Experimental Study on Heterograft of Glomus Ccl ls of Carotid Body for Hemioarkinsonian Rats

Summary: To observe the effects of heterograft of glomus cells of carotid body on hemiparkinsonian rat models, rats with unilateral 6-hydroxydopamine (6-OHDA)-induced lesions of the right dopamin ergic neurons of substantia nigra received intrastriatal glomus cells heterograft. Apomorphine-induced rotation was monitored for 30 rmin at various time points after grafting. The striata were cut and ex-amined for dopamine content by HPLC and for immunohistochemical staining of tyrosine hydroxylase positive neurons (TH ) at the end of the experiments. The results showed that apomorphine-induced rotational behavior was significantly reduced for 12 weeks and the dopamine contents were signifi cantly elevated after grafting (P＜0.01), and TH cells survived better. The present study demon strates that intrastriatal heterograft of glomus cells within carotid body in rats with 6-OHDA-elicited lesions could reduce apomorphine-induced rotational behavior and elevate the dopamine contents and numbers of TH cell surviving within striatum, and can serve as a new and effective alternative for Parkinson disease.     

Transplantation of VEGF165-gene-transfected endothelial progenitor cells in the treatment of chronic venous thrombosis in rats

Background The organization and recanalization of thrombi is a dynamic and complex process. The aim of this research was to study the cotherapeutic effect of stem cell transplantation and gene transfection on chronic venous thrombosis. Methods We constructed a recombinant adenoviral vector carrying the vascular endothelial growth factor 165 （VEGF165） gene by using the pAdEasy system, which was subsequently identified and amplified. Simultaneously, endothelial progenitor cells （EPCs） were isolated from rat bone marrow using Ficoll, cultured in EBM-2MV medium, and identified. Then, the cells were transfected with the recombinant Ad-VEGF165. The EPCs were labeled with 1 ,1＇-dioctadecyl-3,3,3＇,3＇-tetramethylindocarbocyanine （Dil） before transplantation. A rat model of chronic vein thrombosis was developed by partial ligation of the inferior vena cava. The rats were randomly divided into 4 groups （n=25, each）： A, Ad-VEGF165/EPC-transplantation group received 1 ml （10^6） of Ad-VEGF165/EPCs; B, EPC-transplantation group received 1 ml （10^6） of EPCs; C, Ad/EPC-transplantation group received 1 ml （10^6） of Ad/EPCs; D, control group received 1 ml of the transplantation medium. The thrombi and adjacent caval walls were harvested 28 days after transplantation; real-time quantitative polymerase chain reaction was used to detect the expression level of vascular endothelial growth factor （VEGF） mRNA; and western blotting was used to measure changes in VEGF protein expression. Hematoxylin-eosin staining and immunohistochemical staining were performed to detect recanalization. Neovascularization was detected by immunohistochemical staining using the antibody for von Willebrand factor （vWF）, which is a component of endothelial cells.The capillary density was quantitatively determined by counting the capillaries under a high-power microscope. Results The Ad-VEGF165 was constructed, and bone-marrow-derived EPCs were cultivated and successfully identified. We determined the optimum transfection ratio that promoted the growth of EPCs. After transfection, the EPCs secreted the VEGF protein. After transplantation, the in vivo survival of EPCs and their differentiation into endothelial cells were determined by detecting the fluorescence associated with the Dil stain. VEGF mRNA was expressed in groups A, B, C and D after transplantation, and the VEGF mRNA level in group A was significantly higher than those in groups B, C and D （P〈0.05）; the VEGF mRNA levels in groups B and C were significantly higher than those in group D （P〈0.05）, and there was no statistical significance between the VEGF mRNA levels in groups B and C. The recanalization capillary density in group A was significantly higher than those in groups B, C （P 〈0.05） and D （P 〈0.01）; the recanalization capillary densities in groups B and C were significantly higher than that in group D （P 〈0.05）. Moreover, there was no statistical significant difference between the values for groups B and C. Conclusions The EPCs were successfully transfected by Ad-VEGF165. A suitable transfection ratio can improve the efficiency of EPCs and the possibility of promotion of angiogenesis after transplantation. Transfected EPCs caused accelerated organization and recanalization of vein thrombi.     

Ultrasound-mediated microbubble delivery of pigment epithelium-derived factor gene into retina inhibits choroidal neovascularization

Background Many studies have suggested that the imbalance of angiogenic factor and anti-angiogenic factor expression contributes significantly to the development of choroidal neovascularization （CNV）, and ultrasound microbubble combination system can increase the gene transfection efficiency successfully. This study was designed to investigate whether ultrasound-mediated microbubble destruction could effectively deliver therapeutic plasmid into the retina of rat, and whether gene transfer of pigment epithelium-derived factor （PEDF） could inhibit CNV.
Methods Human retinal pigment epithelial cells were isolated and treated either with ultrasound or plasmid alone, or with a combination of plasmid, ultrasound and microbubbles to approach feasibility of microbubble-enhanced ultrasound enhance PEDFgene expression; For in vivo animal studies, CNV was induced by argon lasgon laser in rats. These rats were randomly assigned to five groups and were treated by infusing microbubbles attached with the naked plasmid DNA of PEDF into the vitreous of rats followed by immediate ultrasound exposure （intravitreal injection）; infusing liposomes with the naked plasmid DNA of PEDF into the vitreous （lipofectamine ＋ PEDF）; infusing microbubbles attached with PEDF into the orbit of rats with ultrasound irradiation immediately （retrobular injection）; infusing microbubbles attached with PEDF into the femoral vein of rats with exposed to ultrasound immediately （vein injection）. The CNV rats without any treatment served as control. Rats were sacrificed and eyes were enucleated at 7, 14, and 28 days after treatment. Gene and protein expression of PEDF was detected by quantitative real-time RT-PCR, Western blotting and immunofluorescence staining, respectively. The effect of PEDF gene transfer on CNV was examined by fluorescein fundus angiography.
Results In vitro cell experiments showed that microbubbles with ultrasound irradiation could significantly enhance PEDF delivery as compared with microbubbles or ultrasound alone. In the rat CNV model, transfection efficiency mediated by ultrasound/microbubbles was significantly higher than that by lipofectamine-mediated gene transfer at 28 days after treatment. The study also showed that with the administration of ultrasound-mediated microbubbles destruction, the CNV of rats was inhibited effectively.
Conclusions Ultrasound-microbubble technique could increase PEDF gene transfer into rats＇ retina and chorioid, in association with a significant inhibition of the development of CNV, suggesting that this noninvasive gene transfer method may provide a useful tool for clinical gene therapy.     

Inhibitory effect of adenoviral vector-mediated AT2R gene transfection on neointimal hyperplasia

Objective： To investigate the effect of adenoviral vector-mediated AT2R gene transfection on neointimal hyperplasia after rat carotid artery balloon injury. Methods ：AT2R gene was transferred into rat carotid arteries by recombinant adenovirus pAd-AT2R after the establishment of rat carotid balloon injury restenosis model. The arteries were harvested on the 14th day after gene transfer. The efficiency of transgene delivery was measured by the expression of adenovirus-encoding green fluorescent protein （GFP） under fluorescent microscope. The expression of AT2R and PCNA （proliferating cell nuclear antigen） was evaluated by RT-PCR, immunocytochemistry, immunofluorescence staining, confocal microscopy, respectively. The ratio of intimal to medial area （I/M） was quantified with images and determined by an image analysis system. Results, GFP-positive area in adventitia, media and the forming neointima was about 40%. Adenoviral delivery of rat AT2R gene up-regulated AT2R expression in balloon-injured rat carotid and reduced PCNA expression and I/M significantly in neointima（P〈0.01）. Double immunofluorescence labeling of AT2R and PCNA also showed that AT2R gene transfer inhibited VSMCs proliferation in neointima. Conclusion： AT2R gene transfer may be a novel promising therapy to limit neointimal hyperplasia.     

Effect of PD Ⅰ Administration on Dopamine Receptors mRNAs Expression in the Lesioned Striatum of PD Rat Model

To study the effect of PD Ⅰ administration on dopamine receptors （DR, , DRz ） mRNAs expression in the lesioned striatum of the PD rat model and confirm if PDⅠ has the effect of dopamine receptor agonist. The PD rats with unilateral 6-hydroxydopamine lesioned were administrated with PD Ⅰ , L-dopa methyl/benserazide, L-dopa methyl/benserazide/ PD Ⅰ , normal saline respectively for 4 weeks and their behavioral changes were observed. Then the rats were sacrificed and RT-PCR technique was used to detect changes of dopamine receptors （DR1, DR2） mRNAs expression in the ipsilateral striatum 1 day after the last treatment. The results showed that treatment with PD Ⅰ plus L-dopa resulted in a stable contralateral rotation behavior; treatment with L-dopa resulted in a progressively increased contralateral rotation behavior. Rotation behavior induced by anhydromorphine decreased with PD Ⅰ or PD Ⅰ plus L-dopa treatment. Treatment With L-dopa or PD Ⅰ plus L-dopa, up-regulation of DR, mRNA and down-regulation of DR2 mRNA were observed in the ipsilateral striatum which were more obvious than that treated with PD Ⅰ or vehicle （P〈0. 05）. It was concluded that long-term treatment with PD Ⅰ could alleviate the behavior of PD rats. PD Ⅰ had no apparent effect on the dopamine receptors （DRI , DRz ） mRNAs expression in the ipsilateral striatum and the PD Ⅰ has no agonist effect on dopamine receptors.     

Effect of behavior training on learning,memory and the expression of NR2B,GluR1 in hippocampus of rats offspring with fetal growth restriction

Objective： To study effects of behavior training on learning, memory and the expression of NR2B, GluR1 in hippocampus of rat＇ s offspring with fetal growth restriction（FGR）. Methods： The rat model of FGR was established by passive smoking method. The rats offspring were divided into the FGR group and the control group, then randomly divided into the trained and untrained group, respectively. Morris water maze test was proceeded on postnatal month（PM2/4） as a behavior training method, then the learning-memory of rats was detected through dark-avoidance and step-down tests. The expressions of NR2B and GluR1 subunits in hippocampal CA1 and CA3 areas were detected by immunohistochemical method. Results： In the dark-avoidance and step-down tests, the performance record of rats with FGR was worse than that of control rats, and the behavior-trained rats was better than the untrained rats, when the FGR model and training factors were analyzed singly. The model factor and training factor had significant interaction（P 〈 0.05）. The expressions of NR2B and GluR1 subunits in hippocampal CA1 and CA3 areas of rats with FGR reduced. In contrast, the expressions of GluR1 and NR2B subunits in CA1 area of behavior-trained rats increased, when the FGR model and training factors were analyzed singly. Conclusion： These findings suggested that the effect of behavior training on the expressions of NR2B and GluR1 subunits in CA1 area should be the mechanistic basis for the training-induced improvement in learning-memory abilities.     

Annexin A2 promotes choroidal neovascularization by increasing vascular endothelial growth factor expression in a rat model of argon laser coagulation-induced choroidal neovascularization

Background Choroidal neovascularization （CNV） is a common cause of visual loss in the elderly patients with age-related macular degeneration and represents the growth of subretinal new vessels in the macular region. This study aimed to investigate the relationship between annexin A2 （ANXA2） and vascular endothelial growth factor （VEGF） in CNV.Methods In a rat model of argon laser coagulation-induced CNV, the mRNA expressions of the annexins and VEGF protein expression in the retina were detected using fluorescent real-time polymerase chain reaction （PCR） and immunohistochemistry, respectively. The interactions between ANXA2 and VEGF in both a retinal pigment epithelial cell line RPE-J and the rat model of CNV were examined by means of RNA interference, real-time PCR, Western blotting, enzyme-linked immunosorbent assay （ELISA） and histopathological examinations. Results Fundus fluorescein angiography （FFA） showed that argon laser coagulation of the retina induced stable CNV models in the rats. Two to three weeks after the coagulation, ANXA2. and VEGF expressions in the coagulated area in the retina and choroid increased to the peak level, while the other annexin members （ANXA4, ANXA5, ANXA7 and ANXA11） showed no obvious changes. In RPE-J cells and the CNV model, RNA interference of ANXA2 gene significantly lowered the VEGF protein and mRNA expressions, and application of an adenoviral vector containing ANXA2 gene markedly increased VEGF expressions in the rat model of CNV, but produced no significant effects on the expressions of the kinase insert domain-containing receptor （KDR） or the fms-like tyrosine kinase （Fit-l）. The expression of KDR inhibited the increment in ANXA2 expression, but VEGF and Rt-1 did not directly affect ANXA2 expression. Conclusion Besides the role as a plasminogen and the receptor of tissue plasminogen activator, ANXA2, which is under regulation of KDR via a negative feedback mechanism, also participates in neovascularization by regulating VEGF expression through a positive feedback mechanism.     

Paraquat induces selective dopaminergic nigrostriatal degeneration in aging C57BL/6 mice

Background Paraquat （PQ; 1,1 ＇-dimethyl-4,4＇-bipyridinium）, a widely used herbicide that is structurally similar to the known dopaminergic neurotoxicant MPTP （1-methyl-l, 2, 3,6-tetrahydropyridine ）, has been suggested as a potential etiologic factor for the development of Parkinson＇ s disease （PD）. Aging is an accepted risk factor for idiopathic Parkinson＇ s disease. The aim of this study was to test the hypothesis that paraquat could induce PD-like nigrostriatal dopaminergic degeneration in aging C57BL/6 mice. Methods Senile male C57BL/6 mice were intraperitoneally injected with either saline or PQ at 2-day intervals for a total of 10 doses. Locomotor activity and performance on the pole test were measured 7 days after the last injection and animals were sacrificed one day later. Level of dopamine （DA） and its metabolites levels in the striatum were measured by high-performance liquid chromatography with an electrochemical detector （ HPLCECD）, and numbers of tyrosine hydroxylase （TH） positive neurons were estimated using immunohistochemistry. Results Locomotor activities were significantly decreased and the behavioral performance on the pole test were significantly impaired in the PQ treated group. Level of DA and its metabolites levels in the striatum were declined by 8 days after the last injection. Immunohistochemical analyses showed that PQ was associated with a reduction in numbers of tyrosine hydroxylase positive neurons. Conclusions Long-term repeated exposes to PQ can selectively impair the nigrostriatal dopaminergic system of senile mice, suggesting that PQ could play an important role in the pathogenesis of Parkinson＇ s disease （PD）. Our results also validate a novel model of PD induced by exposure to a toxic environmental agent.     

Screening of differentially expressed genes in the hypothalamus of a rat neuropathic pain model following sciatic nerve injury

Background Neuropathic pain is induced by injury or disease of the nervous system. Most studies have so far focused only on a few known molecules and signaling pathways among neurons. However, all signal transmissions involved in neuropathic pain appear to be an integral system at different molecular levels. This study was designed to screen the differentially expressed genes of the hypothalamus in chronic constriction injury （CCI） rats and analyze their functions in developing neuropathic pain. Methods Ten adult female Sprague-Dawley rats （（200±10） g） were used in experimental group and sham group （n=-5 in each group）. Mechanical allodynia tests were performed to ensure that the CCI rat model was constructed successfully. Total hypothalamus RNAs were isolated from each group. Forward suppression subtractive hybridization （SSH） library of rat hypothalamus was constructed and up-regulated cDNA clones at neuropathic pain states were obtained via suppressed subtractive hybridization technique and the functions of these genes were analyzed bioinformatically. Results Mechanical allodynia tests showed that the experimental rats had a significantly reduced mechanical allodynia threshold 3 to 13 days after CCI vs sham surgery rats （P 〈0.01）, indicating that the model was successful. Forward SSH library of the rat hypothalamus was constructed successfully and 26 over-expressed expression sequence tags （ESTs） were obtained from these up-regulated cDNA clones. Conclusion Twenty-six up-regulated genes, involved in the regulation of cell cycle and apoptosis, signal transduction, and neuroprotection, may play key roles in decreasing mechanical withdraw thresholds in CCI rats, which implicates a multidimensional and integrated molecular mechanism at gene level in developing neuropathic pain with the supraspinal contributions.     

Effect of deep brain stimulation on substantia nigra neurons in a rat model of Parkinson’s disease

Background  Parkinson’s disease (PD) is a common neurodegenerative disease, which occurs mainly in the elderly. Recent studies have demonstrated that apoptosis plays an important role in the occurrence and development of PD. Subthalamic nucleus deep brain stimulation (STN-DBS) has been recognized as an effective treatment for PD. Recent clinical observations have shown that STN-DBS was able to delay early PD progression, and experiments in animal models have also demonstrated a protective effect of STN-DBS on neurons. However, the correlation between the neuron-protective effect of STN-DBS and the progression of substantia nigra pars compacta (SNc) neuronal apoptosis is still unknown. The aim of this study was to investigate the protective effect and potential mechanism of STN-DBS on SNc neurons in PD rats.

Methods  After the establishment of a PD rat model by unilateral/2-point injection of 6-hydroxydopamine in the medial forebrain bundle of the brain, DBS by implanting electrodes in the STN was administered. Behavioral changes were observed, and morphological changes of SNc neurons were analyzed by Nissl staining and DNA in situ end-labeling. Through extracellular recording of single neuron discharges and microelectrophoresis, the causes of and changes in SNc excitability during STN-DBS were analyzed, and the protective effect and potential mechanism of action of STN-DBS on SNc neurons in PD rats was investigated.

Results  SNc neuron apoptosis was significantly decreased (P <0.05) in the stimulation group, compared with the sham stimulation PD group. Spontaneous discharges of SNc neurons were observed in normal rats and PD model rats, and the mean frequency of spontaneous discharges of SNc neurons in normal rats ((40.65±11.08) Hz) was higher than that of residual SNc neurons in PD rats ((36.71±9.23) Hz). Electrical stimulation of the STN in rats was associated with elevated excitation in unilateral SNc neurons. However, administering the gamma-aminobutyric acid receptor blocker, bicuculline significantly reduced SNc neuron excitation, but the change in SNc neuron excitation was not present when MK801, a glutamate receptor blocker, was administered.

Conclusions  High-frequency stimulation of the STN has a protective effect on SNc neurons in PD rats. The possible molecular mechanism may be related to changes in the distribution and metabolism of neurotransmitters in the SNc region.

     

Effects of exercise on behavior and peripheral blood lymphocyte apoptosis in a rat model of chronic fatigue syndrome

This study examined the effects of exercise on behavior and peripheral blood leukocyte apoptosis in a rat model of chronic fatigue syndrome （CFS）. Thirty-six healthy male Sprague-Dawley rats were equally randomized into 3 groups： the control group, CFS model group and the exercise group in terms of body weight. A total of 25 rats entered the final statistical analysis due to 11 deaths during the study. CFS model was established by subjecting the rats in CFS model group and exercise group to electric shock, chronic restraint stress and cold water swim. Besides, rats in the exercise group took rtmning wheel exercise. After a week of conditioning feeding, model construction and running wheel exercise were performed simultaneously, and lasted for 23 consecutive days. The behavior experiments, including running wheel exercise, open-field test, tail suspension test and Morris water maze test, were conducted, either before or after the model establishment. Rats were sacrificed and peripheral blood was obtained for the assessment of lymphocyte apoptosis index by flow cytometry （FCM）. It was found that as compared with those in the control group, the weight of the rats was decreased obviously （P〈0.01）, the mobility time in the open-field and the tail suspension tests was shortened significantly （P〈0.01）, the time to locate the platform was enhanced （P〈0.01） and the cell apoptosis index was increased substantially （P〈0.01） in the CSF model group. Meanwhile, in comparison to the model group, the behavior in the open-field and the tail suspension tests was improved significantly （P〈0.05）, and the apoptosis index decreased remarkably （P〈0.01） in the exercise group. It is concluded that sport intervention can prevent lymphocyte apoptosis and improve animal behavior rather than the memory.     

Effects of extract of Ginkgo biloba with venlafaxine on brain injury in a rat model of depression

Background Recent studies have indicated that chronic stress may give rise to brain damage,which is related to the genesis of depression. The purpose of this study is to investigate the effects of extract of Ginkgo biloba (EGb) and venlafaxine on depression. Methods Rats were treated with chronic and comprehensive stress to create a depression model. Immunohistochemistry was used to detect the expression of brain-derived neurotrophic factor (BDNF) in the hippocampal CA3 neurons of rats treated with different drugs. Behavioral changes of these rats were also examined.Results The expression of BDNF in the hippocampal CA3 neurons of the depression model decreased with a reduction in exploring behavior and a significant increase in fecal production. The expression of neuron nitricoxide synthase (nNOS) protein also increased in the rats compared to normal controls. The rats treated with EGb and venlafaxine showed an increase in expression of BDNF and exploring behavior compared to untreated rats, but a decrease in nNOS and fecal production. Conclusions Rats sustain damage to the brain after being subjected to chronic and comprehensive stress. Our research has indicated that combined EGb with venlafaxine enhances the protection of neurons and decreases damage to the brain, while relieving the side effects of synthetic antidepressants.     

Transplantation of VEGF165-gene-transfected endothelial progenitor cells

Background: To study the cotherapeutic effect of stem cell transplantation and gene transfection on chronic venous thrombosis. Methods: We constructed a recombinant adenoviral vector carrying the VEGF165 gene by using the pAdEasy system, which was subsequently identified and amplified. Simultaneously, endothelial progenitor cells (EPCs) were isolated from rat bone marrow by using Ficoll, cultured in EBM-2MV medium, and identified. Then, the cells were transfected with the recombinant Ad-VEGF165. The EPCs were labeled with 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine (Dil) before transplantation. An experimental rat model of chronic vein thrombosis was developed by partial ligation of the inferior vena cava. The rats were randomly divided into 4 groups: A (n = 25), Ad-VEGF165/EPC-transplantation group, which received 1 ml (106) of Ad-VEGF165/EPCs; B (n = 25), EPC-transplantation group, which received 1 ml (106) of EPCs; C (n = 25), Ad/EPC-transplantation group, which received 1 ml (106) of Ad/EPCs; D (n = 25), control group, which received 1 ml of the transplantation medium. The thrombi and adjacent caval walls were harvested 28 days after transplantation; real-time quantitative polymerase chain reaction (PCR) was used to detect the expression level of VEGF mRNA; and western blotting was used to measure thrombosis and changes in VEGF protein expression. Hematoxylin-eosin (HE) staining and immunohistochemical staining were performed to detect recanalization, and neovascularization was observed by scanning electron microscopy. The capillary density was quantitatively determined by counting the capillaries under a high-power microscope. SPSS 11.5 software used for analysis, and differences at P < 0.05 were considered to be significant. Results: The Ad-VEGF165 was constructed, and bone-marrow-derived EPCs were cultivated and successfully identified. We determined the optimum transfection ratio that promoted the growth of EPCs. After transfection, the EPCs secreted the VEGF protein. After transplantation, the in vivo survival of EPCs and their differentiation into endothelial cells were determined by detecting the fluorescence associated with the Dil stain. VEGF mRNA was expressed in groups A, B, C, and D after transplantation, and the VEGF mRNA level in group A was significantly higher than those in groups B, C, and D (P < 0.05); the VEGF mRNA levels in groups B and C were significantly higher than those in group D (P < 0.05), and there was no statistical significance between the VEGF mRNA levels in groups B and group C. The recanalization capillary density in group A was significantly higher than those in groups B, C (P < 0.05), and D (P < 0.01); the recanalization capillary densities in groups B and C were significantly higher than that in group D (P < 0.05). Moreover, there was no statistical significant difference between the values for groups B and C. Neovascularization was detected by immunohistochemical staining using the antibody for vWF, which is a component of endothelial cells. Conclusion: The EPCs were successfully transfected by Ad-VEGF165. A suitable transfection ratio can improve the efficiency of EPCs, improving the possibility of promotion of angiogenesis after transplantation. Transfected EPCs caused accelerated organization and recanalization of vein thrombi.     

Study of apoptosis pattern of dopaminergic neurons and neuroprotective effect of nicotine in MPTP mouse model

Objective：To investigate the apoptosis of dopaminergic neurons and the protective effect of nicotine in 1-methyl-4-phenyl- 1, 2,3,6-tetrahydropyridine （MPTP）-induced mouse model of Parkinson＇s disease. Methods：The mouse model of Parkinson＇s disease were formed by MPTP （30 mg/kg/d×7, i.p. ）; and the loss and apoptosis of dopaminergic neurons was observed by Tyrosine Hydroxylase（TH） and TUNEL stains.In ＂Nicotime plus MPTP＂ group, mice were pretreated with nicotine before MPTP injection. The putative protective effect of nicotine was analyzed. Results：The number of TH-positive cells decreased during MPTP treatment. Apoptotic neurons began to appear after three injections of MPTP and peaked on the 8th day. In the MPTP-intoxicated mice treated with nicotine, the loss of TH-positive cells was significantly less than that of MPTP- treated group （30 mg/kg/d×7）（P 〈 0.05）. Conclusion：The chronic treatment of MPTP can induce the apoptosis of dopaminergic neurons in substantia nigra, and nicotine might have a neuroprotecitve effect on dopaminergic neurons against MPTP toxicity.     

6-OHDA induces cycle reentry and apoptosis of PC12 cells through activation of ERK1/2 signaling pathway

This study investigated the effect and mechanism of cell cycle reentry induced by 6-hydrodopamine （6-OHDA） in PC12 cells. By using neural differentiated PC12 cells treated with 6-OHDA, the apoptosis model of dopaminergic neurons was established. Cell viability was measured by MTT. Cell apoptosis and the distribution of cell cycle were assessed by flow cytometry. Western blot was used to detect the activation of extracellular regulator kinasel/2 （ERK1/2） pathway and the phosphorylation of retinoblastoma protein （RB）. Our results showed that after PC12 cells were treated wtih 6-OHDA, the viability of PC12 cells was declined in a concentration-dependent manner. Flow cytornetry revealed that 6-OHDA could increase the apoptosis ratio of PC12 cells in a time-dependent manner. The percentage of ceils in G0/G1 phase of cell cycle was decreased and that in S phase and G2/M phase increased. Simultaneously, ERK1/2 pathway was activated and phosphorylated RB increased. It was concluded that 6-OHDA could induce cell cycle reentry of dopaminergic neurons through the activation of ERK1/2 pathway and RB phosphorylation. The aberrant cell cycle reentry contributes to the apoptosis of dopaminergic neurons.     

Altered angiotensin-converting enzyme and its effects on the brain in a rat model of Alzheimer disease

Background Alzheimer disease （AD） is a neurodegenerative disease related to aging. At present, its pathological mechanisms remain unclear. Family members of the renin-angiotensin system （RAS） play a role in neuronal plasticity, as well as formation of learning and memory. In this study, we explore the effects of altered angiotensin-converting enzyme （ACE）, and investigate the possible mechanisms of perindopril, an ACE inhibitor, on brain structure and function in a rat model of AD, as well as the role that ACE plays in AD. Methods Sixty Sprague-Dawley rats were selected and randomly divided into 3 groups： control, AD, and perindopril. Each group consisted of 20 rats, with 10 rats for determining pathology, and the remaining 10 rats for quantifying ACE activity. The rat AD model was established by stereotactically injecting amyloid beta protein （A-beta） 1-42 into the right hippocampus. Learning and memory functions were tested using the Y-type electric maze. The number and morphology of abnormal neurons were determined by haematoxylin and eosin staining. Amyloid deposition was measured by Congo red staining. Finally, ACE activity was estimated by spectrophotometry. Results Compared with the control group, the number of times needed to escape electrical stimuli increased （23.70±3.13, P 〈0.001）, the number of normal neurons in the CA1 region was reduced （density of 96.5±32.6/mm, P 〈0.001）, amyloid deposition was obvious, and ACE activity increased （（34.4±6.6） nmol.g-1.min-1, P 〈0.001） in the AD group. In the perindopril group, the number of times needed to escape electrical stimuli decreased （18.50±3.66, P 〈0.001）, the number of abnormal neurons increased （density of CA1 neurons was 180.8±28.5/mm, P 〈0.001）, amyloid deposition was reduced, and ACE activity was down-regulated （（26.2±6.2） nmol.g-1.min-1, P 〈0.001）. Conclusions ACE activity increased in the brains of AD rats. Perindopril improved learning and memory in AD rats, which correlated with de     

Screening for glutamate-induced and dexamethasone-downregulated epilepsy-related genes in rats by mRNA differential display

Background It is known that excessive release of glutamate can induce excitotoxicity in neurons and lead to seizure. Dexamethasone has anti-seizure function. The aim of this study was to investigate glutamatedexamethasone interaction in the pathogenesis of epilepsy, identify differentially expressed genes in the hippocampus of glutamate-induced epileptic rats by mRNA differential display, and observe the effects of dexamethasone on these genes expression. Methods Seizure models were established by injecting 5μl （250 μg/μl） monosodium glutamate （MSG） into the lateral cerebral ventricle in rats. Dexamethasone （5 mg/kg） was injected intraperitoneally at 30 minutes after MSG inducing convulsion. The rats＇ behavior and electroencephalogram （EEG） were then recorded for 1 hour. The effects of dexamethasone on gene expression were observed in MSG-induced epileptic rats at 1 hour and 6 hours after the onset of seizure by mRNA differential display. The differentially expressed genes were confirmed by Dot blot. Results EEG and behaviors showed that MSG did induce seizure, and dexamethasone could clearly alleviate the symptom, mRNA differential display showed that MSG increased the expression of some genes in epileptic rats and dexamethasone could downregulate their expression. From more than 10 differentially expressed eDNA fragments, we identified a 226 bp eDNA fragment that was expressed higher in the hippocampus of epileptic rats than that in the control group. Its expression was reduced after the administration of dexamethasone. Sequence analysis and protein alignment showed that the predicted amino acid sequence of this cDNA fragment kept 43% identity to agmatinase, a member of the ureohydrolase superfamily. Conclusions The results of the current study suggest that the product of the 226 bp eDNA has a function similar to agmatinase. Dexamethasone might relax alleviate seizure by inhibiting expression of the gene.     

Pretreatment with Rhodiola Rosea Extract Reduces Cognitive Impairment Induced by Intracerebroventricular Streptozotocin in Rats: Implication of Anti-oxidative and Neuroprotective Effects

Objective To investigate the pretreatment effects of Rhodiola rosea （R. rosea） extract on cognitive dysfunction, oxidative stress in hippocampus and hippocampal neuron injury in a rat model of Alzheimer＇s disease （AD）. Methods Male Sprague-Dawley rats were pretreated with R. rosea extract at doses of 1.5, 3.0, and 6.0 g/kg for 3 weeks, followed by bilateral intracerebroventricular injection with streptozotocin （1.5 mg/kg） on days 1 and 3. Behavioral alterations were monitored after 2 weeks from the lesion using Morris water maze task. Three weeks after the lesion, the rats were sacrificed for measuring the malondialdehyde （MDA）, glutathione reductase （GR） and reduced glutathione （GSH） levels in hippocampus and histopathology of hippocampal neurons. Results The MDA level was significantly increased while the GR and GSH levels were significantly decreased with striking impairments in spatial learning and memory and severe damage to hippocampal neurons in the model rat induced by intracerebroventricular injection of streptozotocin. These abnormalities were significantly improved by pretreatment with R. rosea extract （3.0 g/kg）. Conclusion R. rosea extract can protect rats against cognitive deficits, neuronal injury and oxidative stress induced by intracerebroventricular injection of streptozotocin, and may be used as a potential agent in treatment of neurodegenerative diseases such as AD.