Comparative study of histopathology changes between the PS1/APP double transgenic mouse model and Aβ1-40 -injected rat model of Alzheimer disease

Objective To identify the genetype of the PS1/APP double transgenie mouse model, then to analyse the histopathological changes in the brain and compare the differences between the transgenie mice models and Aβ1-40-injeeted rats models of Alzheimer disease. Methods The modified congo red staining, Nissl＇s staining and immunohistology staining was used to observe the Aβ deposits, activation of astrocyte respectively. Results ①The PS1/APP transgenic mouse extensively displayed Aβ deposits in the cortex and hippocampal structures, and GFAP positive cells were aggregated in mass and surrounded the congo red-positive plaque. ②The Aβ1-40-intrahippocmnpal-injeeted rat model showed the Aβ plaque deposits in the dentate gyrus of the hippocampus, with the astrocyte surrounded. The neurons loss was significant in the injection point and pin hole of injection with Nissl＇s staining methods. GFAP-positive cells increased significantly compared with the uninjected lateral of the hippocampus. Conclusion Although Aβ1-40-injected rat models could simulate some characteristic pathological features of human Alzheimer diseases, Aβ deposits and neurons loss in partial hippocampal, it would not simulate the progressive degenenration in the brain of AD. The double transgenie PS1/APP mice could simulate the specific pathogenesis and progressive changes of AD, mainly is Aβ deposits and the spongiocyte response , while no neurons loss were observed in this model.     

Reactive oxidative species enhance amyloid toxicity in APP/PS1 mouse neurons

Objective To investigate whether intracellular amyloid β (iAβ) induces toxicity in wild type (WT) and APP/PS1 mice, a mouse model of Alzheimer’s disease. Methods Different forms of Aβ aggregates were microinjected into cultured WT or APP/PS1 mouse hippocampal neurons. TUNEL staining was performed to examine neuronal cell death. Reactive oxidative species (ROS) were measured by MitoSOXTM Red mitochondrial superoxide indicator. Results Crude, monomer and protofibrilAβ induced more toxicity inAPP/PS1 neurons than in WT neurons. ROS are involved in mediating the vulnerability of APP/PS1 neurons to iAβ toxicity. Conclusion Oxidative stress may mediate cell death induced by iAβ in neurons.     

Degenerative alterations in noradrenergic neurons of the locus coeruleus in Alzheimer’s disease

Mice carrying mutant amyloid-β precursor protein and presenilin-1 genes (APP/PS1 double transgenic mice) have frequently been used in studies of Alzheimer’s disease; however, such studies have focused mainly on hippocampal and cortical changes. The severity of Alzheimer’s disease is known to correlate with the amount of amyloid-β protein deposition and the number of dead neurons in the locus coeruleus. In the present study, we assigned APP/PS1 double transgenic mice to two groups according to age: young mice (5-6 months old) and aged mice (16-17 months old). Age-matched wild-type mice were used as controls. Immunohistochemistry for tyrosine hydroxylase (a marker of catecholaminergic neurons in the locus coeruleus) revealed that APP/PS1 mice had 23% fewer cells in the locus coeruleus compared with aged wild-type mice. APP/PS1 mice also had increased numbers of cell bodies of neurons positive for tyrosine hydroxylase, but fewer tyrosine hydroxylase-positive fibers, which were also short, thick and broken. Quantitative analysis using unbiased stereology showed a significant age-related increase in the mean volume of tyrosine hydroxylase-positive neurons in aged APP/PS1 mice compared with young APP/PS1 mice. Moreover, the mean volume of tyrosine hydroxylase-positive neurons was positively correlated with the total volume of the locus coeruleus. These findings indicate that noradrenergic neurons and fibers in the locus coeruleus are predisposed to degenerative alterations in APP/PS1 double transgenic mice.     

7.0T nuclear magnetic resonance evaluation of the amyloid beta(1–40) animal model of Alzheimer's disease: comparison of cytology verification

3.0T magnetic resonance spectroscopic imaging is a commonly used method in the research of brain function in Alzheimer's disease.However,the role of 7.0T high-field magnetic resonance spectroscopic imaging in brain function of Alzheimer's disease remains unclear.In this study,7.0T magnetic resonance spectroscopy showed that in the hippocampus of Alzheimer's disease rats,the N-acetylaspartate wave crest was reduced,and the creatine and choline wave crest was elevated.This finding was further supported by hematoxylin-eosin staining,which showed a loss of hippocampal neurons and more glial cells.Moreover,electron microscopy showed neuronal shrinkage and mitochondrial rupture,and scanning electron microscopy revealed small size hippocampal synaptic vesicles,incomplete synaptic structure,and reduced number.Overall,the results revealed that 7.0T high-field nuclear magnetic resonance spectroscopy detected the lesions and functional changes in hippocampal neurons of Alzheimer's disease rats in vivo,allowing the possibility for assessing the success rate and grading of the amyloid beta(1–40) animal model of Alzheimer's disease.     

Effects of triptolide on hippocampal microglial cells and astrocytes in the APP/PS1 double transgenic mouse model of Alzheimer’s disease

The principal pathology of Alzheimer's disease includes neuronal extracellular deposition of amyloid-beta peptides and formation of senile pl aques,which in turn induce neuroinflammation in the brain.Triptolide,a natural extract from the vine-like herb Tripterygium wilfordii Hook F,has potent anti-inflammatory and immunosuppressive efficacy.Therefore,we determined if triptolide can inhibit activation and proliferation of microglial cells and astrocytes in the APP/PS1 double transgenic mouse model of Alzheimer's disease.We used 1 or 5 μg/kg/d triptolide to treat APP/PS1 double transgenic mice(aged 4–4.5 months) for 45 days.Unbiased stereology analysis found that triptolide dose-dependently reduced the total number of microglial cells,and transformed microglial cells into the resting state.Further,triptolide(5 μg/kg/d) also reduced the total number of hippocampal astrocytes.Our in vivo test results indicate that triptolide suppresses activation and proliferation of microglial cells and astrocytes in the hippocampus of APP/PS1 double transgenic mice with Alzheimer's disease.     

MiR-206 decreases brain-derived neurotrophic factor levels in a transgenic mouse model of Alzheimer＇s disease

MicroRNA alterations have been reported in patients with Alzheimer＇s disease （AD） and AD mouse models. We now report that miR-206 is upregulated in the hippocampal tissue, cerebrospinal fluid, and plasma of embryonic APP/PS1 transgenic mice. The increased miR-206 downregulates the expression of brain-derived neurotrophic factor （BDNF）. BDNF is neuroprotective against cell death after various insults, but in embryonic and newborn APP/PS1 mice it is decreased. Thus, a specific microRNA alteration may contribute to AD pathology by downregulating BDNF.     

Effects of electro-acupuncture on Noxa and caspase-3 expression in hippocampal CA1 region of a vascular dementia rat model*★

BACKGROUND：Noxa, a pro-apoptotic member of the Bcl-2 protein family, has been shown to induce the mitochondrial pathway of apoptosis and to mediate hypoxic cell death in a rat model of cerebral ischemia. This suggests that Noxa could participate in apoptosis during vascular dementia （VD）. OBJECTIVE： To detect Noxa and caspase-3 expression after electro-acupuncture in VD rats to further validate the mechanism of electro-acupuncture-induced effects in the treatment of VD. DESIGN, TIME AND SETTING： A randomized, controlled study was performed at the Center for the Neurobiology of Fujian Medical University between January 2006 and March 2007. MATERIALS： A total of forty adult, male, Sprague Dawley rats were included in this study. The following equipment was used： confocal laser scanning microscope （Sp5, Leica, Germany）, water maze （Bejing Suntendy Science and Technology Co., Ltd., China）, and SDZ-II electronic acupuncture treatment instruments （Suzhou Medical Appliance Factory, China）. METHODS： Thirty-eight rats with sufficient learning and memory abilities were selected by Morris water maze criteria. Twelve rats received sham-surgery; the remaining 26 rats were used to establish a VD model by bilateral occlusion of the common carotid arteries. The rats that survived the occlusion procedure were randomly assigned into an electro-acupuncture group （n = 11） and a VD model group （n = 12）. MAIN OUTCOME MEASURES： Neuropathological changes were observed with hematoxylin-eosin staining of the hippocampus and expression of Noxa and caspase-3 in the hippocampal CA1 region was analyzed by confocal laser scanning microscope following immunofluorescence staining. RESULTS： Expressions of Noxa and caspase-3 in the electro-acupuncture group and sham-operated group were less than in the VD model group （P 〈 0.01）. Electro-acupuncture reduced the amount of apoptotic neurons in hippocampal CA1 area of rats with VD. The average latency in the Morris water maze test was significantly shorter     

Blocking beta 2-adrenergic receptor inhibits dendrite ramification in a mouse model of Alzheimer's disease

Dendrite ramification affects synaptic strength and plays a crucial role in memory. Previous studies revealed a correlation between beta 2-adrenergic receptor dysfunction and Alzheimer's disease(AD), although the mechanism involved is still poorly understood. The current study investigated the potential effect of the selective β2-adrenergic receptor antagonist, ICI 118551(ICI), on Aβ deposits and AD-related cognitive impairment. Morris water maze test results demonstrated that the performance of AD-transgenic(TG) mice treated with ICI(AD-TG/ICI) was significantly poorer compared with Na Cl-treated AD-TG mice(AD-TG/Na Cl), suggesting that β2-adrenergic receptor blockage by ICI might reduce the learning and memory abilities of mice. Golgi staining and immunohistochemical staining revealed that blockage of the β2-adrenergic receptor by ICI treatment decreased the number of dendritic branches, and ICI treatment in AD-TG mice decreased the expression of hippocampal synaptophysin and synapsin 1. Western blot assay results showed that the blockage of β2-adrenergic receptor increased amyloid-β accumulation by downregulating hippocampal α-secretase activity and increasing the phosphorylation of amyloid precursor protein. These findings suggest that blocking the β2-adrenergic receptor inhibits dendrite ramification of hippocampal neurons in a mouse model of AD.     

C.elegans as a model system for Parkinson disease

Parkinson disease(PD) is characterized by the selective loss of dopaminergic neurons in the substantia nigra. Although investigation in mammalian animal models of PD has enhanced our understanding of PD, the complexity of the mammalian nervous system and our inability to visualize DA neurons in vivo restricts the advances in elucidating the molecular mechanisms of PD. Conservation between C. elegans and mammals in genomic, biosynthetic and metabolic pathways as well as the advantages of observing DA neurons morphology in vivo and the ease of transgenic and genetic manipulation make C. elegans an excellent model organism for PD.     

Characterization of hippocampal Cajal-Retzius cells during development in a mouse model of Alzheimer＇s disease （Tg2576）

Cajal-Retzius cells are reelin-secreting neurons in the marginal zone of the neocortex and hippocampus. The aim of this study was to investigate Cajal-Retzius cells in Alzheimer＇s disease pathology. Results revealed that the number of Cajal-Retzius cells markedly reduced with age in both wild type and in mice over-expressing the Swedish double mutant form of amyloid precursor protein 695 （transgenic （Tg） 2576 mice）. Numerous reelin-positive neurons were positive for activated caspase 3 in Tg2576 mice, suggesting that Cajal-Retzius neuronal loss occurred via apoptosis in this Alzheimer＇s disease model. Compared with wild type, the number of Cajal-Retzius cells was significantly lower in Tg2576 mice. Western blot analysis confirmed that reelin levels were markedly lower in Tg2576 mice than in wild-type mice. The decline in Cajal-Retzius cells in Tg2576 mice was found to occur concomitantly with the onset of Alzheimer＇s disease amyloid pathology and related behavioral deficits. Overall, these data indicated that Cajal-Retzius cell loss occurred with the onset and development of Alzheimer＇s disease.     

Adipose-derived mesenchymal stem cell transplantation promotes adult neurogenesis in the brains of Alzheimer’s disease mice

In the present study,we transplanted adipose-derived mesenchymal stem cells into the hippocampi of APP/PS1 transgenic Alzheimer’s disease model mice.Immunofluorescence staining revealed that the number of newly generated(BrdU+)cells in the subgranular zone of the dentate gyrus in the hippocampus was significantly higher in Alzheimer’s disease mice after adipose-derived mesenchymal stem cell transplantation,and there was also a significant increase in the number of BrdU+/DCX+neuroblasts in these animals.Adipose-derived mesenchymal stem cell transplantation enhanced neurogenic activity in the subventricular zone as well.Furthermore,adipose-derived mesenchymal stem cell transplantation reduced oxidative stress and alleviated cognitive impairment in the mice.Based on these findings,we propose that adipose-derived mesenchymal stem cell transplantation enhances endogenous neurogenesis in both the subgranular and subventricular zones in APP/PS1 transgenic Alzheimer’s disease mice,thereby facilitating functional recovery.     

Dab2 attenuates brain injury in APP/PS1 mice via targeting transforming growth factor-beta/SMAD signaling简

Transforming growth factor-beta(TGF-β)type II receptor(TβRII)levels are extremely low in the brain tissue of patients with Alzheimer’s disease.This receptor inhibits TGF-β1/SMAD signaling and thereby aggravates amyolid-beta deposition and neuronal injury.Dab2,a specific adapter protein,protects TβRII from degradation and ensures the effective conduction of TGF-β1/SMAD signaling.In this study,we used an adenoviral vector to overexpress the Dab2 gene in the mouse hippocampus and investigated the regulatory effect of Dab2 protein on TGF-β1/SMAD signaling in a mouse model of Alzheimer’s disease,and the potential neuroprotective effect.The results showed that the TβRII level was lower in APP/PS1 mouse hippocampus than in normal mouse hippocampus.After Dab2 expression,hippocampal TβRII and p-SMAD2/3 levels were significantly increased,while amyloid-beta deposition,microglia activation,tumor necrosis factor-βand interleulin-6 levels and neuronal loss were significantly attenuated in APP/PS1 mouse brain tissue.These results suggest that Dab2 can exhibit neuroprotective effects in Alzheimer’s disease by regulating TGF-β1/SMAD signaling.     

Inhibitory effects of scorpion venom heat-resistant protein on neurotoxicity of exogenous amyloid beta peptide 1-40

BACKGROUND： Studies have shown that scorpion venom heat-resistant protein （SVHRP） exhibits protective effects on primary cultured hippocampal neurons. OBJECTIVE： To determine the effects of SVHRP on astrocyte activity and synaptic density in the hippocampus induced by amyloid β peptide 1-40 （Aβ1-40） neurotoxicity. DESIGN, TIME AND SETTING： The randomized, controlled, animal experiment was performed at the Central Laboratory, the Laboratory of Human Anatomy, and the Laboratory of Physiology, in Dalian Medical University between March 2006 and June 2008. MATERIALS： Aβ1-40 was provided by Biosource, USA; SVHRP was a patented biological product of Dalian Medical University （No. ZL01 1 06166.9）. METHODS： A total of 27 healthy, 2-month-old, male SD rats were randomly assigned to 3 groups： control, Aβ, and SVHRP, with 9 rats in each group. Alzheimer＇s disease was simulated with 10 μg Aβ1-40 bilaterally injected into the hippocampus of the Aβ and SVHRP groups. The control group was injected with 2 μL 0.05% trifluoroacetic acid. One day following model establishment, the SVHRP group received an intraperitoneal injection of 2 μg/100 g SVHRP, while the control group and Aβ group received 0.5 mL/100 g tri-distilled water, once per day, for 10 consecutive days. MAIN OUTCOME MEASURES： At 16 days following model establishment, synaptophysin （p38） expression in CA1-CA4 regions of the rat hippocampus was determined by immunohistochemistry. Glial fibrillary acidic protein （GFAP） expression surrounding the hippocampal Aβ1-40 injected area was also detected. At 11 days following model establishment, escape latency, swimming time, and distance to target quadrant were measured using the Morris water maze. RESULTS： Compared with the control group, the Aβ group exhibited notably reduced p38 expression （P 〈 0.05） and notably increased GFAP expression in the rat hippocampus （P 〈 0.05）. Water maze results demonstrated that escape latency was prolonged （P 〈 0.05）, and swimming time and distance to the target quadrant were shortened in the Aβ group. Compared with the Aβ group, the SVHRP group exhibited notably increased p38 expression （P 〈 0.05） and notably decreased GFAP expression in the rat hippocampus （P 〈 0.05）. Water maze results demonstrated that escape latency was significantly reduced （P 〈 0.05）, and swimming time and distance to the target quadrant were significantly prolonged. CONCLUSION： SVHRP inhibited exogenous Aβ1-40-induced astrocyte activation and synaptic density decline in the rat hippocampus. Place navigation and spatial searching results showed that SVHRP blocked Aβ1-40-induced impaired learning and memory.     

Mutant amyloid precursor protein and presenilin-1 genes effect on ischemia vulnerability via calcium homeostasis disturbance

BACKGROUND： Previous studies have demonstrated that mutant amyloid precursor protein （APP） or presenilin-1 （PS1） genes increase susceptibility to ischemic brain damage induced by middle cerebral artery occlusion. Possible mechanisms include over-production of beta-amyloid peptide （Aβ）. OBJECTIVE： Because Aβ is over-produced in the APP/PS1 double-transgenic mouse, the present study focused on mechanisms of increased ischemic damage due to mutant APP and PS1 genes by measuring oxidative stress, mitochondrial function, and calcium homeostasis. DESIGN, TIME AND SETTING： The non-randomized, controlled, in vivo and in vitro experiments were performed at the Medical Research Center, Second Clinical College, Jinan University between May and October 2008. MATERIALS： Male APP transgenic mice carrying the mutant 695swe gene and female PS1 transgenic mice carrying the mutant Leu235Pro gene were donated from the University of Hong Kong. SHSY5Y human neureblastoma cells were purchased from ATCC （Manassas, VA, USA）, and Aβ1-42 was obtained from Sigma-Aldrich （St. Louis, MO, USA）. METHODS： APP transgenic mice were mated with PS1 transgenic mice to produce APP/PS1 double-transgenic mice and wildtype littermates mice. The photothrombotic stroke model was induced in six APP/PS1 double-transgenic and 6 wildtype littermates mice. SHSY5Y human neuroblastoma cells were cultured in vitro, and were divided into 4 groups： Aβ group, cells were exposed to 5 pmol/L Aβ for 24 hours; oxygen-glucose deprivation （OGD） group, cells were exposed to OGD for 1 hour after treatment with sterile, ultra-pure water for 24 hours; OGD＋Aβ group, cells were exposed to OGD and Aβfor 1 hour after treatment with 5 pmol/L Aβ for 24 hours; sham control group： cells were exposed to sterile, ultra-pure water for 25 hours. OGD was achieved by exposing the cells to glucose-free DMEM and placing the cells in an anaerobic chamber flushed with 5% CO2 and 95% N2 （v/v） at 37 ℃ for 1 hour. MAIN OUTCOME MEASURES： TTC staining was used to measure infarct volume 7 days after photothrombotic stroke. Cell viability was evaluated using the MTT kit. Opening of the mitochondrial permeability transition pore, intracellular concentration of superoxide anion, and calcium after OGD were detected with fluorescence intensity of calcein-AM, hydroethidine, and fluo-3/AM. RESULTS： At 7 days after stroke, total infarct volume and cortical infarct volume were significantly greater in the APP/PS1 transgenic mice compared with the wildtype littermates mice （P 〈 0.01）. Aβ, OGD, and Aβ ＋ OGD significantly decreased cell viability and increased fluorescence intensity of hydroethidine and fluo-3/AM （P 〈 0.01）. Compared with the Aβ or OGD group, Aβ ＋ OGD significantly decreased cell viability （P 〈 0.01） and significantly increased fluorescence intensity of calcein-AM, hydroethidine, and fluo-3/AM （P 〈 0.01 or P 〈 0.05）. CONCLUSION： The APP/PS1 double-transgenic mice were more vulnerable to ischemia. The possible mechanisms included enhanced opening of the mitochondrial permeability transition pore, overproduction of superoxide anion due to pore opening, and disturbed calcium homeostasis induced by excess superoxide anion.     

Genistein suppresses the mitochondrial apoptotic pathway in hippocampal neurons in rats with Alzheimer’s disease

Genistein is effective against amyloid-β toxicity,but the underlying mechanisms are unclear.We hypothesized that genistein may protect neurons by inhibiting the mitochondrial apoptotic pathway,and thereby play a role in the prevention of Alzheimer's disease.A rat model of Alzheimer's disease was established by intraperitoneal injection of D-galactose and intracerebral injection of amyloid-β peptide(25–35).In the genistein treatment groups,a 7-day pretreatment with genistein(10,30,90 mg/kg) was given prior to establishing Alzheimer's disease model,for 49 consecutive days.Terminal deoxyribonucleotidyl transferase-mediated d UTP nick end labeling assay demonstrated a reduction in apoptosis in the hippocampus of rats treated with genistein.Western blot analysis showed that expression levels of capase-3,Bax and cytochrome c were decreased compared with the model group.Furthermore,immunohistochemical staining revealed reductions in cytochrome c and Bax immunoreactivity in these rats.Morris water maze revealed a substantial shortening of escape latency by genistein in Alzheimer's disease rats.These findings suggest that genistein decreases neuronal loss in the hippocampus,and improves learning and memory ability.The neuroprotective effects of genistein are associated with the inhibition of the mitochondrial apoptotic pathway,as shown by its ability to reduce levels of caspase-3,Bax and cytochrome c.     

Amentoflavone protects hippocampal neurons: anti-inflammatory,antioxidative, and antiapoptotic effects

Amentoflavone is a natural biflavone compound with many biological properties, including anti-inflammatory, antioxidative, and neuroprotective effects. We presumed that amentoflavone exerts a neuroprotective effect in epilepsy models. Prior to model establishment, mice were intragastrically administered 25 mg/kg amentoflavone for 3 consecutive days. Amentoflavone effectively prevented pilocarpine-induced epilepsy in a mouse kindling model, suppressed nuclear factor-κB activation and expression, inhibited excessive discharge of hippocampal neurons resulting in a reduction in epileptic seizures, shortened attack time, and diminished loss and apoptosis of hippocampal neurons. Results suggested that amentoflavone protected hippocampal neurons in epilepsy mice via anti-inflammation, antioxidation, and antiapoptosis, and then effectively prevented the occurrence of seizures.     

Amelioration of Alzheimer's disease pathology and cognitive deficits by immunomodulatory agents in animal models of Alzheimer's disease

The most common age-related neurodegenerative disease is Alzheimer's disease(AD) characterized by aggregated amyloid-β(Aβ) peptides in extracellular plaques and aggregated hyperphosphorylated tau protein in intraneuronal neurofibrillary tangles,together with loss of cholinergic neurons,synaptic alterations,and chronic inflammation within the brain.These lead to progressive impairment of cognitive function.There is evidence of innate immune activation in AD with microgliosis.Classically-activated microglia(M1 state) secrete inflammatory and neurotoxic mediators,and peripheral immune cells are recruited to inflammation sites in the brain.The few drugs approved by the US FDA for the treatment of AD improve symptoms but do not change the course of disease progression and may cause some undesirable effects.Translation of active and passive immunotherapy targeting Aβ in AD animal model trials had limited success in clinical trials.Treatment with immunomodulatory/anti-inflammatory agents early in the disease process,while not preventive,is able to inhibit the inflammatory consequences of both Aβ and tau aggregation.The studies described in this review have identified several agents with immunomodulatory properties that alleviated AD pathology and cognitive impairment in animal models of AD.The majority of the animal studies reviewed had used transgenic models of early-onset AD.More effort needs to be given to creat models of late-onset AD.The effects of a combinational therapy involving two or more of the tested pharmaceutical agents,or one of these agents given in conjunction with one of the cell-based therapies,in an aged animal model of AD would warrant investigation.     

Astrocyte reactivity in related brain regions in a mouse model of MPTP-induced Parkinson’s disease

BACKGROUND： Severe injury to dopaminergic neuronal cell bodies and their axon terminals in the substantia nigra pars compacta （SNC） has been observed in both Parkinson＇s disease （PD） patients or in 1-methy-4-phenyl-1,2,3,6-tetrahydropyrindine（MPTP）-induced PD animal models, but only slight injury occurs in the adjacent ventral tegmentat area （VTA）. The mechanisms underlying this selective injury remain poorly understood. OBJECTIVE： To comparatively observe astrocyte reactivity in the SNC, caudate putamen （CPu）, VTA, and frontal association cortex （FrA）.
DESIGN, TIME AND SETTING： A cellular and molecular biology, randomized, controlled experiment was performed at the Institute of Neurobiology, Department of Human Anatomy, Medical School of Nantong University, between December 2006 and September 2008.
MATERIALS： A total of 80 healthy adult male C57BL/6 mice were included in this study. MPTP was purchased from Sigma, USA.
METHODS： Mice were randomly divided into a model group （n = 64） and a sham-operated group （n = 16）. PD was induced in the mice from the model group by intraperitoneal injection of 20 mg/kg MPTP, once every three hours, for a total of 4 times.
MAIN OUTCOME MEASURES： Tyrosine hydroxylase （TH）-immunoreactive neurons and glial fibrillary acidic protein （GFAP）-immunoreactive astrocytes were examined by dual immunofluorescence labeling. GFAP-immunoreactive astrocytes in the CPu and FrA were determined by immunofluorescent staining. GFAP mRNA expression in the SNC, CPu, VTA, and FrA was detected using real-time polymerase chain reaction. TH protein levels in the TH-immunoreactive axon terminals of the CPu and FrA were detected by Western blotting.
RESULTS： Numbers of TH-immunoreactive neurons in the SNC, and TH protein level in the CPu, markedly decreased （by approximately 68%） 1 day after MPTP injection, and gradually increased at 3 days. Simultaneously, astrocyte reactivity was strengthened, in particular at 7 days. However, after MPTP injection, decreases in the numbers of TH-immunoreactive neurons in the VTA, and TH protein levels in the FrA, were less apparent （approximately 15%）. Also, no obvious astrocyte reactivity was observed.
CONCLUSION： In a mouse model of PD, astrocyte reactivity was apparent in the SNC and CPu, but not the VTA or FrA. In addition, astrocyte reactivity was greater in regions where injury to dopaminergic neurons was more severe.     

Inhibiting p38 mitogen-activated protein kinase attenuates cerebral ischemic injury in Swedish mutant amyloid precursor protein transgenic mice

Cerebral ischemia was induced using photothrombosis 1 hour after intraperitoneal injection of the p38 mitogen-activated protein kinase (MAPK) inhibitor SB239063 into Swedish mutant amyloid precursor protein (APP/SWE) transgenic and non-transgenic mice. The number of surviving neurons in the penumbra was quantified using Nissl staining, and the activity of p38 MAPKs was measured by western blotting. The number of surviving neurons in the penumbra was significantly reduced in APP/SWE transgenic mice compared with non-transgenic controls 7 days after cerebral ischemia, but the activity of p38 MAPKs was significantly elevated compared with the non-ischemic hemisphere in the APP/SWE transgenic mice. SB239063 prevented these changes. The APP/SWE mutation exacerbated ischemic brain injury, and this could be alleviated by inhibiting p38 MAPK activity.     

Loss of canonical Wnt signaling is involved in the pathogenesis of Alzheimer's disease

Alzheimer's disease(AD) is the most common form of dementia in the older population, however, the precise cause of the disease is unknown. The neuropathology is characterized by the presence of aggregates formed by amyloid-β(Aβ) peptide and phosphorylated tau; which is accompanied by progressive impairment of memory. Diverse signaling pathways are linked to AD, and among these the Wnt signaling pathway is becoming increasingly relevant, since it plays essential roles in the adult brain. Initially, Wnt signaling activation was proposed as a neuroprotective mechanism against Aβ toxicity. Later, it was reported that it participates in tau phosphorylation and processes of learning and memory. Interestingly, in the last years we demonstrated that Wnt signaling is fundamental in amyloid precursor protein(APP) processing and that Wnt dysfunction results in Aβ production and aggregation in vitro. Recent in vivo studies reported that loss of canonical Wnt signaling exacerbates amyloid deposition in a transgenic(Tg) mouse model of AD. Finally, we showed that inhibition of Wnt signaling in a Tg mouse previously at the appearance of AD signs, resulted in memory loss, tau phosphorylation and Aβ formation and aggregation; indicating that Wnt dysfunction accelerated the onset of AD. More importantly, Wnt signaling loss promoted cognitive impairment, tau phosphorylation and Aβ1–42 production in the hippocampus of wild-type(WT) mice, contributing to the development of an Alzheimer's-like neurophatology. Therefore, in this review we highlight the importance of Wnt/β-catenin signaling dysfunction in the onset of AD and propose that the loss of canonical Wnt signaling is a triggering factor of AD.