Tau propagation and its modulation in Alzheimer's disease

The microtubule-associated protein tau plays an important role in maintaining microtubule stabiliza-tion, while the aggregation of hyperphosphorylated tau takes part in the pathophysiology of Alzheimer's disease. Recent studies show that the tau in pathological forms behaves like a prion, which can be propagated between cells and different brain regions. Oligomeric tau clusters in the affected neurons can be released as pathological " seeds" through vesicular and non-vesicular mechanism, then enter the recipient neuron through endocytosis and receptor-mediated uptake. The rate of tau propagation is modulated by the change of β-amyloid, or the activity of neuronal as well as glial cell. With better under-standings on pathological tau propagation, it is hoped that a novel therapy targeting the transmission of tau pathology will be developed for the treatment of Alzheimer's disease.     

The function of GAP-43 on the recovery of brain injury

Neuronal growth associated protein (GAP-43) is a membrane bound phosphoprotein found in the axonal growth cones of sprouting central nervous system axons. It is neuron specific and is proposed to play a critical role in growth cone function during development of the nervous system or the regenerative recovery from axon injury. The injury leads to the transfection of fibroblasts with the GAP-43 gene, which result in increasing GAP-43 expression. GAP-43 is expressed at high levels during the course of recovery of brain injury. GAP-43 acts with calmodulin and G protein to regulate metabolic responses that initates axonal growth. It is important to reestablish neuronal structure and axonal sprouting. The level of GAP-43 returns to basal level once sprouting has finished. So more and more researchers attach importance to the study of GAP-43, which will improve the level of treatment with brain injury.     

Neuroprotective effect of novel Rho kinase inhibitor FSD-C10 on a mouse model of Alzheimer disease

AIM: To explore the neuroprotective effect of novel Rho kinase inhibitor FSD-C10 on Alzheimer disease (AD) model of APP/PS1 double transgenic (Tg) mice. METHODS: Male APP/PS1 Tg mice (n=20) at 8 months of age were randomly divided into 2 groups:model group and FSD-C10 treatment group. The mice were treated with normal saline or FSD-C10 (25 mg·kg^-1·d^-1) by intraperitoneal injection, once daily for 2 months. Age-and sex-matched wild-type (WT) mice without treatment were used as the control. The Morris water maze (MWM) test and SMART 3.0 behavioral record system were applied to examine and analyze the spatial cognitive function of the mice. The protein levels and distribution of Aβ, p-tau and synapse-associated proteins such as synaptophysin, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) and postsynaptic density protein 95 (PSD-95) were determined by immunofluorescence staining. The protein levels of phosphorylated amyloid precursor protein at Thr668[p-APP(Thr668)], beta-site APP-cleaving enzyme 1 (BACE1) and synapse-associated proteins in the brain were analyzed by Western blot. RESULTS: Compared with model group, FSD-C10 treatment significantly improved the cognitive function of the APP/PS1 Tg mice, accompanied by reduced Aβ deposition and p-tau level, increased protein level of p-APP (Thr668) in the central nervous system, decreased expression of BACE1, and increased expression of synapse-associated proteins in the brain of the mice (P<0.05). CONCLUSION: FSD-C10 has neuroprotective potential in the APP/PS1 Tg mice. The mechanism may be related to enhancing the non-amyloidogenic APP cleavage pathway, reducing the production of Aβ oligomers, the deposition of senile plaques and the amount of tau protein, up-regulating synapse-associated proteins, and increasing synaptic plasticity.     

Protective effect of folate and vitamin B12 on Alzheimer-like pathological changes in brain of aged rats with hyperhomocysteinemia

AIM:To explore the effect of hyperhomocysteinemia on the Alzheimer-like pathological changes in the brain of aged rat. METHODS:The rats were treated with homocysteine(Hcy) by intravenous injection through vena caudalis with or without a simultaneous supplementation of folate and Vitamin B₁₂(FB) in the drinking water for 28 weeks. The distribution and aggregation of tau protein were detected by Bielschowsky silver staining. Western blotting was used to determine the protein levels of tau phosphorylation, glycogen synthase kinase 3β(GSK-3β) and protein phosphatase 2A(PP2A). RESULTS:Treatment with Hcy induced hyperhomocysteinemia in aged rats and resulted in the formation of neurofibrillary tangles in the brain. Supplementation of FB effectively reduced the tangles. Hyperhomocysteinemia also induced Alzheimer-like tau hyperphosphorylation at multiple sites(Ser^199/202and Ser³⁹⁶). Hyperhomocysteinemia activated GSK-3β and inhibited the activity of PP2A. Supplementation of FB alleviated the changes of tau and the activities of GSK-3β and PP2A. CONCLUSION:Supplementation of FB ameliorates the hyperhomocysteinemia-induced Alzheimer-like pathological changes of tau protein possibly through regulating the activity of GSK-3β and PP2A in aged rats.     

Role of agrin in repair of nervous system injury

Agrin plays an important role in the development, occurrence and stability of the neuromuscular junction. It also plays an indispensable role in the central nervous system. In the repair process of the nervous system injury, agrin maintains the integrity of the blood-brain barrier, promotes synaptic regeneration of damaged areas, and improves the injured neural networks, which contributes to brain area remodeling and neurological function recovery. In this paper, we briefly review the role and possible mechanism of agrin in nervous system damage and repair process     

Changes in phosphorylation of tau protein and COX-2 expression in colon submucosal neurons of IBD model rats induced by TNBS

AIM: To investigate the change of phosphorylation of tau protein and expression of cyclooxygenase 2 (COX-2) in colon submucosal neurons of enteric nerve system in inflammatory bowel disease (IBD) rats induced by trinitrobenzene sulfonic acid (TNBS). METHODS: Male rats (n=30) were randomly assigned to 3 groups (n=10 each): control group, IBD group and TNBS group. The IBD rats were induced by TNBS+ethanol enema for 14 d. The control and TNBS rats were given an equal volume of saline and TNBS, respectively. The general situation and the histopathologic change of the rat colon were observed. Immunofluorescence was used to check the change of phosphalated tau protein and COX-2 expression in the submucosal neurons of the colon. The expression of COX-2 and phosphorylated tau231 and tau262 in the rat colon submucosal neurons was observed by double immunofluorescence staining. RESULTS: Compared with control group, the number of neurons in the colon of IBD rats decreased obviously and the expression of phospholated tau231 and tau262 was significantly increased. The number of neurons in the colon of TNBS rats showed no significant difference compared with control rats. The rat neurons in control group and TNBS group did not express COX-2. COX-2 expression was observed in the nucleus and cytoplasm of colonic neurons in IBD rats, which showed significantly different from control and TNBS rats. CONCLUSION: The decreased neurons in the enteric nerve system of IBD rats might be associated with the phosphorylation of tau protein and the expression of inducible COX-2.     

Urocortin,a novel peptide of the corticotropin releasing hormone family

Urocortin, a novel peptide of the cortiotropin releasiong hormone (CRH) family, was discovered in 1995 in the rat brain and subsequently cloned and localized to human chromosome 2. It can bind to both CRH type 1 receptor and CRH type 2 receptor, as well as CRH binding protein. Especially to CRH type 2 receptor, urocortin binds to it with 40 times more potency than CRH does. Therefore, urocortin is thought to be an en dogenous ligand for CRH type 2 receptor. Immunoreactive urocortin and urocortin mRNA were localized in many areas such as mammalian brain, cardiovascular system, placenta. It is believed that urocortinmay play important physiological roles as a neuropeptide not only in the central nervous system but also in peripheral tissues.     

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

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

Autophagy induces mitochondrial dysfunction in neurons from neonatal rats with hypoxic ischemic encephalopathy

AIM: To explore the influence of autophagy on the induction of mitochondrial dysfunction in the neurons in a neonatal rat hypoxic ischemic encephalopathy (HIE) model. METHODS: Ten-day-old rat pups (n=30) were randomly divided into sham group and model group. The rats in the latter group were subject to hypoxia-ischemia treatment via unilateral common carotid artery ligation. The rats were sacrificed for brain pathological examination, and the protein levels of cleaved caspase-3 and LC3B-II were detected by immunohistochemical analysis. For the in vitro experiments, the autophagy of primarily cultured rat neurons was observed after hypoxia, and Western blot and mitochondrial function testing were also performed. RESULTS: Compare with sham group, the hypoxia-ischemia treatment caused atrophy and apoptosis of neurons, and ventricular area enlargement of rat brains. Immunohistochemical results demonstrated significantly higher levels of apoptosis- and autophagy-associated proteins, such as cleaved caspase-3 and LC3B-II (P<0.01). In vitro experiments demonstrated that hypoxia induced autophagy and apoptosis in the neurons. Compared with sham group, there were higher levels of reactive oxygen species and mitochondrial superoxide, and lower mitochondrial membrane potential in the model group (P<0.01). CONCLUSION: In neonatal HIE rat model, the hypoxia-induced mitochondrial dysfunction is related to apoptosis and autophagy. It will provide a new idea for administration of autopahgy inducer agents in treatment of HIE.     

Effects of Astragalus polysaccharide on expression of HSP70, PKB and P53 in rat cerebral cortex with cerebral ischemia and reperfusion

AIM:To explore the molecular effects of Astragalus polysaccharide(AP) on improving nervous functions and preventing neuronal apoptosis in rat cerebral cortex with cerebral ischemia and reperfusion. METHODS:One hundred and twenty male Wister rats were randomly divided into sham operation group(SOG), model groups(MG-1 d, 3 d and 7 d), low-dose AP treatment groups(L-APTG-1 d, 3 d and 7 d), and high-dose AP treatment groups(H-APTG-1 d, 3 d and 7 d). The right middle cerebral artery of the rats in MG and AGTG was intercepted by operation to induce ischemic brain injury. The rats in L-APTG and H-APTG were treated with AP at the doses of 5 mg/kg and 15 mg/kg by intraperitoneal injection, respectively. On the 1st day, 3rd day and 7th day after operation, those animals were sacrificed to collect the brain specimens for the study after cerebral blood flow reperfusion and determination of neurological deficit scores. The structural changes of the neurons were observed under electron microscope. Apoptosis was analyzed by flow cytometry. The protein levels of heat-shock protein 70(HSP70), protein kinase B(PKB) and P53 in cerebral corical neurons were determined by immunohistochemical staining and Western blotting. RESULTS:The neurological deficit scores and the apoptotic rate of cerebral cortical neurons in H-APTG were significantly lower than those in MG and L-APTG(P<0.05). The structures of the neurons in H-APTG, such as ribosome endoplasmic reticulum, nucleolus, Golgi complex, mitochondria, etc, were better than those in MG and L-APTG. On the 1st day, 3rd day and 7th day, the protein levels of HSP70 and PKB in cerebral cortical neurons in H-APTG were significantly higher than those in L-APTG, which were significantly higher than those in MG(P<0.05). However, the P53 protein level in H-APTG was significantly lower than that in L-APTG, which was significantly lower than that in MG(P<0.05). CONCLUSION:AP improves nervous functions and inhibits neuronal apoptosis during ischemia and reperfusion. The molecular mechanisms are associated with variations of protein expression in cerebral cortical neurons, such as promotion of HSP70 and PKB and inhibition of P53.     

Ellagic acid attenuates hypoxic-ischemic brain injury by alleviating autophagy

AIM:To investigate whether ellagic acid (EA) attenuates hypoxic-ischemic encephalopathy (HIE) by down-regulating autophagy. METHODS:In vivo, Sprague-Dawley rats (n=17) were randomly divided into 3 groups:5 rats for sham group, 6 rats for HIE group and 6 rats for HIE+EA pretreatment group. The rats in HIE+EA pretreatment group were treated with EA (10 mg/kg, 10 mL/kg, suspended in corn oil, ig). After 24 h of operation, the rats from each group were sacrificed and their brains were collected. TTC staining and HE staining were used to define the infarct areas and brain structure. The autophagy-related proteins beclin-1, P62, LC3-Ⅱ/-I and Atg5 in the cortex in each group were compared by Western blot. In vitro, PC12 cells were divided into 3 groups:control group, CoCl₂ group and CoCl₂+EA pretreatment group. CoCl₂ at 800 μmol/L was added to the PC12 cells to induce an anoxic environment. The PC12 cells were pretreated with EA at 8 μmol/L and the cell viability was measured by CCK-8 assay. The production of reactive oxidative species (ROS) in the cells was detected by flow cytometry with DCFH-DA staining. MDC staining and TMRE staining were applied to reflect the extent of autophagy and the state of apoptosis, respectively. The autophagy-related proteins in PC12 cells were also investigated. RESULTS:In HIE group, 7-day-old rats were given the operations and the their large infarct areas in the hemisphere were observed by TTC staining. HE staining displayed the injured hemispheres which contained few neurons, and exhibited edema status and serious structural damage. EA pretreatment decreased the infarct area and alleviated the damage to hemisphere with more visible neurons, compared with HIE group. Compared with sham group, the levels of autophagy-related proteins Atg5, beclin-1 and LC3-Ⅱ/-I in the cortex were increased (P<0.01), and P62 protein expression was decreased (P<0.01) in HIE group. Compared with HIE group, the protein expression of Atg5, beclin-1 and LC3-Ⅱ/-I was decreased (P<0.01) and P62 protein expression was increased in HIE+EA pretreatment group (P<0.01). In vitro, compared with CoCl₂ group, the PC12 cells in CoCl₂+EA pretreatment group showed a lower ROS level. Moreover, the cells in CoCl₂+EA pretreatment group exhibited higher mitochondrial membrane potential than that in CoCl₂ group. MDC staining in CoCl₂ group showed high value of fluorescence and increased number of autophagosomes. EA pretreatment reduced the number of autophagosomes and the extent of autophagy to protect PC12 cells. Furthermore, the protein levels of Atg5, beclin-1 and LC3-Ⅱ/-I in CoCl₂ group were higher (P<0.01), and the protein expression of P62 was lower (P<0.01) than those in control group. In CoCl₂+EA pretreatment group, the protein levels of Atg5, beclin-1 and LC3-Ⅱ/-I were decreased (P<0.01) and the protein expression of P62 was increased as compared with CoCl₂ group (P<0.01). CONCLUSION:EA pretreatment attenuates autophagy to protect the neurons against HIE injury.     

Intracerebroventricular injection of streptozotocin induces dysfunction of insulin signaling in brain and cognitive deficits in rats

AIM：To investigate the effect of insulin signaling on the development of Alzheimer disease (AD) and to explore its potential mechanisms. METHODS：The rats were treated with streptozotocin (STZ, 3 mg/kg) intracerebroventricularly (ICV) at the 1st day and the 3rd day of the experiment to induce dementia model. Twenty-one days after the injection of STZ at the 1st day, spatial learning and memory of the rats were determined by Morris water maze test. The expression levels of insulin-degrading enzyme (IDE), glycogen synthase kinase 3β (GSK-3β), phosphorylated GSK-3β (p-GSK-3β), tau and phosphorylated tau (p-tau) were measured by Western blotting. The levels of amyloid β-proteins (Aβ1-40 and Aβ1-42) in the brain of the rats were detected by the method of immunohistochemistry. The mRNA levels of insulin, insulin receptor, tau and IDE were measured by real-time RT-PCR. RESULTS：ICV-STZ deteriorated the abilities of spatial learning and memory of the rats and reduced the activity of IDE and the mRNA levels of insulin and insulin receptor. STZ treatment enhanced GSK-3β activity and tau phosphorylation. The levels of Aβ1-40 and Aβ1-42 in cerebral cortex were significantly increased in the rats treated with STZ. CONCLUSION：ICV-STZ results in AD-like behaviors and pathological changes via damaging the brain insulin signaling, indicating that insulin signaling may play important roles in the AD pathogenesis.     

Effect of limb ischemic postconditioning on brain focal ischemia and reperfusion injury in mice

AIM: To establish the mouse model in which the limbic ischemic postconditionning (LIPostC) enhances the tolerance against brain ischemia, and to investigate the effects of LIPostC on the ischemic extent and roles of heat shock protein 70 (HSP70) in ischemia and reperfusion injury. METHODS: The male Kunming mice were used in the study. The brain ischemia reperfusion (I/R) model was made by middle cerebral artery occlusion (MCAO). In the first test, the male mice were randomly divided into 9 groups (n=10): sham group, ischemia/reperfusion (I/R) groups (with ischemia for 0.5 h, 1 h,1.5 h and 2 h) and LIPostC+I/R groups (0.5 h+LIPostC,1 h+LIPostC,1.5 h+LIPostC,2 h+LIPostC). The reperfusion was performed after LIPostC for 24 h. After the neurologic deficit scores were evaluated, the brains were taken out to measure the infarct volume with TTC staining and to observe the pathological changes of cerebral cortex with HE staining. The neuronal apoptosis was determined by TUNEL. In the second test, the male mice were randomized into 4 groups (n=6): sham group, I/R group, LIPostC+I/R group and LIPostC+I/R+quercetin group (2 h ischemia). The neurological deficit scores were evaluated at 24 h after operation. The expression of HSP70 was determined by Western blotting.RESULTS: The duration of brain ischemia was related to the motor behavior and degree of brain injury. The longer the ischemic duration of the brain was performed, the more severe the pathological and behavioral changes were observed. The brain injury in 2 h MCAO mice was more severe than that in 1 h and 1.5 h MCAO mice (P<0.05). Compared to I/R group, each LIPostC group showed lower neurological score, less infarct volume and TUNEL positive neuron. The expression of HSP70 protein was increased and neurological functions were improved significantly in the mice with LIPostC. However, the neuroprotective role of LIPostC was attenuated by treating with quercetin, an inhibitor of HSP70.CONCLUSION: LIPostC promotes the expression of HSP 70, improves the neurological functions and attenuates the ischemia and reperfusion injury in MCAO mice. HSP70 produces a marked effect on the ischemic tolerance induced by LIPostC in MCAO mice.     

Mortalin,a mitochondrial chaperone,in neurodegenerative disorder

Mortalin(mtHSP70/HSP75/Grp75/TRAP-1/PBP74) is an essential mitochondrial chaperone and is believed to regulate multiple cellular functions ranging from cell survival, cell proliferation, stress response, mitochondrial biogenesis and intracellular trafficking. Recent studies have shown that mortalin is relevant to the pathogenesis of Alzheimer's disease(AD) and Parkinson's disease(PD). Proteomic studies demonstrate the differential expression of mortalin not only in the models of AD or PD but also in PD human brains as compared to the controls. Mortalin seems to modulates the development of diseases through association with the critical molecules such as apoE, amyloid β-protein, amyloid precursor protein(APP) in AD, and α-synuclein, DJ-1, PINK1 in PD. Mortalin may regulate PD development via the pathways involving mitochondrial and proteasomal functions as well as oxidative stress. Furthermore, it is reported that mortalin participates in the pathological processes of several other neurological disorders, such as ischemic brain injury, absence seizure and Friedreich's ataxia(FRDA).     

Common pathogenesis of type 2 diabetes and Alzheimers disease: a potential mechanism

AIM: Some epidemiologic evidences suggest an association between type 2 diabetes mellitus (T2DM) and Alzheimer disease (AD). The present study was designed to explore the common pathogenesis in these two diseases by comparing the pathological changes in pancreas and hippocampus, the activity of glucogen synthase kinase 3β (GSK-3β) and protein phosphatase 2A (PP2A) in T2DM rats with those in AD rats. METHODS: The SD rats were fed with high glucose, high fat and high protein for 8 weeks, and then injected with streptozocin (STZ) to establish the T2DM models. The model of AD was made by injection of STZ in hippocampus. The levels of hyperphosphorylated tau protein and β-amyloid protein (Aβ) in hippocampus and pancreas were analyzed by Western blotting and immunochemistry. The activities of GSK-3β and PP2A were determined by using γ-32P-ATP and the specific peptide substrate. RESULTS: In hippocampus of T2DM rats, the tau protein was hyperphosphorylated, the Aβ level was raised, the activity of PP2A was increased and the activity of GSK-3β was decreased, which were also observed in the hippocampus of AD rats. In the AD rats, the Aβ level in pancreas was found to rise, the activity of PP2A decreased and the activity of GSK-3β increased, which were similar to the changes in pancreas of T2DM rats. However, tau protein was not detected in the pancreas of both groups. CONCLUSION: These findings suggest that there are some common pathological changes between T2DM and AD. The hyperphosohorylation of tau protein in hippocampus, the raised Aβ level in hippocampus and pancreas, as well as the corresponding activities of PP2A and GSK-3β may contribute to the pathogenesis in the development of T2DM and AD.     

Resveratrol modulates SDF-1/CXCR4 signaling to inhibit hypoxia-ischemia-induced apoptosis of neurons from the brain of newborn rats

AIM:To investigate the effect of resveratrol (RSV) on apoptosis and stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) pathway in hypoxia-ischemia-induced neurons from the brain of newborn rats and its mechanism. METHODS:The cortex neurons from the brain of newborn rats were given oxygen-glucose deprivation (OGD) treatment to mimic neonatal hypoxic-ischemic encephalopathy (HIE). The cortex neurons were randomly divided into 4 groups:control group, HIE model group, HIE+RSV-low (10 μmol/L) group, and HIE+RSV-high (50 μmol/L) group. After OGD treatment for 2 h, the neurons were cultured with indicated dose of RSV for 24 h. The apoptosis was analyzed by flow cytometry. Western blot was used to determine the levels of apoptosis-related proteins, SDF-1 and CXCR4. Real-time PCR was used to detect the mRNA expression of SDF-1 and CXCR4. Additionally, to explore the effects of RSV on cell apoptosis and apoptosis-related proteins after the suppression of SDF-1/CXCR4 signaling, a CXCR4 antagonist AMD3100, and RSV were used to co-treat OGD-injured neurons for 24 h. RESULTS:RSV alleviated OGD-induced neuronal apoptosis, down-regulated cleaved caspase-3 and cytochrome C levels, and up-regulated the ratio of Bcl-2/Bax. Compared with the control group, OGD treatment increased the expression of SDF-1 and CXCR4 (P<0.05). Compared with the HIE model group, RSV further up-regulated the expression of SDF-1 and CXCR4 (P<0.05). AMD3100 reversed the effects of RSV on OGD-induced cell apoptosis. CONCLUSION:RSV suppresses hypoxia-ischemia-induced apoptosis of neurons from the brain of newborn rats via up-regulating SDF-1/CXCR4 signaling pathway.     

Effectiveness and pathologic changes of transplantation of human mesenchymal stem cells in SOD1-G93A mouse model of familial amyotrophic lateral sclerosis

AIM: To study intravenous transplantation of human mesenchymal stem cells (hMSCs) on the life span and pathological change of SOD1-G93A amyotrophic lateral sclerosis (ALS) mice. METHODS: hMSCs were cultured and expanded from heparinized bone marrow cells from healthy donors and the purity and features were identified with FCM. hMSCs (3×106) resuspended in 0.3 mL DMEM or 0.3 mL DMEM only were injected into the tail vein of genotyped SOD1-G93A ALS mice. The mice were evaluated for signs of motor deficit with 4-point scoring system according to Weydt and the onset and life span were assessed. The pathological change was observed with Nissl staining and number of motor neuron was counted. RESULTS: The onset symptoms in untreated SOD1-G93A ALS mice appeared at (156.6±3.6) d of age and the average life span was (188.3±3.5) d. hMSCs transplantation delayed the onset of ALS type symptoms about 14 d and prolonged the life span about 18 d compared to the untreated SOD1-G93A littermates. The loss of motor neurons in untreated mice was much faster and severer than that in hMSCs transplanted mice. At 16 th week and 20 th week, motor neurons of untreated mice were significantly fewer than those of transplanted mice. β-globin gene in brain was detected in transplanted ALS mice. CONCLUSION: hMSCs migrate to central nervous system after intravenous transplantation, prolong the life span and delay the onset and motor neuron loss in SOD1-G93A ALS mice.     

Expression and distribution of C1C-3 in human glioma specimen

AIM: To investigate the expression of voltage-gated chloride channels (ClC)-3 protein and mRNA in human glioma specimen and its biological function. METHODS: The expression of C1C-3 was observed by immunohistochemical staining in 24 cases of human glioma, 4 cases of brain metastic cancer specimens and 5 cases of normal brain tissue as control; The C1C-3 mRNA expression were detected in the specimens with positive expression of ClC-3 protein by RT-PCR. RESULTS: ClC-3 protein was found negative in 4 cases of normal brain tissues and positive in 19 cases of human glioma and 4 cases of brain metastic cancer specimens. ClC-3 protein was mainly expressed in the membrane or cytoplasm of neoplastic cells and microvascular endothelial cells. The expression of ClC-3 mRNA was detected in 16 cases of human glioma and 4 cases of brain metastasis cancer specimens among the tissues with the positive expression of ClC-3 protein. The level of protein and RNA of ClC-3 in high malignant oligodendrogliomas was higher than that in low malignant ones. CONCLUSION: ClC-3 is generally expressed in human glioma and brain metastic cancer and is probably correlated with the classification of its pathological malignance.     

Basic fibroblast growth factor and Alzheimer's disease

Alzheimer's disease (AD), which is one type of senile deimentia,has three remarkable pathologic characteristics-senile plaque, neurofibrillar tangles and neuronal death. As a neurotrophic factor, basic fibroblast growth factor (bFGF) is closely related to AD. This art icle reviewed the interaction between bFGF and AD-associated gene products (such as amyliod protein, presenilin, apoloprotein E and microtubulin-associated protein tau) and neuronal apoptosis. Some researchers suggested that bFGF may be put forward as potential therapeutic agent in AD and play a role in preventing or retarding the pathological process of this disease, alleviating or even eradicat ing the pathological insults of this disease.     

rAAV-mediated VLDLR gene transfection reduces tau hyperphosphorylation in hippocampus of type 2 diabetic rats

AIM: Abnormal hyperphosphorylation of tau plays a critical role in the pathogenesis of Alzheimers disease(AD), and tau protein was hyperphosphorylated in type 2 diabetes. The present study was designed to explore the phosphorylation level of tau in hippocampus of type 2 diabetes rats which interrupted by very low density lipoprotein receptor(VLDLR)gene transfection. METHODS: Wistar male rats were randomized into 3 groups. The control group(CTL)was fed with normal food. The T2DM group and T2DM mediated VLDLR gene group were on high sugar, high fat and high protein diet for 3 months. The plasma insulin level was measured by RIA method, and the plasma glucose was determined by glucose-oxidase method. Total tau level, the phosphorylation level of tau at individual phosphorylation sites and the level of VLDLR were analyzed by Western blotting. The activity of glycogen synthase kinase 3β, a key component of insulin signal transduction pathway and a known tau kinase, in the hippocampus of rats was determined by using ［γ-32P］-ATP and the specific peptide substrate. RESULTS: No significant difference of total tau level in hippocampus between T2DM group and T2DM mediated VLDLR gene group was observed. Tau protein in T2DM group was found to be more hyperphosphorylated at several AD-related phosphorylation sites(Ser214, Thr217, Ser396, Ser422 and Ser199/202)than that in CTL, while the immunoreaction at tau-1 site is weaker than that in CTL. VLDLR gene therapy reduced hyperphosphorylation sites of Thr217, Ser396, Ser422 and Ser199/202 of tau to almost the control level, but did not change the phosphorylation of Ser214 or Ser422 on tau. The expression of Ser214 was also observed by immunohistochemical assay. The phosphorylated tau modestly increased in hippocampus in T2DM group compared to CTL, but VLDLR gene treatment did not change the phosphorylation level. The phosphorylation of GSK-3β was decreased dramatically in the hippocampus in T2DM rats, and this phosphorylation was significantly increased after VLDLR gene treatment. CONCLUSION: These findings suggest that Raav mediated VLDLR gene treatment partially reverses tau hyperphosphorylation at several sites in T2DM rat hippocampus, which may mediate by inhibition of GSK-3β activity.