Persistent inflammation and neuronal loss in the mouse brain induced by a modified form of attenuated herpes simplex virus type I

Herpes simplex virus-1(HSV-1)is a widespread neurotropic virus that can reach the brain and cause a rare but acute herpes simplex encephalitis(HSE)with a high mortality rate.Most patients present with changes in neurological and behavioral status,and survivors suffer long-term neurological sequelae.To date,the pathogenesis leading to brain damage is still not well understood.HSV-1 induced encephalitis in the central nervous system(CNS)in animals are usually very diffuse and progressing rapidly,and mostly fatal,making the analysis difficult.Here,we established a mouse model of HSE via intracerebral inoculation of modified version of neuralattenuated strains of HSV-1(deletion of ICP34.5 and inserting a strong promoter into the latency-associated transcript region),in which the LMR-αΔpA strain initiated moderate productive infection,leading to strong host immune and inflammatory response characterized by persistent microglia activation.This viral replication activity and prolonged inflammatory response activated signaling pathways in neuronal damage,amyloidosis,Alzheimer's disease,and neurodegeneration,eventually leading to neuronal loss and behavioral changes characterized by hypokinesia.Our study reveals detailed pathogenic processes and persistent inflammatory responses in the CNS and provides a controlled,mild and non-lethal HSE model for studying long-term neuronal injury and increased risk of neurodegenerative diseases due to HSV-1 infection.

Therapeutic advances in neural regeneration for Huntington’s disease

Huntington’s disease is a neurodegenerative disease caused by the expansion mutation of a cytosine-adenine-guanine triplet in the exon 1 of the HTT gene which is responsible for the production of the huntingtin (Htt) protein. In physiological conditions, Htt is involved in many cellular processes such as cell signaling, transcriptional regulation, energy metabolism regulation, DNA maintenance, axonal trafficking, and antiapoptotic activity. When the genetic alteration is present, the production of a mutant version of Htt (mHtt) occurs, which is characterized by a plethora of pathogenic activities that, finally, lead to cell death. Among all the cells in which mHtt exerts its dangerous activity, the GABAergic Medium Spiny Neurons seem to be the most affected by the mHtt-induced excitotoxicity both in the cortex and in the striatum. However, as the neurodegeneration proceeds ahead the neuronal loss grows also in other brain areas such as the cerebellum, hypothalamus, thalamus, subthalamic nucleus, globus pallidus, and substantia nigra, determining the variety of symptoms that characterize Huntington’s disease. From a clinical point of view, Huntington’s disease is characterized by a wide spectrum of symptoms spanning from motor impairment to cognitive disorders and dementia. Huntington’s disease shows a prevalence of around 3.92 cases every 100,000 worldwide and an incidence of 0.48 new cases every 100,000/year. To date, there is no available cure for Huntington’s disease. Several treatments have been developed so far, aiming to reduce the severity of one or more symptoms to slow down the inexorable decline caused by the disease. In this context, the search for reliable strategies to target the different aspects of Huntington’s disease become of the utmost interest. In recent years, a variety of studies demonstrated the detrimental role of neuronal loss in Huntington’s disease condition highlighting how the replacement of lost cells would be a reasonable strategy to overcome the neurodegeneration. In this view, numerous have been the attempts in several preclinical models of Huntington’s disease to evaluate the feasibility of invasive and non-invasive approaches. Thus, the aim of this review is to offer an overview of the most appealing approaches spanning from stem cell-based cell therapy to extracellular vesicles such as exosomes in light of promoting neurogenesis, discussing the results obtained so far, their limits and the future perspectives regarding the neural regeneration in the context of Huntington’s disease.

Reduced mesencephalic astrocyte-derived neurotrophic factor expression by mutant androgen receptor contributes to neurodegeneration in a model of spinal and bulbar muscular atrophy pathology

Spinal and bulbar muscular atrophy is a neurodegenerative disease caused by extended CAG trinucleotide repeats in the androgen receptor gene,which encodes a ligand-dependent transcription facto r.The mutant androgen receptor protein,characterized by polyglutamine expansion,is prone to misfolding and forms aggregates in both the nucleus and cytoplasm in the brain in spinal and bulbar muscular atrophy patients.These aggregates alter protein-protein interactions and compromise transcriptional activity.In this study,we reported that in both cultured N2a cells and mouse brain,mutant androgen receptor with polyglutamine expansion causes reduced expression of mesencephalic astrocyte-de rived neurotrophic factor.Overexpressio n of mesencephalic astrocyte-derived neurotrophic factor amelio rated the neurotoxicity of mutant androgen receptor through the inhibition of mutant androgen receptor aggregation.Conversely.knocking down endogenous mesencephalic astrocyte-derived neurotrophic factor in the mouse brain exacerbated neuronal damage and mutant androgen receptor aggregation.Our findings suggest that inhibition of mesencephalic astrocyte-derived neurotrophic factor expression by mutant androgen receptor is a potential mechanism underlying neurodegeneration in spinal and bulbar muscular atrophy.

STAT3 ameliorates truncated tau-induced cognitive deficits

Proteolytic cleavage of tau by asparagine endopeptidase(AEP)creates tau-N368 fragments,which may drive the pathophysiology associated with synaptic dysfunction and memory deterioration in the brain of Alzheimer’s disease patients.Nonetheless,the molecular mechanisms of truncated tau-induced cognitive deficits remain unclear.Evidence suggests that signal transduction and activator of transcription-3(STAT3)is associated with modulating synaptic plasticity,cell apoptosis,and cognitive function.Using luciferase reporter assays,electrophoretic mobility shift assays,western blotting,and immunofluorescence,we found that human tau-N368 accumulation inhibited STAT3 activity by suppressing STAT3 translocation into the nucleus.Overexpression of STAT3 improved tau-N368-induced synaptic deficits and reduced neuronal loss,thereby improving the cognitive deficits in tau-N368 mice.Moreover,in tau-N368 mice,activation of STAT3 increased N-methyl-D-aspartic acid receptor levels,decreased Bcl-2 levels,reversed synaptic damage and neuronal loss,and thereby alleviated cognitive deficits caused by tau-N368.Taken together,STAT3 plays a critical role in truncated tau-related neuropathological changes.This indicates a new mechanism behind the effect of tau-N368 on synapses and memory deficits.STAT3 can be used as a new molecular target to treat tau-N368-induced protein pathology.

Altered seizure susceptibility and vesicular glutamate transporter subtype 1 immunoreactivity in a rat model of hypoxic brain injury

BACKGROUND：To the best of our knowledge, few studies have analyzed the effects of hypoxic brain injury on seizure susceptibility and pathophysiological mechanisms underlying seizure susceptibility following hypoxic brain injury. OBJECTIVE： To investigate changes in seizure susceptibility and neuronal loss, as well as expression of vesicular glutamate transporter subtype 1（VGluT1）, following hypoxic cerebral insult. DESIGN, TIME AND SETTING： A randomized controlled animal experiment was performed in the Department of Neurology, The Second Affiliated Hospital, Chongqing Medical University, between May 2006 and September 2007. MATERIALS： Seventy, male, Sprague Dawley rats, weighing 230–270 g, were used in the present study. Pentylenetetrazol （PTZ） was purchased from Sigma. Mouse NeuN monoclonal antibody and rabbit VGluT-1 polyclonal antibody were purchased from Chemicon and Gene Tex, respectively. METHODS： Rats were randomly assigned to control and hypoxia groups （n = 35 for each group）. Hypoxia was induced in rats using 8% oxygen-nitrogen gas mixture. Control rats were subjected to the same procedures, but with exposure to room air. MAIN OUTCOME MEASURES： Rats （n = 15 for each group） received intraperitoneal injections of PTZ, a sub-convulsive dose of 35 mg/kg/2 d for 20 days. The success of model establishment, as well as seizure scales, was measured. Rats from both groups, which were successfully kindled with PTZ, were divided into simple kindling and post-hypoxic kindling, respectively. A separate group, including rats from simple kindling and post-hypoxic kindling, was studied for neuronal loss and VGluT1 expression in the temporal cortex, midbrain, and hippocampal CA1 subfield using immunohistochemistry and western blot techniques, respectively. RESULTS： Seventy rats were included in the final analysis. （1）Compared with control animals （n = 7）, seizure scales were greater in hypoxic rats （n = 11）, which indicates that post-hypoxic rats reacted more sensitive to kindling. （2）The average number of neurons within the temporal cortex, midbrain, and hippocampal CA1 subfield was less in hypoxic rats than in control rats. After comparing post-hypoxia kindling with simple kindling, both the temporal cortex and hippocampal CA1 subfield exhibited obvious neuronal loss in the post-hypoxic kindling group （P 〈 0.05）. （3）Compared with hypoxia and simple kindling, the number of VGluT1 immunopositive cells was greater in the post-hypoxic kindling group （P 〈 0.05）. CONCLUSION： Hypoxic brain injury leads to increased seizure susceptibility, neuronal loss, and enhanced of VGluT1 expression.

Combined treatment with valproic acid and estrogen has neuroprotective effects in ovariectomized mice with Alzheimer’s disease

Postmenopausal women with Alzheimer’s disease exhibit dramatically reduced sensitivity to estrogen replacement therapy,which is though to be related to an estrogen receptor(ER)α/ERβratio imbalance arising from a significantly decreased level of ERs of the brain.The aim of our study was to investigate whether valproic acid(VPA)can enhance the beneficial effects of estrogen on cognitive function through restoration of ERαand ERβexpression in the brain.We removed the ovaries of female APP/PS1 mice to simulate the low estrogen levels present in postmenopausal women and then administered VPA(30 mg/kg,intraperitoneal injection,once daily),17β-estradiol(E2)(2.4μg,intraperitoneal injection,once daily),liquiritigenin(LG)(50μg/kg,intragastric infusion,once daily),VPA+E2,or VPA+LG for 4 successive weeks.Compared with treatment with a single drug,treatment with VPA+E2 or VPA+LG significantly increased the level of glycogen synthase kinase 3β,increased the expression of estrogen receptorα,reduced the expression of small ubiquitin-like modifiers,and increased the level of estrogen receptorβ.This resulted in enhanced sensitivity to estrogen therapy,reduced amyloidβaggregation,reduced abnormal phosphorylation of the tau protein,reduced neuronal loss,increased dendritic spine and postsynaptic density,and significantly alleviated memory loss and learning impairment in Alzheimer’s disease.This study was approved by the Chongqing Medical University Animal Protection and Ethics Committee,China on March 6,2013.

Neuroprotective effect of rapamycin on spinal cord injury via activation of the Wnt/β-catenin signaling pathway

The Wnt/β-catenin signaling pathway plays a crucial role in neural development, axonal guid- ance, neuropathic pain remission and neuronal survival. In this study, we initially examined the effect of rapamycin on the Wnt/β-catenin signaling pathway after spinal cord iniury, by intraperitoneally injecting spinal cord injured rats with rapamycin over 2 days. Western blot analysis and immunofluorescence staining were used to detect the expression levels of β-catenin protein, caspase-3 protein and brain-derived neurotrophic factor protein, components of the Wnt/β-catenin signaling pathway. Rapamycin increased the levels of β-catenin and brain-derived neurotrophic factor in the injured spinal cord, improved the pathological morphology at the injury site, reduced the loss of motor neurons, and promoted motor functional recovery in rats after spinal cord injury. Our experimental fndings suggest that the neuroprotective effect of rapamycin intervention is mediated through activation of the Wnt/β-catenin signaling pathway after spinal cord injury.

DNA vaccines targeting amyloid-βoligomer ameliorate cognitive deficits of aged APP/PS1/tau triple-transgenic mouse models of Alzheimer’s disease

The amyloid-β(Aβ)oligomer,rather than the Aβmonomer,is considered to be the primary initiator of Alzheimer’s disease.It was hypothesized that p(Aβ3-10)10-MT,the recombinant Aβ3-10 gene vaccine of the Aβoligomer has the potential to treat Alzheimer’s disease.In this study,we intramuscularly injected the p(Aβ3-10)10-MT vaccine into the left hindlimb of APP/PS1/tau triple-transgenic mice,which are a model for Alzheimer’s disease.Our results showed that the p(Aβ3-10)10-MT vaccine effectively reduced Aβoligomer levels and plaque deposition in the cerebral cortex and hippocampus,decreased the levels tau protein variants,reduced synaptic loss,protected synaptic function,reduced neuron loss,and ameliorated memory impairment without causing any cerebral hemorrhaging.Therefore,this novel DNA vaccine,which is safe and highly effective in mouse models of Alzheimer’s disease,holds a lot of promise for the treatment of Alzheimer’s disease in humans.

LW-AFC,a new formula derived from Liuwei Dihuang decoction,ameliorates behavioral and pathological deterioration via modulating the neuroendocrine-immune abnormalities in PrP-hAβPPswe/PS1^(ΔE9) transgenic mice

OBJECTIVE To investigate the effect of LW-AFC,a new formula of the main active components extracted fromLiuwei Dihuang decoction,on treatment of Alzheimer disease(AD) in mouse models.METHODS After treatment LW-AFC,mice were cognitively evaluated in behavioral experiments.Neuron loss,amyloid-β(Αβ) deposition,and Αβ level were analyzed using Nissl staining,immunofluorescence,and an Alpha LISA assay,respectively.Multiplex bead analysis,a radioimmunoassay,immunochemiluminometry,and an ELISA were used to measure cytokine and hormone levels.Lymphocyte subsets were detected using flow cytometry.RESULTS LW-AFC ameliorated the cognitive impairment observed in APP/PS1 mice,including the impairment of object recognition memory,spatial learning and memory,and active and passive avoidance.In addition,LW-AFC alleviated the neuron loss in the hippocampus,suppressed Αβ deposition in the brain,and reduced the concentration of Aβ1-42 in the hippocampus and plasma of APP/PS1 mice.LW-AFC treatment also significantly decreased the secretion of corticotropin-releasing hormone and gonadotropin-releasing hormone in the hypothalamus,and adrenocorticotropic hormone,luteinizing hormone,and follicle-stimulating hormone in the pituitary.Moreover,LW-AFC increased CD8+CD28+T cells,and reduced CD4^+CD25^+Foxp3^+T cells in the spleen lymphocytes,down-regulated interleukin(IL)-1β,IL-2,IL-6,IL-23,granulocyte-macrophage colony stimulating factor,and tumor necrosis factor-α and-β,and up-regulated IL-4 and granulocyte colony stimulating factor in the plasma of APP/PS1 mice.CONCLUSION LW-AFC ameliorated the behavioral and pathological deterioration of APP/PS1 transgenic micevia the restoration of the NIM network to a greater extent than either memantineor donepezil,which supports the use of LW-AFC as a potential agent for AD therapy.

Cinnamon Attenuates Cognitive Dysfunction,Hippocampal Oxidative Stress and Neurodegeneration Following Status Epilepticus in Young Male Rats

The present study explores the neuroprotective effects of the natural food product Cinnamomum cassia or Cinnamon(CIN)on lithium pilocarpine(Li-Pc)induced SE in experimental rats to look into a possibility of it being used as antiepileptic drug.Recent studies have shown significant potential of pharmacological,prophylactic or therapeutic use of CIN in many beneficial activities in the body.The animals received CIN pre-treatment before induction of SE.Besides the severity of the seizures,other parameters like cognitive behavioral dysfunction,hippocampal oxidative stress and histological abnormalities in the hippocampus of animals induced with SE by lithium(Li)in 3 mEq/ml/kg dose,i.p.followed 20 h later by pilocarpine(Pc)in 20 mg/ml/kg dose,s.c.CIN was administered intraperitoneally at the doses of 25 and 50 mg/mL/kg,30 minutes before Pc injection.Mortality(if any)within 24 hours was also recorded.Ethical approval was obtained from the Ethics Committee Review Board of the College of Pharmacy of King Saud University,Riyadh,Saudi Arabia.Treatment with CIN significantly ameliorated the frequency and severity of epileptic seizures in a dose-dependent manner.The cognitive dysfunctions were improved,hippocampal oxidative stress was ameliorated and neuronal cell loss in the hippocampus were also attenuated significantly and dose-dependently by CIN.Possible therapeutic application of CIN as an antiepileptic and as an antioxidant for the treatment of SE has a great potential and warrants further studies.

Selective loss of basal forebrain cholinergic neurons in APP_(770) transgenic mice

To determine whether cholinergic neurons in the basal nucleus magnocellularis (NBM) and the medial septum are affected in transgenic mice overexpressing human amyloid precursor protein 770 (APP 770 ) Methods Eight age groups, from 3 months old to 10 months old, of either heterozygous transgenic or non transgenic mice were used for choline acetyltransferase (ChAT) staining using immunohistochemistry The number of ChAT positive neurons was counted on the MCID Image Analysis System Neurons in the cerebral cortex and area CA1 of hippocampus were also stained with cresyl violet and counted using optical dissector technique Results There is no change in the number of forebrain cholinergic neurons in the transgenic mice up to 9 months of age A loss of these cholinergic neurons starts in 9 months old transgenic mice, with a further decrease in the number of NBM and medial septum neurons in 10 month old transgenic mice On the other hand, the number of neurons in the cerebral cortex and hippocampal area CA1 remained unchanged Conclusion These results demonstrate a selective loss of basal forebrain cholinergic neurons in APP 770 transgenic mice

Shenqi Xingnao Granules ameliorates cognitive impairments and Alzheimer’s disease-like pathologies in APP/PS1 mouse model

Objective:Alzheimer’s disease(AD)is along with cognitive decline due to amyloid-β(Aβ)plaques,tau hyperphospho rylation,and neuron loss.Shenqi Xingnao Granules(SQXN),a traditional Chinese medicine,significantly ameliorated the cognitive function and daily living abilities of patients with AD.However,till date,no study has investigated the mechanism of action of SQXN on AD.The present study aimed to verify the effects of SQXN treatment on cognitive impairments and AD-like pathologies in APP/PS1 mice.Methods:Four-month-old APP/PS1 transgenic(Tg)mice were randomly divided into a model group and SQXN-treated(3.5,7,14 g/kg per day)groups.Learning-memory abilities were determined by Morris water maze and object recognition test.All mice were sacrificed and the brain samples were collected after 75 d.The soluble Aβcontents were detected by Elisa kit;The levels of expression of NeuN,APP,phosphorylated tau and related protein were measured by Western blotting;The inflammation factors were detected by the proinflammatory panel kit.Results:Four-month-old APP/PS1 mice were administered SQXN by oral gavage for 2.5 months.Using the Morris water maze tests and Novel object recognition,we found that SQXN restored behavioral deficits in the experimental group of Tg mice when compared with the controls.SQXN also inhibited neuronal loss(NeuN marker).SQXN treatment decreased soluble Aβ42 through inhibiting the expression of sAPPβand BACE-1 without regulating full-length amyloid precursor protein(FL APP).Insulin degrading enzyme(IDE),the Aβdegrading enzyme,were increased by SQXN.In addition,SQXN reduced hyperphosphorylated tau protein levels and prevented excessive activation of p-GSK-3βin the brain of APP/PS1 mice.Compared with APP/PS1 transgenic negative mice,IFN-γ,IL-1β,IL-2,IL-4,IL-5,IL-6,IL-12 p70,KC/GRO and TNF-αwere not obviously changed in the brain of 6.5-month-old APP/PS1 transgenic(Tg)mice.However,SQXN could inhibited the expression of IL-2.Conclusion:These results demonstrate that SQXN ameliorates the cognitive impairments in APP/PS1 mice.The possible mechanisms involve its inhibition of neuronal loss,soluble Aβdeposition,tau hyperphosphorylation and inflammation.

Evidence of neurodegeneration in autism spectrum disorder

Autism spectrum disorder(ASD)is a neurological disorder in which a significant number of children experience a developmental regression characterized by a loss of previously-acquired skills and abilities.Loss of neurological function in ASD,as observed in affected children who have regressed,can be explained as neurodegeneration.Although there is research evidence of neurodegeneration or progressive encephalopathy in ASD,the issue of neurodegeneration in ASD is still under debate.Evidence of neurodegeneration in the brain in ASD includes:(1)neuronal cell loss,(2)activated microglia and astrocytes,(3)proinflammatory cytokines,(4)oxidative stress,and(5)elevated 8-oxo-guanosine levels.The evidence from this review suggests that neurodegeneration underlies the loss of neurological function in children with ASD who have experienced regression and loss of previously acquired skills and abilities,and that research into treatments to address the issue of neurodegeneration in ASD are warranted.