Upregulation Of Neurotrophins Research Articles

Effects of regenerative peripheral nerve interface on dorsal root ganglia neurons following peripheral axotomy.

BackgroundLong-term delayed reconstruction of injured peripheral nerves always results in poor recovery. One important reason is retrograde cell death among injured sensory neurons of dorsal root ganglia (DRG). A regenerative peripheral nerve interface (RPNI) was capable of generating new synaptogenesis between the proximal nerve stump and free muscle graft. Meanwhile, sensory receptors within the skeletal muscle can also be readily reinnervated by donor sensory axons, which allows the target muscles to become sources of sensory information for function reconstruction. To date, the effect of RPNI on injured sensory neurons is still unclear. Here, we aim to investigate the potential neuroprotective role of RPNI on sensory DRG neurons after sciatic axotomy in adult rats.Materials and methodsThe sciatic nerves of sixty rats were transected. The rats were randomly divided into three groups following this nerve injury: no treatment (control group, n = 20), nerve stump implantation inside a fully innervated muscle (NSM group, n = 20), or nerve stump implantation inside a free muscle graft (RPNI group, n = 20). At 8 weeks post-axotomy, ipsilateral L4 and L5 DRGs were harvested in each group. Toluidine blue staining was employed to quantify the neuronal densities in DRGs. The neuronal apoptosis index was quantified with TUNEL assay. Western blotting was applied to measure the expressions of Bax, Bcl-2, and neurotrophins (NTs) in ipsilateral DRGs.ResultsThere were significantly higher densities of neurons in ipsilateral DRGs of RPNI group than NSM and control groups at 8 weeks post-axotomy (p < 0.01). Meanwhile, neuronal apoptosis index and the expressions of pro-apoptotic Bax within the ipsilateral DRGs were significantly lower in the RPNI group than those in the control and NSM groups (p < 0.05), while the opposite result was observed in the expression of pro-survival Bcl-2. Furthermore, the expressions of NGF, NT-3, BDNF, and GDNF were also upregulated in the ipsilateral DRGs in the RPNI group (p < 0.01).ConclusionThe present results demonstrate that RPNI could prevent neuronal loss after peripheral axotomy. And the neuroprotection effect has a relationship with the upregulation of NTs in DRGs, such as NGF, NT-3, BDNF, and GDNF. These findings provide an effective therapy for neuroprotection in the delayed repair of the peripheral nerve injury.

Phloridzin ameliorates type 2 diabetes-induced depression in mice by mitigating oxidative stress and modulating brain-derived neurotrophic factor.

Type 2 diabetes (T2D) is linked with depression due to insulin resistance, oxidative stress and disruption of neurotrophic factors. We evaluated potential benefits of phloridzin in ameliorating depressive symptoms in T2D. Adult male Swiss-albino mice (25-30g) on high-fat-diet (HFD) for 2 weeks were administered with streptozotocin (STZ; 35mg/kg, intraperitoneal) to induce T2D. Seven days after STZ administration, diabetic mice on HFD were distributed into different groups. Animals were subjected daily tooral treatment of saline (0.25ml), fluoxetine (10-20mg/kg) or phloridzin (10-20mg/kg) for a period of4 weeks. One hour after last dose, the immobility time of animals was evaluated in forced swim test (FST) and tail suspension test (TST). To further confirm the mechanisms involved in antidepressant effect of phloridzin, biochemical parameters like brain derived neurotropic factor (BDNF), glutathione (GSH), extracellular signal-regulated kinase (ERK), tyrosine receptor kinaseB (TrkB) and cAMP-response element binding protein (CREB) were estimated in the brain. Animals with T2D showed a significant increase in immobility as compared to control in FST and TST. However, 4 weeks administration of fluoxetine or phloridzin attenuated this effect. A significant decline in GSH, BDNF, TrkB, CREB and ERK levels were noticed in the brain of mice with T2D. These changes were alsoattenuated by administration of phloridzin. Phloridzin may ameliorates T2D-induced depression by mitigating the oxidative stress, and up-regulation of neurotrophins in the brain. Therefore, phloridzin can be used as a therapeutic intervention for the management of depression co-morbid with T2D.

Walking Training Enhances Corticospinal Excitability in Progressive Multiple Sclerosis—A Pilot Study

Background: Inflammatory lesions and neurodegeneration lead to motor, cognitive, and sensory impairments in people with multiple sclerosis (MS). Accumulation of disability is at least partially due to diminished capacity for neuroplasticity within the central nervous system. Aerobic exercise is a potentially important intervention to enhance neuroplasticity since it causes upregulation of neurotrophins and enhances corticospinal excitability, which can be probed using single-pulse transcranial magnetic stimulation (TMS). Whether people with progressive MS who have accumulated substantial disability could benefit from walking rehabilitative training to enhance neuroplasticity is not known.Objective: We aimed to determine whether 10 weeks of task-specific walking training would affect corticospinal excitability over time (pre, post, and 3-month follow-up) among people with progressive MS who required walking aids.Results: Eight people with progressive MS (seven female; 29–74 years old) with an Expanded Disability Status Scale of 6–6.5 underwent harness-supported treadmill walking training in a temperature controlled room at 16°C (10 weeks; three times/week; 40 min at 40–65% heart rate reserve). After training, there was significantly higher corticospinal excitability in both brain hemispheres, reductions in TMS active motor thresholds, and increases in motor-evoked potential amplitudes and slope of the recruitment curve (REC). Decreased intracortical inhibition (shorter cortical silent period) after training was noted in the hemisphere corresponding to the stronger hand only. These effects were not sustained at follow-up. There was a significant relationship between increases in corticospinal excitability (REC, area under the curve) in the hemisphere corresponding to the stronger hand and lessening of both intensity and impact of fatigue on activities of daily living (Fatigue Severity Scale and Modified Fatigue Impact Scale, respectively).Conclusion: Our pilot results support that vigorous treadmill training can potentially improve neuroplastic potential and mitigate symptoms of the disease even among people who have accumulated substantial disability due to MS.

Upregulation of neurotrophins and transforming growth factor-β expression in the bladder may lead to nerve hyperplasia and fibrosis in patients with severe ketamine-associated cystitis.

To investigate the mechanism of bladder nerve hyperplasia and fibrosis in the patients with ketamine-associated cystitis (KC). Sixteen patients with severe KC, six patients with mild KC, and five patients with localized invasive bladder cancer served as control patients. Bladder mucosa specimens were taken during the operations, and the specimens were stained for nerve growth factor (NGF) and S-100 to evaluated nerve hyperplasia. The quantitative Western blot analysis was performed for NGF, brain-derived neurotrophic factor (BDNF), growth-associated protein 43 (GAP-43), tropomyosin receptor kinase A and B (TrkA and TrkB), transforming growth factor-β (TGF-β), phosphorylated extracellular signal-regulated kinases (p-ERK), protein kinase B (p-Akt), and glycogen synthase kinase 3β (p-GSK-3β). The results demonstrated diffuse NGF expression in KC bladder epithelium, lamina propria, and muscle. The GAP-43, NGF, BDNF, TrkA, TGF-β, p-ERK, P-AKT, and p-GSK-3β expression in the bladder mucosa specimens of patients with severe KC was significantly higher than in patients with mild KC and control patients. Expression of neurotrophins was significantly correlated with bladder capacity and pain. NGF and BDNF expression were significantly higher in the KC bladder specimens with strongly positive S-100 staining. TGF-β expression in the bladder specimens was significantly correlated with neurotrophins, p-ERK, P-AKT, and p-GSK-3β levels. Our findings indicate upregulation of neurotrophins, TGF-β, and activation of the cell proliferation kinases plays an important role in nerve hyperplasia and fibrosis mechanisms in severe KC bladders. The neurotrophins and TGF-β interact as cause and effect, leading to bladder hypersensitivity and fibrosis in severe KC.

Astrocyte: An Innovative Approach for Alzheimer's Disease Therapy.

Alzheimer's disease (AD) is a devastating neurological illness with a heavy economic impact. Further comorbidities in combination with the social impact of this disorder increase the urgency of a clearer comprehension of its etiopathogenesis, allowing the execution of novel therapeutic strategies. Despite astrocytes have been widely described as active participant in the regulation of cerebral circuits, available data are still poor. Even less information is available about their precise role in the pathogenesis of illness. Moreover, the scant knowledge about the astrocyte-neuron interplay in health and disease still impedes pioneering discoveries. The focus of this review is to look for new and innovative pharmacological approaches against AD. In order to perform this, we used the following keywords in PubMed search engine: astrocytes, therapy, Alzheimer's disease, and glia in different combinations. With this review, we collected data available in literature describing how also astrocytes besides neurons might be new potential targets for drug discovery. Different approaches currently being studied include modulation of glutamate transporters expression, astroglial genetic manipulation, free radicals inhibition, up-regulation of neurotrophins, and regulation of astrogliosis and neuroinflammation. Since several studies already demonstrated that astrocytes are definitely involved in AD pathogenesis, these cells can represent a promising new therapeutic target.

Role of Physical Activity in Parkinson's Disease.

Parkinson's disease (PD) is common, age-dependent neurodegenerative disorder caused by a severe loss of the nigrostriatal dopaminergic neurons. Given the projected increase in the number of people with PD over the coming decades, interventions aimed at minimizing morbidity and improve quality of life are crucial. There is currently no fully proven pharmacological therapy that can modify or slow the disease progression. Physical activity (PA) can complement pharmacological therapy to manage the inherent decline associated with the disease. The evidence indicates that upregulation of neurotrophins and nerve growth factors are potentially critical mediators of the beneficial effects associated with PA. Accumulating evidence suggests that patients with PD might benefit from PA in a number of ways, from general improvements in health to disease-specific effects and potentially, disease-modifying effects. Various forms of PA that have shown beneficial effects in PD include – aerobic exercises, treadmill training, dancing, traditional Chinese exercise, yoga, and resistance training. In this review, we explored available research that addresses the impact of exercise and PA on PD. The original articles with randomized control trials, prospective cohort studies, longitudinal studies, meta-analysis, and relevant review articles from 2005 to 2017 were selected for the present review. Many gaps remain in our understanding of the most effective exercise intervention for PD symptoms, the mechanisms underlying exercise-induced changes and the best way to monitor response to therapy. However, available research suggests that exercise is a promising, cost-effective, and low-risk intervention to improve both motor and nonmotor symptoms in patients with PD. Thus, PA should be prescribed and encouraged in all PD patients.

Post-stroke depression: Mechanisms and pharmacological treatment.

Depression, the most frequent psychiatric disorder following ischaemic stroke, negatively affects survivals' functional outcome, response to rehabilitation and quality of life. Approximately, one-third of them are affected by post-stroke depression (PSD), making it a serious social and public health problem and anti-depressant preventive and curative therapies worth investigating. However, a two-way association between depression and stroke has been also established: stroke increases the risk of PSD, but depression is an independent risk factor for stroke. The pathophysiology of PSD is presumably multifactorial, involving a combination of various ischaemia-induced neurobiological dysfunctions in the context of psychosocial distress. The damage of frontal-basal ganglia brainstem pathway suggested alterations of monoaminergic neurotransmitter systems. Several lines of evidence point to a relationship between neuroinflammatory response to acute ischaemic stroke, stress activation of the hypothalamic-pituitary-adrenal (HPA) axis and the impairment of adaptive response (neurogenesis) within a background of altered energy metabolism (i.e. mitochondrial dysfunction). The complexity of PSD mechanisms makes its biologically-based prevention and treatment a difficult task. So far, especially the selective serotonin (5-hydroxytriptamine, 5-HT) reuptake inhibitors (SSRIs) have mainly proved to be clinically active in preventing and treating PSD, although their effects have not been demonstrated unequivocally and they may cause bleeding and intracerebral haemorrhage. Besides the primary pharmacological activity of SSRIs (i.e. the inhibition of neuronal 5-HT reuptake) there is evidence supporting their pleiotropic mechanisms of action: anti-inflammatory and enhanced neurogenesis through the up-regulation of neurotrophins, conceivably supported by the stimulation of mitochondrial energy metabolism. In the future, novel developments might point at anti-cytokine modulators which can improve symptoms of depression, especially in subjects affected by inflammation processes. This review will address the various areas of epidemiology, pathophysiology, preventive and therapeutic strategies for PSD. The activity of SSRIs in clinical trials, as well as their pharmacology, pharmacokinetics, safety and mechanisms of action, will be examined in detail. A final section will deal with the effect of depression as risk factor for stroke. The literature on PubMed from 1990 to 2017 was reviewed.

Upregulation of neurotrophins by S 47445, a novel positive allosteric modulator of AMPA receptors in aged rats

At molecular levels, it has been shown that aging is associated with alterations in neuroplastic mechanisms. In this study, it was examined if the altered expression of neurotrophins observed in aged rats could be corrected by a chronic treatment with S 47445 (1–3–10mg/kg, p.o.), a novel selective positive allosteric modulator of the AMPA receptors. Both the mRNA and the protein levels of the neurotrophins Bdnf, NT-3 and Ngf were specifically measured in the prefrontal cortex and hippocampus (ventral and dorsal) of aged rats. It was found that 2-week-treatment with S 47445 corrected the age-related deficits of these neurotrophins and/or positively modulated their expression in comparison to vehicle aged rats in the range of procognitive and antidepressant active doses in rodents.Collectively, the ability of S 47445 to modulate various neurotrophins demonstrated its neurotrophic properties in two major brain structures involved in cognition and mood regulation suggesting its therapeutic potential for improving several diseases such as Alzheimer’s disease and/or Major Depressive Disorders.

Exogenous Modulation of Retinoic Acid Signaling Affects Adult RGC Survival in the Frog Visual System after Optic Nerve Injury.

After lesions to the mammalian optic nerve, the great majority of retinal ganglion cells (RGCs) die before their axons have even had a chance to regenerate. Frog RGCs, on the other hand, suffer only an approximately 50% cell loss, and we have previously investigated the mechanisms by which the application of growth factors can increase their survival rate. Retinoic acid (RA) is a vitamin A-derived lipophilic molecule that plays major roles during development of the nervous system. The RA signaling pathway is also present in parts of the adult nervous system, and components of it are upregulated after injury in peripheral nerves but not in the CNS. Here we investigate whether RA signaling affects long-term RGC survival at 6 weeks after axotomy. Intraocular injection of all-trans retinoic acid (ATRA), the retinoic acid receptor (RAR) type-α agonist AM80, the RARβ agonist CD2314, or the RARγ agonist CD1530, returned axotomized RGC numbers to almost normal levels. On the other hand, inhibition of RA synthesis with disulfiram, or of RAR receptors with the pan-RAR antagonist Ro-41-5253, or the RARβ antagonist LE135E, greatly reduced the survival of the axotomized neurons. Axotomy elicited a strong activation of the MAPK, STAT3 and AKT pathways; this activation was prevented by disulfiram or by RAR antagonists. Finally, addition of exogenous ATRA stimulated the activation of the first two of these pathways. Future experiments will investigate whether these strong survival-promoting effects of RA are mediated via the upregulation of neurotrophins.

Novel Physiotherapy Approach for Multiple Sclerosis

Multiple sclerosis is a chronic, complex disease with a variety of clinical symptoms and affects mainly young and middle-aged people. Research and therapies are focused on the early phase of MS, especially relapsing-remitting MS (RRMS). There is the need for novel therapeutic strategies especially oriented towards neuroprotection in the chronic phase. Accumulating data outlines the beneficial role of physiotherapy in individuals with MS. A physiotherapy program improves muscle strength, balance, walking capacity and decreases spasticity, while also enhancing mood, cognitive function and reducing fatigue. Currently, neurorehabilitation programs are among themost popular therapies for reducing the disabilities and social disadvantages of MS patients. Rehabilitation strategies in MS should be based on the promotion of motor learning-related neuroplasticity improving functional outcomes. Therefore, the interdisciplinary team is essential for maximizing the patient's ability to function. In this review current treatment, symptoms and clinical phenotypes, the role of rehabilitation, main measures that are recommended to estimate disability, impairment and handicap of MS are presented. Additionally, aerobic training as a factor enhances cognitive function by upregulation of neurotrophins, such as brain-derived neurotrophic factor(BDNF) was showed. First of all this review focuses on the novel methods used in multiple sclerosis patients including telerehabilitation and cryostimulation.

Molecular Mechanisms of Environmental Enrichment: Impairments in Akt/GSK3β, Neurotrophin-3 and CREB Signaling

Experience of mice in a complex environment enhances neurogenesis and synaptic plasticity in the hippocampus of wild type and transgenic mice harboring familial Alzheimer's disease (FAD)-linked APPswe/PS1ΔE9. In FAD mice, this experience also reduces levels of tau hyperphosphorylation and oligomeric β-amyloid. Although environmental enrichment has significant effects on brain plasticity and neuropathology, the molecular mechanisms underlying these effects are unknown. Here we show that environmental enrichment upregulates the Akt pathway, leading to the downregulation of glycogen synthase kinase 3β (GSK3β), in wild type but not FAD mice. Several neurotrophic signaling pathways are activated in the hippocampus of both wild type and FAD mice, including brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF), and this increase is accompanied by the upregulation of the BDNF receptor, tyrosine kinase B (TrkB). Interestingly, neurotrophin-3 (NT-3) is upregulated in the brains of wild type mice but not FAD mice, while insulin growth factor-1 (IGF-1) is upregulated exclusively in the brains of FAD mice. Upregulation of neurotrophins is accompanied by the increase of N-Methyl-D-aspartic acid (NMDA) receptors in the hippocampus following environmental enrichment. Most importantly, we observed a significant increase in levels of cAMP response element- binding (CREB) transcripts in the hippocampus of wild type and FAD mice following environmental enrichment. However, CREB phosphorylation, a critical step for the initiation of learning and memory-required gene transcription, takes place in the hippocampus of wild type but not of FAD mice. These results suggest that experience of wild type mice in a complex environmental upregulates critical signaling that play a major role in learning and memory in the hippocampus. However, in FAD mice, some of these pathways are impaired and cannot be rescued by environmental enrichment.

Minocycline up-regulates the expression of brain-derived neurotrophic factor and nerve growth factor in experimental autoimmune encephalomyelitis

Previous evidence demonstrated that minocycline could ameliorate clinical severity of experimental autoimmune encephalomyelitis and exhibit several anti-inflammatory and neuroprotective activities. However, few studies have been carried out to assess its effects on the expression of neurotrophins in experimental autoimmune encephalomyelitis or multiple sclerosis. Here we investigated the alteration of brain-derived neurotrophic factor and nerve growth factor in the sera, cerebral cortex, and lumbar spinal cord of experimental autoimmune encephalomyelitis C57 BL/6 mice in vivo as well as the splenocytes culture supernatants in vitro after minocycline administration. Our results demonstrated that minocycline could up-regulate the expression of brain-derived neurotrophic factor and nerve growth factor both in peripheral (sera and splenocytes culture supernatants) and target organs (cerebral cortex and lumber spinal cord) of mice with experimental autoimmune encephalomyelitis. These data suggest that up-regulation of neurotrophins in experimental autoimmune encephalomyelitis may be a novel neuroprotective mechanism of minocycline.

Nicotine dependence and serum BDNF levels in male patients with schizophrenia

Schizophrenia is associated with a significantly high prevalence of smoking. Upregulation of neurotrophins by nicotine is well established. Accumulating evidence shows that brain-derived neurotrophic factor (BDNF) may be involved in the pathophysiology of schizophrenia. The purposes of this study were to compare BDNF levels in smokers to nonsmokers with schizophrenia and examine the association between BDNF levels and psychopathological symptoms. Serum BDNF levels were measured in 139 male inpatients with DSM-IV schizophrenia: 102 smokers and 37 nonsmokers. Symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS). The positive PANSS symptoms were lower in smokers than in nonsmokers, while the negative symptoms were lower in those who smoked more cigarettes. BDNF levels were significantly higher in smokers than in nonsmokers (p < 0.05). Higher BDNF levels correlated with fewer negative symptoms and with smoking more cigarettes. The fewer positive symptoms in smokers and fewer negative symptoms in those who smoked more cigarettes may be associated with nicotine-induced upregulation of BDNF.

Tarenflurbil Protection from Cytotoxicity is Associated with an Upregulation of Neurotrophins

Both epidemiological and clinical trial data have demonstrated the value of some non-steroidal anti-inflammatory drugs (NSAIDs) and NSAID derivatives for lowering the incidence, slowing the progression, and reducing the symptomatic severity of Alzheimer's disease (AD). Tarenflurbil (R-flurbiprofen, MPC-7869, Myriad Pharmaceuticals) is an attractive compound because its usage is not associated with the adverse side effects of NSAIDs. Although tarenflurbil has been reported to be a selective amyloid-beta 42 (Abeta_{42})-lowering agent, the concentrations of drug that achieved an IC50 for Abeta_{42}-lowering activity are approximately two orders of magnitude higher than the concentrations found in the brain (i.e., 1-5 microM). Therefore, the mechanism by which this compound accomplishes behavioral/physiological effects requires further study. The present investigation reports that clinically relevant concentrations of tarenflurbil (i.e., 1-5 microM) protect both cultured human neuroblastoma cell lines and primary neurons from cytotoxicity associated with exposure to Abeta_{42} or H_{2}O_{2}. In concert with this protection, there is an upregulation of neurotrophins [i.e., nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF)]. Furthermore, blocking exogenous NGF or BDNF by binding it to antibody prevents tarenflurbil from protecting human neuronal cells from Abeta_{42} and H_{2}O_{2} cytotoxicity. These findings suggest that up-regulation of neurotrophins might represent an underlying mechanism contributing to the beneficial effects seen with tarenflurbil in AD.

Enhanced Neurotrophin Synthesis and Molecular Differentiation in Non-Transformed Human Retinal Progenitor Cells Cultured in a Rotating Bioreactor

One approach to the treatment of retinal diseases, such as retinitis pigmentosa, is to replace diseased or degenerating cells with healthy cells. Even if all of the problems associated with tissue transplant were to be resolved, the availability of tissue would remain an ongoing problem. We have previously shown that transformed human retinal cells can be grown in a NASA-developed horizontally rotating culture vessel (bioreactor) to form three-dimensional-like structures with the expression of several retinal specific proteins. In this study, we have investigated growth of non-transformed human retinal progenitors (retinal stem cells) in a rotating bioreactor. This rotating culture vessel promotes cell-cell interaction between similar and dissimilar cells. We cultured retinal progenitors (Ret 1-4) alone or as a co-culture with human retinal pigment epithelial cells (RPE, D407) in this system to determine if 3D structures can be generated from non-transformed progenitors. Our second goal was to determine if the formation of 3D structures correlates with the upregulation of neurotrophins, basic fibroblast growth factor (bFGF), transforming growth factor alpha (TGFalpha), ciliary neurotrophic factor (CNTF), and brain-delivered neurotrophic factor (BDNF). These factors have been implicated in progenitor cell proliferation, commitment, differentiation, and survival. We also investigated the expression of the following retinal specific proteins in this system: neuron specific enolase (NSE); tyrosine hydroxylase (TH); D(2)D(3), D(4) receptors; protein kinase-C alpha (PKCalpha), and calbindin. The 3D structures generated were characterized by phase and scanning transmission electron microscopy. Retinal progenitors, cultured alone or as a co-culture in the rotating bioreactor, formed 3D structures with some degree of differentiation, accompanied by the upregulation of bFGF, CNTF, and TGFalpha. Brain-derived neurotrophic factor, which is expressed in vivo in RPE (D407), was not expressed in monolayer cultures of RPE but expressed in the rotating bioreactor-cultured RPE and retinal progenitors (Ret 1-4). Upregulation of neurotrophins was noted in all rotating bioreactor-cultured cells. Also, upregulation of D(4) receptor, calbindin, and PKCalpha was noted in the rotating bioreactor-cultured cells. We conclude that non-transformed retinal progenitors can be grown in the rotating bioreactor to form 3D structures with some degree of differentiation. We relied on molecular and biochemical analysis to characterize differentiation in cells grown in the rotating bioreactor.

Familial Amyloid Polyneuropathy: Receptor for Advanced Glycation End Products-Dependent Triggering of Neuronal Inflammatory and Apoptotic Pathways

Familial amyloid polyneuropathy (FAP) is a neurodegenerative disorder associated with extracellular deposition of mutant transthyretin (TTR) amyloid fibrils, particularly in the peripheral nervous system. We have hypothesized that binding of TTR fibrils to the receptor for advanced glycation end products (RAGE) on critical cellular targets is associated with a destructive stress response underlying peripheral nerve dysfunction. Analysis of nerve biopsy samples from patients with FAP (n = 16) at different stages of disease (0-3), compared with age-matched controls (n = 4), by semiquantitative immunohistology and in situ hybridization showed increased levels of RAGE, beginning at the earliest stages of the disease (FAP 0; p < 0.02) and especially localized in axons. Upregulation of proinflammatory cytokines (tumor necrosis factor-alpha and interleukin-1beta) (approximately threefold; p < 0.02) and the inducible form of nitric oxide synthase (iNOS) ( approximately 2.5-fold; p < 0.04) was also observed in a distribution overlapping RAGE expression. Tyrosine nitration and increased activated caspase-3 in axons from FAP patients (p < 0.03) were apparent. Although these data suggest the presence of ongoing neuronal stress, there was no upregulation of neurotrophins (nerve growth factor and neurotrophin-3) in FAP nerves. Studies on cultured neuronal-like, Schwann, and endothelial cells incubated with TTR fibrils displayed RAGE-dependent expression of cytokines and iNOS at early times (6 and 12 hr, respectively), followed by later (24 hr) activation of caspase-3 and DNA fragmentation. We propose that the interaction of TTR fibrils with RAGE may contribute to cellular stress and toxicity in FAP. Furthermore, there is an apparent lack of responsiveness of Schwann cells in FAP nerve to provide neurotrophic factors.

Suppression of post-ischemic-induced Fos protein expression by an antisense oligonucleotide to c-fos mRNA leads to increased tissue damage

Activation of c-fos, an immediate early gene, and the subsequent upregulation of Fos protein expression occur following neural injury, including focal cerebral ischemia (fci). Fos and Jun form a heterodimer known as activator protein 1, which regulates the expression of many late effector genes. To study the downstream effects of c-fos expression following ischemia, we suppressed the translation of c-fos by administering an antisense oligonucleotide (AO) to c-fos mRNA. Eighteen hours prior to fci, male, Long Evans (LE) rats received intraventricular injections of AO, mismatched AO (MS) or artificial cerebrospinal fluid (aCSF). Fci was induced by permanent right middle cerebral artery occlusion. At 24-h post-occlusion, neurological function was assessed, and the animals were sacrificed. The brains were removed and stained with triphenyltetrazolium chloride for infarct volume determination. Fos immunohistochemistry was performed in separate animals to determine the effects of treatment on Fos expression number of Fos positive cells. AO administration reduced the number of cells with fci-induced Fos expression by ∼75%. No differences in neurological scores existed between any of the groups. AO-treated LE developed larger infarcts (40.1±1.0%, mean±S.D., p<0.001) than MS- or aCSF-treated controls (34.3±1.0%, 34.6±1.0%, respectively). These results suggest that c-fos activation and subsequent Fos protein expression exerts a neuroprotective effect, which is likely via upregulation of neurotrophins, following focal cerebral ischemia. This response, among others, may contribute to brain adaptation to injury that underlies functional recovery after stroke.

Role of neurotrophins and neurotrophins receptors in the in vitro invasion and heparanase production of human prostate cancer cells.

The role of the neurotrophins (NTs) and their corresponding receptors (NTRs) TrkA, TrkB, TrkC, and p75NTR in neoplasia has received relatively little attention. However, because malignant cell migration within the prostate occurs predominantly by direct extension around prostatic nerves, the presence and possible upregulation of NTs from autocrine/paracrine sources and NTR expression within prostate epithelial tumor cells may be important in metastasis. We have been addressing their expression and interactions in human prostate cancer cell lines (LNCaP, PC-3, and DU145) and their role in prostate cancer invasion. In this study, we demonstrated that nerve growth factor (NGF), the prototypic NT, and NT-4/5 increased in vitro invasion through a reconstituted basement membrane and induced time- and dose-dependent expression of heparanase, a heparan sulfate-specific endo-beta-D-glucuronidase, an important molecular determinant of tumor metastasis. The NT effects were most marked in the DU 145 brain-metastatic cells and were detected at NT concentrations sufficient to fully saturate both low- and high-affinity NTRs. Additionally, we characterized the molecular expression of NT high-affinity (Trk) and low-affinity (p75NTR) receptors in these cell lines by reverse transcription-polymerase chain reaction. These lines had negligible trkA and trkC expression, although trkB was expressed in the three prostatic tumor cell lines examined. The brain-metastatic DU 145 cells were also positive for p75NTR. Our data showed that the NTs and NTRs are important in metastasis and that their expression coincides with transformation to a malignant phenotype capable of invasion along the perineural space and extracapsular metastasis to distant sites. These findings set the stage for more research into this area as related to prostate cancer evolution and may improve therapy for prostate cancer metastasis.