Pathological and therapeutic effects of extracellular vesicles in neurological and neurodegenerative diseases

Extracellular vesicles are released by all cell types and contain proteins,microRNAs,mRNAs,and other bioactive molecules.Extracellular vesicles play an important role in intercellular communication and in the modulation of the immune system and neuroinflammation.The cargo of extra cellular vesicles(e.g.,proteins and microRNAs)is altered in pathological situations.Extracellular vesicles contribute to the pathogenesis of many pathologies associated with sustained inflammation and neuroinflammation,including cance r,diabetes,hype rammonemia and hepatic encephalopathy,and other neurological and neurodegenerative diseases.Extracellular vesicles may cross the blood-brain barrier and transfer pathological signals from the periphery to the brain.This contributes to inducing neuroinflammation and cognitive and motor impairment in hyperammonemia and hepatic encephalopathy and in neurodegenerative diseases.The mechanisms involved are beginning to be unde rstood.For example,increased tumor necrosis factor a in extracellular vesicles from plasma of hype rammonemic rats induces neuroinflammation and motor impairment when injected into normal rats.Identifying the mechanisms by which extracellular vesicles contribute to the pathogenesis of these diseases will help to develop new treatments and diagnostic tools for their easy and early detection.In contrast,extra cellular vesicles from mesenchymal stem cells have therapeutic utility in many of the above pathologies,by reducing inflammation and neuroinflammation and improving cognitive and motor function.These extra cellular vesicles recapitulate the beneficial effects of mesenchymal stem cells and have advantages as therapeutic tools:they are less immunoge nic,may not diffe rentiate to malignant cells,cross the blood-brain barrier,and may reach more easily target organs.Extracellular vesicles from mesenchymal stem cells have beneficial effects in models of ischemic brain injury,Alzheimer's and Parkinson's diseases,hyperammonemia,and hepatic encephalopathy.Extracellular vesicles from mesenchymal stem cells modulate the immune system,promoting the shift from a pro-inflammato ry to an anti-inflammatory state.For example,extracellular vesicles from mesenchymal stem cells modulate the Th17/Treg balance,promoting the anti-inflammatory Treg.Extracellular vesicles from mesenchymal stem cells may also act directly in the brain to modulate microglia activation,promoting a shift from a pro-inflammatory to an anti-inflammatory state.This reduces neuroinflammation and improves cognitive and motor function.Two main components of extracellular vesicles from mesenchymal stem cells which contribute to these beneficial effects are transforming growth factor-βand miR-124.Identifying the mechanisms by which extracellular vesicles from mesenchymal stem cells induce the beneficial effects and the main molecules(e.g.,proteins and mRNAs)involved may help to improve their therapeutic utility.The aims of this review are to summarize the knowledge of the pathological effects of extracellular vesicles in different pathologies,the therapeutic potential of extra cellular vesicles from mesenchymal stem cells to recover cognitive and motor function and the molecular mechanisms for these beneficial effects on neurological function.

Dopamine in the prefrontal cortex plays multiple roles in the executive function of patients with Parkinson's disease

Parkinson’s disease can affect not only motor functions but also cognitive abilities,leading to cognitive impairment.One common issue in Parkinson’s disease with cognitive dysfunction is the difficulty in executive functioning.Executive functions help us plan,organize,and control our actions based on our goals.The brain area responsible for executive functions is called the prefrontal co rtex.It acts as the command center for the brain,especially when it comes to regulating executive functions.The role of the prefrontal cortex in cognitive processes is influenced by a chemical messenger called dopamine.However,little is known about how dopamine affects the cognitive functions of patients with Parkinson’s disease.In this article,the authors review the latest research on this topic.They start by looking at how the dopaminergic syste m,is alte red in Parkinson’s disease with executive dysfunction.Then,they explore how these changes in dopamine impact the synaptic structure,electrical activity,and connection components of the prefrontal cortex.The authors also summarize the relationship between Parkinson’s disease and dopamine-related cognitive issues.This information may offer valuable insights and directions for further research and improvement in the clinical treatment of cognitive impairment in Parkinson’s disease.

Regulation of specific abnormal calcium signals in the hippocampal CA1 and primary cortex M1 alleviates the progression of temporal lobe epilepsy

Temporal lobe epilepsy is a multifactorial neurological dysfunction syndrome that is refractory,resistant to antiepileptic drugs,and has a high recurrence rate.The pathogenesis of temporal lobe epilepsy is complex and is not fully understood.Intracellular calcium dynamics have been implicated in temporal lobe epilepsy.However,the effect of fluctuating calcium activity in CA1 pyramidal neurons on temporal lobe epilepsy is unknown,and no longitudinal studies have investigated calcium activity in pyramidal neurons in the hippocampal CA1 and primary motor cortex M1 of freely moving mice.In this study,we used a multichannel fiber photometry system to continuously record calcium signals in CA1 and M1 during the temporal lobe epilepsy process.We found that calcium signals varied according to the grade of temporal lobe epilepsy episodes.In particular,cortical spreading depression,which has recently been frequently used to represent the continuously and substantially increased calcium signals,was found to correspond to complex and severe behavioral characteristics of temporal lobe epilepsy ranging from gradeⅡto gradeⅤ.However,vigorous calcium oscillations and highly synchronized calcium signals in CA1 and M1 were strongly related to convulsive motor seizures.Chemogenetic inhibition of pyramidal neurons in CA1 significantly attenuated the amplitudes of the calcium signals corresponding to gradeⅠepisodes.In addition,the latency of cortical spreading depression was prolonged,and the above-mentioned abnormal calcium signals in CA1 and M1 were also significantly reduced.Intriguingly,it was possible to rescue the altered intracellular calcium dynamics.Via simultaneous analysis of calcium signals and epileptic behaviors,we found that the progression of temporal lobe epilepsy was alleviated when specific calcium signals were reduced,and that the end-point behaviors of temporal lobe epilepsy were improved.Our results indicate that the calcium dynamic between CA1 and M1 may reflect specific epileptic behaviors corresponding to different grades.Furthermore,the selective regulation of abnormal calcium signals in CA1 pyramidal neurons appears to effectively alleviate temporal lobe epilepsy,thereby providing a potential molecular mechanism for a new temporal lobe epilepsy diagnosis and treatment strategy.

Promotion of structural plasticity in area V2 of visual cortex prevents against object recognition memory deficits in aging and Alzheimer's disease rodents

Memory deficit,which is often associated with aging and many psychiatric,neurological,and neurodegenerative diseases,has been a challenging issue for treatment.Up till now,all potential drug candidates have failed to produce satisfa ctory effects.Therefore,in the search for a solution,we found that a treatment with the gene corresponding to the RGS14414protein in visual area V2,a brain area connected with brain circuits of the ventral stream and the medial temporal lobe,which is crucial for object recognition memory(ORM),can induce enhancement of ORM.In this study,we demonstrated that the same treatment with RGS14414in visual area V2,which is relatively unaffected in neurodegenerative diseases such as Alzheimer s disease,produced longlasting enhancement of ORM in young animals and prevent ORM deficits in rodent models of aging and Alzheimer’s disease.Furthermore,we found that the prevention of memory deficits was mediated through the upregulation of neuronal arbo rization and spine density,as well as an increase in brain-derived neurotrophic factor(BDNF).A knockdown of BDNF gene in RGS14414-treated aging rats and Alzheimer s disease model mice caused complete loss in the upregulation of neuronal structural plasticity and in the prevention of ORM deficits.These findings suggest that BDNF-mediated neuronal structural plasticity in area V2 is crucial in the prevention of memory deficits in RGS14414-treated rodent models of aging and Alzheimer’s disease.Therefore,our findings of RGS14414gene-mediated activation of neuronal circuits in visual area V2 have therapeutic relevance in the treatment of memory deficits.

FOXO1 reshapes neutrophils to aggravate acute brain damage and promote late depression after traumatic brain injury

Background:Neutrophils are traditionally viewed as first responders but have a short onset of action in response to traumatic brain injury(TBI).However,the heterogeneity,multifunctionality,and time-dependent modulation of brain damage and outcome mediated by neutrophils after TBI remain poorly understood.Methods:Using the combined single-cell transcriptomics,metabolomics,and proteomics analysis from TBI patients and the TBI mouse model,we investigate a novel neutrophil phenotype and its associated effects on TBI outcome by neurological deficit scoring and behavioral tests.We also characterized the underlying mechanisms both invitro and invivo through molecular simulations,signaling detections,gene expression regulation assessments[including dual-luciferase reporter and chromatin immunoprecipitation(ChIP)assays],primary cultures or co-cultures of neutrophils and oligodendrocytes,intracellular iron,and lipid hydroperoxide concentration measurements,as well as forkhead box protein O1(FOXO1)conditional knockout mice.Results:We identified that high expression of the FOXO1 protein was induced in neutrophils after TBI both in TBI patients and the TBI mouse model.Infiltration of these FOXO1high neutrophils in the brain was detected not only in the acute phase but also in the chronic phase post-TBI,aggravating acute brain inflammatory damage and promoting late TBI-induced depression.In the acute stage,FOXO1 upregulated cytoplasmic Versican(VCAN)to interact with the apoptosis regulator B-cell lymphoma-2(BCL-2)-associated X protein(BAX),suppressing the mitochondrial translocation of BAX,which mediated the antiapoptotic effect companied with enhancing interleukin-6(IL-6)production of FOXO1high neutrophils.In the chronic stage,the“FOXO1-transferrin receptor(TFRC)”mechanism contributes to FOXO1high neutrophil ferroptosis,disturbing the iron homeostasis of oligodendrocytes and inducing a reduction in myelin basic protein,which contributes to the progression of late depression after TBI.Conclusions:FOXO1high neutrophils represent a novel neutrophil phenotype that emerges in response to acute and chronic TBI,which provides insight into the heterogeneity,reprogramming activity,and versatility of neutrophils in TBI.

Mechanisms of neuroplasticity and brain degeneration: strategies for protection during the aging process

Aging is a dynamic and progressive process that begins at conception and continues until death.This process leads to a decrease in homeostasis and morphological,biochemical and psychological changes,increasing the individual’s vulnerability to various diseases.The growth in the number of aging populations has increased the prevalence of chronic degenerative diseases,impairment of the central nervous system and dementias,such as Alzheimer’s disease,whose main risk factor is age,leading to an increase of the number of individuals who need daily support for life activities.Some theories about aging suggest it is caused by an increase of cellular senescence and reactive oxygen species,which leads to inflammation,oxidation,cell membrane damage and consequently neuronal death.Also,mitochondrial mutations,which are generated throughout the aging process,can lead to changes in energy production,deficiencies in electron transport and apoptosis induction that can result in decreased function.Additionally,increasing cellular senescence and the release of proinflammatory cytokines can cause irreversible damage to neuronal cells.Recent reports point to the importance of changing lifestyle by increasing physical exercise,improving nutrition and environmental enrichment to activate neuroprotective defense mechanisms.Therefore,this review aims to address the latest information about the different mechanisms related to neuroplasticity and neuronal death and to provide strategies that can improve neuroprotection and decrease the neurodegeneration caused by aging and environmental stressors.

Neurotoxicity of the pesticide rotenone on neuronal polarization: a mechanistic approach

Neurons are the most extensive and polarized cells that display a unique single long axon and multiple dendrites, which are compartments exhibiting structural and functional differences. Polarity occurs early in neuronal development and it is maintained by complex subcellular mechanisms throughout cell life. A well-defined and controlled spatio-temporal program of cellular and molecular events strictly regulates the formation of the axon and dendrites from a non-polarized cell. This event is critical for an adequate neuronal wiring and therefore for the normal functioning of the nervous system. Neuronal polarity is very sensitive to the harmful effects of different factors present in the environment. In this regard, rotenone is a crystalline, colorless and odorless isoflavone used as insecticide, piscicide and broad spectrum pesticide commonly used earlier in agriculture. In the present review we will summarize the toxicity mechanism caused by this pesticide in different neuronal cell types, focusing on a particular biological mechanism whereby rotenone could impair neuronal polarization in cultured hippocampal neurons. Recent advances suggest that the inhibition of axonogenesis produced by rotenone could be related with its effect on microtubule dynamics, the actin cytoskeleton and their regulatory pathways, particularly affecting the small RhoGTPase RhoA. Unveiling the mechanism by which rotenone produces neurotoxicity will be instrumental to understand the cellular mechanisms involved in neurodegenerative diseases influenced by this environmental pollutant, which may lead to research focused on the design of new therapeutic strategies.

Transcranial pulse current stimulation improves the locomotor function in a rat model of stroke

Previous studies have shown that transcranial pulse current stimulation(tPCS) can increase cerebral neural plasticity and improve patients' locomotor function.However, the precise mechanisms underlying this effect remain unclear.In the present study, rat models of stroke established by occlusion of the right cerebral middle artery were subjected to tPCS, 20 minutes per day for 7 successive days.tPCS significantly reduced the Bederson score, increased the foot print area of the affected limbs, and reduced the standing time of affected limbs of rats with stroke compared with that before intervention.Immunofluorescence staining and western blot assay revealed that tPCS significantly increased the expression of microtubule-associated protein-2 and growth-associated protein-43 around the ischemic penumbra.This finding suggests that tPCS can improve the locomotor function of rats with stroke by regulating the expression of microtubule-associated protein-2 and growth-associated protein-43 around the ischemic penumbra.These findings may provide a new method for the clinical treatment of poststroke motor dysfunction and a theoretical basis for clinical application of tPCS.The study was approved by the Animal Use and Management Committee of Shanghai University of Traditional Chinese Medicine of China(approval No.PZSHUTCM190315003) on February 22, 2019.

Establishment of model of visceral pain due to colorectal distension and its behavioral assessment in rats

AIM： To establish a visceral pain model via colorectal distension （CRD） and to evaluate the efficiency of behavioral responses of CRD by measuring the score of abdominal withdrawal reflex （AWR） in rats. METHODS： Thirty-eight male SD rats weighing 180-240g were used to establish the visceral pain model. The rat was inserted intra-anally with a 7 cm long flexible latex balloon under ether anesthesia, and colorectal distensions by inflating the balloon with air were made 30 min after recovering from the anesthesia. Five AWR scores （AWR0 to AWR4） were used to assess the intensity of noxious visceral stimuli. It was regarded as the threshold of the minimal pressure （kPa）. For abdominal flatting was induced by colorectal distension. RESULTS： A vigorous AWR to distension of the descending colon and rectum was found in 100% of the awake rats tested. The higher the pressure of distension, the higher the score of AWR. The distension pressures of 0, 2.00, 3.33, 5.33 and 8.00 kPa produced different AWR scores （P〈0.05）. The pain threshold of AWR was constant for up to 80 min after the initial windup （first 1-3 distensions）, the mean threshold was 3.69±0.35 kPa. Systemic administration of morphine sulfate elevated the threshold of visceral pain in a dosedependent and naloxone reversible manner. CONCLUSION： Scoring the AWR during colorectal distensions can assess the intensity of noxious visceral stimulus. Flatting of abdomen （AWR 3） to CRD as the visceral pain threshold is clear, constant and reliable. This pain model and its behavioral assessment are good for research on visceral pain and analgesics.

Serum levels of angiotensin converting enzyme as a biomarker of liver fibrosis

The renin angiotensin system(RAS) is classically conceived as a circulating hormonal system involved in blood pressure control and hydroelectrolyte balance. The discovery that RAS components are locally expressed in a wide range of organs and tissues,including the liver,pointed to a role for this system in the pathogenesis of several conditions including hepatic fibrosis and cirrhosis. It has been widely reported that the classical RAS axis composed by the angiotensin converting enzyme(ACE)-angiotensin(Ang) Ⅱ-Ang type 1(AT1) receptor mediates pro-inflammatory,pro-thrombotic,and pro-fibrotic processes. On the other hand,the alternative axis comprising ACE2-Ang-(1-7)-Mas receptor seems to play a protective role by frequently opposing Ang Ⅱ action. Chronic hepatitis B(CHB) is one of the leading causes of liver fibrosis,accounting for the death of nearly one million people worldwide. Liver fibrosis is a key factor to determine therapeutic interventions for patients with CHB. However,the establishment of non-invasive and accurate methods to detect reversible stages of liver fibrosis is still a challenge. In an elegant study published in the 36 th issue of the World Journal of Gastroenterology,Noguchi et al showed the predictive value of serum ACE levels in detecting not only advanced stages of liver fibrosis but also initial and intermediate fibrotic stages. The serum levels of ACE might represent an accurate,non-invasive,widely available,and easy method to evaluate fibrosis related to CHB. Moreover,therapies involving the inhibition of the classical RAS axis components might be promising in the control of CHB-related liver fibrosis.

Contribution of altered signal transduction associated to glutamate receptors in brain to the neurological alterations of hepatic encephalopathy

Patients with liver disease may present hepatic enceph- alopathy (HE), a complex neuropsychiatric syndrome covering a wide range of neurological alterations, including cognitive and motor disturbances. HE reduces the quality of life of the patients and is associated with poor prognosis. In the worse cases HE may lead to coma or death. The mechanisms leading to HE which are not well known are being studied using animal models. The neurological alterations in HE are a consequence of impaired cerebral function mainly due to alterations in neurotransmission. We review here some studies indicating that alterations in neurotransmission associated to different types of glutamate receptors are responsible for some of the cognitive and motor alterations present in HE. These studies show that the function of the signal transduction pathway glutamate-nitric oxide-cGMP associated to the NMDA type of glutamate receptors is impaired in brain in vivo in HE animal models as well as in brain of patients died of HE. Activation of NMDA receptors in brain activates this pathway and increases cGMP. In animal models of HE this increase in cGMP induced by activation of NMDA receptors is reduced, which is responsible for the impairment in learning ability in these animal models. Increasing cGMP by pharmacological means restores learning ability in rats with HE and may be a new therapeutic approach to improve cognitive function in patients with HE. However, it is necessary to previously assess the possible secondary effects.Patients with HE may present psychomotor slowing, hypokinesia and bradykinesia. Animal models of HE also show hypolocomotion. It has been shown in rats with HE that hypolocomotion is due to excessive activation of metabotropic glutamate receptors (mGluRs) in substantia nigra pars reticulata. Blocking mGluR1 in this brain area normalizes motor activity in the rats, suggesting that a similar treatment for patients with HE could be useful to treat psychomotor slowing and hypokinesia. However, the possible secondary effects of mGluR1 antagonists should be previously evaluated. These studies are setting the basis for designing therapeutic procedures to specifically treat the individual neurological alterations in patients with HE.

Neurogenesis in the hippocampus of adult humans: controversy “fixed” at last

The presence of adult neurogenesis in the mammalian brain has been a theme of intense controversy for a long time since the original report by Altman and Das (1965). The scientific community, for about 30 years, has difficulties to accept that progenitor cells give rise to new neurons in some specific regions of the mammalian adult brain, the neurogenic niches (Kuhn et al., 1996;Doetsch et al., 1997, 1999).

New insights into the immunologic role of oligodendrocyte lineage cells in demyelination diseases

Oligodendrocyte lineage cells(OL-lineage cells)are a cell population that are crucial for mammalian central nervous system(CNS)myelination.OL-lineage cells go through developmental stages,initially differentiating into oligodendrocyte precursor cells(OPCs),before becoming immature oligodendrocytes,then mature oligodendrocytes(OLs).While the main function of cell lineage is in myelin formation,and increasing number of studies have turned to explore the immunological characteristics of these cells.Initially,these studies focused on discovering how OPCs and OLs are affected by the immune system,and then,how these immunological changes influence the myelination process.However,recent studies have uncovered another feature of OL-lineage cells in our immune systems.It would appear that OL-lineage cells also express immunological factors such as cytokines and chemokines in response to immune activation,and the expression of these factors changes under various pathologic conditions.Evidence suggests that OL-lineage cells actually modulate immune functions.Indeed,OL-lineage cells appear to play both"victim"and"agent"in the CNS which raises a number of questions.Here,we summarize immunologic changes in OL-lineage cells and their effects,as well as consider OL-lineage cell changes which influence immune cells under pathological conditions.We also describe some of the underlying mechanisms of these changes and their effects.Finally,we describe several studies which use OL-lineage cells as immunotherapeutic targets for demyelination diseases.

Possible role of glial cell line-derived neurotrophic factor for predicting cognitive impairment in Parkinson’s disease:a case-control study

Glial cell line-derived neurotrophic factor(GDNF)plays an important role in the protection of dopaminergic neurons,but there are few reports of the relationship between GDNF and its precursors(α-pro-GDNF andβ-pro-GDNF)and cognitive impairment in Parkinson’s disease.This study aimed to investigate the relationship between the serum levels of GDNF and its precursors and cognitive impairment in Parkinson’s disease,and to assess their potential as a diagnostic marker.Fifty-three primary outpatients and hospitalized patients with Parkinson’s disease(23 men and 30 women)with an average age of 66.58 years were enrolled from the Affiliated Hospital of Xuzhou Medical University of China in this case-control study.The patients were divided into the Parkinson’s disease with cognitive impairment group(n=27)and the Parkinson’s disease with normal cognitive function group(n=26)based on their Mini-Mental State Examination,Montreal Cognitive Assessment,and Clinical Dementia Rating scores.In addition,26 age-and sex-matched healthy subjects were included as the healthy control group.Results demonstrated that serum GDNF levels were significantly higher in the Parkinson’s disease with normal cognitive function group than in the other two groups.There were no significant differences in GDNF precursor levels among the three groups.Correlation analysis revealed that serum GDNF levels,GDNF/α-pro-GDNF ratios,and GDNF/β-pro-GDNF ratios were moderately or highly correlated with the Mini-Mental State Examination,Montreal Cognitive Assessment,and Clinical Dementia Rating scores.To explore the risk factors for cognitive impairment in patients with Parkinson’s disease,logistic regression analysis and stepwise linear regression analysis were performed.Both GDNF levels and Hoehn-Yahr stage were risk factors for cognitive impairment in Parkinson’s disease,and were the common influencing factors for cognitive scale scores.Neitherα-pro-GDNF norβ-pro-GDNF was risk factors for cognitive impairment in Parkinson’s disease.A receiver operating characteristic curve of GDNF was generated to predict cognitive function in Parkinson’s disease(area under the curve=0.859).This result indicates that the possibility that serum GDNF can correctly distinguish whether patients with Parkinson’s disease have cognitive impairment is 0.859.Together,these results suggest that serum GDNF may be an effective diagnostic marker for cognitive impairment in Parkinson’s disease.However,α-pro-GDNF andβ-pro-GDNF are not useful for predicting cognitive impairment in this disease.This study was approved by Ethics Committee of the Affiliated Hospital of Xuzhou Medical University,China(approval No.XYFY2017-KL047-01)on November 30,2017.

Potential use of lactate for the treatment of neonatal hypoxic-ischemic encephalopathy

Function of lactate:Lactate is a three-carbon molecule produced by glycolytic metabolism that is a metabolic waste product with no known use in clinical therapy.Conversely,it is a metabolite that the body should quickly guarantee the clearance.However,lactate is now recognized as a potential energy substrate,as well as an anti-inflammatory signaling molecule.These actions were first reported in adult animal models with a brain injury,including a traumatic brain injury and cerebral ischemia,and have also been observed in human patients(Magistretti and Allaman,2018).Recently,however,two studies by independent research groups described promising n euro p rotective results from the use of lactate in animal models with neonatal hypoxia-ischemia(Roumes et al.,2021;Tassinari et al.,2020).

Effects of gamma-aminobutyric acid A-receptor antagonist on sleep-wakefulness cycles following lesion to the ventrolateral preoptic area in rats

BACKGROUND： Neurons expressing gamma-aminobutyric acid （GABA） play an important role in the regulation of wakefulness to sleep, as well as the maintenance of sleep. However, the role of GABAergic neurons in the tuberomammillary nucleus （TMn）, with regard to the sleep-wakefulness cycle, is poorly understood. OBJECTIVE： To investigate the effects of GABAergic neurons in the TMn on the sleep-wakefulness cycle. DESIGN, TIME AND SETTING： Randomized controlled study, performed at the Laboratory of Neurobiology, Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Lanzhou University from July 2007 to February 2008. MATERIALS： Fifteen healthy, adult, male, Sprague Dawley rats were randomly divided into three groups（n = 5）： control, ventrolateral preoptic area （VLPO） lesion, and VLPO lesion plus GABAA receptor antagonist-treated. Ibotenic acid and bicuculline were provided by Sigma （St. Louis, USA）. METHODS： Four electroencephalogram screw electrodes were implanted into the skull at a frontal region （two） and parietal bones （two） on each side. Three flexible electromyogram wire electrodes were placed into the nuchal muscles. On day 8, a fine glass micropipette （10–20 mm tip diameter） containing ibotenic acid solution （10 nmol/L） was injected into the VLPO in both hemispheres following bone wax removal under anesthesia. One week after the second surgery, sleep-wakefulness states were recorded in rats from the VLPO lesion group. On day 10 after VLPO lesion, bicuculline （10 nmol/L）, a GABAA-receptor antagonist, was microinjected into the TMn and sleep-wakefulness states were recorded for 24 hours. MAIN OUTCOME MEASURES： Duration of the sleep-wakefulness cycle in each group using a Data acquisition unit （Micro1 401 mk2） and Data collection software （Spike Ⅱ）. RESULTS： VLPO lesion induced an increased duration of wakefulness （W, 13.17%） and light slow-wave sleep （SWS1, 28.9%）, respectively. Deep slow-wave sleep （SWS2, 43.74%） and paradoxical sleep （PS, 44.07%） were respectively decreased for 24 hours at day 9 post-lesion, compared with pre-lesion （P 〈 0.01）. Microinjection of bicuculline into the TMn following VLPO lesion at 10：00 am on the 10th day elicited a wake state for 40–55 minutes, with a latency of 15 minutes. However, 24-hour sleep-wake states demonstrated that the ratio of W and SWS1 were increased by 12.61% （P 〈 0.01） and 50.97% （P 〈 0.01）, respectively. In addition, SWS2 and PS were decreased by 68.08% （P 〈 0.01） and 39.92% （P 〈 0.05）, respectively, compared with prior to VLPO lesion. CONCLUSION： The evidence of decreased deep slow-wave sleep, which was induced by VLPO lesion, suggested that GABAergic neurons in the VLPO play an important role in maintaining sleep. Bicuculline microinjection into the TMn, following VLPO lesion, elicited wakefulness and sleep depression for 50 minutes, with contrary increased light slow-wave sleep for 24 hours, which suggested that GABAergic neurons in the TMn play a role in sleep drive （sleepiness） via local circuit to directly inhibit histaminergic neurons.

Dynamic changes of glial fibrillary acidic protein and nestin in the hippocampus of adult rat brain following ischemic vascular dementia

Vascular dementia produced by permanent ligation of bilateral common carotid arteries involves progressive deterioration of intellectual and cognitive function in rats, which are closely associated with the hippocampus. This study used immunohistochemical analysis to detect the expression of glial fibrillary acidic protein and nestin in the hippocampus in a vascular dementia model. The results revealed that both glial fibrillary acidic protein and nestin expression were increased 1 day after permanent ligation of the bilateral common carotid arteries, compared with a sham-operated group. The expression of glial fibrillary acidic protein peaked at 7 days post-surgery. The expression of nestin was a little weaker than that of glial fibrillary acidic protein, and peaked at 14 days （P 〈 0.01）. The expression of both proteins slightly decreased at 21 and 28 days, accompanied by recovery of cerebral blood flow. In conclusion, this study demonstrated that glial fibrillary acidic protein and nestin exhibited dynamic expression in the rat hippocampus after permanent ligation of bilateral common carotid arteries. This finding suggests that dynamic alterations in protein expression play an important role in the pathogenesis of vascular dementia.

Anodal transcranial direct current stimulation alleviates cognitive impairment in an APP/PS1 model of Alzheimer’s disease in the preclinical stage

Anodal transcranial direct current stimulation(AtDCS)has been shown to alleviate cognitive impairment in an APP/PS1 model of Alzheimer’s disease in the preclinical stage.However,this enhancement was only observed immediately after AtDCS,and the long-term effect of AtDCS remains unknown.In this study,we treated 26-week-old mouse models of Alzheimer’s disease in the preclinical stage with 10 AtDCS sessions or sham stimulation.The Morris water maze,novel object recognition task,and novel object location test were implemented to evaluate spatial learning memory and recognition memory of mice.Western blotting was used to detect the relevant protein content.Morphological changes were observed using immunohistochemistry and immunofluorescence staining.Six weeks after treatment,the mice subjected to AtDCS sessions had a shorter escape latency,a shorter path length,more platform area crossings,and spent more time in the target quadrant than sham-stimulated mice.The mice subjected to AtDCS sessions also performed better in the novel object recognition and novel object location tests than sham-stimulated mice.Furthermore,AtDCS reduced the levels of amyloid-β42 and glial fibrillary acidic protein,a marker of astrocyte activation,and increased the level of neuronal marker NeuN in hippocampal tissue.These findings suggest that AtDCS can improve the spatial learning and memory abilities and pathological state of an APP/PS1 mouse model of Alzheimer’s disease in the preclinical stage,with improvements that last for at least 6 weeks.

Effect of cyclovirobuxine D on human growth-associated protein 43 and neurocan expression in ischemic brain tissue of stroke-prone renovascular hypertensive rats

BACKGROUND： Experimental data indicate that human growth-associated protein 43 mRNA expression coincides with axonal growth during nerve ganglion development; while neurocan, secreted from astrocytes, can inhibit sprouting and elongation of the axonal growth cone. OBJECTIVE： To verify regulatory effects of cyclovirobuxine D （CVB-D） extracted from Chinese box branchlet on human growth-associated protein 43 （GAP-43）, and neurocan expression in brain tissue of stroke-prone renovascular hypertensive （RHRSP） rats, at different time points after cerebral ischemia/reperfusion. DESIGN： Randomized grouping design and controlled animal study. SETTING： This study was performed at the Center of Guangdong Hospital of Traditional Chinese Medicine （a national key laboratory） from March 2003 to September 2006. MATERIALS： 100 healthy male Sprague-Dawley rats, aged 2 3 months and weighing 90-120 g, were selected for this study. CVB-D was provided by Nanjing Xiaoying Pharmaceutical Factory （Batch number： 307701）. METHODS： The initial tip of renal arteries was clamped bilaterally for 10 weeks to establish the RHRSP model. 100 RHRSP rats were randomly divided into 4 groups： naive group （n = 10）, sham surgery group （n = 10）, CVB-D group （n = 40）, and lesion group （n = 40）. Rats in the naive group did not undergo any treatment, and cervical vessels of rats in the sham surgery group were exposed, but not blocked. The right middle cerebral artery of rats in the CVB-D group and lesion group were occluded to establish cerebral ischemia. Rats in the CVB-D group were intraperitoneally injected with CVB-D （6.48 mg/kg） every day and with saline （1.5 mL/injection） twice a day. Rats in the lesion group were intraperitoneally injected with saline （2 mL/injection）. MAIN OUTCOME MEASURES： Immunohistochemistry was applied to detect GAP-43 and neurocan expression in the ischemic penumbra region of CVB-D and lesion brains at 2 hours post-cerebral ischemia and at 1, 7, 14, and 30 days post-perfusion （n = 10 at each time point）. Similarly, GAP-43 and neurocan expression was detected in the right hemisphere of naive and sham-operated animals. The results were expressed as positive cells. RESULTS： A total of 100 rats were included in the final analysis. The number of GAP-43 positive cells increased in the CVB-D group 1, 7, 14, and 30 days post-cerebral ischemia/perfusion compared to the lesion group, as indicated by a significant difference between the CVB-D and lesion group （P 〈 0.054）.01）. The number of neurocan-positive cells decreased in the CVB-D group on the first day compared to the model group; however, there was no significant difference between the two groups （P 〉 0.05）. On post-ischemia days 7, 14, and 30, the number of neurocan-positive cells in the CVB-D group was significantly less than in the lesion group （P 〈 0.05）. Both, GAP-43 and neurocan expression was not detectable in brains of naive and sham-operated animals. CONCLUSION： CVB-D treatment up-regulated GAP-43 expression and down-regulated neurocan expression in the ischemic region of RHRSP rats.

Implication of 14-3-3ζ-BDNF pathway in long-lasting memory enhancement and the rescue from memory deficits

Intact memory function is critical for carrying out daily life activities,such as managing finances,remembering to take medications,driving in familiar environments,remembering a grandchild’s birthday,and learning to use a new computer.However,memory deficits not only accompany normal aging but are also comorbid with many psychiatric,neurological,and neurodegenerative diseases.Intellectual disability,autism,attention deficit disorder,learning disability,schizophrenia,and depression all have memory deficit components,as do Alzheimer’s disease,Parkinson’s disease,Huntington’s disease,and other neurodegenerative diseases(Khan et al.,2014).Therefore,a large proportion of the human population is affected by this brain disorder.