CNS & Neurological Disorders - Drug Targets (Formerly Current Drug Targets - CNS & Neurological Disorders) - Volume 15, Issue 4, 2016

Background: Hitherto literature indicates that mood stabilizers exert variable effects on oxidative and antioxidative systems, which are involved in the pathogenesis of Bipolar Disorder. Herein we primarily sought to characterize markers of peripheral oxidative stress during euthymia in adults with Bipolar Disorder under current intake of different mood stabilizers (lithium, anticonvulsants and atypical antipsychotics/AAPs). Methods: Peripheral oxidative stress parameters (TBARS/Thiobarbituric acid-reactive-substances, MDA/ malondialdehyde and carbonyl proteins) and antioxidative markers (SOD/Cu/Zn superoxide dismutase, GST/glutathione Stransferase and TAC/total antioxidative capacity) were measured in serum of 115 euthymic bipolar individuals (50 females, 65 males; HAMD<11 and YMRS<8). Differences in (anti)oxidative markers between bipolar participants treated with different mood stabilizing medication were tested with MANCOVAS and ANCOVAS with SPSS.21. Results: Bipolar individuals taking lithium had significantly lower oxidative parameters than test persons without lithium (multivariate effect for MDA and TBARS: F(2/182)= 3.956, p= 0.021; univariate effect for MDA: F(2/182)= 7.880, p= 0.006, Partial η2= 0.041). Subjects with AAPs had significantly higher MDA and TBARS levels compared to participants without AAPs (multivariate effect F(2/182)= 3.122, p= 0.046, Partial η2= 0.033). Patients taking anticonvulsants had significantly lower GST levels than patients without antiepileptic medication (F(1/165)= 4.501, p= 0.035, Partial η2= 0.027). Conclusion: Lithium taking participants had the lowest MDA and TBARS levels, while AAP taking test persons had high oxidative stress markers. The observed effects on oxidative markers may provide a mechanistic basis for understanding lithium’s neuroprotective effects.

Autism spectrum disorder (ASD) and Alzheimer's disease (AD) are neurodevelopmental and neurodegenerative disorders respectively, with devastating effects not only on the individual but also the society. Collectively, a number of factors contribute to the expression of ASD and AD. It is of utmost curiosity that these disorders express at different stages of life and there is an involvement of certain susceptible genes. This genetic basis makes the background of common associations like memory deficits, cognition changes, demyelination, oxidative stress and inflammation, an integral part of both disorders. Modern technology resulting in genetically modified crops and increase in gadgets emitting electromagnetic frequencies have resulted in enhanced risks for neurological dysfunctions and disorders like ASD and AD. Subsequent advances in the psychological, pharmacological, biochemical and nutritional aspects of the disorders have resulted in the development of newer therapeutic approaches. The common clinical features like language impairment, executive functions, and motor problems have been discussed along with the patho-physiological changes, role of DNA methylation, myelin development, and heavy metals in the expression of these disorders. Psychopharmacological and nutritional approaches towards the reduction and management of risk factors have gained attention from the researchers in recent years. Current major therapies either target the inflammatory pathways or reduce cellular oxidative stress. This contribution focuses on the commonalities of the two disorders.

Bipolar Disorder (BD) is characterized by recurring mood swings, which are not completely understood yet. So far, it is an accepted theory that multiple factors contribute to pathogenesis of BD according to the vulnerability-stressmodel. This model combines on the one hand biological predisposing vulnerability, and on the other hand several chronic and acute stressful negative events as underlying mechanisms of BD. Recently, ER (Endoplasmic Reticulum) stress reached the spotlight of BD research again. The expression of the chaperone BiP (syn. GRP78/glucose-regulated protein, 78kDa), which is highly expressed in the Endoplasmic Reticulum (ER), is upregulated by different kinds of mood stabilizers. These results implied that the ER, an organelle which is prone towards different kinds of cellular stress, might be involved in the pathophysiology of BD. This hypothesis was further strengthened by hypothesis driven genetic association studies, which showed significant association of BiP promotor polymorphisms with BD. Also other ER-stress associated genes like XBP1 (X-box binding protein 1) or GRP94 (glucose-regulated protein, 94kDa, synonym for heat shock protein HSP90B1) were recently linked to BD in hypothesis driven gene association studies. In addition to the proteins mentioned before, our review focuses on further UPR (Unfolded Protein Response) related proteins associated with BD and raises the hypothesis that ER-stress may represent a common interface between BD and obesity which is overrepresented in BD patients. Finally, members of the UPR pathway are discussed as putative targets for mood stabilizers.

Progression of major depression, a multifactorial disorder with a neuroinflammatory signature, seems to be associated with the disruption of body allostasis. High rates of comorbidity between depression and specific medical disorders, such as, stroke, chronic pain conditions, diabetes mellitus, and human immunodeficiency virus (HIV) infection, have been extensively reported. In this review, we discuss how these medical disorders may predispose an individual to develop depression by examining the impact of these disorders on some hallmarks of neuroinflammation known to be impaired in depressed patients: altered permeability of the blood brain barrier, immune cells infiltration, activated microglia, increased cytokines production, and the role of inflammasomes. In all four pathologies, blood brain barrier integrity was altered, allowing the infiltration of peripheral factors, known to activate resident microglia. Evidence indicated morphological changes in the glial population, increased levels of circulating pro-inflammatory cytokines or increased production of these mediators within the brain, all fundamental in neuroinflammation, for the four medical disorders considered. Moreover, activity of the kynurenine pathway appeared to be enhanced. With respect to the inflammasome NLRP3, a new target whose role in neuroinflammation is emerging as being important, accumulating data suggest its involvement in the pathogenesis of brain injury following stroke, chronic pain conditions, diabetes mellitus or in HIV associated immune impairment. Finally, data gathered over the last 10 years, indicate and confirm that depression, stroke, chronic pain, diabetes, and HIV infection share a combination of underlying molecular, cellular and network mechanisms leading to a general increase in the neuroinflammatory burden for the individual.

In Alzheimer's disease and Down syndrome, cholinergic neurons of the basal forebrain progressively degenerate. This neurotransmitter system is the main source of acetylcholine to the cortex and hippocampus. In the mature and fully differentiated central nervous system, the phenotype of forebrain cholinergic neurons and their nerve terminals in cortex and hippocampus depend on the continuous endogenous supply of nerve growth factor (NGF). It has been recently demonstrated that NGF is secreted from cortical neurons in an activity-dependent manner as a precursor molecule, proNGF. Individuals with Alzheimer’s disease and Down syndrome exhibit proNGF accumulation in cortex, yet cholinergic neurons become atrophic in both diseases, despite the apparent abundance of the NGF precursor. This review illustrates the recent evidence that NGF metabolism is affected both in Alzheimer’s disease and in Down syndrome brains and also discusses a role for amyloid-β peptides and central nervous system inflammation in unleashing such deficits. It further considers the potential of the NGF metabolic pathway as a new pharmacological target to slow down the neurodegenerative process both in Alzheimer’s disease and in individuals with Down syndrome.

Intellectual disability (ID) and autism are present in several neurodevelopmental disorders and are often associated in genetic syndromes, such as Fragile X and Rett syndromes. While most evidence indicates that a genetic component plays an important role in the aetiology of both autism and ID, a number of studies suggest that immunological dysfunctions may participate in the pathophysiology of these disorders. Brain-specific autoantibodies have been detected in the sera of many autistic children and autoimmune disorders are increased in families of children with autism. Furthermore, cytokine imbalance has been reported in children with autism. These results may reflect an inappropriate immune response to environmental factors, such as infectious or toxic exposure. The role of microglia as sensors of pre- and post-natal environmental stimuli and its involvement in the regulation of synaptic connectivity, maturation of brain circuitry and neurogenesis has recently emerged. An abnormal immune response during critical windows of development and consequent abnormal production of neuro-inflammatory mediators may have an impact on the function and structure of brain and can play a role in the pathogenesis of non syndromic autism. Recent evidence suggests an involvement of neuro-inflammation also in syndromic forms of autism and ID. Immune dysregulation has been found in children with Fragile X syndrome and an intrinsic microglia dysfunction has been recently reported in Rett syndrome. The present review summarizes the current literature suggesting that neuro-inflammatory mechanisms may contribute to the pathogenesis of different ID- and autism-associated disorders, thus representing common pathophysiological pathways and potential therapeutic targets.

Major depressive disorder (MDD) is a debilitating illness that affects a significant percentage of the world population. This disorder is associated with diminshed productivity and reduced quality of life; unfortunately the underlying pathophysiological mechanisms are not fully clarified. Recently, several studies have suggested that psychiatric disorders could be considered as inflammatory disorders; nevertheless.. Inflammation is therefore an important biological event that might increase the risk of major depressive episodes, much like the more traditional psychosocial factorsThere is strong evidence that depression involves alterations in multiple aspects of immunity that may contribute to the development or exacerbation of a number of medical disorders and also may play a role in the pathophysiology of depressive symptoms. This review highlights the role of neuroinflammation and immunity in the pathophysiology of psychiatric disorders such as MDD.

Schizophrenia, a psychological disorder with enormous societal impact, is a result of abnormalities in gene expression and dysregulation of the immune response in the brain. Few studies have been conducted to understand its etiology, however, the exact molecular mechanism largely remains unknown, though some poorly understood theories abound. Present meta-study links the role of central nervous system, immunological system and psychological disorders by using global expression approach and pathway analysis. We retrieved genome-wide mRNA expression data and clinico-pathological information from five independent studies of schizophrenic patients from Gene Expression Omnibus database. We continued further with three studies having common platform. Our result showed a total of 527 differentially expressed genes of which 314 are up regulated and 213 are down regulated. After adjusting the sources of variation, we carried out pathway and gene ontology analysis, and observed alteration of 14-3-3-mediated signaling, γ-aminobutyric acid receptor signaling, role of nuclear factor of activated T-cells in regulation of the immune response, G beta gamma signaling, dopamine- and cyclic AMP-regulated phosphoprotein of relative molecular mass 32,000 feedback in cAMP signaling, complement system, axonal guidance signaling, dendritic cell maturation, cAMP response element-binding protein signaling in neurons and interleukin-1 signaling pathways and networks. Conclusively, our global gene expression pathway and gene set enrichment analysis studies suggest disruption of many common pathways and processes, which links schizophrenia to immune and central nervous system. Present meta-study links the role of central nervous system, immunological system and psychological disorders by using global expression approach and pathway analysis.

Neurodegeneration is the progressive loss of central neurons which may instigate many disabling psychological and neurological disorders like Alzheimer’s disease, schizophrenia, parkinson’s disease, prion’s disease, and Huntington’s disease. It has become imperative to address the need to discover novel molecular targets and therapeutic strategies to combat neurodegeneration. It is more essential to do so, because most of the accessible treatment focuses on correcting the symptoms of such diseases rather than its underlying pathophysiology. In the present article, we sought to discuss plausible connections between brain ischemic preconditioning and protective measures against chemical neurotoxicity. Brain ischemic preconditioning is reported to be effective against stroke like conditions and is studied chiefly to identify culpable molecular targets. Similarly chemical stressors are reported to be effective in preconditioning neuronal cells against chemical neurotoxicity. Keeping the concept of cross-tolerance in mind this article encompasses the putative targets of both chemical preconditioning and ischemic preconditioning in search for a suitable connection based on the published literature. The distinctive groups of targets are individually discussed and principal targets such as oncogene Akt, glycogen synthase kinase 3-beta and heat shock proteins are emphasised. Identification of these targets may help to develop sophisticated newer therapeutic strategies to cure neurodegenerative disorders.

Breakdown of normal blood-brain barrier function and accompanying vascular leakage are fundamental stages in the onset of multiple sclerosis and its animal counterpart, experimental allergic encephalomyelitis. In the present study, angiopoietin-1, an endothelial growth factor well known for its role in establishing and maintaining vascular integrity, and C16, a peptide that competitively binds to integrin αvβ3 expressed on endothelial cells, were used to treat acute experimental allergic encephalomyelitis in Lewis rats. Angiopoietin-1 was more effective than C16 for reducing inflammation-induced vascular leakage. Moreover, treatment with a combination of angiopoietin-1 and C16 resulted in greater effects, not only in alleviating inflammation and reducing axonal loss/demyelination but also in down-regulating pro-inflammatory cytokine expression and improving electrophysiological dysfunction, than treatment with either angiopoietin-1 or C16 alone. Different protective effects were observed with angiopoietin-1 and C16 treatment suggesting that these proteins target specific receptors to act through different pathways. Furthermore, angiopoietin-1 and C16 may form the basis of a promising therapeutic strategy for experimental allergic encephalomyelitis and multiple sclerosis.

Tetrahydroxystilbene glucoside (TSG), one of the main ingredients of Polygonum multiflorum, has a great number of beneficial effects for health including anti-oxidant, free radicalscavenging and anti-inflammatory properties. However, the potential effects of TSG on neurotrophic factors release remain unclear. In this study, rat primary astroglia cultures were applied to investigate TSG-mediated neurotrophic effects. The protein levels and production of glial cell-line derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in astroglia and the culture medium were determined by western blotting assay and ELISA, respectively. Results indicated that TSG increased the production of neurotrophic factors in a concentration-dependent manner. At different time points of TSG treatment, the BDNF and NGF production in the culture medium was increased 48 h after treatment, while GDNF secretion was initially induced 24 h after TSG treatment. Consistent with the neurotrophic factors release, TSG significantly increased the BDNF, GDNF and NGF protein expressions in astroglia. Furthermore, TSG significantly induced the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and a specific ERK inhibitor-U0126 inhibited TSG-mediated secretion of BDNF, GDNF and NGF. Overall, this study demonstrated that TSG induces astroglia-derived neurotrophic factors release, suggesting TSG might hold a therapeutic potential for neurological disorders.