All Articles

Simon Wing Fai Mok, Vincent Kam Wai Wong, Betty Yuen Kwan Law*

Chronic diseases are the leading causes of physical impairments and mortality in the world. The functional role of autophagy in maintaining cellular homeostasis implies that the molecular machinery is a compelling pharmaceutical target for such disorders involving overall body imbalance. Therefore, autophagy modulators appeared to be the ideal source for hunting of novel and effective pharmaceutical interventions. Law et al., have performed a systematic review on more than 30 different Chinese herbal medicine (CHM)-derived bioactive compounds capable of regulating autophagy activity. The successful experimental and clinical applications of these compounds which have not been previously documented have been discussed. Notably, most of the reported novel applications are associated with chronic dysfunctions.

John R. Zuniga^1*, Tara F. Renton²

In the absence of effective non-surgical methods to permanently resolve neuropathic pain involving the lip, chin, or tongue following inferior alveolar and/or lingual nerve injury, microsurgery of these nerves has been a recommended modality. In two ambispective clinical trials, we demonstrated that phenotypic differences exist between individuals with neuropathic pain and those without neuropathic pain of the trigeminal nerve. In those without neuropathic pain before microsurgery there was a 2% incidence of neuropathic pain after microsurgery whereas there was a 67% incidence of neuropathic pain after microsurgery, some reporting an increase in pain levels, when neuropathic pain was present before microsurgery. The recurrence of neuropathic pain after trigeminal microsurgery is likely multifactorial and might not depend on factors that normally affect useful or functional sensory recovery in those who have no neuropathic pain. These results indicate that the understanding of post-traumatic trigeminal neuropathic pain is incomplete. Predictive outcomes of treatment will probably improve when the etiology is better defined to allow mechanistic or target-/site-specific treatment. Until then, non-surgical treatment for post-traumatic trigeminal neuropathic pain remains a safer option. Risk factors have been identified for patients developing chronic post -surgical pain due to post-traumatic neuropathy. These include psychological, medical, and age related factors. The best management may lie in preoperative screening and avoidance of elective surgery for high risk patients as the prevention of post-traumatic trigeminal neuropathic pain in the absence of effective medical or surgical interventions.

Milena A. Gianfrancesco and Lisa F. Barcellos*

Several studies conducted around the world over the last decade have demonstrated that early childhood and adolescent obesity are significant risk factors for MS susceptibility. This association has been largely confirmed in females, while evidence supporting a strong role for obesity and risk of MS in males has been mixed. Further, interaction between increased body mass index and genetic as well as environmental factors in MS susceptibility has been proposed, and evidence of a causal relationship has recently been established. In this review, we discuss findings supporting the significant association between obesity and MS, as well as identify areas for future investigation.

Alejandro K. Samhan-Arias^1*, Carmen López-Sánchez^2*, Dorinda Marques-da-Silva¹, Ricardo Lagoa^1,2,3Virginio Garcia-Lopez^2,4, Virginio García-Martínez²Carlos Gutierrez-Merino^1,#

Cytochrome b5 reductase (Cb5R) and cytochrome b5 (Cb5) are coupled redox systems with a high potential as biomarkers of health and disease in the brain because they regulate metabolic pathways that are essential to maintain normal neuronal function, like lipid biosynthesis, steroid and xenobiotics metabolism, neuronal bioenergetics and production of reactive oxygen species. Mutations of the Cb5R reported in humans produce recessive congenital methemoglobinemia of type II, a disease with severe clinical neurological dysfunctions. The isoform 3 of Cb5R (Cb5R3) and Cb5 are highly expressed in pyramidal neurons of the primary and secondary motor areas of frontoparietal cerebral cortex, hippocampus, vestibular, reticular and motor nuclei of the cerebellum and brain stem, and also in Purkinje and granule neurons of the cerebellum cortex. These brain areas are highly prone to undergo oxidative stress-induced neurodegeneration and their functional impairment can account for neurological deficits reported in type II congenital methemoglobinemia.

John F. Crary

Extensive data supports the amyloid cascade hypothesis, which states that Alzheimer’s disease (AD) stems from neurotoxic forms of the amyloid-beta(Aβ)peptide. But the poor correlation between Aβ plaques and neurodegeneration/cognitive impairment, the spaciotemporal disparity between Aβ and tau pathology, and the disappointing results following several large clinical trials using Aβ-targeting agents are inconsistent with this explanation. The most perplexing inconsistency is the existence of AD-type dementia patients that develop abundant neurofibrillary tangles that are indistinguishable from those in early to moderate-stage AD in the absence of compelling evidence of amyloid toxicity. This neuropathological phenotype, which is distinct from other diseases with tangles, represents a conceptual disconnect, because it does not fall within any previously established category of tauopathy and ostensibly invalidates the amyloid cascade hypothesis. Instead, recent efforts have led to consensus criteria for a new alternative diagnostic category, which presupposes that these tangle-only dementia patients represent extreme examples of a distinct primary age-related tauopathy (PART) that is universally observed, albeit to varying degrees, in the aging brain. The cause of PART is unknown, but sufficient evidence exists to hypothesize that it stems from an Aβ-independent mechanism, such as mechanical injury. Should the PART hypothesis withstand further experimental testing, it would represent a shift in the way a subset of subjects with AD neuropathological change are classified and has the potential to focus and reaffirm the amyloid cascade hypothesis.

Maria Amelia Chang

This is a clinical commentary that expands on an initial attempt to classify possible adverse effects (AE) of repeated and long-term use of Botox A (BTX) to manage post-stroke spasticity into three types, local, systemic and subclinical AE. Clinical manifestations of non-local, systemic AE from widespread diffusion of BTX are presented to help clinicians and researchers recognize changes that may develop in post-stroke patients. Subclinical AE of muscle atrophy and bone degradation may hinder return of motor control and increase certain risk factors. Even with increased trend in the use of BTX, very little is written about long term effects of repeated BTX injections for post-stroke spasticity coupled by fewer clinicians who report what they find in actual practice. Although published studies infrequently report AE, it will be an error if it is attributed to an extension of the disease process in stroke.

Kimbra Kenney, Margalit Haber, Franck Amyot, Cora Davis, Angela Pronger, Carol Moore, Ramon Diaz-Arrastia*

Traumatic cerebral vascular injury (TCVI) is a frequent, perhaps universal, feature after traumatic brain injury (TBI) and may be responsible for some TBI-related chronic disability. Because there are multiple pharmacologic and non-pharmacologic therapies that promote vascular health, TCVI is an attractive target for therapeutic intervention after TBI. The cerebral microvasculature (CMV) is a component of the neurovascular unit (NVU) coupling neuronal metabolism with local cerebral blood flow. The NVU participates in the pathogenesis of TBI, either directly from physical trauma or as part of the cascade of secondary injury that occurs after TBI. Pathologically, there is extensive microvascular injury in humans and experimental animals, identified with either conventional light microscopy or ultrastructural examination. It is seen in acute and chronic TBI and even described in chronic traumatic encephalopathy (CTE). Non-invasive, physiologic measures of cerebral microvascular function show dysfunction after TBI in humans and experimental animal models of TBI. These include imaging sequences Arterial Spin Labeling (ASL), Transcranial Doppler, Near InfraRed Spectroscopy (NIRS), etc. Understanding the pathophysiology of TCVI, a relatively under-studied component of TBI, has promise for developing novel TBI therapies.

Rohit Aiyer^1*, Lynne Voutsinas², Yasir El-Sherif³

Barbro H Skogman^1*, Johanna Sjöwall², Per-Eric Lindgren³

Erna A. van Niekerk^*

 Spinal cord injury (SCI) research continues to make substantial progress in identifying both neuron-intrinsic and neuron-extrinsic mechanisms that limit central nervous system (CNS) plasticity and regeneration. The identification of these mechanisms has in turn led to several novel strategies for therapeutically enhancing recovery of the injured CNS. Despite this progress, clinical translation remains a challenge for several reasons, including: 1) problems in projecting beneficial outcomes from small animal models to primate systems, 2) a lack of robust improvement in functional outcomes in animal models, and 3) difficulty replicating published reports in the field. Collectively, while the field has seen great progress, reconstructing the exquisite circuitry of the injured human CNS will require yet greater progress in both understanding of basic mechanisms underlying axonal growth and guidance, and testing of optimized therapies in models more predictive of potential human benefit.

Vera Clemens, Francesca Regen, Julian Hellmann-Regen*

Major depression (MDD) is one of the leading global causes of all non-fatal burden of disease. Involving monoaminergic imbalances, but also hormonal, structural and inflammatory alterations, the underlying pathogenesis remains incompletely understood. The antidepressant drug fluoxetine, which may be considered the “prototype” of all selective serotonin reuptake inhibitors (SSRI), appears to affect all of these processes. Interestingly, this is also the case for retinoic acid (RA), the highly potent active metabolite of vitamin A. In this review, we discuss RA signaling as a central mechanism of action – and missing link – for the multiple, pleiotropic effects of fluoxetine in the CNS, suggesting that direct inhibition of CYP-450-mediated RA catabolism by fluoxetine results in increased local concentration, and enhanced paracrine RA signaling in the CNS.

Gregory D. Arnone¹, Matt Wonais², Andreas Linninger^1,3, Ankit I. Mehta^1*

Deepika Rajesh, H. Ian Robins*, Steven P. Howard

The poor prognosis of malignant glioma patients highlights the need to develop low toxicity, tumor specific agents with the ability to synergize with proven efficacious treatment modalities, e.g., ionizing irradiation. This paper investigates the potential of BNP1350 (karenitecin), a topoisomerase I-targeting anticancer agent, and flavopridol a cyclin-dependent kinase inhibitor as radiosensitizers at clinically relevant doses in glioblastoma cell lines. A clonogenic survival and apoptosis assays were performed to test the effect of karenitecin (0.1 nM to 10 nM), flavopridol, (50 nM to 500 nM), radiation (1 Gy to 5.5 Gy) and a combination of radiation and karenitecin or radiation and flavopridol on the glioma cell lines T986 and M059K. Cells were stained for cyclins B and D using antibodies followed by flow cytometry. Propidium Iodide staining was used to reveal the various phases of the cell cycle; cyclin staining in the G0/G1 and G2/M phase of the cell cycle was estimated as the Mean Fluorescence Intensity (MFI) after subtracting the MFI recorded by the isotype controls. Results demonstrated that in irradiated cells, pretreatment with karenitecin induced apoptosis, a transient arrest in the G2/M phase of the cell cycle and increased the expression of cyclin B1. Flavopridol treatment also induced apoptosis and a transient block in the G2/M phase of the cell cycle. The combined effects of karenitecin and flavopridol displayed synergistic effects. The unique radiosensitizing activity of orally administrable karenitecin and flavopridol is consistent with continued investigation of these compounds preclinically, as well as in the clinical setting.

Yeu-Shiuan Su^1*, Wei-Hsin Sun^1,2*

Serotonin [5-hydroxytryptamine (5-HT)] is an inflammatory mediator which contributes to inflammatory pain. We previously demonstrated that 5-HT-induced mechanical hyperalgesia is mediated by 5-HT2B, but not by other 5-HT receptors. Our recent article provided further evidence how 5-HT2B regulates 5-HT-induced mechanical hyperalgesia, and suggested, that 5-HT2Bmediates mechanical hyperalgesia through Gq/11-phospholipase Cβ (PLCβ)-protein kinase Cε (PKCε) pathway. Interestingly, transient receptor potential vanilloid 1 (TRPV1) also involves in 5-HT2B-mediated hyperalgesia. It was the first evidence that 5-HT receptor regulates TRP channel to affect mechanical hyperalgesia. It is a commentary on the recent article that suggests distinct roles of peptidergic (IB4-negative) and non-peptidergic (IB4-positive) nociceptors in regulating 5-HT-induced mechanical hyperalgesia. In IB4-negative neurons, 5-HT2B in response to 5-HT mediates PLCβ-PKCε to regulate TRPV1 function. In IB4-positive neurons, 5-HT2B may control 5-HT3 or other channels to regulate mechanical hyperalgesia.

Lara A. Haeusser, Lothar Kanz, Marcus M. Schittenhelm, Kerstin M. Kampa-Schittenhelm^*

The endocannabinoid system is extensively studied in neuroscience and clinical use of cannabinoid derivatives as substances with remarkable spasmolytic effects in multiple sclerosis and antiemetic potential in cancer therapy as well as pain-relieving properties is broadly acknowledged.

However, it becomes increasingly apparent, that in addition cannabinoids exert manifold functions in various organ systems, such as the immune system, the reproductive or cardiovascular system among others. Moreover, interactions with signaling pathways involved in programmed cell death, angiogenesis, metastasis or anti-tumor immunity make it highly suggestive that cannabinoids may have therapeutic potential in the treatment of cancer. Indeed, detailed reports have repeatedly shown anticancer efficacy in solid and hematologic tumor models, best characterized in human gliomas.

Anecdotal evidence of blast control in a young patient with acute myeloid leukemia has led us to systematically investigate the potential use of cannabinoids in the treatment of acute leukemia.

Owing to the critical cellular role of lysosomes in the myelination, mounting studies focus on the mechanisms underlying exocytosis of lysosome in nervous system has emerged. In this paper, we briefly introduce the recent advances in this respect.

These data are summarized herein in the context of key data regarding anticancer efficacy of cannabinoids.

James Giordano^1,2*, Kira Becker^1,3, John R. Shook⁴

Neuroethics is a relatively new, yet ever expanding discipline, which focuses on the “neuroscience of ethics” and the “ethics of neuroscience”. In this essay, we discuss the literature describing the “neuroscience of ethics”. Current approaches to employing neuroscientific techniques and tools to elucidate brain processes serving ethical decision making has evolved from prior psychological studies of how and why humans believe and act in ways deemed to be moral. While a number of neuroanatomical pathways have been defined as participatory in certain types of decision-making, it appears that none are exclusively dedicated to moral cognition or actions. Moreover, attempts at enhancing morality through neurological interventions are plagued by differing constructs of what constitutes moral action in various contexts. Herein, we review developments in neuroscientific studies of morality, and present a rational view of the capabilities, limitations and responsibilities that any genuine neuroethical address and discourse should regard.

GJ de Borst*, V.E.C. Pourier

Eduardo NC Bergamaschi¹, Fernanda C Nunes^2,3, Victor W de Oliveira³, Alessandra Laitart³, Maria L Benevides³, Jean C Nunes^2,3*

 Pain is a common and often disabling symptom in Parkinson’s disease (PD) which has received increasing attention in recent years. Headache represents a common form of pain among the general population, but there are few studies on this symptom in PD. In 2014, our group reported a lower prevalence of headache in PD patients compared to the general population, as well as an association between the predominant side of headache and the side of initial motor signs of PD. Since then, there has been few new data on the specific issue of headache in PD patients, though several recent studies have contributed to the understanding of pain in PD, both in terms of clinical and pathophysiological aspects, including new observations on pain association with side of motor symptom onset. Here, we review those studies, and re-discuss our own findings in comparison to the current information available. A better comprehension of pain physiology in PD could facilitate the development of new therapeutic approaches, thus providing a better quality of life for PD patients.

Masashi Kanayama¹, Mari L. Shinohara^2*

 Abstract Autoimmune diseases of the central nervous system (CNS), such as multiple sclerosis (MS), are characterized by infiltration of pathogenic immune cells in the CNS. Cells infiltrated in the CNS express pro-inflammatory molecules and cause demyelination. The direct impact of lung immune responses was not previously considered in the pathogenesis of CNS inflammation. However, it recently became clear that the lung acts as a hub organ of pathogenic T cells that are migrating to the CNS. More recent studies further showed that inflamed lung has a critical impact on autoimmune CNS inflammation. Here, we discuss the contribution of the lung in the pathogenesis of CNS autoimmune diseases based on recent reports.

Yun-Tian Shen¹, Ying Yuan^1,2, Wen-Feng Su¹, Yun Gu¹, Gang Chen^1*

 The myelin sheath wraps axons is an intricate process required for rapid conduction of nerve impulses, which is formed by two kinds of glial cells, oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. Myelin biogenesis is a complex and finely regulated process and accumulating evidence suggests that myelin protein synthesis, storage and transportation are key elements of myelination, however the mechanisms of regulating myelin protein trafficking are still not very clear. Recently, the evidences of lysosomal exocytosis in oligodendrocytes and Schwann cells are involved in regulated myelination have emerged. In this paper, we briefly summarize how the major myelin-resident protein, as proteolipid protein in the central nervous system and P0 in the peripheral nervous system, transport from lysosome to cell surface to form myelin sheath and focus on the possible mechanisms involved in these processes. Advances in our understanding of glia, as well as new tools engineering, will further improve the knowing of myelin biogenesis.

Esther A. Pelzer^1,2*, Lars Timmermann², Marc Tittgemeyer¹

 Subcortical communication is an important underlying feature for the smooth performance of motor behaviour. Especially movement disorders like Parkinson’s disease show impairment in the basal-ganglio-thalamic and cerebello-thalamic communication; but also an impairment of the direct communication between these two structures has been proposed.

In this review we highlight important clinical findings concerning the pathological communication between these subcortical structures; additionally we propose a new hypothesis in the development of neurodegenerative disease: we assume that axon degeneration is crucially implicated in the development of parkinsonian symptoms and link the current findings to the development of pathological oscillatory activity. New techniques like probabilistic tractography now offer the possibility to in vivo measure axon degeneration by the determination of connectivity decline and allow the combination with electrophysiological recording. We hypothesize that a change in frequency bands in oscillatory activity might be a product of underlying axonal degeneration; moreover axonal degeneration might be worsened by pathological oscillatory activity resulting in a vicious circle. The thalamus, as main relay station between the basal ganglia and the cerebellum seems to be involved in this disease pathology in Parkinson’s disease.

Robert C.A.M. van Waardenburg*

 Tyrosyl-DNA phosphodiesterase I (TDP1), like most DNA repair associated proteins, is not essential for cell viability. However, dysfunctioning TDP1 or ATM (ataxia telangiectasia mutated) results in autosomal recessive neuropathology with similar phenotypes, including cerebellar atrophy. Dual inactivation of TDP1 and ATM causes synthetic lethality. A TDP1H493R catalytic mutant is associated with spinocerebellar ataxia with axonal neuropathy (SCAN1), and stabilizes the TDP1 catalytic obligatory enzyme-DNA covalent complex. The ATM kinase activates proteins early on in response to DNA damage. Tdp1-/- and Atm-/- mice exhibit accumulation of DNA topoisomerase I-DNA covalent complexes (TOPO1-cc) explicitly in neuronal tissue during development. TDP1 resolves 3’- and 5’-DNA adducts including trapped TOPO1-cc and TOPO1 protease resistant peptide-DNA complex. ATM appears to regulate the response to TOPO1-cc via a noncanonical function by regulating SUMO/ubiquitin-mediated TOPO1 degradation. In conclusion, TDP1 and ATM are critical factors for neuronal cell viability via two independent but cooperative pathways.

Becker L¹, Kutz DF², Voelcker-Rehage C^1*

Willemieke M. Kouwenhoven and Marten P. Smidt*

 Two essential monoaminergic neurotransmitter systems are located within the midbrain and the hindbrain region: the mesodiencephalic dopaminergic (mdDA) neurons, which can be divided in the substantia nigra (SN), the ventral tegmental area (VTA), and the serotonergic (5-HT) neurons. In the adult brain these two types of monoaminergic neurons are critical to our neurological health. Dysfunction of the mdDA system has been associated with schizophrenia and Parkinson's Disease (PD), while dysfunction of the 5HT system has in turn been associated with psychiatric diseases such as depression and autism. The homeobox transcription factor Engrailed 1 (En1) is expressed in both types monoaminergic neurons, and is required for the correct programming and survival of the mdDA and 5HT neurons. Recently, we reported on the dual role of En1 in both neurotransmitter systems through its central role in the maintenance of the Isthmic Organizer, which is the embryonic signaling center that instructs and separates dopaminergic and serotonergic neuronal development.

Ramón Martínez-Mármol¹, Mercè Salla-Martret², Daniel Sastre², Irene Estadella², Antonio Felipe^2*

 The adult mammalian brain contains neural stem cells (NSCs) that generate neurons and glial cells throughout the lifetime of an organism. NSCs reside in at least two germinal epithelium regions of the adult brain, the subventricular zone (SVZ) of the lateral ventricles and the subgranular zone of the hippocampus. Newborn neurons incorporate into the existing functional networks and play important innate and adaptive roles in cognition, behavior and tissue repair1,2. The identity of particular neural stem cells that generate different classes of neurons and glia, as well as the molecular mechanisms that governs this process in vivo, is a subject of extensive research and debate. Epidermal Growth Factor Receptor (EGFR) activation is one of the most important pathways controlling neural stem cell number and self-renewal3,4. On the other hand, the Shaker-type delayed rectifier K+ channel Kv1.3 functions during cell proliferation, differentiation and migration in many cell types5. This channel is expressed in brain progenitor cells where participates in modulating their final fate. This review summarizes the major findings concerning Kv1.3 and neural stem cell modulation, emphasizing the combination of Kv1.3 with EGFR as promising pharmacological targets against autoimmune neuro-degenerative diseases.