Central Nervous System Impairment Research Articles

25-Hydroxycholesterol and inflammation in Lovastatin-deregulated mevalonate pathway.

Mevalonate pathway deregulation has been observed in several diseases, including Mevalonate kinase deficiency (MKD). MKD is a hereditary auto-inflammatory disorder, due to mutations at mevalonate kinase gene (MVK), encoding mevalonate kinase (MK) enzyme. MVK mutations have been reported as associated with impairment of mevalonate pathway with consequent decrease of protein prenylation levels, defective autophagy and increase of IL-1β secretion, followed by cell death. Since 25-hydroxycholesterol (25-HC), a metabolite of cholesterol, can suppress IL-1β production, thus reducing inflammation, we evaluated the effect of 25-HC in an in vitro model of mevalonate pathway alteration, obtained using Lovastatin. Human glioblastoma cell line (U87-MG) was chosen to mimic, at least in part, the central nervous system impairment observed in MKD; 25-HC effects were evaluated aimed at disclosing if this compound could be considered as novel potential drug for MKD. Our results showed that 25-HC is able to reduce inflammation but it is ineffective to restore autophagy flux and to decrease apoptosis levels, both caused by lower protein prenylation; so, in spite of its anti-inflammatory action it is not useful to rescue defective prenylation/autophagy impairment-driven apoptosis in Lovastatin impaired mevalonate pathway. We hypothesize the presence in the mevalonate pathway of alternative mechanisms acting between inflammation and apoptotic autophagy impairment.

Visual recognition memory is impaired in rhesus monkeys repeatedly exposed to sevoflurane in infancy

BackgroundExperimental studies in animals have shown that exposure to general anaesthesia in infancy can cause loss of cells in the central nervous system and long-term impairments in neurocognitive function. Some human epidemiological studies have shown increased risk of learning disability after repeated anaesthesia exposure in early childhood. Thus, we investigated in a highly translational rhesus monkey model, whether repeated exposure in infancy to the inhalation anaesthetic sevoflurane is associated with impaired visual recognition memory during the first two yr of life. MethodsRhesus monkeys of both sexes were exposed to sevoflurane inhalation anaesthesia on approximately postnatal day 7 and then again 14 and 28 days later, for four h each time. Visual recognition memory was tested using the visual paired comparison task, which measures memory by assessing preference for looking at a new image over a previously-viewed image. Monkeys were tested at 6–10 months of age, again at 12–18 months of age, and again at 24–30 months of age. ResultsNo memory impairment was detected at 6–10 months old, but significant impairment (reduced time looking at the novel image) was observed at 12–18 and 24–30 months old. ConclusionsRepeated exposure of infant rhesus monkeys to sevoflurane results in visual recognition memory impairment that emerges after the first yr of life. This is consistent with epidemiological studies that show increased risk of learning disability after repeated exposure to anaesthesia in infancy/early childhood. Moreover, these deficits may emerge at later developmental stages, even when memory performance is unaffected earlier in development.

Oral narrative of individuals with Fetal Alcohol Spectrum Disorder.

To investigate and compare the oral narrative of individuals with FASD and individuals with typical language development (TLD), as well as to correlate the narrative performance with the score from 4-Digit Diagnostic Code. Participants were 20 individuals with FASD, of both genders, with chronological age between 6 and 16 years, and 20 individuals with TLD, same gender and similar to the FASD group in age and socioeconomic status. The oral narrative was elicited using the book Frog, where are you? and the data were analyzed in terms of macrostructure, microstructure and global coherence level. Measures regarding the macrostructure included the presence of typical structural elements of storytelling, while the microstructural aspects included words (total and different words), communication units (C-Units), lexical diversity, and mean length of C-Units. Low performance was found in the FASD group for all macrostructural aspects, with the exception of linguistic markers. Among the microstructural aspects, lexical diversity and incomplete C-Units were different between the FASD and TLD groups. The FASD group presented lower global coherence level compared to the TLD group. Negative correlations were found between macrostructural aspects, facial characteristics, and Central Nervous System impairment. Restricted use of typical structural elements of storytelling with lower levels of coherence and reduced vocabulary distinguished the FASD from the TDL group. Future studies may explore whether the association between narrative performance and the 4-Digit Diagnostic Code items present predictive values in the narrative performance of individuals with FASD.

Drug Misuse in Adolescents Presenting to the Emergency Department.

Drug misuse is a disturbing, common practice among youth. One in 4 American adolescents reports consuming prescription medications without a clinical indication. We sought to explore current trends of drug misuse in adolescents. Using the 37 participating sites of the ToxIC (Toxicology Investigators Consortium) Case Registry, a cross-country surveillance tool, we conducted an observational cohort study of all adolescents (aged 13-18 years) who presented to emergency departments with drug misuse and required a bedside medical toxicology consultation between January 2010 and June 2013. Of 3043 poisonings, 202 (7%) involved drug misuse (139 [69%] were males). Illicit drugs (primarily synthetic cannabinoids and "bath salts") were encountered in 101 (50%), followed by prescription medications (56 [28%]) and over-the-counter (OTC) drugs (51 [25%]). Dextromethorphan was the most commonly misused legal medication (24 [12%]). Polypharmacy exposure was documented in 74 (37%). One hundred sixty-three adolescents (81%) were symptomatic; of these, 81% had central nervous system impairments: psychosis (38%), agitation (30%), coma (26%), myoclonus (11%), and seizures (10%); and 66 (41%) displayed a specific toxidrome, most commonly sedative-hypnotic. Benzodiazepines were the most frequently administered medications (46%). Antidotes were administered to 28% of adolescents, primarily naloxone, physostigmine, N-acetyl-cysteine, and flumazenil. No deaths were recorded. Adolescents presenting with drug misuse may be exposed to a wide range and combinations of therapeutics or illicit substances and frequently display central nervous system abnormalities, compromising the ability to obtain a reliable history. Frontline clinicians should maintain a high index of suspicion, as routine toxicology screenings fail to detect most contemporary misused legal and designer drugs.

Central conduction abnormalities in patients receiving levodopa-carbidopa intestinal gel infusion.

In recent years, several studies have reported a relatively high frequency of polyneuropathy in patients with Parkinson's disease (PD), in particular, in patients receiving levodopa-carbidopa intestinal gel (LCIG) infusion. In spite of the several patients investigated with nerve conduction studies, no study has prospectively explored a possible central nervous system involvement of patients receiving LCIG infusion. We prospectively evaluated eight PD patients receiving LCIG infusion, who underwent neurophysiological evaluations with nerve conduction studies, visual, somatosensory and motor evoked potentials before LCIG infusion, and 1 and 6months after. At 6months follow-up, we found significant reduction in sural nerve SNAP amplitude, increase of central sensory conduction time N22-P40, and increases of central motor conduction time recorded from I dorsal interosseous and tibialis anterior. In PD patients with LCIG infusion, we found a subclinical neurophysiological impairment of both peripheral and central nervous system.

Prevalence of externalizing disorders and Autism Spectrum Disorders among children with Fetal Alcohol Spectrum Disorder: systematic review and meta-analysis.

Owing to their central nervous system impairments, children with Fetal Alcohol Spectrum Disorder (FASD) commonly exhibit externalizing behaviours such as hyperactivity, impulsivity, and (or) delinquency. The purpose of this study was to estimate the prevalence of neurodevelopmental disorders with prominent externalizing behaviours, namely Attention-Deficit Hyperactivity Disorder (ADHD), Conduct Disorder (CD), Oppositional Defiant Disorder (ODD), as well as Autism Spectrum Disorders (ASD) among children with FASD. A comprehensive systematic literature search was performed, followed by disorder-specific random-effects meta-analyses. Of the disorders investigated, ADHD was found to be the most common co-morbid disorder among children with FASD (52.9%), followed by ODD (12.9%), CD (7.0%), and ASD (2.6%). When compared with the general population of the USA, these rates are notably higher: 15 times higher for ADHD, 2 times higher for ASD, 3 times higher for CD, and 5 times higher for ODD. The results call attention to the need for identifying a distinct neurodevelopmental profile to aid in the accurate identification of children with FASD and the discrimination of FASD from certain idiopathic neurodevelopmental disorders.

Influence of n-hexane on vascular endothelial active substances in brain tissue in mice

Objective: To investigate the influence of n-hexane on vascular endothelial active substances in brain tissue in mice and its significance. Methods: A total of 48 healthy Kunming mice were randomly divided into high-dose exposure group, middle-dose exposure group, low-dose exposure group, and control group, with 12 mice in each group. All groups except the control group were exposed to n-hexane via static inhalation (0.035 g/L, 0.018 g/L, and 0.009 g/L for the high-, middle-, and low-dose exposure groups, respectively) 4 hours a day for 21 days. the mice in the control groups were not exposed to n-hexane. After the exposure, the lev-els of endothelin-1 (ET-1) , nitric oxide (NO) , and angiotensin II (Ang II) in brain tissue were measured in all groups. Results: There were significant differences in the levels of ET-1, NO, and Ang II between the three ex-posure groups and the control group (P<0.05). Compared with the control group, the high-and middle-dose expo-sure group had significant increases in the levels of ET-1 and Ang II and the high-dose exposure group had a sig-nificant reduction in the level of NO (P<0.05 or P<0.01). Conclusion: n-Hexane can affect the vascular endothe-lial active substances in brain tissue in mice, and the changes and imbalance in vascular endothelial active sub-stances may be one of the reasons for central nervous system impairment caused by n-hexane.

Roles of Mesenchymal Stem Cells in Spinal Cord Injury.

Spinal cord injury (SCI) represents one of the most complicated and heterogeneous pathological processes of central nervous system (CNS) impairments, which is still beyond functional regeneration. Transplantation of mesenchymal stem cells (MSCs) has been shown to promote the repair of the injured spinal cord tissues in animal models, and therefore, there is much interest in the clinical use of these cells. However, many questions which are essential to improve the therapy effects remain unanswered. For instance, the functional roles and related molecular regulatory mechanisms of MSCs in vivo are not yet completely determined. It is important for transplanted cells to migrate into the injured tissue, to survive and undergo neural differentiation, or to play neural protection roles by various mechanisms after SCI. In this review, we will focus on some of the recent knowledge about the biological behavior and function of MSCs in SCI. Meanwhile, we highlight the function of biomaterials to direct the behavior of MSCs based on our series of work on silk fibroin biomaterials and attempt to emphasize combinational strategies such as tissue engineering for functional improvement of SCI.

Gut-Microbiota Link in Parkinson’s Disease: Current Perspectives

Parkinson’s disease(PD) is a metacentric neurodegenerative disorder results with accumulation and aggregation of alpha-synculein(α-Syn) (or alpha-synculeinopathy) in the substantia nigra in the central nervous system(CNS).Contributory factors include pesticide exposure, head injury and agriculture background. PD has been considered to be a non-genetic disorder, however around 15% individuals with PD have firstdegree relative who has the disease Mutations in genes including SNCA,LRRK2 and gluococerebrosidase (GBA) found to be risk factor for sporadic PD. Brain cells could be lost due to an abnormal accumulation of the protein alpha-synculein.This insoluble protein accumulates inside neurons forming inclusions called Lewy bodies. Other cell death mechanisms include proteasomal and lysosomal system dysfunction, but the mechanisms are not fully understood. Brain –gut axis(GBA) refers to central nervous system(CNS) control of the enteric nervous system(ENS) through vagus nerve intervention. PD is characterized by alphasynculeinopathy affecting all levels of the brain-gut axis.Both clinical and neuropathological evidences indicate the neurodegenerative changes in PD are accompanied by gastrointestinal symptoms that may precede or follow the central nervous systemimpairment. Frequent symptoms in PD include tremor, rigidity, slowness of movement and difficulty with walking. Treatment with L-DOPA(levodopa),with dopamine agonist, medications become less effective and produce complications. Research studies recommend new therapeutic approach in PD based on modification of the gut microbiota with probiotics, prebiotics, or even fecal microbiota transplantation.

Inflammasome Activation Underlying Central Nervous System Deterioration in HIV-Associated Tuberculosis.

Tuberculous meningitis (TBM) is a frequent cause of meningitis in individuals with human immunodeficiency virus (HIV) infection, resulting in death in approximately 40% of affected patients. A severe complication of antiretroviral therapy (ART) in these patients is neurological tuberculosis–immune reconstitution inflammatory syndrome (IRIS), but its underlying cause remains poorly understood. To investigate the pathogenesis of TBM-IRIS, we performed longitudinal whole-blood microarray analysis of HIV-infected patients with TBM and reflected the findings at the protein level. Patients in whom TBM-IRIS eventually developed had significantly more abundant neutrophil-associated transcripts, from before development of TBM-IRIS through IRIS symptom onset. After ART initiation, a significantly higher abundance of transcripts associated with canonical and noncanonical inflammasomes was detected in patients with TBM-IRIS than in non-IRIS controls. Whole-blood transcriptome findings complement protein measurement from the site of disease, which together suggest a dominant role for the innate immune system in the pathogenesis of TBM-IRIS.

Prognostic analysis of children diagnosed hemophagocytic lymphohistiocytosis with central nervous system involvement in children

Objective To explore the prognostic outcomes of children with hemophagocytic lymphohistiocytosis (HLH) and central nervous system (CNS) involvement. Methods Clinical data of 61 HLH children including CNS symptoms, cranial imaging findings (CT/MRI) and cerebrospinal fluid (CSF) results were collected retrospectively, who were admitted to Hematology Oncology Center of Beijing Children′s Hospital, Capital Medical University from January 2012 to December 2013.The relationship was evaluated between CNS involvement and prognosis by comparing the overall survival (OS) rate. Results In the total 61 cases, median age on diagnosis was 28.1 months, and median follow-up time was 45 months; OS rate was 61.1%(33/54 cases, 7 cases lost follow-up). Thirty-three children (54.1%) were diagnosed as EB virus-HLH, with median age of 48.9 months and OS rate of 69.0% (20/29 cases, 4 cases lost to follow-up), which was higher than other HLHs (52.0%, 13/25 cases), but the difference was not significant(χ2=1.626, P=0.202). There were 24.6% of children with CNS clinical manifestations, and the OS rate was 35.7% (5/14 cases), which was lower than those who had no CNS symptoms (70.0%, 28/40 cases), and the difference was significant (χ2=5.129, P=0.024). There were 61.5% of patients with changed imaging findings, and their OS rate was 54.8% (17/31 cases), which was also lower than those with no changes in CT and/or MRI (87.5%, 14/16 cases), and the difference was significant (P=0.049). While children with abnormal CSF accounted for 19.2% of those who received lumbar puncture, and their OS rate was 40.0% (2/5 cases), which was lower than those with normal CSF (81.0%, 17/21 cases), but the difference was not significant(P=0.101). Any change in CNS symptom, imaging finding or CSF was regarded as CNS involvement.Apart from children who did not have data of CT/MR and/or CSF, the proportion of patients with CNS involvement was 70.4%(38/54 cases), their OS rate was 54.1%(20/37 cases, and 1 case lost follow-up), which was lower than those without CNS impairment (91.7%, 11/12 cases), and the difference was significant (P=0.036). Conclusions Pediatric patients with HLH always have poor prognosis once CNS symptoms or abnormal imaging findings can be founded.CNS involvement is an important risk factor to estimating the patients′ outcome.Cranial MRI and CSF test are necessary for newly diagnosed HLH children, regardless of whether neurological manifestation could be discovered. Key words: Child; Hemophagocytic lymphohistiocytosis; Central nervous system

High Pressure and [Ca 2+ ] Produce an Inverse Modulation of Synaptic Input Strength and Network Excitability in the Rat Dentate Gyrus.

Hyperbaric environments induce the high pressure neurological syndrome (HPNS) characterized by hyperexcitability of the central nervous system (CNS) and memory impairment. Human divers and other animals experience the HPNS at pressures beyond 1.1 MPa. High pressure depresses synaptic transmission and alters its dynamics in various animal models. Medial perforant path (MPP) synapses connecting the medial entorhinal cortex with the hippocampal formation are suppressed by 50% at 10.1MPa. Reduction of synaptic inputs is paradoxically associated with enhanced ability of dentate gyrus (DG)’ granule cells (GCs) to generate spikes at high pressure. This mechanism allows MPP inputs to elicit standard GC outputs at 0.1–25 Hz frequencies under hyperbaric conditions. An increased postsynaptic gain of MPP inputs probably allows diving animals to perform in hyperbaric environments, but makes them vulnerable to high intensity/frequency stimuli producing hyperexcitability. Increasing extracellular Ca2+ ([Ca2+]o) partially reverted pressure-mediated depression of MPP inputs and increased MPP’s low-pass filter properties. We postulated that raising [Ca2+]o in addition to increase synaptic inputs may reduce network excitability in the DG potentially improving its function and reducing sensitivity to high intensity and pathologic stimuli. For this matter, we activated the MPP with single and 50 Hz frequency stimuli that simulated physiologic and deleterious conditions, while assessing the GC’s output under various conditions of pressure and [Ca2+]o. Our results reveal that the pressure and [Ca2+]o produce an inverse modulation on synaptic input strength and network excitability. These coincident phenomena suggest a potential general mechanism of networks that adjusts gain as an inverse function of synaptic inputs’ strength. Such mechanism may serve for adaptation to variable pressure and other physiological and pathological conditions and may explain the increased sensitivity to strong sensory stimulation suffered by human deep-divers and cetaceans under hyperbaric conditions.

Percutaneous needle tenotomy in the treatment of neuro-orthopedic complications of upper limb related to central nervous system impairment: Open study on 12 patients

The musculotendinous retractions are common complications of central neurological damage with consequences for comfort and function. Treatment of uncomfortable retractions is often surgical, mainly based on tendon gestures. The objective of this study was to evaluate the efficiency of percutaneous needle tenotomy in these indications. The indication was accepted at a medical-surgical consultation. Tenotomy was performed using an 18 Gauge needle. The patients were older than 18 years, had a history of central neurological disease, and had a musculotendinous retraction regarding a superficial tendon of upper limb. The primary endpoint was the Goal Attainment Scale (GAS). Secondary outcomes were pain, the pulp-palm distance and range of motion gain. The evaluation was conducted in pre-tenotomy, immediately post-tenotomy, 3 months and 6 months. Twelve patients (8 women) were included in our study. The mean age was 62.91 years (28–87). Neuro-orthopedic disorders were related to a stroke ( n = 4), head trauma ( n = 2), to Parkinsonian syndrome ( n = 3) at a cerebral palsy ( n = 3). The objectives identified were nursing ( n = 12), pain ( n = 11), the skin condition ( n = 5), gripping ( n = 2), posture ( n = 1) and dressing ( n = 1). The targets were achieved in all cases. The average score GAS per patient ranged from 0 to 2. GAS score was unchanged at 3 months and 6 months. Our experience confirms the locations already described for percutaneous needle tenotomy of the flexor of the fingers. We also report the effectiveness of percutaneous tenotomy in the wrist and elbow flexors without vascular and nerve injury elbow.

Solvent exposure and cognitive function in automotive technicians

Automotive technicians are commonly exposed to organic and chlorinated solvents, particularly through use of cleaning products. Occupational solvent exposures have been associated with deficits in cognitive function but, to our knowledge, no previous studies have investigated automotive technicians. The purpose of the present study was to investigate whether previous exposures to n-hexane, in particular, or general solvents posed a persistent neurotoxic hazard to automotive workers.Enrolled in the study were 830 San Francisco Bay Area automotive repair workers. Each participant underwent a battery of cognitive function tests to investigate central nervous system impairment, with a primary focus on the domains of psychomotor speed, fine motor function, memory and mood. Cognitive test results regressed against estimated hexane and total solvent exposures showed little evidence of associations. Exposures to both solvents and hexane were well below the occupational exposure limits.Our results provide some reassurance about persistent neuropsychological effects in automotive workers who use solvent-based products and those who previously used hexane-containing automotive cleaning products, since this solvent is believed no longer to be used in automotive cleaning products. The lack of observed effect in this study may be attributable to low exposures, or it may reflect improved cognitive function since hexane use in automotive cleaning products was discontinued. However, impacts on results of exposure misclassification and/or the healthy worker survivor effect cannot be discounted. Irrespective of the outcome of this study, the main known neurologic effect of n-hexane is peripheral neuropathy, and such an association in automotive technicians is not excluded by these results.

EP 147. Electrophysiological evaluation of uremic patients undergoing hemodialisys: Proposal of a clinical and numerical scale for severity and prognosis

Introduction Conduction studies (ENMG) have been used since long time for evaluation of chronic uremia ( O’Regan et al., 2012 ) and the blink reflex is important for this purpose. Neurological alterations are easy to detect in uremic patients ( Vellanki and Bansal, 2015 ), such as deep hyperreflexia, asterixis, reading and memory disturbances and sleep disorders ( Merlino et al., 2008 ). They can occur together or alone in early stages of chronic uremia, but they have not been quantified to this moment, the purpose of this study. Methods Peripheral neuropathy was diagnosed by ENMG and classified into four levels: Normal – 0.0 point; mild – 1,0 point; moderate – 2,0 points; marked – 3,0 points. The blink reflex was classified into Normal – 0.0 point; R1 alterations – 1,0 point; one side R2 alteration – 2,0 points; both sides R2 alterations – 3,0 points. Maximal electrophysiological assessment: 6,0 points. Clinical alterations were defined as having or not asterixis (0.0 or 1,0 point, respectively), having or not deep hyperreflexia (0.0 or 1,0 point); having or not reading and/or memory disorders (0.0 or 1.0), having or not sleep disorders (0.0 or 1.0). Clinical evaluation: maximum of 4,0 points. The full scale ranges from zero to ten (10) points in ascending graduation related to the severity ( Table 1 ). Results In previous studies of 30 patients in our Service were documented several alterations of the blink reflex, some of them with prognostic value. Attenuated R2 responses occurred in patients who died soon after the study. The application of the proposed scale for the first 10 patients showed results between 1 to 7 points. Values of 1 to 3 were observed in patients with shorter time of dialysis treatment and 6 or 7 values in patients with longer time of dialysis. Conclusions This study propose a new scale of assessment of the central and peripheric nervous system impairment in chronic uremia. The procedures are non-invasive, fast, easy to apply and already showed to be useful. They can be applied by nephrologists and neurologists, to teaching and research in interdisciplinarity Neurology/Nephrology.

Study of Brainstem Auditory Evoked Response in Type 2 Diabetes Mellitus

Background: Diabetes is a major cause of morbidity and among its complications neuropathies are the most common. Diabetes may alter both the central and peripheral nerve functions but the peripheral manifestations of diabetic neuropathy are more frequently discussed in the literature than the impairment of central nervous system. Objective: To study the Brainstem Auditory Evoked Response (BAER) in 30 type 2 diabetes mellitus patients and compared to age and sex matched 30 non diabetic group. Methods: 30 Type 2 diabetics and 30 age and sex matched control group were selected and subjected to BAER. Duration of latencies, interpeak latencies and amplitudes were recorded. Results: According to BAER report, Left side latencies III , both left and right IPL III–V , right side ampliude V decreased with p > 0.05 in type 2 DM compared to control group. Conclusion: The study showed bilateral changes in BAER report in type 2 DM. This indicates use of evoked potentials like BAER helps in evaluating central neuropathy in patients with type2 DM. Earlier diagnosis of central neuropathy is recommended for proper management.

Precise and accurate assay of pregnenolone and five other neurosteroids in monkey brain tissue by LC–MS/MS

A series of steroids present in the brain have been named “neurosteroids” following the possibility of their role in the central nervous system impairments such as anxiety disorders, depression, premenstrual dysphoric disorder (PMDD), addiction, or even neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases. Study of their potential role requires a sensitive and accurate assay of their concentration in the monkey brain, the closest model to the human. We have thus developed a robust, precise and accurate liquid chromatography–tandem mass spectrometry method for the assay of pregnenolone, pregnanolone, epipregnanolone, allopregnanolone, epiallopregnanolone, and androsterone in the cynomolgus monkey brain. The extraction method includes a thorough sample cleanup using protein precipitation and phospholipid removal, followed by hexane liquid-liquid extraction and a Girard T ketone-specific derivatization. This method opens the possibility of investigating the potential implication of these six steroids in the most suitable animal model for neurosteroid-related research.

Activity and MeCP2-dependent regulation of nNOS levels in enteric neurons.

Rett syndrome (RTT) is a neurological disorder characterized by severe cognitive impairment, motor dyspraxia, and seizures. Rett syndrome arises predominantly from mutations in MECP2, the gene coding for methyl-CpG-binding protein 2 (MeCP2). MeCP2 is an important mediator of synaptic development and is essential in regulating homeostatic synaptic plasticity (HSP) in the brain. In addition to demonstrating central nervous system impairment, RTT patients also suffer from gastrointestinal (GI) dysmotility. We hypothesize that this is due to a similar impairment of plasticity-dependent synaptic function in the enteric nervous system (ENS). We recently reported that MeCP2 is expressed in the ENS, providing evidence that neuronal dysfunction may mediate the GI pathology. Baseline measures of MeCP2-KO vs wild-type (WT) GI neuronal nitric oxide synthase (nNOS) were assessed in tissue samples and in vitro. Experiments were carried out to measure nNOS in baseline vs activated plasticity states in vitro. Functional in vivo studies were carried out to determine whether MeCP2-KO mice reproduced the RTT GI hypomotility. Methyl-CpG-binding protein 2-KO mice reproduced the GI hypomotility seen in RTT. MeCP2-KO GI tissue demonstrated elevated nNOS levels. Cultured WT enteric neurons showed upregulation of nNOS following moderate, prolonged stimulation by hyperkalemia; neurons from MeCP2-KO mice failed to show this nNOS upregulation. MeCP2 is required for proper GI motility and normal nNOS levels. Neuronal nitric oxide synthase imbalances could mediate the GI dysmotility seen in RTT. Disruption of MeCP2-dependent HSP may be the basis for aberrant nNOS levels and hence GI dysmotility in MeCP2-KO and RTT.

Long-term epigenetic alterations in a rat model of Gulf War Illness

Gulf War Illness (GWI) is a chronic, multisymptom illness that affects 25% of the 700,000 US veterans deployed to the Persian Gulf during the 1990–1991 Gulf War. Central nervous system impairments are among the most common symptoms reported, including memory dysfunction and depression. After 25 years, the diagnosis remains elusive, useful treatments are lacking, and the cause is poorly understood, although exposures to pyridostigmine bromide (PB) and pesticides are consistently identified to be among the strongest risk factors. Epigenetic changes including altered microRNA (miRNA) expression and DNA methylation play an important role in learning, memory, and emotion regulation and have been implicated in various neurological disorders. In this study, we used an established rat model of GWI to determine whether 1) chronic alterations in miRNA expression and global DNA methylation and DNA hydroxymethylation are mechanisms involved in the pathobiology of GWI, and 2) plasma exosome small RNAs may serve as potential noninvasive biomarkers of this debilitating disease. One year after a 28-day exposure regimen of PB, DEET (N,N-diethyl-3-methylbenzamide), permethrin, and mild stress, expression of 84 mature miRNAs and global 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) content were analyzed in the brains of GWI rats and vehicle controls by PCR array and enzyme-linked immunosorbent assay, respectively. Plasma exosome RNA next-generation sequencing analysis was performed in pooled samples to discover potential noninvasive biomarkers. We found that combined exposure to low doses of GW-related chemicals and mild stress caused epigenetic modifications in the brain that persisted one year after exposure, including increased expression of miR-124-3p and miR-29b-3p in the hippocampus and regional alterations in global 5mC and 5hmC content. GW-relevant exposures also induced the differential expression of two piwi-interacting RNAs (piRNAs) in circulation (piR-007899 and piR-019162). Results from this study implicate a role for epigenetic alterations in GWI. Evaluation of the diagnostic potential of plasma exosome RNAs in veterans with GWI is warranted.

Sensitization of Ion Channels Contributes to Central and Peripheral Dysfunction in Neurofibromatosis Type 1.

Neurofibromatosis type 1 (Nf1) is a progressive, autosomal disorder with a large degree of variability and severity of manifestations including neurological, cutaneous, ocular/orbital, orthopedic, and vascular abnormalities. Nearly half of Nf1 patients presents with cognitive impairment, specifically spatial learning deficits. These clinical manifestations suggest a global impairment of both central and peripheral nervous system functions in neurofibromatosis. Nf1 encodes for neurofibromin, a Ras GTPase-activating protein (Ras GAP) that has been implicated in the regulation of long-term potentiation (LTP), Ras/ERK (extracellular signal-regulated kinase) signaling, and learning in mice. Over the last decades, mice with a targeted mutation in the Nf1 gene, Nf1 -/- chimeric mice, Nf1 exon-specific knockout mice, and mice with tissue-specific inactivation of Nf1 have been generated to model the human Nf1 disease. These studies have implicated neurofibromin in regulation of the release of the inhibitory neurotransmitter γ-amino butyric acid (GABA) in the hippocampus and frontal lobe, which can regulate memory. Mutations in neurofibromin thus lead to perturbed ERK signaling, which alters GABA release, LTP, and subsequently leads to learning deficits. In addition to these cognitive deficits, Nf1 patients also have defects in fine and gross motor coordination as well as decreased muscle strength. Although the mechanisms underlying these motor deficits are unknown, deficits in GABAergic neurotransmission in both the motor cortex and cerebellum have been suggested. In this review, we present evidence to support the hypothesis that alterations of ion channel activity in Nf1 underscore the dysregulated neuronal communication in non-neuronal and neuronal cells that likely contributes to the clinical cornucopia of Nf1.