Functions and dysfunctions of nitric oxide in brain

The emerging role of nitric oxide in the synaptic dysfunction of vascular dementia

With an increase in global aging, the number of people affected by cerebrovascular diseases is also increasing, and the incidence of vascular dementia-closely related to cerebrovascular risk-is increasing at an epidemic rate. However, few therapeutic options exist that can markedly improve the cognitive impairment and prognosis of vascular dementia patients. Similarly in Alzheimer's disease and other neurological disorders, synaptic dysfunction is recognized as the main reason for cognitive decline. Nitric oxide is one of the ubiquitous gaseous cellular messengers involved in multiple physiological and pathological processes of the central nervous system. Recently, nitric oxide has been implicated in regulating synaptic plasticity and plays an important role in the pathogenesis of vascular dementia. This review introduces in detail the emerging role of nitric oxide in physiological and pathological states of vascular dementia and summarizes the diverse effects of nitric oxide on different aspects of synaptic dysfunction, neuroinflammation, oxidative stress, and blood-brain barrier dysfunction that underlie the progress of vascular dementia. Additionally, we propose that targeting the nitric oxide-sGC-cGMP pathway using certain specific approaches may provide a novel therapeutic strategy for vascular dementia.

Integrated approach to reducing polypharmacy in older people: exploring the role of oxidative stress and antioxidant potential therapy

Increased life expectancy, attributed to improved access to healthcare and drug development, has led to an increase in multimorbidity, a key contributor to polypharmacy. Polypharmacy is characterised by its association with a variety of adverse events in the older persons. The mechanisms involved in the development of age-related chronic diseases are largely unknown; however, altered redox homeostasis due to ageing is one of the main theories. In this context, the present review explores the development and interaction between different age-related diseases, mainly linked by oxidative stress. In addition, drug interactions in the treatment of various diseases are described, emphasising that the holistic management of older people and their pathologies should prevail over the individual treatment of each condition.

Multifunctional Nanomaterials for Advancing Neural Interfaces: Recording, Stimulation, and Beyond

ConspectusNeurotechnology has seen dramatic improvements in the last three decades. The major focus in the field has been to design electrical communication platforms with high spatial resolution, stability, and translatability for understanding and affecting neural pathways. The deployment of nanomaterials in bioelectronics has enhanced the capabilities of conventional approaches employing microelectrode arrays (MEAs) for electrical interfaces, allowing the construction of miniaturized, high-performance neuroelectronics (Garg, R.; et al. ACS Appl. Nano Mater. 2023, 6, 8495). While these advancements in the electrical neuronal interface have revolutionized neurotechnology both in scale and breadth, an in-depth understanding of neurons' interactions is challenging due to the complexity of the environments where the cells and tissues are laid. The activity of large, three-dimensional neuronal systems has proven difficult to accurately monitor and modulate, and chemical cell-cell communication is often completely neglected. Recent breakthroughs in nanotechnology have provided opportunities to use new nonelectric modes of communication with neurons and to significantly enhance electrical signal interface capabilities. The enhanced electrochemical activity and optical activity of nanomaterials owing to their nonbulk electronic properties and surface nanostructuring have seen extensive utilization. Nanomaterials' enhanced optical activity enables remote neural state modulation, whereas the defect-rich surfaces provide an enormous number of available electrocatalytic sites for neurochemical detection and electrochemical modulation of cell microenvironments through Faradaic processes. Such unique properties can allow multimodal neural interrogation toward generating closed-loop interfaces with access to more complete neural state descriptors. In this Account, we will review recent advances and our efforts spearheaded toward utilizing nanostructured electrodes for enhanced bidirectional interfaces with neurons, the application of unique hybrid nanomaterials for remote nongenetic optical stimulation of neurons, tunable nanomaterials for highly sensitive and selective neurotransmitter detection, and the utilization of nanomaterials as electrocatalysts toward electrochemically modulating cellular activity. We highlight applications of these technologies across cell types through nanomaterial engineering with a focus on multifunctional graphene nanostructures applied though several modes of neural modulation but also an exploration of broad material classes for maximizing the potency of closed-loop bioelectronics.

Phytochemical composition of aerial parts and roots of Pfaffia glomerata (Spreng.) Pedersen and anticholinesterase, antioxidant, and antiglycation activities

The Pfaffia glomerata, a plant popularly called Brazilian ginseng, is widely used in Brazil for the treatment of various pathologies, including those associated with the Central Nervous System. 20-hydroxyecdysone (20E), a phytosteroid present in this plant, can promote adaptogenic effects in the organism, providing greater body resistance to stressors. This study aimed to evaluate the phytochemical composition and the anticholinesterase, antioxidant, and antiglycation effects of extracts and fractions of aerial parts and roots of P. glomerata, also analyzing their possible cytotoxic effects. The fractions were obtained by partitioning methanol extracts from the aerial part and roots of P. glomerata with hexane, dichloromethane, ethyl acetate, n-butanol, and water. The samples were initially tested in anticholinesterase, antioxidant, and antiglycation assays, and the most promising samples were submitted for cytotoxicity and chromatographic analyses. Mass spectrometry and chromatography methods revealed that 20E was the main compound in the dichloromethane fractions, there being 35% more 20E in the aerial part (APD) than in the roots (RD). Added to the higher concentration of 20E, the APD fraction also presented more promising results than the RD fraction in anticholinesterase and antioxidant analyses, indicating that their effects may be related to the concentration of 20E. These same fractions showed no hemolytic effects but were cytotoxic in high concentrations. These new findings contribute to scientific information about P. glomerata and open more perspectives for the understanding of its therapeutic properties, allowing the association of biological activity with the presence of 20E.

The tissue-specific nature of physiological zebrafish mitochondrial bioenergetics

Zebrafish are a powerful tool to study a myriad of experimental conditions, including mitochondrial bioenergetics. Considering that mitochondria are different in many aspects depending on the tissue evaluated, in the zebrafish model there is still a lack of this investigation. Especially for juvenile zebrafish. In the present study, we examined whether different tissues from zebrafish juveniles show mitochondrial density- and tissue-specificity comparing brain, liver, heart, and skeletal muscle (SM). The liver and brain complex IV showed the highest O2 consumption of all ETC in all tissues (10x when compared to other respiratory complexes). The liver showed a higher potential for ROS generation. In this way, the brain and liver showed more susceptibility to O2- generation when compared to other tissues. Regarding Ca2+ transport, the brain showed greater capacity for Ca2+ uptake and the liver presented low Ca2+ uptake capacity. The liver and brain were more susceptible to producing NO. The enzymes SOD and Catalase showed high activity in the brain, whereas GPx showed higher activity in the liver and CS in the SM. TEM reveals, as expected, a physiological diverse mitochondrial morphology. The essential differences between zebrafish tissues investigated probably reflect how the mitochondria play a diverse role in systemic homeostasis. This feature may not be limited to normal metabolic functions but also to stress conditions. In summary, mitochondrial bioenergetics in zebrafish juvenile permeabilized tissues showed a tissue-specificity and a useful tool to investigate conditions of redox system imbalance, mainly in the liver and brain.

Impacts of SARS-CoV-2 on brain renin angiotensin system related signaling and its subsequent complications on brain: A theoretical perspective

Cellular ACE2 (cACE2), a vital component of the renin-angiotensin system (RAS), possesses catalytic activity to maintain AngII and Ang 1-7 balance, which is necessary to prevent harmful effects of AngII/AT2R and promote protective pathways of Ang (1-7)/MasR and Ang (1-7)/AT2R. Hemostasis of the brain-RAS is essential for maintaining normal central nervous system (CNS) function. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a viral disease that causes multi-organ dysfunction. SARS-CoV-2 mainly uses cACE2 to enter the cells and cause its downregulation. This, in turn, prevents the conversion of Ang II to Ang (1-7) and disrupts the normal balance of brain-RAS. Brain-RAS disturbances give rise to one of the pathological pathways in which SARS-CoV-2 suppresses neuroprotective pathways and induces inflammatory cytokines and reactive oxygen species. Finally, these impairments lead to neuroinflammation, neuronal injury, and neurological complications. In conclusion, the influence of RAS on various processes within the brain has significant implications for the neurological manifestations associated with COVID-19. These effects include sensory disturbances, such as olfactory and gustatory dysfunctions, as well as cerebrovascular and brain stem-related disorders, all of which are intertwined with disruptions in the RAS homeostasis of the brain.

The underlying mechanism of calcium toxicity-induced autophagic cell death and lysosomal degradation in early stage of cerebral ischemia

Cerebral ischemia is the important cause of worldwide disability and mortality, that is one of the obstruction of blood vessels supplying to the brain. In early stage, glutamate excitotoxicity and high level of intracellular calcium (Ca2+) are the major processes which can promote many downstream signaling involving in neuronal death and brain tissue damaging. Moreover, autophagy, the reusing of damaged cell organelles, is affected in early ischemia. Under ischemic conditions, autophagy plays an important role to maintain energy of the brain and its function. In the other hand, over intracellular Ca2+ accumulation triggers excessive autophagic process and lysosomal degradation leading to autophagic process impairment which finally induce neuronal death. This article reviews the association between intracellular Ca2+ and autophagic process in acute stage of ischemic stroke.

Ultra-High Dose Rate Helium Ion Beams: First In Vivo Evidence for Neuroprotective FLASH Effect

Purpose

To investigate ultra-high-dose rate helium ion irradiation and its potential FLASH sparing effect with the endpoint acute brain injury in preclinical in vivo settings.

Material and methods

Raster-scanned helium ion beams were administered to explore and compare the impact of dose rate variations between standard dose rate (SDR at 0.2 Gy/s) and FLASH (at 141 Gy/s) radiotherapy (RT). Irradiation-induced brain injury was investigated in healthy C57BL/6 mice via DNA damage response kinetic studies using nuclear γH2AX as a surrogate for double-strand breaks (DSB). The integrity of the neurovascular and immune compartments was assessed via CD31+ microvascular density and microglia/macrophages activation. Iba1+ ramified and CD68+ phagocytic microglia/macrophages were quantified, together with the expression of inducible nitric oxide synthetase (iNOS).

Results

Helium FLASH RT significantly prevented acute brain tissue injury compared with SDR. This was demonstrated by reduced levels of DSB and structural preservation of the neurovascular endothelium after FLASH RT. Moreover, FLASH RT exhibited reduced activation of neuroinflammatory signals compared with SDR, as detected by quantification of CD68+ iNOS+ microglia/macrophages.

Conclusion

To our knowledge, this is the first report on the FLASH-sparing neuroprotective effect of raster scanning helium ion radiotherapy in vivo.

DDAH-1 maintains endoplasmic reticulum-mitochondria contacts and protects dopaminergic neurons in Parkinson's disease

The loss of dopaminergic neurons in the substantia nigra is a hallmark of pathology in Parkinson's disease (PD). Dimethylarginine dimethylaminohydrolase-1 (DDAH-1) is the critical enzyme responsible for the degradation of asymmetric dimethylarginine (ADMA) which inhibits nitric oxide (NO) synthase and has been implicated in neurodegeneration. Mitochondrial dysfunction, particularly in the mitochondria-associated endoplasmic reticulum membrane (MAM), plays a critical role in this process, although the specific molecular target has not yet been determined. This study aims to examine the involvement of DDAH-1 in the nigrostriatal dopaminergic pathway and PD pathogenesis. The distribution of DDAH-1 in the brain and its colocalization with dopaminergic neurons were observed. The loss of dopaminergic neurons and aggravated locomotor disability after rotenone (ROT) injection were showed in the DDAH-1 knockout rat. L-arginine (ARG) and NO donors were employed to elucidate the role of NO respectively. In vitro, we investigated the effects of DDAH-1 knockdown or overexpression on cell viability and mitochondrial functions, as well as modulation of ADMA/NO levels using ADMA or ARG. MAM formation was assessed by the Mitofusin2 oligomerization and the mitochondrial ubiquitin ligase (MITOL) phosphorylation. We found that DDAH-1 downregulation resulted in enhanced cell death and mitochondrial dysfunctions, accompanied by elevated ADMA and reduced NO levels. However, the recovered NO level after the ARG supplement failed to exhibit a protective effect on mitochondrial functions and partially restored cell viability. DDAH-1 overexpression prevented ROT toxicity, while ADMA treatment attenuated these protective effects. The declines of MAM formation in ROT-treated cells were exacerbated by DDAH-1 downregulation via reduced MITOL phosphorylation, which was reversed by DDAH-1 overexpression. Together, the abundant expression of DDAH-1 in nigral dopaminergic neurons may exert neuroprotective effects by maintaining MAM formation and mitochondrial function probably via ADMA, indicating the therapeutic potential of targeting DDAH-1 for PD.

Research progress of prodrugs for the treatment of cerebral ischemia

It is well-known that pharmacotherapy plays a pivotal role in the treatment and prevention of cerebral ischemia. Nevertheless, existing drugs, including numerous natural products, encounter various challenges when applied in cerebral ischemia treatment. These challenges comprise poor brain absorption due to low blood-brain barrier (BBB) permeability, limited water solubility, inadequate bioavailability, poor stability, and rapid metabolism. To address these issues, researchers have turned to prodrug strategies, aiming to mitigate or eliminate the adverse properties of parent drug molecules. In vivo metabolism or enzymatic reactions convert prodrugs into active parent drugs, thereby augmenting BBB permeability, improving bioavailability and stability, and reducing toxicity to normal tissues, ultimately aiming to enhance treatment efficacy and safety. This comprehensive review delves into multiple effective prodrug strategies, providing a detailed description of representative prodrugs developed over the past two decades. It underscores the potential of prodrug approaches to improve the therapeutic outcomes of currently available drugs for cerebral ischemia. The publication of this review serves to enrich current research progress on prodrug strategies for the treatment and prevention of cerebral ischemia. Furthermore, it seeks to offer valuable insights for pharmaceutical chemists in this field, offer guidance for the development of drugs for cerebral ischemia, and provide patients with safer and more effective drug treatment options.

Local force constants and charges of the nitrosyl ligand in photoinduced NO linkage isomers in a prototypical ruthenium nitrosyl complex

Photoinduced linkage isomers (PLI) of the NO ligand in transition-metal nitrosyl compounds can be identified by vibrational spectroscopy due to the large shifts of the (NO) stretching vibration. We present a detailed experimental and theoretical study of the prototypical compound K2[RuCl5NO], where (NO) shifts by ≈150 cm-1 when going from the N-bound (κN) ground state (GS) to the oxygen-bound (κO) metastable linkage isomer MS1, and by ≈360 cm-1 when going to the side-on (κ2N,O) metastable linkage isomer MS2. We show that the experimentally observed N-O stretching modes of the GS, MS1, and MS2 exhibit strong coupling with the Ru-N and Ru-O stretching modes, which can be decoupled using the local mode vibrational theory formalism. From the resulting decoupled pure two-atomic harmonic oscillators the local force constants are determined, which all follow the same quadratic behavior on the wavenumber. A Bader charge analysis shows that the total charge on the NO ligand is not correlated to the observed frequency shift of (NO).

Comprehensive insights into fluorescent probes for the determination nitric oxide for diseases diagnosis

Nitric oxide (NO) plays an important role in multiple physiological processes of the body involved in regulation, such as cardiovascular relaxation, neural homeostasis, and immune regulation, etc. The real-time monitoring of NO is of great significance in the investigation of related disease mechanisms and the evaluation of pharmacodynamics. Fluorescent probes are considered as a highly promising approach for pharmaceutical analysis and bioimaging due to their non-invasive character, real-time detection, and high sensitivity. However, there are still some challenges in the determination of biological nitric oxide with fluorescent probes, such as low anti-interference ability, poor function modifiability, and low organ specificity. Therefore, it would be beneficial to develop a new generation of fluorescent probes for real-time bioimaging of NO in vivo after this systematic summary.

Clinical characteristics and molecular mechanisms underlying bladder cancer in individuals with spinal cord injury: a systematic review

BACKGROUND

Patients with spinal cord injury have a relatively high risk for bladder cancer and often complicated with bladder cancer in advanced stages, and the degree of aggressiveness of malignancy is high. Most of the literature is based on disease clinical features while, our study reviews the clinical characteristics and molecular mechanisms of spinal cord injury patients with bladder cancer, so that it might help clinicians better recognize and manage these patients.

METHOD

We searched PubMed, Web of Science and Embase, using retrieval type like ("Neurogenic Lower Urinary Tract Dysfunction" OR "Spinal cord injury" OR "Spinal Cord Trauma") AND ("bladder cancer" OR "bladder neoplasm" OR "bladder carcinoma" OR "Urinary Bladder Neoplasms" OR "Bladder Tumor"). In Web of Science, the retrieval type was searched as "Topic", and in PubMed and Embase, as "All Field". The methodological quality of eligible studies and their risk of bias were assessed using the Newcastle-Ottawa scale. This article is registered in PROSPERO with the CBD number: CRD42024508514.

RESULT

In WOS, we searched 219 related papers, in PubMed, 122 and in Embase, 363. Thus, a total of 254 articles were included after passing the screening, within a time range between 1960 and 2023. A comprehensive analysis of the data showed that the mortality and incidence rates of bladder cancer in spinal cord injury patients were higher than that of the general population, and the most frequent pathological type was squamous cell carcinoma. In parallel to long-term urinary tract infection and indwelling catheterization, the role of molecules such as NO, MiR 1949 and Rb 1. was found to be crucial pathogenetically.

CONCLUSION

This review highlights the risk of bladder cancer in SCI patients, comprehensively addressing the clinical characteristics and related molecular mechanisms. However, given that there are few studies on the molecular mechanisms of bladder cancer in spinal cord injury, further research is needed to expand the understanding of the disease.

Can alternative medical methods evoke somatosensory responses and functional improvement?

Background

Evidence-based scientific studies focusing on complementary alternative medicine (CAM) and potential functional improvement after an insult of the central nervous system are lacking.

Aims

We aim to demonstrate that functional recovery after stimulation applied as a CAM treatment through cauterization might trigger neural repair and regenerative paths similarly as acupuncture, cupping, electrical or magnetic stimulations. Those paths are important in recovery of function.

Procedures

Medical records and information of ten patients, with initial presentations of cerebral trauma or spinal cord insult inducing paralysis, were studied. Patients ages ranged from 17 to 95-year-old. Patients consulted for alternative medical treatment one year or more after initial diagnosis.CAM treatment consisted in 10-point stimulation on the skull and 4-point stimulation located at the right and left calves and forearms. Stimulations consisted of a heated steel rod application (cautery) in a one-time session. The duration of each stimulation was about 0.5 s.

Results

Most studies using CAM stimulations (acupuncture, cautery, cupping, moxibustion, electrical and magnetic stimulations) describe improvement. In all 10 medical records and information from our practitioner, patients had improvement in their motor skills, including gain of weight support, unassisted small walks, independent and voluntary movements of limbs. Improvement was steady over a period of one to several years.

Conclusion

We compared our findings to acupuncture, electrical, magnetic field effects to highlight common paths and to provide scientific evidence for recovery of the function. We believe that CAM treatments triggered existing or new neuronal networks as well as synaptic efficiency or reactivation, through highly increased, sensory nociceptive coupled to proprioceptive, afferences. Those results also highlight the need to further investigate neural function of cortical and subcortical areas through indirect pathways stimulations.

Hemin as a Molecular Probe for Nitric Oxide Detection in Physiological Solutions: Experimental and Theoretical Assessment

Given its pivotal role in modulating various pathological processes, precise measurement of nitric oxide (●NO) levels in physiological solutions is imperative. The key techniques include the ozone-based chemiluminescence (CL) reactions, amperometric ●NO sensing, and Griess assay, each with its advantages and drawbacks. In this study, a hemin/H2O2/luminol CL reaction was employed for accurately detecting ●NO in diverse solutions. We investigated how the luminescence kinetics was influenced by ●NO from two donors, nitrite and peroxynitrite, while also assessing the impact of culture medium components and reactive species quenchers. Furthermore, we experimentally and theoretically explored the mechanism of hemin oxidation responsible for the initiation of light generation. Although both hemin and ●NO enhanced the H2O2/luminol-based luminescence reactions with distinct kinetics, hemin's interference with ●NO/peroxynitrite- modulated their individual effects. Leveraging the propagated signal due to hemin, the ●NO levels in solution were estimated, observing parallel changes to those detected via amperometric detection in response to varying concentrations of the ●NO-donor. The examined reactions aid in comprehending the mechanism of ●NO/hemin/H2O2/luminol interactions and how these can be used for detecting ●NO in solution with minimal sample size demands. Moreover, the selectivity across different solutions can be improved by incorporating certain quenchers for reactive species into the reaction.

Drugs/agents for the treatment of ischemic stroke: Advances and perspectives

Ischemic stroke (IS) poses a significant threat to global human health and life. In recent decades, we have witnessed unprecedented progresses against IS, including thrombolysis, thrombectomy, and a few medicines that can assist in reopening the blocked brain vessels or serve as standalone treatments for patients who are not eligible for thrombolysis/thrombectomy therapies. However, the narrow time windows of thrombolysis/thrombectomy, coupled with the risk of hemorrhagic transformation, as well as the lack of highly effective and safe medications, continue to present big challenges in the acute treatment and long-term recovery of IS. In the past 3 years, several excellent articles have reviewed pathophysiology of IS and therapeutic medicines for the treatment of IS based on the pathophysiology. Regretfully, there is no comprehensive overview to summarize all categories of anti-IS drugs/agents designed and synthesized based on molecular mechanisms of IS pathophysiology. From medicinal chemistry view of point, this article reviews a multitude of anti-IS drugs/agents, including small molecule compounds, natural products, peptides, and others, which have been developed based on the molecular mechanism of IS pathophysiology, such as excitotoxicity, oxidative/nitrosative stresses, cell death pathways, and neuroinflammation, and so forth. In addition, several emerging medicines and strategies, including nanomedicines, stem cell therapy and noncoding RNAs, which recently appeared for the treatment of IS, are shortly introduced. Finally, the perspectives on the associated challenges and future directions of anti-IS drugs/agents are briefly provided to move the field forward.

Neurotoxic Microglial Activation via IFNγ-Induced Nrf2 Reduction Exacerbating Alzheimer's Disease

Microglial neuroinflammation appears to be neuroprotective in the early pathological stage, yet neurotoxic, which often precedes neurodegeneration in Alzheimer's disease (AD). However, it remains unclear how the microglial activities transit to the neurotoxic state during AD progression, due to complex neuron-glia interactions. Here, the mechanism of detrimental microgliosis in AD by employing 3D human AD mini-brains, brain tissues of AD patients, and 5XFAD mice is explored. In the human and animal AD models, amyloid-beta (Aβ)-overexpressing neurons and reactive astrocytes produce interferon-gamma (IFNγ) and excessive oxidative stress. IFNγ results in the downregulation of mitogen-activated protein kinase (MAPK) and the upregulation of Kelch-like ECH-associated Protein 1 (Keap1) in microglia, which inactivate nuclear factor erythroid-2-related factor 2 (Nrf2) and sensitize microglia to the oxidative stress and induces a proinflammatory microglia via nuclear factor kappa B (NFκB)-axis. The proinflammatory microglia in turn produce neurotoxic nitric oxide and proinflammatory mediators exacerbating synaptic impairment, phosphorylated-tau accumulation, and discernable neuronal loss. Interestingly, recovering Nrf2 in the microglia prevents the activation of proinflammatory microglia and significantly blocks the tauopathy in AD minibrains. Taken together, it is envisioned that IFNγ-driven Nrf2 downregulation in microglia as a key target to ameliorate AD pathology.

Control of astrocytic Ca2+ signaling by nitric oxide-dependent S-nitrosylation of Ca2+ homeostasis modulator 1 channels

BACKGROUND

Astrocytes Ca2+ signaling play a central role in the modulation of neuronal function. Activation of metabotropic glutamate receptors (mGluR) by glutamate released during an increase in synaptic activity triggers coordinated Ca2+ signals in astrocytes. Importantly, astrocytes express the Ca2+-dependent nitric oxide (NO)-synthetizing enzymes eNOS and nNOS, which might contribute to the Ca2+ signals by triggering Ca2+ influx or ATP release through the activation of connexin 43 (Cx43) hemichannels, pannexin-1 (Panx-1) channels or Ca2+ homeostasis modulator 1 (CALHM1) channels. Hence, we aim to evaluate the participation of NO in the astrocytic Ca2+ signaling initiated by stimulation of mGluR in primary cultures of astrocytes from rat brain cortex.

RESULTS

Astrocytes were stimulated with glutamate or t-ACPD and NO-dependent changes in [Ca2+]i and ATP release were evaluated. In addition, the activity of Cx43 hemichannels, Panx-1 channels and CALHM1 channels was also analyzed. The expression of Cx43, Panx-1 and CALHM1 in astrocytes was confirmed by immunofluorescence analysis and both glutamate and t-ACPD induced NO-mediated activation of CALHM1 channels via direct S-nitrosylation, which was further confirmed by assessing CALHM1-mediated current using the two-electrode voltage clamp technique in Xenopus oocytes. Pharmacological blockade or siRNA-mediated inhibition of CALHM1 expression revealed that the opening of these channels provides a pathway for ATP release and the subsequent purinergic receptor-dependent activation of Cx43 hemichannels and Panx-1 channels, which further contributes to the astrocytic Ca2+ signaling.

CONCLUSIONS

Our findings demonstrate that activation of CALHM1 channels through NO-mediated S-nitrosylation in astrocytes in vitro is critical for the generation of glutamate-initiated astrocytic Ca2+ signaling.

Significance of nitrosative stress and glycoxidation products in the diagnosis of COVID-19

Nitrosative stress promotes protein glycoxidation, and both processes can occur during an infection with the SARS-CoV-2 virus. Therefore, the aim of this study was to assess selected nitrosative stress parameters and protein glycoxidation products in COVID-19 patients and convalescents relative to healthy subjects, including in reference to the severity of COVID-19 symptoms. The diagnostic utility of nitrosative stress and protein glycoxidation biomarkers was also evaluated in COVID-19 patients. The study involved 218 patients with COVID-19, 69 convalescents, and 48 healthy subjects. Nitrosative stress parameters (NO, S-nitrosothiols, nitrotyrosine) and protein glycoxidation products (tryptophan, kynurenine, N-formylkynurenine, dityrosine, AGEs) were measured in the blood plasma or serum with the use of colorimetric/fluorometric methods. The levels of NO (p = 0.0480), S-nitrosothiols (p = 0.0004), nitrotyrosine (p = 0.0175), kynurenine (p < 0.0001), N-formylkynurenine (p < 0.0001), dityrosine (p < 0.0001), and AGEs (p < 0.0001) were significantly higher, whereas tryptophan fluorescence was significantly (p < 0.0001) lower in COVID-19 patients than in the control group. Significant differences in the analyzed parameters were observed in different stages of COVID-19. In turn, the concentrations of kynurenine (p < 0.0001), N-formylkynurenine (p < 0.0001), dityrosine (p < 0.0001), and AGEs (p < 0.0001) were significantly higher, whereas tryptophan levels were significantly (p < 0.0001) lower in convalescents than in healthy controls. The ROC analysis revealed that protein glycoxidation products can be useful for diagnosing infections with the SARS-CoV-2 virus because they differentiate COVID-19 patients (KN: sensitivity-91.20%, specificity-92.00%; NFK: sensitivity-92.37%, specificity-92.00%; AGEs: sensitivity-99,02%, specificity-100%) and convalescents (KN: sensitivity-82.22%, specificity-84.00%; NFK: sensitivity-82,86%, specificity-86,00%; DT: sensitivity-100%, specificity-100%; AGE: sensitivity-100%, specificity-100%) from healthy subjects with high sensitivity and specificity. Nitrosative stress and protein glycoxidation are intensified both during and after an infection with the SARS-CoV-2 virus. The levels of redox biomarkers fluctuate in different stages of the disease. Circulating biomarkers of nitrosative stress/protein glycoxidation have potential diagnostic utility in both COVID-19 patients and convalescents.

Effect of leptin on nitrergic neurons in the lateral hypothalamic area and the supraoptic nucleus of rats

The adipocyte-derived hormone, leptin, plays a key role in the maintenance of energy homeostasis. Leptin binds to the long form of its receptor, which is predominantly expressed in various hypothalamic regions, including the lateral hypothalamic area (LH) and supraoptic nucleus (SO). Several studies have suggested that leptin directly activates neuronal nitric oxide synthase, leading to increased nitric oxide production. We used histochemistry for nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) as a marker for nitric oxide synthase activity and assessed the effect of leptin on nitrergic neurons in the LH and SO of rats. We found that intraperitoneal administration of leptin led to a significant increase in the number of NADPH-d-positive neurons in the LH and SO. In addition, the intensity (optical density) of NADPH-d staining in LH and SO neurons was significantly elevated in rats that received leptin compared with saline-treated rats. These findings suggest that nitrergic neurons in the LH and SO may be implicated in mediating the central effects of leptin.

Nitric oxide involvement in the disability and active disease of multiple sclerosis: Systematic review and meta-analysis

BACKGROUND

Multiple sclerosis (MS) is a chronic and immune-mediated disease of unknown etiology and leading to a physical and cognitive disability. Different studies suggest that nitrosative stress may play a pivotal role in the pathogenesis and disability in MS. Besides, reports evaluated NO and their metabolites, expressed by nitrite and nitrate (NOx) levels of MS patients compared with other pathologies, but did not evaluate disability and relapse/remission phases.

OBJECTIVE

Thus, this study aimed to conduct a systematic review and meta-analysis of NOx levels in MS patients in relapse/remission phases and its involvement in patient disability.

METHODS

The protocol was registered in PROSPERO (CRD42022327161). We used GRADE to estimate the articles' quality and evaluated the publication bias using Egger's and Begg's tests.

RESULTS

Here, through a search in the Pubmed, Scopus, and EMBASE databases, 5.276 studies were found, and after the selection process, 20 studies were included in this systematic review and meta-analysis. The studies included data from 1.474 MS patients and 1.717 healthy controls, 1.010 RRMS and 221 primary progressive MS (PPMS).

CONCLUSION

NOx levels are increased in relapsing-remitting MS (RRMS) patients in the relapse phase. Also, NOx levels were increased in MS patients with higher disability. However, further studies are still needed to control lifestyle habits, pain, and MS treatment effects in biased NOx levels.

Moringa oleifera leaves ethanolic extract counteracts cortical neurodegeneration induced by aluminum chloride in rats

Background

Aluminum, a well-recognized neurotoxin, is implicated in various neurodegenerative disorders. Moringa oleifera (M. oleifera), known as a miracle tree, is utilized as a functional food and nutritional supplement. This study investigates the potential preventive effects of M. oleifera extract on aluminum chloride (AlCl3)-induced cortical neurodegeneration in rats.

Materials and methods

Therefore, 24 adult male Wistar rats were randomly divided into four distinct groups: negative control, M. oleifera extract (MOE), AlCl3, and AlCl3 + MOE. Treatments were administered orally for 28 consecutive days. Cognitive performance, brain oxidative/nitrosative stress, neuroinflammation, apoptotic-cell death, and associated histopathological alterations were assessed.

Results

Our results showed that MOE improved spatial learning and memory, enhanced antioxidant superoxide dismutase enzyme activity, antagonized nitrosative stress, reduced inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6), decreased caspase-3, increased Bcl-2, and facilitated repair of cortical and hippocampal structures.

Conclusions

We concluded that MOE exhibits protective effects against cortical neurodegeneration, making it a promising supplement to counteract aluminum-induced neurotoxic effects.

4R-cembranoid suppresses glial cells inflammatory phenotypes and prevents hippocampal neuronal loss in LPS-treated mice

Chronic neuroinflammation has been implicated in neurodegenerative disease pathogenesis. A key feature of neuroinflammation is neuronal loss and glial activation, including microglia and astrocytes. 4R-cembranoid (4R) is a natural compound that inhibits hippocampal pro-inflammatory cytokines and increases memory function in mice. We used the lipopolysaccharide (LPS) injection model to study the effect of 4R on neuronal density and microglia and astrocyte activation. C57BL/6J wild-type mice were injected with LPS (5 mg/kg) and 2 h later received either 4R (6 mg/kg) or vehicle. Mice were sacrificed after 72 h for analysis of brain pathology. Confocal images of brain sections immunostained for microglial, astrocyte, and neuronal markers were used to quantify cellular hippocampal phenotypes and neurons. Hippocampal lysates were used to measure the expression levels of neuronal nuclear protein (NeuN), inducible nitrous oxide synthase (iNOS), arginase-1, thrombospondin-1 (THBS1), glial cell-derived neurotrophic factor (GDNF), and orosomucoid-2 (ORM2) by western blot. iNOS and arginase-1 are widely used protein markers of pro- and anti-inflammatory microglia, respectively. GDNF promotes neuronal survival, and ORM2 and THBS1 are astrocytic proteins that regulate synaptic plasticity and inhibit microglial activation. 4R administration significantly reduced neuronal loss and the number of pro-inflammatory microglia 72 h after LPS injection. It also decreased the expression of the pro-inflammatory protein iNOS while increasing arginase-1 expression, supporting its anti-inflammatory role. The protein expression of THBS1, GDNF, and ORM2 was increased by 4R. Our data show that 4R preserves the integrity of hippocampal neurons against LPS-induced neuroinflammation in mice.

Recent advances in DDAH1 inhibitor design and discovery: insights from structure-activity relationships and X-ray crystal structures

Nitric oxide (NO) is an important signalling molecule which modulates several biological and pathological processes. Dimethylarginine dimethylaminohydrolase 1 (DDAH1) plays a key role indirectly regulating NO concentrations in the body. It has been shown that DDAH1 inhibition may be an effective therapeutic strategy in certain pathological states in which excessive NO is produced. In recent years, specific DDAH1 inhibitors have shown promise in suppressing abnormal neovascularization in cancer. However, the available DDAH1 inhibitors lack potency and selectivity and are mostly arginine-based. Further, these inhibitors display unfavourable pharmacokinetics and have not been tested in humans. Thus, the development of potent, selective, and chemically diverse DDAH1 inhibitors is essential. In this review, we examine the structure activity relationships (SARs) and X-ray crystal structures of known DDAH1 inhibitors. Then, we discuss current challenges in the design and development of novel DDAH1 inhibitors and provide future directions for developing potent and chemically diverse compounds.

Recent advances on the development of NO-releasing molecules (NORMs) for biomedical applications

Nitric oxide (NO) is an important biological messenger as well as a signaling molecule that participates in a broad range of physiological events and therapeutic applications in biological systems. However, due to its very short half-life in physiological conditions, its therapeutic applications are restricted. Efforts have been made to develop an enormous number of NO-releasing molecules (NORMs) and motifs for NO delivery to the target tissues. These NORMs involve organic nitrate, nitrite, nitro compounds, transition metal nitrosyls, and several nanomaterials. The controlled release of NO from these NORMs to the specific site requires several external stimuli like light, sound, pH, heat, enzyme, etc. Herein, we have provided a comprehensive review of the biochemistry of nitric oxide, recent advancements in NO-releasing materials with the appropriate stimuli of NO release, and their biomedical applications in cancer and other disease control.

Alterations in glutamate, arginine, and energy metabolism characterize cerebrospinal fluid and plasma metabolome of persons with HIV-associated dementia

OBJECTIVES

HIV-associated dementia (HAD) is the most severe clinical expression of HIV-mediated neuropathology, and the processes underlying its development remain poorly understood. We aimed to exploit high-dimensional metabolic profiling to gain insights into the pathological mechanisms associated to HAD.

DESIGN

In this cross-sectional study, we utilized metabolomics to profile matched cerebrospinal fluid (CSF) and plasma samples of HAD individuals ( n  = 20) compared with neurologically asymptomatic people with HIV (ASYM, n  = 20) and healthy controls (NEG, n  = 20).

METHODS

Identification of plasma and CSF metabolites was performed by liquid-chromatography or gas-chromatography following a validated experimental pipeline. The resulting metabolic profiles were analyzed by machine-learning algorithms, and altered pathways were identified by comparison with KEGG pathway database.

RESULTS

In CSF, HAD patients displayed an imbalance in glutamine/glutamate ratio, decreased levels of isocitrate and arginine, and increased oxidative stress when compared with ASYM or NEG. These changes were confirmed in matched plasma samples, which in addition revealed an accumulation of eicosanoids and unsaturated fatty acids in HAD individuals. Pathway analysis in both biological fluids suggested that alterations in several metabolic processes, including protein biosynthesis, glutamate and arginine metabolism, and energy metabolism, in association to a perturbed eicosanoid metabolism in plasma, may represent the metabolic signature associated to HAD.

CONCLUSION

These findings show that HAD may be associated with metabolic modifications in CSF and plasma. These preliminary data may be useful to identify novel metabolic biomarkers and therapeutic targets in HIV-associated neurological impairment.

Modulatory effect of olanzapine on neuronal nitric oxide synthase (nNOS) expression in the rat striatum

Nitric oxide (NO) has been thought to be a novel factor involved in the mechanisms of mental disorders pathogenesis for quite some time. However, little is known about potential crosstalk between neuronal NO signaling and neuroleptics action. The present work was, therefore, focused on gene expression of neuronal NO synthase (nNOS) in the brains of rats chronically treated with olanzapine, an atypical antipsychotic drug. Studies were carried out on adult, male Sprague-Dawley rats that were divided into 2 groups: control and experimental animals treated with olanzapine (28-day-long intraperitoneal injection, at dose 5 mg/kg daily). All individuals were killed under anesthesia and the whole brains excised. Immunohistochemical procedure was used for histological assessment of the whole brain, and for both descriptive and quantitative analysis of nNOS protein distribution in selected brain structures. Long-term treatment with olanzapine is reflected in different changes in the number of enzyme-expressing cells in the rat brain. Olanzapine decreased the number of nNOS-expressing cells and possibly reduced NO synthesis in the rat striatum. Olanzapine can be taken into account as a potential inhibitor of NO synthesis in the rat striatum.

PSD-95 inhibitor Tat-NR2B9c (NA-1) protects the integrity of the blood-brain barrier after transient middle artery occlusion in rats by downregulating matrix metalloprotease-9 and upregulating endothelial nitric oxide synthase

BACKGROUND

Protection against ischemic stroke may be most effective when multiple components of the neurovascular unit are protected, yet current treatments target mainly neurons. Here we explored whether the PSD-95 inhibitor Tat-NR2B9c (NA-1) can protect not only neurons but also the blood-brain barrier.

METHODS

Adult male Sprague-Dawley rats were randomly divided into three groups, which were subjected to either sham surgery or transient cerebral ischemia-reperfusion, after which some animals were treated with Tat-NR2B9c. The therapeutic efficacy of Tat-NR2B9c was assessed in terms of the degree of neurological deficit and cerebral infarction, integrity of the blood-brain barrier, cerebral water content, as well as expression of PSD-95, nitric oxide synthase, and matrix metalloprotease-9.

RESULTS

Tat-NR2B9c (NA-1) ameliorated neurofunctional deficit, reduced cerebral infarction, mitigated blood-brain barrier injury and improved its integrity following ischemia-reperfusion, leading to less cerebral edema. These improvements were associated with upregulation of tight junction proteins in the blood-brain barrier. At the same time, Tat-NR2B9c (NA-1) downregulated neuronal nitric oxide synthase and matrix metalloprotease-9, while reversing the ischemia-induced downregulation of endothelial nitric oxide synthase in brain. We report here the first evidence that PSD-95 is expressed in vascular endothelial cells in the brain.

CONCLUSION

Our experiments in a rat model of transient occlusion of the middle cerebral artery suggest that Tat-NR2B9c (NA-1) can mitigate ischemic injury to the blood-brain barrier, and that it may do so by downregulating matrix metalloprotease-9 and upregulating endothelial nitric oxide synthase.

Advances in nitric oxide regulators for the treatment of ischemic stroke

Ischemic stroke (IS) is a life-threatening disease worldwide. Nitric oxide (NO) derived from l-arginine catalyzed by NO synthase (NOS) is closely associated with IS. Three isomers of NOS (nNOS, eNOS and iNOS) produce different concentrations of NO, resulting in quite unlike effects during IS. Of them, n/iNOSs generate high levels of NO, detrimental to brain by causing nerve cell apoptosis and/or necrosis, whereas eNOS releases small amounts of NO, beneficial to the brain via increasing cerebral blood flow and improving nerve function. As a result, a large variety of NO regulators (NO donors or n/iNOS inhibitors) have been developed for fighting IS. Regrettably, up to now, no review systematically introduces the progresses in this area. This article first outlines dynamic variation rule of NOS/NO in IS, subsequently highlights advances in NO regulators against IS, and finally presents perspectives based on concentration-, site- and timing-effects of NO production to promote this field forward.

Nitric oxide modulates NMDA receptor through a negative feedback mechanism and regulates the dynamical behavior of neuronal postsynaptic components

Nitric oxide (NO) is known to be an important regulator of neurological processes in the central nervous system which acts directly on the presynaptic neuron and enhances the release of neurotransmitters like glutamate into the synaptic cleft. Calcium influx activates a cascade of biochemical reactions to influence the production of nitric oxide in the postsynaptic neuron. This has been modeled in the present work as a system of ordinary differential equations, to explore the dynamics of the interacting components and predict the dynamical behavior of the postsynaptic neuron. It has been hypothesized that nitric oxide modulates the NMDA receptor via a feedback mechanism and regulates the dynamic behavior of postsynaptic components. Results obtained by numerical analyses indicate that the biochemical system is stimulus-dependent and shows oscillations of calcium and other components within a limited range of concentration. Some of the parameters such as stimulus strength, extracellular calcium concentration, and rate of nitric oxide feedback are crucial for the dynamics of the components in the postsynaptic neuron.

Effects of extended-release 7-nitroindazole gel formulation treatment on the behavior of Shank3 mouse model of autism

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by behavioral deficits such as abnormalities in communication, social interaction, anxiety, and repetitive behavior. We have recently shown that the Shank3 mutation in mice representing a model of ASD causes excessive nitric oxide (NO) levels and aberrant protein S-nitrosylation. Further, 10-day daily injections of 7-NI, a neuronal nitric oxide synthase inhibitor, into Shank3Δ4-22 and Cntnap2(-/-) mutant mice (models of ASD) at a dose of 80 mg/kg reversed the manifestations of ASD phenotype. In this study, we proposed an extended release of 7-NI using a novel drug system. Importantly, unlike the intraperitoneal injections, our new preparation of poly (sebacic acid-co-ricinoleic acid) (PSARA) gel containing 7-NI was injected subcutaneously into the mutant mice only once. The animals underwent behavioral testing starting from day 3 post-injection. It should be noted that the developed PSARA gel formulation allowed a slow release of 7-NI maintaining the plasma level of the drug at ∼45 μg/ml/day. Further, we observed improved memory and social interaction and reduced anxiety-like behavior in Shank3 mutant mice. This was accompanied by a reduction in 3-nitrotyrosine levels (an indicator of nitrative/nitrosative stress) in plasma. Overall, we suggest that our single-dose formulation of PSARA gel is very efficient in rendering a therapeutic effect of 7-NI for at least 10 days. This approach may provide in the future a rational design of an effective ASD treatment using 7-NI and its clinical translation.

The effect of MK-801 on stress-ethanol cross-sensitization is dissociable from its effects on nNOS activity

Locomotor behavioral sensitization represents an animal model for understanding neuroadaptive processes related to repeated drug exposure. Repeated stress can elicit a cross-sensitization to the stimulant response of ethanol, which involves neuronal nitric oxide synthase (nNOS). Activation of N-methyl d-aspartate (NMDA) glutamate receptors triggers nNOS and the synthesis of nitric oxide (NO). In this study, we investigated the effects of blocking NMDA receptors using the NMDA receptor antagonist MK-801 on the cross-sensitization between restraint stress and ethanol. We also evaluated the nNOS activity in the prefrontal cortex (PFC) and hippocampus. Mice were pretreated with saline or MK-801 30 min before an injection of saline or stress exposure for 14 days. On the following day, they were challenged with either saline or 1.8 g/kg ethanol. Swiss male mice pretreated with 0.25 mg/kg MK-801 exhibited a sensitized response to ethanol. Moreover, MK-801 potentiated the cross-sensitization between stress and ethanol. However, MK-801 prevented the enhanced nNOS activity in stress-exposed groups (challenged with saline or ethanol) in the PFC; the antagonist also prevented the ethanol-induced increase in nNOS activity and reduced this enzyme activity in mice exposed to stress in the hippocampus. These data indicate that systemic treatment with the NMDA antagonist potentiated, rather than blocked, ethanol-induced behavioral sensitization and that this effect is dissociable from the capacity of NMDA antagonists to reduce ethanol/stress-induced NOS stimulation in the PFC and hippocampus.

ASCL1 Is Involved in the Pathogenesis of Schizophrenia by Regulation of Genes Related to Cell Proliferation, Neuronal Signature Formation, and Neuroplasticity

Schizophrenia (SZ) is a common psychiatric neurodevelopmental disorder with a complex genetic architecture. Genome-wide association studies indicate the involvement of several transcription factors, including ASCL1, in the pathogenesis of SZ. We aimed to identify ASCL1-dependent cellular and molecular mechanisms associated with SZ. We used Capture-C, CRISPR/Cas9 systems and RNA-seq analysis to confirm the involvement of ASCL1 in SZ-associated pathogenesis, establish a mutant SH-SY5Y line with a functional ASCL1 knockout (ASCL1-del) and elucidate differentially expressed genes that may underlie ASCL1-dependent pathogenic mechanisms. Capture-C confirmed the spatial interaction of the ASCL1 promoter with SZ-associated loci. Transcriptome analysis showed that ASCL1 regulation may be through a negative feedback mechanism. ASCL1 dysfunction affects the expression of genes associated with the pathogenesis of SZ, as well as bipolar and depressive disorders. Genes differentially expressed in ASCL1-del are involved in cell mitosis, neuronal projection, neuropeptide signaling, and the formation of intercellular contacts, including the synapse. After retinoic acid (RA)-induced differentiation, ASCL1 activity is restricted to a small subset of genes involved in neuroplasticity. These data suggest that ASCL1 dysfunction promotes SZ development predominantly before the onset of neuronal differentiation by slowing cell proliferation and impeding the formation of neuronal signatures.

Does dietary nitrate boost the effects of caloric restriction on brain health? Potential physiological mechanisms and implications for future research

Dementia is a highly prevalent and costly disease characterised by deterioration of cognitive and physical capacity due to changes in brain function and structure. Given the absence of effective treatment options for dementia, dietary and other lifestyle approaches have been advocated as potential strategies to reduce the burden of this condition. Maintaining an optimal nutritional status is vital for the preservation of brain function and structure. Several studies have recognised the significant role of nutritional factors to protect and enhance metabolic, cerebrovascular, and neurocognitive functions. Caloric restriction (CR) positively impacts on brain function via a modulation of mitochondrial efficiency, endothelial function, neuro-inflammatory, antioxidant and autophagy responses. Dietary nitrate, which serves as a substrate for the ubiquitous gasotransmitter nitric oxide (NO), has been identified as a promising nutritional intervention that could have an important role in improving vascular and metabolic brain regulation by affecting oxidative metabolism, ROS production, and endothelial and neuronal integrity. Only one study has recently tested the combined effects of both interventions and showed preliminary, positive outcomes cognitive function. This paper explores the potential synergistic effects of a nutritional strategy based on the co-administration of CR and a high-nitrate diet as a potential and more effective (than either intervention alone) strategy to protect brain health and reduce dementia risk.

Botanical Mixture Containing Nitric Oxide Metabolite Enhances Neural Plasticity to Improve Cognitive Impairment in a Vascular Dementia Rat Model

Vascular dementia (VD), caused by impaired cerebral blood flow, is the most common form of dementia after Alzheimer's disease (AD) in the elderly and is characterized by severe neuronal damage and cognitive decline. Nitric oxide (NO) is an important determinant of vascular homeostasis, and its deficiency is associated with the progression of VD. In this study, we investigated the role of nitrite ion, a NO metabolite in a botanical mixture (BM) of fermented garlic, fermented Scutellaria baicalensis, and Rhodiola rosea on neuron loss and cognitive impairment using a VD rat model. The BM containing the NO metabolite alleviated cognitive deficits and enhanced neural plasticity, as reflected by an increase in long-term potentiation. The BM also alleviated neuron apoptosis, decreased GFAP expression, and oxidative stress, and increased parvalbumin and brain-derived neurotrophic factor (BDNF) levels. These results indicate that BM exerts neuroprotective effects and alleviates cognitive dysfunction while enhancing neuroplasticity, and thus has therapeutic potential against VD.

Neuroprotective Effect of Ethanolic Extract of Scoparia dulcis on Acrylamide-Induced Neurotoxicity in Zebrafish Model

All herbal medicines are reported to be safe and have better results in curing disabilities. Scoparia dulcis is known for its anti-inflammatory and antioxidant properties. This study has been executed to explore the neuroprotective effects of ethanolic extract of Scoparia dulcis (EESD) against acrylamide using adult zebrafish. The experimental period was 72 h. After fixing the optimum acrylamide concentration and EESD, the healthy adult fish were grouped into control, induction, and treatment. During the experimental period, behavioural changes such as memory and locomotion were observed in control and experimental groups using the T-maze experiment. After 72 h, the neuronal tissues were isolated from the grouped fishes and analysed for various biochemical and enzymatic assays. The mRNA of the HSP-70 gene in control and experimental groups was expressed using RT-PCR. The optimum dosages for acrylamide and EESD were found to be 0.75 mM and 20 µg/mL, respectively. Memory improvement was observed in S. dulcis-treated fish, compared to the acrylamide-treated group using the T-maze assay. The extract reduced the toxicity induced by acrylamide from the various biochemical and histopathological parameters. The result shows the potential neuroprotective effects of ethanolic extract of Scoparia dulcis (EESD) against acrylamide-induced neurotoxicity in adult zebrafish. Therefore, Scoparia dulcis is a potent neuroprotective agent.

RNA-Seq-Based Transcriptome Analysis of Nitric Oxide Scavenging Response in Neurospora crassa

While the biological role of naturally occurring nitric oxide (NO) in filamentous fungi has been uncovered, the underlying molecular regulatory networks remain unclear. In this study, we conducted an analysis of transcriptome profiles to investigate the initial stages of understanding these NO regulatory networks in Neurospora crassa, a well-established model filamentous fungus. Utilizing RNA sequencing, differential gene expression screening, and various functional analyses, our findings revealed that the removal of intracellular NO resulted in the differential transcription of 424 genes. Notably, the majority of these differentially expressed genes were functionally linked to processes associated with carbohydrate and amino acid metabolism. Furthermore, our analysis highlighted the prevalence of four specific protein domains (zinc finger C2H2, PLCYc, PLCXc, and SH3) in the encoded proteins of these differentially expressed genes. Through protein-protein interaction network analysis, we identified eight hub genes with substantial interaction connectivity, with mss-4 and gel-3 emerging as possibly major responsive genes during NO scavenging, particularly influencing vegetative growth. Additionally, our study unveiled that NO scavenging led to the inhibition of gene transcription related to a protein complex associated with ribosome biogenesis. Overall, our investigation suggests that endogenously produced NO in N. crassa likely governs the transcription of genes responsible for protein complexes involved in carbohydrate and amino acid metabolism, as well as ribosomal biogenesis, ultimately impacting the growth and development of hyphae.

Nitric Oxide: Physiological Functions, Delivery, and Biomedical Applications

Nitric oxide (NO) is a gaseous molecule that has a central role in signaling pathways involved in numerous physiological processes (e.g., vasodilation, neurotransmission, inflammation, apoptosis, and tumor growth). Due to its gaseous form, NO has a short half-life, and its physiology role is concentration dependent, often restricting its function to a target site. Providing NO from an external source is beneficial in promoting cellular functions and treatment of different pathological conditions. Hence, the multifaceted role of NO in physiology and pathology has garnered massive interest in developing strategies to deliver exogenous NO for the treatment of various regenerative and biomedical complexities. NO-releasing platforms or donors capable of delivering NO in a controlled and sustained manner to target tissues or organs have advanced in the past few decades. This review article discusses in detail the generation of NO via the enzymatic functions of NO synthase as well as from NO donors and the multiple biological and pathological processes that NO modulates. The methods for incorporating of NO donors into diverse biomaterials including physical, chemical, or supramolecular techniques are summarized. Then, these NO-releasing platforms are highlighted in terms of advancing treatment strategies for various medical problems.

Neuronal Nitric Oxide Synthase and Post-Translational Modifications in the Development of Central Nervous System Diseases: Implications and Regulation

In the Central Nervous System (CNS), Nitric Oxide (NO) is mainly biosynthesized by neuronal Nitric Oxide Synthase (nNOS). The dysregulated activation of nNOS in neurons is critical in the development of different conditions affecting the CNS. The excessive production of NO by nNOS is responsible for a number of proteins' post-translational modifications (PTMs), which can lead to aberrant biochemical pathways, impairing CNS functions. In this review, we briefly revise the main implications of dysregulated nNOS in the progression of the most prevalent CNS neurodegenerative disorders, i.e., Alzheimer's disease (AD) and Parkinson's disease, as well as in the development of neuronal disorders. Moreover, a specific focus on compounds able to modulate nNOS activity as promising therapeutics to tackle different neuronal diseases is presented.

Effect of indoor air quality on the association of long-term exposure to low-level air pollutants with cognition in older adults

BACKGROUND

How indoor air quality affects the temporal associations of long-term exposure to low-level air pollutants with cognition remains unclear.

METHODS

This cohort study (2011-2019) included 517 non-demented older adults at baseline with four repeated cognitive assessments. The time-varying exposure to PM2.5, PM10, NO2, SO2, CO, and O3 was estimated for each participant from 1994 to 2019. Indoor air quality was determined by ventilation status and daily indoor time. Generalized linear mixed models were used to analyze the association of air pollutants, indoor air quality, and cognition adjusting for important covariates.

RESULTS

Over time, per 2.97 μg/m3 (i.e., an interquartile range) increment of PM2.5 was associated with the poor performance of memory (Z score of a cognitive test, βˆ:-0.14), attention (βˆ:-0.13), and executive function (βˆ:-0.20). Similarly, per 2.05 μg/m3 increase in PM2.5-10 was associated with poor global cognition [adjusted odds ratio (aOR): 1.48, βˆ:-0.28], attention (βˆ:-0.07), and verbal fluency (βˆ:-0.09); per 4.94 μg/m3 increase in PM10 was associated with poor global cognition (aOR: 1.78; βˆ:-0.37). In contrast, per 2.74 ppb increase in O3 was associated with better global cognition (βˆ:0.36 to 0.47). These associations became more evident in participants with poor ventilation or short daily indoor time (<12.5 h/day). For global cognition, the exposure to a 10-μg/m3 increment in PM2.5, PM2.5-10, and PM10 corresponded to 1.4, 5.8, and 2.8 years of aging, respectively.

CONCLUSION

This study demonstrated how indoor air quality in areas using clean fuels differentially affected the associations of long-term exposure to low-level air pollutants with cognition. Tightening air quality standards may help prevent dementia.

Differential G Protein-Coupled Estrogen Receptor-1 Regulation of Counter-Regulatory Transmitter Marker and 5'-AMP-Activated Protein Kinase Expression in Ventrolateral versus Dorsomedial Ventromedial Hypothalamic Nucleus

INTRODUCTION

The ventromedial hypothalamic nucleus (VMN) is an estrogen receptor (ER)-rich structure that regulates glucostasis. The role of nuclear but not membrane G protein-coupled ER-1 (GPER) in that function has been studied.

METHODS

Gene silencing and laser-catapult microdissection/immunoblot tools were used to examine whether GPER regulates transmitter and energy sensor function in dorsomedial (VMNdm) and/or ventrolateral (VMNvl) VMN counter-regulatory nitrergic and γ-Aminobutyric acid (GABA) neurons.

RESULTS

Intra-VMN GPER siRNA administration to euglycemic animals did not affect VMNdm or -vl nitrergic neuron nitric oxide synthase (nNOS), but upregulated (VMNdm) or lacked influence on (VMNvl) GABA nerve cell glutamate decarboxylase65/67 (GAD) protein. Insulin-induced hypoglycemia (IIH) caused GPER knockdown-reversible augmentation of nNOS, 5'-AMP-activated protein kinase (AMPK), and phospho-AMPK proteins in nitrergic neurons in both divisions. IIH had dissimilar effects on VMNvl (unchanged) versus VMNdm (increased) GABAergic neuron GAD levels, yet GPER knockdown affected these profiles. GPER siRNA prevented hypoglycemic upregulation of VMNvl and -dm GABA neuron AMPK without altering pAMPK expression.

CONCLUSIONS

Outcomes infer that GPER exerts differential control of VMNdm versus -vl GABA transmission during glucostasis and is required for hypoglycemic upregulated nitrergic (VMNdm and -vl) and GABA (VMNdm) signaling. Glycogen metabolism is reported to regulate VMN nNOS and GAD proteins. Data show that GPER limits VMNvl glycogen phosphorylase (GP) protein expression and glycogen buildup during euglycemia but mediates hypoglycemic augmentation of VMNvl GP protein and glycogen content; VMNdm glycogen mass is refractory to GPER control. GPER regulation of VMNvl glycogen metabolism infers that this receptor may govern local counter-regulatory transmission in part by astrocyte metabolic coupling.

Record-High Ultrasound-Sensitive NO Nanogenerators for Cascade Tumor Pyroptosis and Immunotherapy

Pyroptosis is a pro-inflammatory cell death that is associated with innate immunity promotion against tumors. Excess nitric oxide (NO)-triggered nitric stress has potential to induce pyroptosis, but the precise delivery of NO is challenging. Ultrasound (US)-responsive NO production has dominant priority due to its deep penetration, low side effects, noninvasion, and local activation manner. In this work, US-sensitive NO donor N-methyl-N-nitrosoaniline (NMA) with thermodynamically favorable structure is selected and loaded into hyaluronic acid (HA)-modified hollow manganese dioxide nanoparticles (hMnO2 NPs) to fabricate hMnO2 @HA@NMA (MHN) nanogenerators (NGs). The obtained NGs have a record-high NO generation efficiency under US irradiation and can release Mn2+ after targeting the tumor sites. Later on, cascade tumor pyroptosis and cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING)-based immunotherapy is achieved and tumor growth is effectively inhibited.

Research progress on gas signal molecular therapy for Parkinson's disease

The pathogenesis of Parkinson's disease (PD) remains unclear. Among the pathological manifestations is the progressive degeneration of the nigrostriatal dopaminergic pathway, leading to massive loss of neurons in the substantia nigra pars compacta and dopamine (DA) depletion. Therefore, the current drug treatment is primarily based on DA supplementation and delaying the progression of the disease. However, as patients' symptoms continue to worsen, the drug effect will gradually decrease or even disappear, thereby further aggravating clinical symptoms. Gas signaling molecules, such as hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and hydrogen (H2), exhibit pleiotropic biological functions and play crucial roles in physiological and pathological effects. In common neurodegenerative diseases including Alzheimer's disease and PD, gas signal molecules can prevent or delay disease occurrence via the primary mechanisms of antioxidation, anti-inflammatory response, and antiapoptosis. This article reviews the therapeutic progress of gas signaling molecules in PD models and discusses the possibility of their clinical applications.

Oxidative Stress and Antioxidant Defense in the Brain of Bat Species with Different Feeding Habits

Assessing the levels of oxidative stress markers and antioxidant enzymes in the brain is crucial in evaluating its antioxidant capacity and understanding the influence of various dietary patterns on brain well-being. This study aimed to investigate the antioxidant status and oxidative damage in the brain of bat species with different feeding habits to gain insights into their protective mechanisms against oxidative stress and their interspecific variation. The levels of oxidative damage markers and the activities of antioxidants were measured in the brain of four bat species with different feeding habits, namely insectivorous, frugivorous, nectarivorous, and hematophagous. Insectivorous bats showed higher levels of SOD and fumarase compared to the other groups, while hematophagous bats showed lower levels of these enzymes. On the other hand, the activities of glutathione peroxidase and glutathione S-transferase were higher in hematophagous bats and lower in insectivorous bats. The carbonyl groups and malondialdehyde levels were lower in frugivores, while they were similar in the other feeding guilds. Nitrite and nitrate levels were higher in the hematophagous group and relatively lower in all other groups. The GSSG/GSH ratio was higher in the hematophagous group and lower in frugivores. Overall, our results indicate that the levels of oxidative stress markers and the activities of antioxidant enzymes in the brain vary significantly among bat species with different feeding habitats. The findings suggest that the antioxidant status of the brain is influenced by diet and feeding habits.

Nitric oxide-induced ribosome collision activates ribosomal surveillance mechanisms

Impairment of protein translation can cause stalling and collision of ribosomes and is a signal for the activation of ribosomal surveillance and rescue pathways. Despite clear evidence that ribosome collision occurs stochastically at a cellular and organismal level, physiologically relevant sources of such aberrations are poorly understood. Here we show that a burst of the cellular signaling molecule nitric oxide (NO) reduces translational activity and causes ribosome collision in human cell lines. This is accompanied by activation of the ribotoxic stress response, resulting in ZAKα-mediated activation of p38 and JNK kinases. In addition, NO production is associated with ZNF598-mediated ubiquitination of the ribosomal protein RPS10 and GCN2-mediated activation of the integrated stress response, which are well-described responses to the collision of ribosomes. In sum, our work implicates a novel role of NO as an inducer of ribosome collision and activation of ribosomal surveillance mechanisms in human cells.

Zinc and selenium attenuate quaternary heavy metal mixture-induced testicular damage via amplification of the antioxidant system, reduction in metal accumulation, inflammatory and apoptotic biomarkers

Heavy metals (HMs) such as cadmium (Cd), lead (Pb), arsenic (As), and mercury (Hg) are highly toxic elements. They are often found together in nature as a heavy metal mixture (HMM) and are known to contribute to subfertility/infertility as environmental pollutants. This study aims to evaluate the potential benefits of treating HMM-induced testicular pathophysiology with zinc (Zn) and/or selenium (Se). Six-week-old male Sprague Dawley rats were grouped into 5 (n = 7). The control group received deionized water, while the other groups were treated with PbCl2 (20 mg kg-1), CdCl2 (1.61 mg kg-1), HgCl2 (0.40 mg kg-1), and Na2AsO3 (10 mg kg-1) in deionized water for 60 days. Additionally, groups III to V received Zn, Se, and Zn/Se, respectively, for 60 days. The study evaluated testis weight, metal accumulation, sperm analysis, FSH, LH, testosterone, prolactin, oxidative stress, antioxidants, pro-inflammatory and apoptotic markers, and presented structural changes in the testis as micrographs. HMM caused a significant increase in testis weight, metal accumulation, prolactin, oxidative stress, and pro-inflammatory and apoptotic markers, while significantly decreasing semen analysis, FSH, LH, and testosterone. Histology showed decreased spermatogenesis and spermiogenesis, as evidenced by the structure of the germ cells and spermatids. However, Zn, Se, or both ameliorated and reversed some of the observed damages. This study provides further evidence for the mitigative potential of Zn, Se, or both in reversing the damage inflicted by HMM in the testis, and as a countermeasure towards improving HM-induced decrease in public health fecundity.

Graphical abstract

Influence of green tea on alcohol aggravated neurodegeneration of cortex, cerebellum and hippocampus of STZ-induced diabetic rats

The main aim of this study was to evaluate the cytotoxic effects of chronic alcohol consumption on various regions of diabetic brain and preventive role of GTE. Clinical, experimental and histopathological observations indicate chronic, excessive alcohol consumption aggravates the free radical-mediated oxidative and nitrosative stress in several tissues including brain. Treatment with Epigallocatechin gallate (EGCG) significantly reduced the levels of oxidative/nitrosative stress paradigms, increased glutathione (GSH) levels and enhanced the activities of antioxidant enzymes. Histopathology evaluation revealed the possible influence of EGCG in reversing alcohol exacerbated diabetes-induced damage in cortex, cerebellum and hippocampus of brain. Furthermore, these studies have provided evidence to show how EGCG can exactly occupy the position in functional sites of nNOS (neuronal nitric oxide synthase) and induce a conformational change, inhibition of enzymatic activity and prevention of neurodegeneration/necrotic changes of tissue, in comparison with the rosiglitazone and glibenclamide. To summarise, this research has offered useful information on the action of EGCG that would provide potential protection against ethanol exacerbated diabetic brain damageand additional evidence for the use of EGCG as a lead compound for drug discovery.

Datura metel stramonium exacerbates behavioral deficits, medial prefrontal cortex, and hippocampal neurotoxicity in mice via redox imbalance

BACKGROUND

Datura metel (DM) stramonium is a medicinal plant often abused by Nigerians due to its psychostimulatory properties. Hallucinations, confusion, agitation, aggressiveness, anxiety, and restlessness are reported amongst DM users. Earlier studies suggest that DM induces neurotoxicity and affect brain physiology. However, the exact neurological effects of DM extract in the medial prefrontal cortex (mPFC) and hippocampal morphology have not been elucidated. In this study, we evaluated the hypothesis that oral exposure to DM extract exerts a neurotoxic effect by increasing oxidative stress in the mPFC and the hippocampus and induces behavioral deficits in mice.

RESULTS

DM methanolic extract exposure significantly increased MDA and NO levels and reduced SOD, GSH, GPx and CAT activities in mice brains. In addition, our results showed that DM exposure produced cognitive deficits, anxiety, and depressive-like behaviour in mice following oral exposure for 28 days. Moreover, the mPFC and hippocampus showed neurodegenerative features, loss of dendritic and axonal arborization, a dose-dependent decrease in neuronal cell bodies' length, width, area, and perimeter, and a dose-dependent increase in the distance between neuronal cell bodies.

CONCLUSIONS

Oral exposure to DM in mice induces behavioural deficits, mPFC and hippocampal neuronal degenerations via redox imbalance in the brain of mice. These observations confirm the neurotoxicity of DM extracts and raises concerns on the safety and potential adverse effects of DM in humans.

Host-Microbiome Interactions: Tryptophan Metabolism and Aromatic Hydrocarbon Receptors after Traumatic Brain Injury

Traumatic brain injury refers to the damage caused to intracranial tissues by an external force acting on the head, leading to both immediate and prolonged harmful effects. Neuroinflammatory responses play a critical role in exacerbating the primary injury during the acute and chronic phases of TBI. Research has demonstrated that numerous neuroinflammatory responses are mediated through the "microbiota-gut-brain axis," which signifies the functional connection between the gut microbiota and the brain. The aryl hydrocarbon receptor (AhR) plays a vital role in facilitating communication between the host and microbiota through recognizing specific ligands produced directly or indirectly by the microbiota. Tryptophan (trp), an indispensable amino acid in animals and humans, represents one of the key endogenous ligands for AhR. The metabolites of trp have significant effects on the functioning of the central nervous system (CNS) through activating AHR signalling, thereby establishing bidirectional communication between the gut microbiota and the brain. These interactions are mediated through immune, metabolic, and neural signalling mechanisms. In this review, we emphasize the co-metabolism of tryptophan in the gut microbiota and the signalling pathway mediated by AHR following TBI. Furthermore, we discuss the impact of these mechanisms on the underlying processes involved in traumatic brain injury, while also addressing potential future targets for intervention.

Habitual dietary nitrate intake and cognition in the Australian Imaging, Biomarkers and Lifestyle Study of ageing: A prospective cohort study

BACKGROUND & AIMS

Dietary nitrate improves cardiovascular health via a nitric oxide (NO) pathway. NO is key to both cardiovascular and brain health. There is also a strong association between vascular risk factors and brain health. Dietary nitrate intake could therefore be associated with better cognitive function and reduced risk of cognitive decline. This is yet to be investigated. The aim of this study was to investigate the association between habitual intake of dietary nitrate from sources where nitrate is naturally present, and cognitive function, and cognitive decline, in the presence or absence of the apolipoprotein E (APOE) ε4 allele.

METHODS

The study included 1254 older adult participants of the Australian Imaging, Biomarkers and Lifestyle Study of Ageing who were cognitively normal at baseline. Plant-derived, vegetable-derived, animal derived nitrate (not including meat where nitrate is an allowed additive), and total nitrate intakes were calculated from baseline food frequency questionnaires using comprehensive nitrate databases. Cognition was assessed at baseline and every 18 months over a follow-up period of 126 months using a comprehensive neuropsychological test battery. Multivariable-adjusted linear mixed effect models were used to examine the association between baseline nitrate intake and cognition over the 126 months (median [IQR] follow-up time of 36 [18-72] months), stratified by APOE ε4 carrier status.

RESULTS

In non APOE ε4 carriers, for every 60 mg/day higher intake of plant-derived nitrate at baseline there was an associated higher language score [β (95% CI): 0.10 (0.01, 0.19)] over 126 months, after multivariable adjustments. In APOE ε4 carriers, there was an associated better episodic recall memory [0.24 (0.08, 0.41)] and recognition memory [0.15 (0.01, 0.30)] scores. Similar associations were seen for the intakes of vegetable-derived and total nitrate. Additionally, in APOE ε4 carriers, for every 6 mg/day higher intake of animal-derived nitrate (excluding meat with nitrate as an allowed additive) at baseline there was an associated higher executive function score [β (95% CI): 1.41 (0.42, 2.39)]. We did not find any evidence of an association between dietary nitrate intake and rate of cognitive decline.

CONCLUSION

Our results suggest that habitual intake of dietary nitrate from sources where nitrate is naturally present impacts cognitive performance in an APOE genotype contingent manner. Further work is needed to validate our findings and understand potential mechanisms underlying the observed effects.