanism for activin A, as well as the influence of activin A on neurons by regulating expressions of vasoactive intestine peptide and inducible nitric oxide synthase.

Optimal concentration and time window for proliferation and differentiation of neural stem cells from embryonic cerebral cortex: 5% oxygen preconditioning for 72 hours

Hypoxia promotes proliferation and differentiation of neural stem cells from embryonic day 12 rat brain tissue, but the concentration and time of hypoxic preconditioning are controversial. To address this, we cultured neural stem cells isolated from embryonic day 14 rat cerebral cortex in 5% and 10% oxygen in vitro. MTT assay, neurosphere number, and immunofluorescent staining found that 5% or 10% oxygen preconditioning for 72 hours improved neural stem cell viability and proliferation. With prolonged hypoxic duration （120 hours）, the proportion of apoptotic cells increased. Thus, 5% oxygen preconditioning for 72 hours promotes neural stem cell prolif- eration and neuronal differentiation. Our findings indicate that the optimal concentration and duration of hypoxic preconditioning for promoting proliferation and differentiation of neural stem cells from the cerebral cortex are 5% oxygen for 72 hours.

Structural changes in pyramidal cell dendrites and synapses in the unaffected side of the sensorimotor cortex following transcranial magnetic stimulation and rehabilitation training in a rat model of focal cerebral infarct

Very little is known about the effects of transcranial magnetic stimulation and rehabilitation training on pyramidal cell dendrites and synapses of the contralateral, unaffected sensorimotor cortex in a rat model of focal cerebral infarct. The present study was designed to explore the mechanisms underlying improved motor function via transcranial magnetic stimulation and rehabilitation training following cerebral infarction. Results showed that rehabilitation training or transcranial magnetic stimulation alone reduced neurological impairment in rats following cerebral infarction, as well as significantly increased synaptic curvatures and post-synaptic density in the non-injured cerebral hemisphere sensorimotor cortex and narrowed the synapse cleft width. In addition, the percentage of perforated synapses increased. The combination of transcranial magnetic stimulation and rehabilitation resulted in significantly increased total dendritic length, dendritic branching points, and dendritic density in layer V pyramidal cells of the non-injured cerebral hemisphere motor cortex. These results demonstrated that transcranial magnetic stimulation and rehabilitation training altered structural parameters of pyramidal cell dendrites and synapses in the non-injured cerebral hemisphere sensorimotor cortex, thereby improving the ability to compensate for neurological functions in rats following cerebral infarction.

Electroacupuncture stimulation of the brachial plexus trunk on the healthy side promotes brain-derived neurotrophic factor mRNA expression in the ischemic cerebral cortex of a rat model of cerebral ischemia/reperfusion injury

A rat model of cerebral ischemia/reperfusion was established by suture occlusion of the left middle cerebral artery. In situ hybridization results showed that the number of brain-derived neurotrophic factor mRNA-positive cells in the ischemic rat cerebral cortex increased after cerebral ischemia/ reperfusion injury. Low frequency continuous wave electroacupuncture （frequency 2-6 Hz, current intensity 2 mA） stimulation of the brachial plexus trunk on the healthy （right） side increased the number of brain-derived neurotrophic factor mRNA-positive cells in the ischemic cerebral cortex 14 days after cerebral ischemia/reperfusion injury. At the same time, electroacupuncture stimulation of the healthy brachial plexus truck significantly decreased neurological function scores and alleviated neurological function deficits. These findings suggest that electroacupuncture stimulation of the brachial plexus trunk on the healthy （right） side can greatly increase brain-derived neurotrophic factor mRNA expression and improve neurological function.

MicroRNA and mRNA profiling of cerebral cortex in a transgenic mouse model of Alzheimer’s disease by RNA sequencing

In a previous study,we found that long non-coding genes in Alzheimer’s disease(AD)are a result of endogenous gene disorders caused by the recruitment of microRNA(miRNA)and mRNA,and that miR-200a-3p and other representative miRNAs can mediate cognitive impairment and thus serve as new biomarkers for AD.In this study,we investigated the abnormal expression of miRNA and mRNA and the pathogenesis of AD at the epigenetic level.To this aim,we performed RNA sequencing and an integrative analysis of the cerebral cortex of the widely used amyloid precursor protein and presenilin-1 double transgenic mouse model of AD.Overall,129 mRNAs and 68 miRNAs were aberrantly expressed.Among these,eight down-regulated miRNAs and seven up-regulated miRNAs appeared as promising noninvasive biomarkers and therapeutic targets.The main enriched signaling pathways involved mitogen-activated kinase protein,phosphatidylinositol 3-kinase-protein kinase B,mechanistic target of rapamycin kinase,forkhead box O,and autophagy.An miRNA-mRNA network between dysregulated miRNAs and corresponding target genes connected with AD progression was also constructed.These miRNAs and mRNAs are potential biomarkers and therapeutic targets for new treatment strategies,early diagnosis,and prevention of AD.The present results provide a novel perspective on the role of miRNAs and mRNAs in AD.This study was approved by the Experimental Animal Care and Use Committee of Institute of Medicinal Biotechnology of Beijing,China(approval No.IMB-201909-D6)on September 6,2019.

THE EFFECT OF LIGUSTRAZINE ON NEUROGENESIS IN CORTEX AFTER FOCAL CEREBRAL ISCHEMIA IN RATS

Objective To explore the effect of Ligustrazine on neurogenesis in cortex after focal cerebral ischemia in rats. Methods Focal cerebral ischemia was induced by left middle cerebral artery occlusion with a suture. Two hours later, injection of Ligustrazine (80mg/kg, 1 time/d) was performed peritoneally. Four hours after the ischemia, 5-bromodeoxyuridine (BrdU) (50mg/kg, 1 time/d) was injected peritoneally. At 7d, 14d and 21d after ischemia, BrdU positive cells in the cortex were observed by immunohistochemical staining. Results In ischemic model group, at 7 day, sparsely-distributed BrdU positive cells were observed in the Ⅱ-Ⅵ layers of the ipsilateral cortex, with a band-like distribution in ischemic penumbra. With the prolongation of ischemia, the number of BrdU positive cells increased. In Ligustrazine group, BrdU positive cells were also observed in the Ⅱ-Ⅵ layers of the cortex, with an intense distribution in ischemic penumbra. The numbers of BrdU positive cells at 7d, 14d and 21d were more than those in ischemic model group respectively. Conclusion Ligustrazine increases the proliferated cells in cortex after focal cerebral ischemia in rats. The results suggest that it may be useful for promoting self-repair after ischemia.

Astrocytes in the cerebral cortex play a role in the spontaneous motor recovery following experimental striatal hemorrhage

Intracerebral hemorrhage （ICH） is a stroke subtype caused by spontaneous rupture of small vessels and bleeding into the brain paren- chyma, resulting in cell death and sensorimotor deficits. Despite the greater prevalence of the ischemic form of stroke （87%）, ICH has the highest mortality rate of all stroke subtypes. The striatum is the most affected structure in hemorrhagic stroke （35-70%）, followed by cere- bral cortex （15-30%）, brain stem and cerebellum （5-10%）; patients suffering striatal and/or cortical ICH bear persistent sensorimotor disabilities. Although chronic sensorimotor impairment is established, a considerable amount of patients experience some degree of spontaneous recovery during the first six months after stroke （Qureshi et al., 2009）, and the neurobiological basis of this process is not understood.

Nerve growth factor downregulates c-jun mRNA and Caspase-3 in striate cortex of rats after transient global cerebral ischemia/reperfusion

BACKGROUND： Immediate early gene （lEG） c-jun is a sensitive marker for functional status of nerve cells. Caspase-3 is a cysteine protease, which is a critical regulator of apoptosis. The effect of exogenous nerve growth factor （NGF） on the expression of c-jun mRNA and Caspase-3 protein in striate cortex of rats with transient global cerebral ischemia/reperfusion （IR） is unclear. OBJECTIVE： To study the protective effect of exogenous NGF on the brain of rats with transient globa cerebral IR and its effecting pathway by observing the expression of c-jun mRNA and Caspase-3 protein. DESIGN： Randomized controlled animal trial SETTING： Department of Neural Anatomy, Institute of Brain, China Medical University MATERIALS：Eighteen healthy male SD rats of clean grade, aged 1 to 3 months, with body mass of 250 to 300 g, were involved in this study. NGF was provided by Dalian Svate Pharmaceutical Co.,Ltd. c-jun in situ hybridization detection kit, Caspase-3 antibody and SABC kit were purchased from Boster Biotechnology Co.. Ltd. METHODS： This trial was carried out in the Department of Neural Anatomy, Institute of Brain, China Medical University during September 2003 to April 2005. （1） Experimental animals were randomized into three groups with 6 in each： sham-operation group, IR group and NGF group.（2）After the rats were anesthetized, the bilateral common carotid arteries and right external carotid arteries of rats were bluntly dissected and bilateral common carotid arteries were clamped for 30 minutes with bulldog clamps. Reperfusion began after buldog clamps were removed. Normal saline of lmL and NGF （1×10^6 U/L） of 1 mL was injected into the common carotid artery of rats via right external carotid arteries in the IR group and NGF group respectively. The injection was conducted within 30 minutes, and then the right external carotid arteries were ligated. In the sham-operation group, occlusion of bilateral common carotid arteries and administration of drugs were omitted.GAll the rats were executed by decollation at 3 hours after modeling. The animals were fixed with phosphate buffer solution （PBS, 0.1 mol/L） containing 40 g/L polyformaldehyde, their brains were quickly removed. The coronal section tissue mass containing striate cortex about 3 mm before line between two ears was taken and made into successive frozen sections.（4）The expression of c-jun mRNA and Caspase-3 protein in striate cortex of global cerebral ischemia rats were detected with in situ hybridization, immunohistochemistry and microscope image analysis. （5）t test was used for comparing the difference of the measurement data. MAIN OUTCOME MEASURES：Comparison of the expression of lEG c-jun mRNA and Caspase-3 protein in striate cortex of brain of rats in each group. RESULTS：All the 18 SD rats were involved in the analysis of results. The c-jun mRNA and Caspase-3 protein positive reaction cells were found brown yellow in the striate cortex of rats, and most of them were in lamellas Ⅱ and Ⅲ, mainly presenting round or oval. The expression of c-jun mRNA and Caspase-3 protein in sham-operation group was weak or negative. The average gray value of c-jun mRNA and Caspase-3 protein in the IR group was significantly lower than that in the sham-operation group （49.52±4.13 vs. 95.48± 5.28; 74.73±4.29 vs. 162.38±9.16,P 〈 0.01）. The average gray value of c-jun mRNA and Caspase-3 protein in the NGF group was significantly higher than that in the IR group （63.96±4.25 vs.49.52±4.13; 83.98± 4.13 vs. 74.73±4.29, P〈 0.05）. CONCLUSION： NGF can protect ischemic neurons by down-regulating the expression of c-jun mRNA and Caspase-3 protein in striate cortex of global cerebral ischemia rats.

Disappearance of unaffected motor cortex activation by repetitive transcranial magnetic stimulation in a patient with cerebral infarct

The ipsilateral motor pathway from the unaffected motor cortex to the affected extremity is one of the motor recovery mechanisms following stroke （Jang, 2011）. Because stroke patients who had shown recovery by this mechanism usually showed poorer motor function, compared with patients who showed recovery by other mechanisms, several researchers have considered this mechanism as a maladaptive plasticity （]ang, 2013）.

Expression of c-Fos protein and nitricoxide synthase in neurons of cerebral cortex from fetal rats in hypoxia and protective role of Angelica sinensis

BACKGROUND： Both c-Fos protein and nitricoxide synthase （NOS） have been used as general indexes in relative research about neurons, but it is lack of reports that c-Fos protein and NOS are applied synchronously to study the neurons of hypoxic fetal rats in uterus. OBJECTIVE： To study the effect of hypoxia in uterus on the expression of c-Fos protein and NOS in neurons of cerebral cortex from fetal rats and whether Angelica sinensis has the protective effect on these neurons in hypoxia. DESIGN： Randomized control experiment.SETTING ： Department of Histology and Embryology, Luzhou Medical College.MATERIALS ： Twelve adult female Wistar rats in oestrum and 1 male Wistar rat with bodymass from 220 to 250 g were chosen. Parenteral solution of Angelica sinensis mainly contained angelica sinensis, 10 mL/ampoule, was provided by Department of Agent of the Second Hospital Affiliated to Hubei Medical University （batch number： 01062310）. METHODS ： This experiment was completed in the Department of Histology and Embryology of Luzhou Medical College from September 2003 to June 2004. ①Twelve adult female Wistar rats in oestrum and 1 male Wistar rat were housed in one rearing cage. Vaginal embolus was performed on conceive female rat at 8： 00 am next day. On the 15^th conceiving day, all conceiving rats were divided randomly into three groups： control group, hypoxia group and Angelica group with 4 in each group. Rats in hypoxia group and Angelica group were modeled with hypotonic hypoxia in uterus. Angelica group： Rats were injected with 8 mL/kg Angelica sinensis injection through caudal veins before hypoxia. Hypoxia group： Rats were injected with the same volume of saline. Control group： Rats were not modeled and fed with normal way. ② Twenty embryos of rats were chosen randomly from each group and then routinely embedded in paraffin. Paraffin sections were cut from the brain of embryos to anterior fontanelle. Double-label staining was used to detect the expression of nNOS and c-Fos in neurons of cerebral cortex from embryos of rats. OLYMPUS Bx-50 microscope was used to observe sections and DP12 digit camera was also used under 400 times to detect types of cells. Under microscope, the number of c-Fos, NOS, c-Fos/NOS positive neurons in cerebral cortex from embryos of rats were counted in 2 fields with magnification of 400 in one section per animal. ③ The data in experiments were analyzed by one-way analysis of variance （ANOVA） followed by q test. MAIN OUTCOME MEASURES： ① Results of immunohistochemical double-label staining of c-Fos/NOS from cerebral cortex; ② Comparison of amount immunohistochemical double-label staining of c-Fos/NOS positive cells from cerebral cortex. RESULTS：① The positive NOS cells and c-Fos/NOS cells in the three groups were mainly distributed in cerebral cortex, but positive c-Fos neurons were not observed. ② Positive NOS cells and c-Fos/NOS cells in hypoxia group were more than those in control group （76.55±12.02, 50.45±10.39; 33.35±7.42, 26.35±6.67, P 〈 0.05）, but those in Angelica group were less than those in hypoxia group （51.70±9.82, 35.65±8.37, P 〈 0.05）. CONCLUSION： Hypoxia can stimulate the increase of expression of c-Fos protein and NOS in neurons of cerebral cortex. However, Angelica sinensis can decrease this expression so as to play a protective role in cerebral neurons of hypoxic fetal rats.

Expression of estrogen receptor (ER) -α and -βtranscripts in the neonatal and adult rat cerebral cortex, cerebellum, and olfactory bulb

In the present study expression of estrogen receptor subtype -alpha (ERalpha) and -beta (ERbeta) in the cerebral cortex, cerebellum, and olfactory bulb was investigated and compared between neonatal (1 to approximately 3-days-old) and adult (250 to approximately 350 g) rats, using reverse transcription-polymerase chain reaction (RT-PCR). No ERalpha transcripts were detectable in the adult cerebellum and olfactory bulb, whereas very weak expression of ERalpha was present in the adult cerebral cortex. No significant difference in ERbeta transcripts was detectable between the neonatal and adult rats. While transcripts for both ER subtypes were co-expressed in these brain areas of neonatal rats, although ERalpha expression was significantly weaker than ERbeta. Even in the cerebral cortex known to contain both ER subtypes in adult rats, ERalpha transcripts in neonatal rats were much higher than in adult. These observations provide evidence for the existence of different expression patterns of ERalpha/ERbeta transcripts in these three brain areas between the neonatal and adult rats, suggesting that each ER subtype may play a distinct role in the regulation of differentiation, development, and functions of the brain by estrogen.

Expression of bone morphogenetic protein 7 in the cerebral cortex of rats after ischemic-hypoxic injury

BACKGROUND： Some researches demonstrate that exogenous bone morphogenetic protein 7 （BMP-7） can protect ischemic cerebral nerve tissue and promote recovery of motor energy function; however, there is lack of direct evidences of endogenous BMP-7 effect. OBJECTIVE： To observe the expression of endogenous BMP-7 in nerve tissue with ischemic-hypoxic injury and investigate the possible effects on damaged nerve tissue. DESIGN： Observational contrast animal study. SETTING： Department of Anatomy and Histoembryology, Peking University Health Science Center. MATERIALS： The experiment was carried out in the Nerve Researching Laboratory of Anatomy Department, Peking University Health Science Center from October 2006 to March 2007. A total of 25 adult male SD rats weighing 250 - 300 g and several newborn SD rats were selected from Experimental Animal Center, Peking University Health Science Center. Rabbit-anti-BMP-7 polyclonal antibody was provided by Wuhan Boster Company. METHODS： ① Adult rats were randomly divided into ischemia group （n =10）, sham operation group （n = 10） and normal group （n =5）. Right external-internal carotid artery occlusion was used to infarct middle cerebral artery of adult rats in the ischemia group so as to copy focal cerebral infarction models. Line cork was inserted in crotch of internal and external carotid artery of adult rats in the sham operation group, while adult rats in the normal group were not given any treatments. ② Cerebral cortex of newborn rats was separated to obtain cell suspension. Cells which were cultured for 10 days were divided into control group and hypoxia/reoxygenation group. And then, cells in the hypoxia/reoxygenation group were cultured in hypoxic incubator for 4 hours and given reoxygenation for 24 hours. MAIN OUTCOME MEASURES： Immunohistochemical method was used to measure expression of BMP-7 in cerebral cortex at 24 hours after ischemia/reperfusion culture and in primary hypoxic culture. RESULTS： ① At 24 hours after cerebral ischemia, expression of BMP-7 in cerebral cortex on ischemic side was stronger than that on non-ischemic side in adult rats; meanwhile, numbers of cell expression were increased. However, expression of BMP-7 was not detected in bilateral cerebral cortex of adult rats in both control group and sham operation group. ② After hypoxia of cerebral cortex in primary culture, positive products of BMP-7 were observed in plasma of neuron, but expression of BMP-7 was not found in normal cerebral cortex. CONCLUSION： Endogenous BMP-7 has protective effects on nerve tissue induced by ischemic-hypoxic injury.

Agmatine reduces nitric oxide synthase expression and peroxynitrite formation in the cerebral cortex in a rat model of transient global cerebral ischemia

Agmatine, an analog of L-arginine, is an endogenous substance synthesized by arginine decarboxylase, which has been shown to possess neuroprotective effects following brain ischemia. Nitric oxide is generated by sequential oxidation of the guanidinium group in L-arginine, and agmatine might protect the brain from ischemic injury by interfering with nitric oxide signaling. This study investigated the effects of agmatine on cerebral cortex neuronal injury following transient global cerebral ischemia and also detected nitric oxide synthase expression and peroxynitrite formation. Results demonstrated that intraperitoneal injection of agmatine in global cerebral ischemia/reperfusion alleviated ischemia/reperfusion-induced cerebral cortical cortex neuronal injury and cellular apoptosis, decreased neuronal and inducible nitric oxide synthase expression at 24, 48, and 72 hours following global cerebral ischemia and reperfusion, and greatly inhibited nitrotyrosine levels, which reflect the amount of peroxynitrite formed. These findings indicated that agmatine alleviates cerebral cortex neuronal injury following global cerebral ischemia and decreases nitric oxide synthase expression and peroxynitrite formation following ischemia/repeffusion.

The observation on the levels of VIP in the cerebral cortex of rats with bilateral hemispheric ischemia

The rat vertebral and common carotid arteries were obstructed to cause bilateralhemispheric ischemia.Vasoactive intestinal peptide(VIP)in the rat cerebral cortex following 10～60min of ischemia was analysed by radioimmunoassay(RIA).The results showed that the levels ofVIP were significantly lower in the ischemic animals than controls(P【0.01).The distribution andmetabolism of VIP in the cerebral cortex and the probable mechanism during ischemia are dis-cussed.

Effect of Reelin signaling on pre-plate splitting during cerebral cortex development

The development of the 6-layered cerebral neocortex is one of the most important events during nervous system development, and disturbances could result in various malformations, causing clinically intractable diseases, such as epilepsy and cerebral palsy. Pre-plate splitting is the first developmental step of the cortical plate formation. Without correct pre-plate splitting, normal cerebral cortex structures are disturbed. The Reelin-Dabl molecular pathway plays a critical role during cerebral cortex development, and deficiencies in this pathway result in failed pre-plate splitting and an inverted cortical plate. This paper summarizes findings involving Reelin and pre-plate splitting and further explores the precise role of Reelin during pre-plate splitting.

Changes in proprotein convertase subtilisin/kexin type 9 mRNA expression in rat cortex after cerebral ischemia

Oxidized low density lipoprotein is a risk factor for cerebrovascular disease. Proprotein convertase subtilisin/kexin type 9 （PCSK9） can increase the level of low density lipoprotein. Therefore, this study assumed that PCSK9 plays important roles in ischemic cerebrovascular disease. The present study established transient focal cerebral ischemia models after 100 minutes of middle cerebral artery occlusion. In situ hybridization demonstrated that PCSK9 mRNA expression increased gradually with prolonged reperfusion time in ischemic cortices. This indicated that transient focal cerebral ischemia upregulated PCSK9 mRNA expression in ischemic cortices.

Exploring human rhythmic gait movement in the role of cerebral cortex signal

The rhythmic movement is a spontaneous behavior due to the central pattern generator （CPG）. At present, the CPG model only shows the spontaneous behavior, but does not refer to the instruction regulation role of the cerebral cortex. In this paper, a modified model based on the Matsuoka neural oscillator theory is presented to better show the regulation role of the cerebral cortex signal to the CPG neuronal network. The complex interaction between the input signal and other parameters in the CPG network is established, making all parameters of the CPG vary with the input signal. In this way, the effect of the input signal to the CPG network is enhanced so that the CPG network can express the self-regulation movement state instead of being limited to the spontaneous behavior, and thus the regulation role of the cerebral cortex signal can be reflected. Numerical simulation shows that the modified model can generate various movement forms with different modes, frequencies, and interchanges between them. It is revealed in theories that the cerebral cortex signal can regulate the mode and frequency of the gait in the ~ourse of the gait movement.