The role of orexin in Parkinson's disease

Emerging evidence has implicated the orexin system in non-motor pathogenesis of Parkinson's disease. It has also been suggested the orexin system is involved in the modulation of motor control, further implicating the orexin system in Parkinson's disease. Parkinson's disease is the second most common neurodegenerative disease with millions of people suffering worldwide with motor and non-motor symptoms, significantly affecting their quality of life. Treatments are based solely on symptomatic management and no cure currently exists. The orexin system has the potential to be a treatment target in Parkinson's disease, particularly in the non-motor stage. In this review, the most current evidence on the orexin system in Parkinson's disease and its potential role in motor and non-motor symptoms of the disease is summarized. This review begins with a brief overview of Parkinson's disease, animal models of the disease, and the orexin system. This leads into discussion of the possible roles of orexin neurons in Parkinson's disease and levels of orexin in the cerebral spinal fluid and plasma in Parkinson's disease and animal models of the disease. The role of orexin is then discussed in relation to symptoms of the disease including motor control, sleep, cognitive impairment, psychological behaviors, and the gastrointestinal system. The neuroprotective effects of orexin are also summarized in preclinical models of the disease.

Role of the Adrenal Medulla in Hypoglycaemia-Associated Autonomic Failure-A Diabetic Perspective

Hypoglycaemia-associated autonomic failure (HAAF) is characterised by an impairment in adrenal medullary and neurogenic symptom responses following episodes of recurrent hypoglycaemia. Here, we review the status quo of research related to the regulatory mechanisms of the adrenal medulla in its response to single and recurrent hypoglycaemia in both diabetic and non-diabetic subjects with particular focus given to catecholamine synthesis, enzymatic activity, and the impact of adrenal medullary peptides. Short-term post-transcriptional modifications, particularly phosphorylation at specific residues of tyrosine hydroxylase (TH), play a key role in the regulation of catecholamine synthesis. While the effects of recurrent hypoglycaemia on catecholamine synthetic enzymes remain inconsistent, long-term changes in TH protein expression suggest species-specific responses. Adrenomedullary peptides such as neuropeptide Y (NPY), galanin, and proenkephalin exhibit altered gene and protein expression in response to hypoglycaemia, suggesting a potential role in the modulation of catecholamine secretion. Of note is NPY, since its antagonism has been shown to prevent reductions in TH protein expression. This review highlights the need for further investigation into the molecular mechanisms involved in the adrenal medullary response to hypoglycaemia. Despite advancements in our understanding of HAAF in non-diabetic rodents, a reliable diabetic rodent model of HAAF remains a challenge.

Time use and dimensions of healthy sleep: A cross-sectional study of Australian children and adults

BACKGROUND

Sleep is increasingly recognized as a multidimensional construct that occurs within the 24-hour day. Despite advances in our understanding, studies continue to consider the relationship between sleep, sedentary time and physical activity separately, and not as part of the 24-hour day.

AIMS

To determine the association between the 24-hour activity composition and dimensions of healthy sleep.

METHODS

This study examined data on 1168 children (mean age 12years; 49% female) and 1360 adults (mean age 44years; 87% female) collected as part of the Child Health CheckPoint study. Participants were asked to wear a GENEActiv monitor (Activinsights, Cambs, UK) on their nondominant wrist for eight consecutive days to measure 24-hour time-use. Compositional data analysis was used to examine the association between time use (actigraphy-derived sleep duration, sedentary time, light physical activity and moderate-vigorous physical activity) and dimensions of healthy sleep. Healthy sleep was conceptualized in terms of continuity/efficiency, timing, alertness/sleepiness, satisfaction/quality, and regularity. Time allocations were also examined.

RESULTS

The 24-hour activity composition was significantly associated with all objectively measured and self-report dimensions of healthy sleep in both children and adults. Allocating more time to sleep was associated with earlier sleep onsets, later sleep offsets, less efficient and more consistent sleep patterns for both children and adults.

CONCLUSION

This study highlights the integral relationship between daily activities and dimensions of sleep. Considering sleep within the 24-hour day activity composition framework may help inform lifestyle decisions to improve sleep health.

The Effects of Chronic Unpredictable Mild Stress and Semi-Pure Diets on the Brain, Gut and Adrenal Medulla in C57BL6 Mice

Chronic stress is known to perturb serotonergic regulation in the brain, leading to mood, learning and memory impairments and increasing the risk of developing mood disorders. The influence of the gut microbiota on serotonergic regulation in the brain has received increased attention recently, justifying the investigation of the role of diet on the gut and the brain in mood disorders. Here, using a 4-week chronic unpredictable mild stress (CUMS) model in mice, we aimed to investigate the effects of a high-fat high-glycaemic index (HFD) and high-fibre fruit & vegetable "superfood" (SUP) modifications of a semi-pure AIN93M diet on behaviour, serotonin synthesis and metabolism pathway regulation in the brain and the gut, as well as the gut microbiota and the peripheral adrenal medullary system. CUMS induced anxiety-like behaviour, dysregulated the tryptophan and serotonin metabolic pathways in the hippocampus, prefrontal cortex, and colon, and altered the composition of the gut microbiota. CUMS reduced the catecholamine synthetic capacity of the adrenal glands. Differential effects were found in these parameters in the HFD and SUP diet. Thus, dietary modifications may profoundly affect the multiple dynamic systems involved in mood disorders.

Sex-Dependent Effects of Chronic Restraint Stress on Mood-Related Behaviours and Neurochemistry in Mice

Anxiety and depressive disorders are closely associated; however, the pathophysiology of these disorders remains poorly understood. Further exploration of the mechanisms involved in anxiety and depression such as the stress response may provide new knowledge that will contribute to our understanding of these disorders. Fifty-eight 8-12-week-old C57BL6 mice were separated into experimental groups by sex as follows: male controls (n = 14), male restraint stress (n = 14), female controls (n = 15) and female restraint stress (n = 15). These mice were taken through a 4-week randomised chronic restraint stress protocol, and their behaviour, as well as tryptophan metabolism and synaptic proteins, were measured in the prefrontal cortex and hippocampus. Adrenal catecholamine regulation was also measured. The female mice showed greater anxiety-like behaviour than their male counterparts. Tryptophan metabolism was unaffected by stress, but some basal sex characteristics were noted. Synaptic proteins were reduced in the hippocampus in stressed females but increased in the prefrontal cortex of all female mice. These changes were not found in any males. Finally, the stressed female mice showed increased catecholamine biosynthesis capability, but this effect was not found in males. Future studies in animal models should consider these sex differences when evaluating mechanisms related to chronic stress and depression.

An Imbalance in the Pro/mature BDNF Ratio Occurs in Multiple Brain Regions During Normal Ageing in Wild-Type Mice

The early transition to Alzheimer's disease is characterized by a period of accelerated brain atrophy that exceeds normal ageing. Identifying the molecular basis of this atrophy could facilitate the discovery of novel drug targets. The precursor of brain-derived neurotrophic factor, a well characterized neurotrophin, is increased in the hippocampus of aged rodents, while its mature isoform is relatively stable. This imbalance could increase the risk of Alzheimer's disease by precipitating its pathological hallmarks. However, less is known about how relative levels of these isoforms change in middle-aged mice. In addition, the underlying mechanisms that might cause an imbalance are unknown. The main aim of this study was to determine how precursor brain-derived neurotrophic factor changes relative to its mature isoform with normal brain ageing in wild type mice. A secondary aim was to determine if signaling through the neurotrophin receptor, p75 influences this ratio. An increasing ratio was identified in several brain regions, except the hippocampus, suggesting a neurotrophic imbalance occurs as early as middle age. Some changes in receptors that mediate the isoforms effects were also identified, but these did not correspond with trends in the isoforms. Relative amounts of precursor brain-derived neurotrophic factor were mostly unchanged in mutant p75 mice. The lack of changes suggested that signaling through the receptor had no influence on the ratio.

The Effects of Walnuts and Academic Stress on Mental Health, General Well-Being and the Gut Microbiota in a Sample of University Students: A Randomised Clinical Trial

Poorer mental health is common in undergraduate students due to academic stress. An interplay between stress and diet exists, with stress influencing food choices. Nutritional interventions may be effective in preventing mental health decline due to complex bidirectional interactions between the brain, the gut and the gut microbiota. Previous studies have shown walnut consumption has a positive effect on mental health. Here, using a randomized clinical trial (Australian New Zealand Clinical Trials Registry, #ACTRN12619000972123), we aimed to investigate the effects of academic stress and daily walnut consumption in university students on mental health, biochemical markers of general health, and the gut microbiota. We found academic stress had a negative impact on self-reported mood and mental health status, while daily walnut consumption improved mental health indicators and protected against some of the negative effects of academic stress on metabolic and stress biomarkers. Academic stress was associated with lower gut microbial diversity in females, which was improved by walnut consumption. The effects of academic stress or walnut consumption in male participants could not be established due to small numbers of participants. Thus, walnut consumption may have a protective effect against some of the negative impacts of academic stress, however sex-dependent mechanisms require further study.

Lipopolysaccharide mouse models for Parkinson's disease research: a critical appraisal

Parkinson's disease, the most common movement disorder, has a strong neuroinflammatory aspect. This is evident by increased pro-inflammatory cytokines in the serum, and the presence of activated microglial cells, and inflammatory cytokines in the substantia nigra of post-mortem brains as well as cerebrospinal fluid of Parkinson's disease patients. The central and peripheral neuroinflammatory aspects of Parkinson's disease can be investigated in vivo via administration of the inflammagen lipopolysaccharide, a component of the cell wall of gram-negative bacteria. In this mini-review, we will critically evaluate different routes of lipopolysaccharide administration (including intranasal systemic and stereotasic), their relevance to clinical Parkinson's disease as well as the recent findings in lipopolysaccharide mouse models. We will also share our own experiences with systemic and intrastriatal lipopolysaccharide models in C57BL/6 mice and will discuss the usefulness of lipopolysaccharide mouse models for future research in the field.

Long term high fat diet induces metabolic disorders and aggravates behavioral disorders and cognitive deficits in MAPT P301L transgenic mice

Most Alzheimer disease (AD) patients present as sporadic late onset AD, with metabolic factors playing an important role in the occurrence and development of AD. Given the link between peripheral insulin resistance and tau pathology in streptozotocin-injected and db/db mouse models of diabetes, we fed high fat diet (HFD) to pR5 mice expressing P301L mutant human tau, with the aim of developing a new model with characteristics of obesity, T2DM and AD to mimic AD patients exacerbated by obesity and T2DM, an increasing trend in modern society. In our study, pR5 and C57BL/6 (WT) mice were randomly allocated to a standard diet (STD) or HFD for 30 weeks starting at 8 weeks of age. Food intake was measured weekly, body weight and fasting glucose levels were measured fortnightly, and a comprehensive behavioral test battery was performed to assess anxiety, depression and cognitive dysfunction. Glucose and insulin tolerance tests were performed after 30 weeks of HFD. We also investigated the effect of long term HFD on tau pathology in the brains of WT and P301L mice by performing western blotting of whole brain homogenates for total tau, phosphorylated tau at Ser396 and Thr231. Our results show that pR5 mice fed with HFD are more vulnerable to diet induced obesity compared to WT, especially with increasing age. In addition, pR5 mice on HFD developed glucose intolerance and insulin resistance. It was identified that long term HFD significantly aggravates depression like behavior and impairs cognitive function in pR5 mice, and also induces anxiety like behavior in both pR5 and WT mice. Long term HFD was also shown to aggravate tau hyperphosphorylation in pR5 transgenic mice, and increase total and hyperphosphorylated tau in WT mice. These results indicate that diet induced obesity of pR5 transgenic mice expressing P301L mutant human tau generates T2DM, and aggravates tau phosphorylation, and is therefore a model useful for investigations that seek to understand the relationships between AD, T2DM and obesity, and the underlying biochemical changes and mechanisms associated with metabolic disorders and AD tauopathy.

Quantitation of methotrexate polyglutamates in human whole blood, erythrocytes and leukocytes collected via venepuncture and volumetric absorptive micro-sampling: a green LC-MS/MS-based method

Low-dose methotrexate (MTX) plays a key role in treatment of rheumatoid arthritis. However, not all patients respond satisfactorily, and no therapeutic drug monitoring has been implemented in clinical practice, despite the fact that MTX therapy has now been available for decades. Analysis of individual intracellular MTX metabolites among rheumatoid arthritis (RA) patients is hampered by the low intracellular concentrations of MTX-PGs which require a highly sensitive method to quantify. Here, we present a rapid and highly sensitive LC (HILIC) MS/MS method with LLOQ 0.1 nM, 0.8 nmol/L for each metabolite of MTX-PG_1-5 and MTX-PG_6-7 respectively. Over a linear range of 0.1-100 nM, 0.8-100 nmol/L for each metabolite of MTX-PG_1-5 and MTX-PG_6-7, respectively, the inter- and intra- accuracy and precision were within 15% of the nominal value for all MTX metabolites. The presented assay was used to assess and compare MTX metabolite concentrations extracted from four different matrices: red blood cells, plasma, peripheral blood mononuclear cells, and whole blood that have been collected either using traditional venepuncture or volumetric absorptive micro-sampling (VAMS) sampling techniques. The presented method not only improves analyte coverage and sensitivity as compared to other published methods; it also improves the greenness.

The Effects of Novel Formulations of Edaravone and Curcumin in the Mouse Intrastriatal Lipopolysaccharide Model of Parkinson's Disease

The major hallmark of Parkinson's disease (PD) is the degeneration of dopaminergic neurons in the substantia nigra (SN), which is responsible for the core motor symptoms of PD. Currently, there is no cure for PD, and its prevalence is increasing, prompting the search for novel neuroprotective treatments. Neuroinflammation is a core pathological process in PD, evident by increased inflammatory biomarkers in the SN and cerebrospinal fluid. Interestingly, epidemiological studies have reported a reduced risk of PD in users of non-steroidal anti-inflammatory drugs compared to non-users, suggesting the neuroprotective potential of anti-inflammatory drugs. Therefore, this study aimed to: (1) test the efficacy of novel oral formulations of edaravone (EDR) and curcumin (CUR) (which possess anti-inflammatory and anti-oxidative properties) to alleviate motor and non-motor symptoms, and associated pathology in the intrastriatal lipopolysaccharide (LPS) model of PD; (2) investigate the expression of proteins linked to familial PD and markers of autophagy in the intrastriatal LPS model treated with EDR and CUR. Fifty-two C57BL/6 mice were divided into 4 groups, namely; (1) control + vehicle; (2) LPS + vehicle; (3) LPS + EDR (made in vehicle) and (4) LPS + CUR (made in vehicle). 10 μg of LPS was administered stereotaxically into the right striatum, and EDR and CUR treatments were initiated 2-weeks after the LPS injections. Behavioural tests were carried out at 4- and 8-weeks after LPS injection followed by tissue collection at 8-weeks. Intrastriatal administration of LPS induced motor deficits and anxiety-like behaviours at 4- and 8-weeks, which were accompanied by astroglial activation, increased protein expression of α-synuclein, heat shock cognate protein of 70 kDa (HSC-70) and Rab-10, and reduced levels of tyrosine hydroxylase (TH) protein in the striatum. Additionally, LPS induced astroglial activation in the olfactory bulb, along with changes in the protein expression of HSC-70. The changes associated with EDR and CUR in the striatum and olfactory bulb were not statistically significant compared to the LPS group. Intrastriatal administration of LPS induced pathological changes of PD such as motor deficits, reduced expression of TH protein and increased α-synuclein protein, as well as some alterations in proteins linked to familial PD and autophagy in the olfactory bulb and striatum, without pronounced therapeutic effects of EDR and CUR. Our results may suggest that EDR and CUR lack therapeutic effects when administered after the disease process was already initiated. Thus, our treatment regimen or the physicochemical properties of EDR and CUR could be further refined to elevate the therapeutic effects of these formulations.

The Effects of Stress and Diet on the "Brain-Gut" and "Gut-Brain" Pathways in Animal Models of Stress and Depression

Compelling evidence is building for the involvement of the complex, bidirectional communication axis between the gastrointestinal tract and the brain in neuropsychiatric disorders such as depression. With depression projected to be the number one health concern by 2030 and its pathophysiology yet to be fully elucidated, a comprehensive understanding of the interactions between environmental factors, such as stress and diet, with the neurobiology of depression is needed. In this review, the latest research on the effects of stress on the bidirectional connections between the brain and the gut across the most widely used animal models of stress and depression is summarised, followed by comparisons of the diversity and composition of the gut microbiota across animal models of stress and depression with possible implications for the gut–brain axis and the impact of dietary changes on these. The composition of the gut microbiota was consistently altered across the animal models investigated, although differences between each of the studies and models existed. Chronic stressors appeared to have negative effects on both brain and gut health, while supplementation with prebiotics and/or probiotics show promise in alleviating depression pathophysiology.

The role of brain-derived neurotrophic factor and the neurotrophin receptor p75NTR in age-related brain atrophy and the transition to Alzheimer's disease

Alzheimer's disease is a neurodegenerative condition that is potentially mediated by synaptic dysfunction before the onset of cognitive impairments. The disease mostly affects elderly people and there is currently no therapeutic which halts its progression. One therapeutic strategy for Alzheimer's disease is to regenerate lost synapses by targeting mechanisms involved in synaptic plasticity. This strategy has led to promising drug candidates in clinical trials, but further progress needs to be made. An unresolved problem of Alzheimer's disease is to identify the molecular mechanisms that render the aged brain susceptible to synaptic dysfunction. Understanding this susceptibility may identify drug targets which could halt, or even reverse, the disease's progression. Brain derived neurotrophic factor is a neurotrophin expressed in the brain previously implicated in Alzheimer's disease due to its involvement in synaptic plasticity. Low levels of the protein increase susceptibility to the disease and post-mortem studies consistently show reductions in its expression. A desirable therapeutic approach for Alzheimer's disease is to stimulate the expression of brain derived neurotrophic factor and potentially regenerate lost synapses. However, synthesis and secretion of the protein are regulated by complex activity-dependent mechanisms within neurons, which makes this approach challenging. Moreover, the protein is synthesised as a precursor which exerts the opposite effect of its mature form through the neurotrophin receptor p75NTR. This review will evaluate current evidence on how age-related alterations in the synthesis, processing and signalling of brain derived neurotrophic factor may increase the risk of Alzheimer's disease.

Neuroimmunological complications arising from chemotherapy-induced gut toxicity and opioid exposure in female dark agouti rats

Cancer patients may experience symptom clusters, including chemotherapy-induced (CI) gut toxicity (CIGT) and cognitive impairment. Analgesic selection for pain associated with CIGT is difficult as opioids induce glial reactivity and unwanted side effects. This study quantified central glial reactivity and proinflammatory effects in rats with CIGT using three mechanistically different analgesics. Regional adaptations were indicative of immune-to-brain signaling routes. Utilizing a 5-fluorouracil-induced GT (5IGT) rat model and analgesic intervention (carprofen (CAR), buprenorphine (BUP), and tramadol (TRAM)), spinal and brain neuroimmune modulation was examined via microglial, astrocyte, and proinflammatory (cluster of differentiation molecule 11b; CD11b, glial fibrillary associated protein; GFAP, and interleukin-1 beta; IL1β) reactivity marker expression changes by western blot analysis. 5IGT significantly increased thoracic GFAP (p < 0.05) and IL-1β (p < 0.0001) expression, CAR and BUP ameliorated these effects. BUP and TRAM with 5-FU synergistically increased hippocampal GFAP expression. CAR administered with 5IGT significantly elevated hippocampal and thoracic CD11b expression levels (p < 0.05). The neuroimmune responses observed in this study suggest activation of peripheral-to-central immune signaling pathways. We speculate that the opioid-induced hippocampal changes inferred a humorally mediated mechanism, whereas thoracic neuroimmune modifications indicated activation of an indirect neural route. Although TRAM ameliorated 5IGT-intestinal inflammation, this opioid presents complications relating to bodyweight and regional glial dysregulation (neuroinflammation) and may not be optimal in the management of pain associated with 5IGT. The chemotherapy-induced gut-derived neuroimmune consequences observed suggest a potential mechanistic contribution to central components of the cancer symptom cluster experience, while the opioid-related glial changes have implications for optimal pain management in this setting warranting further investigation.

Cell Therapy for Neurological Disorders: The Perspective of Promising Cells

Neurological disorders are big public health challenges that are afflicting hundreds of millions of people around the world. Although many conventional pharmacological therapies have been tested in patients, their therapeutic efficacies to alleviate their symptoms and slow down the course of the diseases are usually limited. Cell therapy has attracted the interest of many researchers in the last several decades and has brought new hope for treating neurological disorders. Moreover, numerous studies have shown promising results. However, none of the studies has led to a promising therapy for patients with neurological disorders, despite the ongoing and completed clinical trials. There are many factors that may affect the outcome of cell therapy for neurological disorders due to the complexity of the nervous system, especially cell types for transplantation and the specific disease for treatment. This paper provides a review of the various cell types from humans that may be clinically used for neurological disorders, based on their characteristics and current progress in related studies.

Further Characterization of Intrastriatal Lipopolysaccharide Model of Parkinson's Disease in C57BL/6 Mice

Parkinson's disease (PD) is the most common movement disorder, characterized by progressive degeneration of the nigrostriatal pathway, which consists of dopaminergic cell bodies in substantia nigra and their neuronal projections to the striatum. Moreover, PD is associated with an array of non-motor symptoms such as olfactory dysfunction, gastrointestinal dysfunction, impaired regulation of the sleep-wake cycle, anxiety, depression, and cognitive impairment. Inflammation and concomitant oxidative stress are crucial in the pathogenesis of PD. Thus, this study aimed to model PD via intrastriatal injection of the inflammagen lipopolysaccharide (LPS)to investigate if the lesion causes olfactory and motor impairments, inflammation, oxidative stress, and alteration in synaptic proteins in the olfactory bulb, striatum, and colon. Ten µg of LPS was injected unilaterally into the striatum of 27 male C57BL/6 mice, and behavioural assessment was conducted at 4 and 8 weeks post-treatment, followed by tissue collection. Intrastriatal LPS induced motor impairment in C57BL/6 mice at 8 weeks post-treatment evidenced by reduced latency time in the rotarod test. LPS also induced inflammation in the striatum characterized by increased expression of microglial marker Iba-1 and astrocytic marker GFAP, with degeneration of dopaminergic neuronal fibres (reduced tyrosine hydroxylase immunoreactivity), and reduction of synaptic proteins and DJ-1 protein. Additionally, intrastriatal LPS induced inflammation, oxidative stress and alterations in synaptic proteins within the olfactory bulb, although this did not induce a significant impairment in olfactory function. Intrastriatal LPS induced mild inflammatory changes in the distal colon, accompanied by increased protein expression of 3-nitrotyrosine-modified proteins. This model recapitulated the major features of PD such as motor impairment and degeneration of dopaminergic neuronal fibres in the striatum, as well as some pathological changes in the olfactory bulb and colon; thus, this model could be suitable for understanding clinical PD and testing neuroprotective strategies.

The efficacy of systemic administration of lipopolysaccharide in modelling pre-motor Parkinson's disease in C57BL/6 mice

Parkinson's disease (PD) is the second most common neurodegenerative disease, characterised by the loss of dopaminergic neurons in the substantia nigra. Mounting evidence indicates a crucial role of inflammation and concomitant oxidative stress in the disease progression. Therefore, the aim of this study was to investigate the ability of systemically administered lipopolysaccharide (LPS) to induce motor and non-motor symptoms of PD, inflammation, oxidative stress and major neuropathological hallmarks of the disease in regions postulated to be affected, including the olfactory bulb, hippocampus, midbrain and cerebellum. Twenty-one male C57BL/6 mice, approximately 20 weeks old, received a dose of 0.3 mg/kg/day of LPS systemically on 4 consecutive days and behavioural testing was conducted on days 14-18 post-treatment, followed by tissue collection. Systemically administered LPS increased latency time in the buried food seeking test (indicative of olfactory impairment), and decreased time spent in central zone of the open field (anxiety-like behaviour). However, there was no change in latency time in the rotarod test or the expression of tyrosine hydroxylase (TH) in the midbrain. Systemically administered LPS induced increased glial markers GFAP and Iba-1 and oxidative stress marker 3-nitrotyrosine (3-NT) in the olfactory bulb, hippocampus, midbrain and cerebellum, and there were region specific changes in the expression of NFκB, IL-1β, α-synuclein, TH and BDNF proteins. The model could be useful to further elucidate early non-motor aspects of PD and the possible mechanisms contributing to the non-motor deficits.

A New Approach to Model Sporadic Alzheimer's Disease by Intracerebroventricular Streptozotocin Injection in APP/PS1 Mice

Alzheimer's disease (AD) is the most common cause of dementia among elderly people. Majority of AD cases are sporadic (SAD) with unknown cause. Transgenic animal models closely reflect the familial (genetic) aspect of the disease but not the sporadic type. However, most new drug candidates which are tested positive in transgenic animal models failed in clinical studies so far. Herein, we aim to develop an AD animal model that combines most of the neuropathological features seen in sporadic AD in humans with amyloid plaques observed in transgenic mice. Four-month-old wild-type and APP/PS1 AD mice were given a single intracerebroventricular (ICV) injection of 3 mg/kg streptozotocin (STZ), a diabetogenic agent. Three weeks later, their cognitive behavior was assessed, and their brain tissues were collected for biochemical and histological analysis. STZ produced cognitive deficits in both non-transgenic mice and AD mice. Biochemical analysis showed a severe decline in synaptic proteins, increase in tau phosphorylation, oxidative stress, disturbed brain insulin signaling with extensive neuroinflammation, and cell death. Significant increase was also observed in the level of the soluble beta amyloid precursor protein (APP) fragments and robust accumulation of amyloid plaques in AD mice compared to the control. These results suggest that STZ ICV treatment causes disturbance in multiple metabolic and cell signaling pathways in the brain that facilitated amyloid plaque accumulation and tau phosphorylation. Therefore, this animal model can be used to evaluate new AD therapeutic agents for clinical translation.

Effect of Sutellarin on Neurogenesis in Neonatal Hypoxia–Ischemia Rat Model: Potential Mechanisms of Action

To investigate the therapeutic efficacy of Scutellarin (SCU) on neurite growth and neurological functional recovery in neonatal hypoxic-ischemic (HI) rats. Primary cortical neurons were cultured to detect the effect of SCU on cell viability of neurons under oxygen-glucose deprivation (OGD). Double immunofluorescence staining of Tuj1 and TUNEL then observed the neurite growth and cell apoptosis in vitro,and double immunofluorescence staining of NEUN and TUNEL was performed to examine the neuronal apoptosis and cell apoptosis in brain tissues after HI in vivo. Pharmacological efficacy of SCU was also evaluated in HI rats by neurobehavioral tests, triphenyl tetrazolium chloride staining, Hematoxylin and eosin staining and Nissl staining. Astrocytes and microglia expression in damaged brain tissues were detected by immunostaining of GFAP and Iba1. A quantitative real-time polymerase chain reaction and western blot were applied to investigate the genetic expression changes and the protein levels of autophagy-related proteins in the injured cortex and hippocampus after HI. We found that SCU administration preserved cell viability, promoted neurite outgrowth and suppressed apoptosis of neurons subjected to OGD both in vitroand in vivo. Meanwhile, 20 mg/kg SCU treatment improved neurological functions and decreased the expression of astrocytes and microglia in the cortex and hippocampus of HI rats. Additionally, SCU treatment depressed the elevated levels of autophagy-related proteins and the p75 neurotrophin receptor (p75NTR) in both cortex and hippocampus. This study demonstrated the potential therapeutic efficacy of SCU by enhancing neurogenesis and restoring long-term neurological dysfunctions, which might be associated with p75NTR depletion in HI rats.

Urine stem cells are equipped to provide B cell survival signals

The interplay between mesenchymal stem cells (MSCs) and immune cells has been studied for MSCs isolated from different tissues. However, the immunomodulatory capacity of urine stem cells (USCs) has not been adequately researched. The present study reports on the effect of USCs on peripheral blood lymphocytes. USCs were isolated and characterized before coculture with resting and with anti‐CD3/CD28 bead stimulated lymphocytes. Similarly to bone marrow mesenchymal stem cells (BM‐MSCs), USCs inhibited the proliferation of activated T lymphocytes and induced their apoptosis. However, they also induced strong activation, proliferation, and cytokine and antibody production by B lymphocytes. Molecular phenotype and supernatant analysis revealed that USCs secrete a range of cytokines and effector molecules, known to play a central role in B cell biology. These included B cell‐activating factor (BAFF), interleukin 6 (IL‐6) and CD40L. These findings raise the possibility of an unrecognized active role for kidney stem cells in modulating local immune cells.

Pharmacokinetic Modelling of Human Recombinant Protein, p75ECD-Fc: A Novel Therapeutic Approach for Treatment of Alzheimer's Disease, in Serum and Tissue of Sprague Dawley Rats

BACKGROUND AND OBJECTIVE

p75ECD-Fc is a novel antagonist of toxic amyloid beta protein and other neurodegenerative factors with potential for the treatment of Alzheimer's disease (AD). Preclinical studies showed that it can alleviate the AD pathologies in animal models of dementia. In a previous paper, we used non-compartmental pharmacokinetic analysis to obtain preliminary pharmacokinetic data for p75ECD-Fc in Sprague Dawley (SD) rats. We also studied the tissue distribution in terms of drug metabolism that helped us to understand possible mechanisms of action. Here, we aim to develop population pharmacokinetic models that can describe the pharmacokinetics of p75ECD-Fc in serum and tissues.

METHODS

p75ECD-Fc was delivered to SD rats via two routes (intravenous and subcutaneous) at a single dose of 3 mg/kg (n = 15). Blood (n = 12) and tissue samples (n = 10-15) were then separated at different time points for a total duration of 42 days post dosage. The concentration of p75ECD-Fc in serum and tissues was measured using an enzyme-linked immunosorbent assay.

RESULTS

Data were best fitted to a 2-compartment model with linear elimination kinetics. The population parameter estimates for clearance, and volume of central and peripheral compartments were 0.000176 L/h, 0.0145 L and 0.0263 L, respectively. The presence of anti-drug antibodies was added to the final model as a covariate on clearance. The subcutaneous bioavailability was estimated to be 53.5% with a first-order absorption rate constant of 0.00745 1/h. By modeling of individual tissue concentrations, p75ECD-Fc was found to exhibit modest tissue distribution with estimated tissue/plasma partition coefficients (R) ranging from 0.004 to 0.2.

CONCLUSION

This is the first report of a pharmacokinetic model for p75ECD-Fc and these results may facilitate the ongoing development of p75ECD-Fc and translation to clinical studies.

Characterization of Urine Stem Cell-Derived Extracellular Vesicles Reveals B Cell Stimulating Cargo

Elucidation of the biological functions of extracellular vesicles (EVs) and their potential roles in physiological and pathological processes is an expanding field of research. In this study, we characterized USC-derived EVs and studied their capacity to modulate the human immune response in vitro. We found that the USC-derived EVs are a heterogeneous population, ranging in size from that of micro-vesicles (150 nm-1 μm) down to that of exosomes (60-150 nm). Regarding their immunomodulatory functions, we found that upon isolation, the EVs (60-150 nm) induced B cell proliferation and IgM antibody secretion. Analysis of the EV contents unexpectedly revealed the presence of BAFF, APRIL, IL-6, and CD40L, all known to play a central role in B cell stimulation, differentiation, and humoral immunity. In regard to their effect on T cell functions, they resembled the function of mesenchymal stem cell (MSC)-derived EVs previously described, suppressing T cell response to activation. The finding that USC-derived EVs transport a potent bioactive cargo opens the door to a novel therapeutic avenue for boosting B cell responses in immunodeficiency or cancer.

Blockage of p75NTR ameliorates depressive-like behaviours of mice under chronic unpredictable mild stress

The precursor of brain derived neurotrophic factor (proBDNF) and its receptor p75NTR are upregulated in depressive patients and chronic stress-induced depressive animals, suggesting that activation of p75NTR signalling may underlie pathogenesis of depression. In the present study we hypothesize that the blockade of p75NTR may have therapeutic effect on depressive mice under chronic stress. The treatment of mice with the recombinant fusion protein of p75NTR extracellular domain and fragment C of immunoglobulin (p75ECD-Fc) significantly reduced the immobility time in the forced swim test and tail suspension test, and increased the time spent in the central zone in the open field test in mice exposed to chronic unpredictable mild stress (CUMS). p75ECD-Fc treatment also significantly increased the length and density of neuronal dendritic spines in the dentate gyrus and amygdala. Our data indicate that blocking p75NTR signalling can alleviate depressive and anxiety-like behaviours of chronically stressed mice and improve the dendritic spinogenesis of neurons under stress.

Vi4-miR-185-5p-Igfbp3 Network Protects the Brain From Neonatal Hypoxic Ischemic Injury via Promoting Neuron Survival and Suppressing the Cell Apoptosis

Neonatal hypoxic ischemic encephalopathy (HIE) due to birth asphyxia is common and causes severe neurological deficits, without any effective therapies currently available. Neuronal death is an important driving factors of neurological disorders after HIE, but the regulatory mechanisms are still uncertain. Long non-coding RNA (lncRNA) or ceRNA network act as a significant regulator in neuroregeneration and neuronal apoptosis, thus owning a great potential as therapeutic targets in HIE. Here, we found a new lncRNA, is the most functional in targeting the Igfbp3 gene in HIE, which enriched in the cell growth and cell apoptosis processes. In addition, luciferase reporter assay showed competitive regulatory binding sites to the target gene Igfbp3 between TCONS00044054 (Vi4) and miR-185-5p. The change in blood miR-185-5p and Igfbp3 expression is further confirmed in patients with brain ischemia. Moreover, Vi4 overexpression and miR-185-5p knock-out promote the neuron survival and neurite growth, and suppress the cell apoptosis, then further improve the motor and cognitive deficits in rats with HIE, while Igfbp3 interfering got the opposite results. Together, Vi4-miR-185-5p-Igfbp3 regulatory network plays an important role in neuron survival and cell apoptosis and further promote the neuro-functional recovery from HIE, therefore is a likely a drug target for HIE therapy.

Pro-BDNF Knockout Causes Abnormal Motor Behaviours and Early Death in Mice

Brain derived neurotrophic factor (BDNF) is a member of the neurotrophin family, best characterized for its survival and differentiative effects in the central nervous system. Pro-BDNF, known as the precursor of BDNF, is believed to have opposite functions to mature BDNF (mBDNF). The opposing effects of Pro-BDNF and mBDNF have led researchers to propose a 'yin' (Pro-BDNF) and 'yang' (mBDNF) model of which, the specific mechanism of its opposing functions is unclear and requires further investigation. In order to elucidate pro-BDNF's explicit role, we established a pro-BDNF knockout (KO) mouse model. This BDNF pro-domain KO mouse model showed significant weight loss, impaired righting reflex, abnormal motor behaviours and short lifespan (less than 22 days), mimicking a Huntington's disease (HD)-like phenotype. ELISA results showed BDNF pro-domain KO not only blocked pro-BDNF, but also significantly affected the level of mBDNF. Abnormal morphologic changes were found in the dentate gyrus (DG) of the hippocampus in pro-BDNF KO mice, and western blot confirmed significant cell apoptosis in pro-BDNF KO mice brains. Furthermore, the expression of glutamic acid decarboxylase 65/67 (GAD65/67) was significantly reduced in pro-BDNF KO mice, indicating impaired inhibitory neurotransmission. Heterozygous (Het) mice showed impaired learning and memory capability and depressive-like behaviours, compared with wild type (WT) mice. Overall, these results support that pro-domain of BDNF is an indispensable part of the BDNF gene; without the proper formation of pro-BDNF, mBDNF cannot be produced successfully and function correctly on its own. Our study also supports the BDNF hypothesis in the pathogenesis of HD.

Preclinical Study of the Pharmacokinetics of p75ECD-Fc, a Novel Human Recombinant Protein for Treatment of Alzheimer’s Disease, in Sprague Dawley Rats

Background:

p75ECD-Fc is a recombinant human protein that has recently been developed as a novel therapy for Alzheimer’s disease. Current studies showed that it is able to alleviate Alzheimer’s disease pathologies in animal models of dementia. Thus, knowledge about the pharmacokinetic behavior and tissue distribution of this novel protein is crucial in order to better understand its pharmacodynamics and more importantly for its clinical development.

Methods:

The aim of this study is to characterize the pharmacokinetics of p75ECD-Fc after single intravenous and subcutaneous injection of 3mg/kg in Sprague Dawley rats. We calculated the bioavailability of the SC route and studied the distribution of that protein in different tissues, cerebrospinal fluid and urine using ELISA and immunofluorescence techniques. In-vitro stability of the drug was also assessed. Data obtained were analyzed with Non-compartmental pharmacokinetic method using R.

Results:

Results showed that the bioavailability of SC route was 66.15%. Half-life time was 7.5 ± 1.7 and 6.2 ± 2.4 days for IV and SC injection, respectively. Tissue distribution of p75ECD-Fc was modest with the ability to penetrate the blood brain barrier. It showed high in vitro stability in human plasma.

Conclusion:

These acceptable pharmacokinetic properties of p75ECD-Fc present it as a potential candidate for clinical development for the treatment of Alzheimer’s disease.

Lipopolysaccharide animal models of Parkinson's disease: Recent progress and relevance to clinical disease

Parkinson's disease (PD) is one of the most common neurodegenerative movement disorders which is characterised neuropathologically by progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the presence of Lewy bodies (made predominately of α-synuclein) in the surviving neurons. Animal models of PD have improved our understanding of the disease and have played a critical role in the development of neuroprotective agents. Neuroinflammation has been strongly implicated in the pathogenesis of PD, and recent studies have used lipopolysaccharide (LPS), a component of gram-negative bacteria and a potent activator of microglia cells, to mimic the inflammatory events in clinical PD. Modulating the inflammatory response could ameliorate PD associated complications and thus, it is essential to understand the extent to which LPS models reflect human PD. This review will outline the routes of administration of LPS such as stereotaxic, systemic and intranasal, their ability to recapitulate neuropathological markers of PD, and mechanisms of LPS induced toxicity. We will also discuss the ability of the models to replicate motor symptoms and non-motor symptoms of PD such as gastrointestinal dysfunction, olfactory dysfunction, anxiety, depression and cognitive dysfunction.

Coating Materials for Neural Stem/Progenitor Cell Culture and Differentiation

Neural stem/progenitor cells (NSPCs) have a potential to treat various neurological diseases, such as Parkinson's Disease, Alzheimer's Disease, and Spinal Cord Injury. However, the limitation of NSPC sources and the difficulty to maintain their stemness or to differentiate them into specific therapeutic cells are the main hurdles for clinical research and application. Thus, for obtaining a therapeutically relevant number of NSPCs in vitro, it is important to understand factors regulating their behaviors and to establish a protocol for stable NSPC proliferation and differentiation. Coating materials for cell culture, such as Matrigel, laminin, collagen, and other coating materials, can significantly affect NSPC characteristics. This article provides a review of coating materials for NSPC culturing in both two dimensions and three dimensions, and their functions in NSPC proliferation and differentiation, and presents a useful guide to select coating materials for researchers.

Conversion of human urine-derived cells into neuron-like cells by small molecules

Neural cell transplantation is an effective way for treatment of neurological diseases. However, the absence of transplantable human neurons remains a barrier for clinical therapies. Human urine-derived cells, namely renal cells and urine stem cells, have become a good source of cells for reprogramming or trans-differentiation research. Here, we show that human urine-derived cells can be partially converted into neuron-like cells by applying a cocktail of small molecules. Gene expression analysis has shown that these induced cells expressed some neuron-specific genes, and a proportion of the cells are GABAergic neurons. Moreover, whole-cell patch clamping recording has shown that some induced cells have neuron-specific voltage gated Na⁺ and K⁺ currents but have failed to generate Ca²⁺ currents and action potentials. Taken together, these results suggest that induced neuronal cells from human urine-derived cells may be useful for neurological disease modelling, drug screening and cell therapies.

The Level of proBDNF in Blood Lymphocytes Is Correlated with that in the Brain of Rats with Photothrombotic Ischemic Stroke

Stroke is accompanied by severe inflammation in the brain. The role of mature brain-derived neurotrophic factor (mBDNF) in ischemic stroke has received intensive attention, but the function of its precursor proBDNF is less understood. Recent studies showed that mBDNF and proBDNF in the ischemic brain are upregulated, but the significance of mBDNF and proBDNF in the lymphocytes in ischemic stroke is not known. Here, we propose that the expression levels of mBDNF and proBDNF in lymphocytes correlate with those in the brain after ischemic stroke and therefore can be surrogate markers for the ischemic brain. Using a photothrombotic model in rats and ELISA assay technique, we found that proBDNF and mBDNF in peripheral lymphocytes were upregulated but produced differential time courses after ischemia. The levels of mBDNF and proBDNF in lymphocytes at early stages of stroke (1 day), showed a strong positive correlation with those in the brain. The levels of p75, sortilin, were also increased in a time-dependent manner after ischemic stroke; however, the levels of p-TrkB in the ischemic brain at 6 h, 1 and 3 days were significantly reduced in the brain. The present study suggests that the levels of proBDNF and mBDNF in the blood lymphocytes in acute ischemic stroke reflect those in the brain at early stages.

miRNA-7a-2-3p Inhibits Neuronal Apoptosis in Oxygen-Glucose Deprivation (OGD) Model

Neuronal apoptosis is a major pathological hallmark of the neonatal hypoxic-ischemic brain damage (HIBD); however, the role of miR-7a-2-3p in the regulation of HIBD remains unknown. The purpose of this study was to explore the possible roles of miR-7a-2-3p in brain injury using a hypoxia-ischemia model in rats and oxygen-glucose deprivation (OGD) model in vitro. Firstly, we established the hypoxia-ischemia (HI) model and verified the model using Zea Longa scores and MRI in rats. Next, the changes of miR-7a-2-3p were screened in the ischemic cortex of neonatal rats by qRT-PCR at 12, 48, and 96 h after HIBD. We have found that the expression of miR-7a-2-3p in the HI rats decreased significantly, compared with the sham group (P < 0.01). Then, we established the OGD model in PC12 cells, SH-SY5Y cells and primary cortical neurons in vitro and qRT-PCR was used to confirm the changes of miR-7a-2-3p in these cells after the OGD. In order to determine the function of miR-7a-2-3p, PC12 cells, SH-SY5Y cells and rat primary cortical neurons were randomly divided into normal, OGD, mimic negative control (mimic-NC) and miR-7a-2-3p groups. Then, Tuj1+ (neuronal marker) staining, TUNEL assay (to detect apoptotic cells) and MTT assay (to investigate cell viability) were performed. We have found that the number of PC12 cells, SH-SY5Y cells and cortical neurons in the miR-7a-2-3p groups increased significantly (P < 0.01) in comparison to the OGD groups. The survival of cortical neurons in the miR-7a-2-3p group was improved markedly (P < 0.01), while the apoptosis of neurons in the miR-7a-2-3p group was significantly decreased (P < 0.01), compared with the normal group. Lastly, we investigated the target genes of miR-7a-2-3p by using the prediction databases (miRDB, TargetScan, miRWalk, and miRmap) and verified the target genes with qRT-PCR in the HI rats. Bioinformatics prediction showed that Vimentin (VIM), pleiomorphic adenoma gene 1(PLAG1), dual specificity phosphatase 10 (DUSP10), NAD(P)H dehydrogenase, quinone 1 (NQO1) and tumor necrosis factor receptor superfamily member 1B (TNFRSF1B) might be the targets of miR-7a-2-3p and the qRT-PCR confirmed that VIM increased in the HI rats (P < 0.01). In conclusion, miR-7a-2-3p plays a crucial role in the hypoxic-ischemic injury, and is associated with regulation of VIM.

Insulin-responsive autonomic neurons in rat medulla oblongata

Low blood glucose activates brainstem adrenergic and cholinergic neurons, driving adrenaline secretion from the adrenal medulla and glucagon release from the pancreas. Despite their roles in maintaining glucose homeostasis, the distributions of insulin-responsive adrenergic and cholinergic neurons in the medulla are unknown. We fasted rats overnight and gave them insulin (10 U/kg i.p.) or saline after 2 weeks of handling. Blood samples were collected before injection and before perfusion at 90 min. We immunoperoxidase-stained transverse sections of perfused medulla to show Fos plus either phenylethanolamine N-methyltransferase (PNMT) or choline acetyltransferase (ChAT). Insulin injection lowered blood glucose from 4.9 ± 0.3 mmol/L to 1.7 ± 0.2 mmol/L (mean ± SEM; n = 6); saline injection had no effect. In insulin-treated rats, many PNMT-immunoreactive C1 neurons had Fos-immunoreactive nuclei, with the proportion of activated neurons being highest in the caudal part of the C1 column. In the rostral ventrolateral medulla, 33.3% ± 1.4% (n = 8) of C1 neurons were Fos-positive. Insulin also induced Fos in 47.2% ± 2.0% (n = 5) of dorsal medullary C3 neurons and in some C2 neurons. In the dorsal motor nucleus of the vagus (DMV), insulin evoked Fos in many ChAT-positive neurons. Activated neurons were concentrated in the medial and middle regions of the DMV beneath and just rostral to the area postrema. In control rats, very few C1, C2, or C3 neurons and no DMV neurons were Fos-positive. The high numbers of PNMT-immunoreactive and ChAT-immunoreactive neurons that express Fos after insulin treatment reinforce the importance of these neurons in the central response to a decrease in glucose bioavailability.

Urine-derived cells for human cell therapy

Desirable cells for human cell therapy would be ones that can be generated by simple isolation and culture techniques using a donor sample obtained by non-invasive methods. To date, the different donor-specific cells that can be isolated from blood, skin, and hair require invasive methods for sample isolation and incorporate complex and costly reagents to culture. These cells also take considerable time for their in-vitro isolation and expansion. Previous studies suggest that donor-derived cells, namely urine stem cells and renal cells, may be isolated from human urine samples using a cost-effective and simple method of isolation, incorporating not such complex reagents. Moreover, the isolated cells, particularly urine stem cells, are superior to conventional stem cell sources in terms of favourable gene profile and inherent multipotent potential. Transdifferentiation or differentiation of human urine-derived cells can generate desirable cells for regenerative therapy. In this review, we intended to discuss the characteristics and therapeutic applications of urine-derived cells for human cell therapy. Conclusively, with detailed study and optimisation, urine-derived cells have a prospective future to generate functional lineage-specific cells for patients from a clinical translation point of view.

Correction to: Cellular Trafficking of Amyloid Precursor Protein in Amyloidogenesis Physiological and Pathological Significance

The original version of this article unfortunately contained mistake. The old version of Fig. 3 was published.

Cellular Trafficking of Amyloid Precursor Protein in Amyloidogenesis Physiological and Pathological Significance

The accumulation of excess intracellular or extracellular amyloid beta (Aβ) is one of the key pathological events in Alzheimer's disease (AD). Aβ is generated from the cleavage of amyloid precursor protein (APP) by beta secretase-1 (BACE1) and gamma secretase (γ-secretase) within the cells. The endocytic trafficking of APP facilitates amyloidogenesis while at the cell surface, APP is predominantly processed in a non-amyloidogenic manner. Several adaptor proteins bind to both APP and BACE1, regulating their trafficking and recycling along the secretory and endocytic pathways. The phosphorylation of APP at Thr668 and BACE1 at Ser498, also influence their trafficking. Neurotrophins and proneurotrophins also influence APP trafficking through their receptors. In this review, we describe the molecular trafficking pathways of APP and BACE1 that lead to Aβ generation, the involvement of different signaling molecules or adaptor proteins regulating APP and BACE1 subcellular localization. We have also discussed how neurotrophins could modulate amyloidogenesis through their receptors.

Bioactive constituents from cinnamon, hemp seed and polygonum cuspidatum protect against H2O2 but not rotenone toxicity in a cellular model of Parkinson's disease

Mitochondrial dysfunction and oxidative stress are two factors that are thought to contribute to the pathogenesis of Parkinson's disease (PD), a debilitating progressive neurodegenerative disorder that results in the loss of catecholamine producing cells throughout specific regions of the brain. In this study we aimed to compare the effects of hydrogen peroxide (H₂O₂) and rotenone (a pesticide and mitochondrial complex 1 inhibitor) on cell viability and the expression of tyrosine hydroxylase (TH) in a cellular model of PD. We also sought to investigate the potential neuroprotective benefits of bioactive constituents from cinnamon, hemp seed and polygonum cuspidatum. To create a model, SH-SY5Y cells transfected with human TH isoform 1 were treated with varying concentrations of H₂O₂ and rotenone, in the presence or absence of bioactive constituents. The effect of these toxins and constituents on cell viability, apoptosis and protein expression was assessed using MTT viability assays and western blotting. Rotenone treatment caused a significant decrease in cell viability but a significant increase in TH in the remaining cells. H₂O₂ treatment caused a significant decrease in cell viability but had no significant effect on TH expression. Curcumin, cinnamaldehyde, caffeoyltyramide (hemp seed extract) and piceatannol glucoside (polygonum cuspidatum extract) were unable to attenuate rotenone induced cell death, however they were able to provide protection against H₂O₂ induced cell death. This is the first study to demonstrate the neuroprotective properties of cinnamaldehyde, caffeoyltyramide and piceatannol glucoside in a dopaminergic cell line in response to H₂O₂.

p75 neurotrophin receptor interacts with and promotes BACE1 localization in endosomes aggravating amyloidogenesis

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deposition of amyloid beta (Aβ) and dysregulation of neurotrophic signaling, causing synaptic dysfunction, loss of memory, and cell death. The expression of p75 neurotrophin receptor is elevated in the brain of AD patients, suggesting its involvement in this disease. However, the exact mechanism of its action is not yet clear. Here, we show that p75 interacts with beta-site amyloid precursor protein cleaving enzyme-1 (BACE1), and this interaction is enhanced in the presence of Aβ. Our results suggest that the colocalization of BACE1 and amyloid precursor protein (APP) is increased in the presence of both Aβ and p75 in cortical neurons. In addition, the localization of APP and BACE1 in early endosomes is increased in the presence of Aβ and p75. An increased phosphorylation of APP-Thr668 and BACE1-Ser498 by c-Jun N-terminal kinase (JNK) in the presence of Aβ and p75 could be responsible for this localization. In conclusion, our study proposes a potential involvement in amyloidogenesis for p75, which may represent a future therapeutic target for AD. Cover Image for this Issue: doi. 10.1111/jnc.14163.

Sortilin inhibits amyloid pathology by regulating non-specific degradation of APP

Amyloid plaque is one of the hallmarks of Alzheimer's disease (AD). The key component beta-amyloid (Aβ) is generated via proteolytic processing of amyloid precursor protein (APP). Sortilin (encoded by the gene Sort1) is a vacuolar protein sorting 10 protein domain-containing receptor, which is up-regulated in the brain of AD, colocalizes with amyloid plaques and interacts with APP. However, its role in amyloidogenesis remains unclear. In this study, we first found that the protein level of sortilin was up-regulated in the neocortex of aged (7 and 9months old) but not young (2 and 5months old) AD mice (APP/PS1). 9months old APP/PS1 transgenic mice with Sort1 gene knockout showed increased amyloid pathology in the brain; and this phenotype was rescued by intrahippocampal injection of AAV-hSORT1. Moreover, the 9months old APP/PS1 mice without Sort1 also displayed a decreased number of neurons and increased astrocyte activation in the hippocampus. In addition, the present study showed that the intracellular domain of sortilin was involved in the regulation of the non-specific degradation of APP. Together, our findings indicate that sortilin is a beneficial protein for the reduction of amyloid pathology in APP/PS1 mice by promoting APP degradation.

ProBDNF inhibits proliferation, migration and differentiation of mouse neural stem cells

ProBDNF, a precursor of brain-derived neurotrophic factor (BDNF), is an important regulator of neurodegeneration, hippocampal long-term depression, and synaptic plasticity. ProBDNF and its receptors pan-neurotrophin receptor p75 (p75NTR), vps10p domain-containing receptor Sortilin and tropomyosin receptor kinase B (TrkB) are expressed in neuronal and glial cells. The role of proBDNF in regulation of neurogenesis is not fully defined. This study aims to uncover the function of proBDNF in regulating the differentiation, migration and proliferation of mouse neural stem cells (NSCs) in vitro. We have found that proBDNF and its receptors are constitutively expressed in NSCs when assessed by immunocytochemistry and western blotting. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay showed that exogenous proBDNF treatment reduced mouse NSCs viability by 38% at 10ng/mL. The migration of NSCs was also reduced by exogenous proBDNF treatment in a concentration-dependent manner (by 90% at 10ng/mL) but increased by anti-proBDNF antibody treatment (by 50%). BrdU (5-Bromo-2'-Deoxyuridine) incorporation was performed for detection of newborn cells. We have found that proBDNF significantly inhibited proliferation of NSCs and reduced the number of differentiated neurons, oligodendrocytes and astrocytes, while anti-proBDNF antibody treatment promoted proliferation and differentiation of NSCs. In conclusion, proBDNF may oppose the functions of mature BDNF by inhibiting the proliferation, differentiation and migration of NSCs during development. Conversely, anti-proBDNF antibody treatment promoted proliferation and differentiation of NSCs.