Parkinsonism in liver diseases or dysfunction

Parkinsonism in liver diseases or dysfunction, mainly including neurological manifestations in hereditary liver diseases and neurological complications of advanced liver diseases, occur in isolation or in combination with other movement disorders, and progress along disease course. Prominent akinetic-rigidity syndrome, various onset and progression, poor levodopa response and metabolism abnormalities reflected by serum biomarkers and neuroimaging, make this atypical parkinsonism recognizable and notable in clinical practice. Different susceptibility of brain areas, especially in basal ganglia, to manganese, iron, copper, ammonia overload, together with subsequent oxidative stress, neurotransmitter alterations, disturbed glia-neuron homeostasis and eventually neurotoxicity, contribute to parkinsonism under the circumstances of insufficient liver clearance ability. These mechanisms are interrelated and may interact collectively, adding to the complexity of clinical manifestations and treatment responses. This review summarizes shared clinical features of parkinsonism in liver diseases or dysfunction, depicts their underlying mechanisms and suggests practical flowchart for differential diagnosis.

Imidacloprid unique and repeated treatment produces cholinergic transmission disruption and apoptotic cell death in SN56 cells

Imidacloprid (IMI), the most widely used worldwide neonicotinoid biocide, produces cognitive disorders after repeated and single treatment. However, little was studied about the possible mechanisms that produce this effect. Cholinergic neurotransmission regulates cognitive function. Most cholinergic neuronal bodies are present in the basal forebrain (BF), regulating memory and learning process, and their dysfunction or loss produces cognition decline. BF SN56 cholinergic wild-type or acetylcholinesterase (AChE), β-amyloid-precursor-protein (βAPP), Tau, glycogen-synthase-kinase-3-beta (GSK3β), beta-site-amyloid-precursor-protein-cleaving enzyme 1 (BACE1), and/or nuclear-factor-erythroid-2-related-factor-2 (NRF2) silenced cells were treated for 1 and 14 days with IMI (1 μM-800 μM) with or without recombinant heat-shock-protein-70 (rHSP70), recombinant proteasome 20S (rP20S) and with or without N-acetyl-cysteine (NAC) to determine the possible mechanisms that mediate this effect. IMI treatment for 1 and 14 days altered cholinergic transmission through AChE inhibition, and triggered cell death partially through oxidative stress generation, AChE-S overexpression, HSP70 downregulation, P20S inhibition, and Aβ and Tau peptides accumulation. IMI produced oxidative stress through reactive oxygen species production and antioxidant NRF2 pathway downregulation, and induced Aβ and Tau accumulation through BACE1, GSK3β, HSP70, and P20S dysfunction. These results may assist in determining the mechanisms that produce cognitive dysfunction observed following IMI exposure and provide new therapeutic tools.

Manganese inhibits HBV transcription and promotes HBsAg degradation at non-toxic levels

Chronic hepatitis B virus (HBV) infection continues to pose a significant global health challenge. However, therapeutic measures for a cure are lacking in clinical practice. Manganese, an essential trace element, has garnered attention due to its potential to activate innate immune pathways and its significant role in antiviral and antitumor immunity. Yet, the specific impact of manganese on chronic hepatitis B has been largely unexplored. Our research reveals that manganese substantially inhibits HBV replication in hepatocellular carcinoma cells at non-toxic levels. This suppression occurs independently of well-known anti-HBV innate immune pathways, such as the cGAS-STING pathway. Mechanistically, manganese decreases HBV transcription by diminishing the levels of liver-specific transcription factors. Furthermore, it activates the mTOR pathway, enhancing HBsAg ubiquitination through the upregulation of the ubiquitin ligase β-TrCP and increasing proteasome activity via the augmentation of its subunits, leading to a ubiquitin-dependent degradation of HBsAg. Significantly, our study also uncovers a notable clinical correlation between manganese levels and chronic hepatitis B infection. These findings position manganese as a critical element in diminishing HBV replication, offering a new direction in the management of chronic hepatitis B.

SS-31 modification alleviates ferroptosis induced by superparamagnetic iron oxide nanoparticles in hypoxia/reoxygenation cardiomyocytes

Superparamagnetic iron oxide nanoparticles (SPION) are widely used in cardiovascular applications. However, their potential to induce ferroptosis in myocardial cells post-ischemia-reperfusion hinders clinical adoption. We investigated the mechanisms behind SPION-induced cytotoxicity in myocardial cells and explored whether co-loading SPION with SS-31 (a kind of mitochondrial-targeted antioxidant peptide) could counteract this toxicity. To create SPION@SS-31, SS-31 was physically adsorbed onto SPION. To study the dose- and time-dependent cytotoxic effects and assess the influence of SS-31 on reducing SPION-induced damage, hypoxia/reoxygenation(H/R) H9C2 cells were treated with either SPION or SPION@SS-31. We examined the relationship between SPION and ferroptosis by measuring mitochondrial ROS, mitochondrial membrane potential (MMP), lipid peroxidation products, ATP, GSH, GPX4, mitochondrial structure, nonheme iron content, cellular iron regulation, and typical ferroptosis markers. The findings showed that SPION induced concentration- and time-dependent toxicity, marked by a significant cell viability loss and an increase in LDH levels. In contrast, SPION@SS-31 produced results comparable to the H/R group, implying that SS-31 can notably reduce cell damage induced by SPION. SPION disrupted cellular iron homeostasis, with FtH and FtMt expression increased and reduced levels of FPN1 and ABCB8, which led to the overload of mitochondrial iron. This iron dysregulation damaged mitochondrial function and integrity, causing ATP depletion, MMP loss, and decreased GPX4 and GSH levels, accompanied by a burst of mitochondrial lipid peroxidation, ultimately resulting in ferroptosis in H/R cardiomyocytes. Notably, SS-31 significantly alleviated SPION-induced ferroptosis by decreasing mitochondrial MDA production and maintaining GSH and GPX4 levels, indicating its possibility to reverse SPION-induced cytotoxicity. The viability of H/R cells and cells treated with SPION and Fer-1 did not differ statistically, whereas cells exposed to SPION along with inhibitors like 3-MA, zVAD, or Nec-1 showed a substantial loss in viability, implying that ferroptosis is the primary mechanism behind SPION-induced myocardial toxicity. SPION triggers mitochondrial lipid peroxidation by causing overload of iron, leading to ferroptosis in H/R H9C2 cells. Mitochondria appear to be the primary target of SPION-induced toxic effects. SS-31 demonstrates potential in inhibiting this ferroptosis by acting as a mitochondria-targeted antioxidant, suggesting that the modification of mitochondria-targeted antioxidant peptides represents an innovative and practical approach to attenuate the myocardial toxicity associated with SPION.

ZIP8 Is Upregulated in the Testis of Zip14-/- Mice

BACKGROUND/OBJECTIVES

Manganese is an essential nutrient involved in various biological processes, including reproductive health, yet the mechanisms regulating its homeostasis in the testis remain poorly understood.

METHODS AND RESULTS

In this study, we investigated the expression and regulation of key manganese transporters-ZIP8, ZIP14, and ZnT10-in mouse testes. Immunoblotting analyses revealed that ZIP8 is expressed in the testes, while ZIP14 and ZnT10 were undetectable. Using Zip14 knockout (Zip14-/-) mice, which exhibit systemic manganese overload, we discovered a significant increase in manganese levels in the testis, accompanied by an upregulation of ZIP8. Importantly, the levels of other essential metals, such as iron, zinc, and copper, remained unchanged.

CONCLUSIONS

Our findings suggest that ZIP8 plays a critical role in manganese transport in the testis, and its increased expression may contribute to manganese accumulation in the absence of ZIP14. This study advances our understanding of manganese homeostasis in the testis and its potential impact on male reproductive health.

Neuronal SLC39A8 deficiency impairs cerebellar development by altering manganese homeostasis

Solute carrier family 39, member 8 (SLC39A8), is a transmembrane transporter that mediates the cellular uptake of zinc, iron, and manganese (Mn). Human genetic studies document the involvement of SLC39A8 in Mn homeostasis, brain development, and function. However, the role and pathophysiological mechanisms of SLC39A8 in the central nervous system remain elusive. We generated Slc39a8 neuron-specific knockout (Slc39a8-NSKO) mice to study SLC39A8 function in neurons. The Slc39a8-NSKO mice displayed markedly decreased Mn levels in the whole brain and brain regions, especially the cerebellum. Radiotracer studies using 54Mn revealed that Slc39a8-NSKO mice had impaired brain uptake of Mn. Slc39a8-NSKO cerebellums exhibited morphological defects and abnormal dendritic arborization of Purkinje cells. Reduced neurogenesis and increased apoptotic cell death occurred in the cerebellar external granular layer of Slc39a8-NSKO mice. Brain Mn deficiency in Slc39a8-NSKO mice was associated with motor dysfunction. Unbiased RNA-Seq analysis revealed downregulation of key pathways relevant to neurodevelopment and synaptic plasticity, including cAMP signaling pathway genes. We further demonstrated that Slc39a8 was required for the optimal transcriptional response to the cAMP-mediated signaling pathway. In summary, our study highlighted the essential roles of SLC39A8 in brain Mn uptake and cerebellum development and functions.

Progress in antibacterial applications of nanozymes

Bacterial infections are a growing problem, and antibiotic drugs can be widely used to fight bacterial infections. However, the overuse of antibiotics and the evolution of bacteria have led to the emergence of drug-resistant bacteria, severely reducing the effectiveness of treatment. Therefore, it is very important to develop new effective antibacterial strategies to fight multi-drug resistant bacteria. Nanozyme is a kind of enzyme-like catalytic nanomaterials with unique physical and chemical properties, high stability, structural diversity, adjustable catalytic activity, low cost, easy storage and so on. In addition, nanozymes also have excellent broad-spectrum antibacterial properties and good biocompatibility, showing broad application prospects in the field of antibacterial. In this paper, we reviewed the research progress of antibacterial application of nanozymes. At first, the antibacterial mechanism of nanozymes was summarized, and then the application of nanozymes in antibacterial was introduced. Finally, the challenges of the application of antibacterial nanozymes were discussed, and the development prospect of antibacterial nanozymes was clarified.

Rehmanniae Radix Praeparata aqueous extract improves hepatic ischemia/reperfusion injury by restoring intracellular iron homeostasis

Hepatic ischemia/reperfusion injury (HIRI) is a common pathophysiological condition occurring during or after liver resection and transplantation, leading to hepatic viability impairment and functional deterioration. Recently, ferroptosis, a newly recognized form of programmed cell death, has been implicated in IRI. Rehmanniae Radix Praeparata (RRP), extensively used in Chinese herbal medicine for its hepatoprotective, anti-inflammatory, and antioxidant properties, presents a potential therapeutic approach. However, the mechanisms by which RRP mitigates HIRI, particularly through the regulation of ferroptosis, remain unclear. In this study, we developed a HIRI mouse model and monocrotaline (MCT)- and erastin-induced in vitro hepatocyte injury models. We conducted whole-genome transcriptome analysis to elucidate the protective effects and mechanisms of RRP on HIRI. The RRP aqueous extract was characterized by the presence of acteoside, rehmannioside D, and 5-hydroxymethylfurfural. Our results demonstrate that the RRP aqueous extract ameliorated oxidative stress, reduced intracellular iron accumulation, and attenuated HIRI-induced liver damage. Additionally, RRP significantly inhibited hepatocyte death by restoring intracellular iron homeostasis both in vivo and in vitro. Mechanistically, the RRP aqueous extract reduced intrahepatocellular iron accumulation by inhibiting ZIP14-mediated iron uptake, promoting hepcidin- and ferroportin-mediated iron efflux, and ameliorating mitochondrial iron aggregation through upregulation of Cisd1 expression. Moreover, siRNA-mediated inhibition of hamp synergistically enhanced the RRP aqueous extract's inhibitory effect on ferroptosis. In conclusion, our study elucidates the mechanisms by which RRP aqueous extracts alleviate HIRI, highlighting the restoration of iron metabolic balance. These findings position RRP as a promising candidate for clinical intervention in HIRI treatment.

Herbal Formula Extract Ameliorates Anxiety and Cognitive Impairment via Regulation of the Reelin/Dab-1 Pathway in a Murine Model of Post-Traumatic Stress Disorder

We investigated the effects of epigenetic modifications on post-traumatic stress disorder (PTSD) using a novel combination of herbal medicines from Panax ginseng, Astragalus membranaceus, Atractylodes macrocephala, and Glycyrrhiza uralensis. The herbal formula extract (HFE) (250 mg/kg) was administered orally once daily for 14 days to determine its effects on PTSD in mice by combining prolonged stress and foot shock. The open field and Y-maze tests determined the effect of HFE on PTSD-induced anxiety and cognition. Hippocampal neuronal plastic changes and molecular mechanism were verified. Treatment with HFE decreased anxiety-like behavior and enhanced cognition. Moreover, it reduced the number of PTSD-related hilar ectopic granule cells in the dentate gyrus (DG). PTSD mice showed reduced neuronal plasticity of doublecortin+ cells in the DG, which was restored by HFE treatment. HFE reversed PTSD-induced inhibition of the Reelin/Dab1 pathway, a critical signaling cascade involved in brain development, and regulated Reelin methylation. Furthermore, DNA methylation, methyl-CpG binding protein 2, and DNA methyltransferase 1, which were elevated in the hippocampus of PTSD mice, were restored following HFE treatment. HFE increased the expression of synaptic plasticity-related factors in the hippocampus of PTSD mice. Our findings suggest that HFE can facilitate PTSD treatment by alleviating behavioral abnormalities through the restoration of hippocampal dysfunction via regulation of the Reelin/Dab-1 pathway and DNA methylation in the hippocampus.

Klotho: molecular mechanisms and emerging therapeutics in central nervous system diseases

Klotho is recognized as an aging-suppressor protein that is implicated in a variety of processes and signaling pathways. The anti-inflammatory, anti-apoptotic, anti-oxidant, and anti-tumor bioactivities of klotho have extended its application in neurosciences and made the protein popular for its lifespan-extending capacity. Furthermore, it has been demonstrated that klotho levels would reduce with aging and numerous pathologies, particularly those related to the central nervous system (CNS). Evidence supports the idea that klotho can be a key therapeutic target in CNS diseases such as amyotrophic lateral sclerosis, Parkinson's disease, stroke, and Alzheimer's disease. Reviewing the literature suggests that the upregulation of klotho expression regulates various signaling pathways related to autophagy, oxidative stress, inflammation, cognition, and ferroptosis in neurological disorders. Therefore, it has been of great interest to develop drugs or agents that boost or restore klotho levels. In this regard, the present review was designed and aimed to gather the delegated documents regarding the therapeutic potential of Klotho in CNS diseases focusing on the molecular and cellular mechanisms.

YTHDF1 mediates translational control by m6A mRNA methylation in adaptation to environmental challenges

Animals adapt to environmental challenges with long-term changes at the behavioral, circuit, cellular, and synaptic levels which often require new protein synthesis. The discovery of reversible N6-methyladenosine (m6A) modifications of mRNA has revealed an important layer of post-transcriptional regulation which affects almost every phase of mRNA metabolism and therefore translational control. Many in vitro and in vivo studies have demonstrated the significant role of m6A in cell differentiation and survival, but its role in adult neurons is understudied. We used cell-type specific gene deletion of Mettl14, which encodes one of the subunits of the m6A methyltransferase, and Ythdf1, which encodes one of the cytoplasmic m6A reader proteins, in dopamine D1 receptor expressing or D2 receptor expressing neurons. Mettl14 or Ythdf1 deficiency blunted responses to environmental challenges at the behavioral, cellular, and molecular levels. In three different behavioral paradigms, gene deletion of either Mettl14 or Ythdf1 in D1 neurons impaired D1-dependent learning, whereas gene deletion of either Mettl14 or Ythdf1 in D2 neurons impaired D2-dependent learning. At the cellular level, modulation of D1 and D2 neuron firing in response to changes in environments was blunted in all three behavioral paradigms in mutant mice. Ythdf1 deletion resembled impairment caused by Mettl14 deletion in a cell type-specific manner, suggesting YTHDF1 is the main mediator of the functional consequences of m6A mRNA methylation in the striatum. At the molecular level, while striatal neurons in control mice responded to elevated cAMP by increasing de novo protein synthesis, striatal neurons in Ythdf1 knockout mice didn't. Finally, boosting dopamine release by cocaine drastically increased YTHDF1 binding to many mRNA targets in the striatum, especially those that encode structural proteins, suggesting the initiation of long-term neuronal and/or synaptic structural changes. While the m6A-YTHDF1 pathway has similar functional significance at cellular level, its cell type specific deficiency in D1 and D2 neurons often resulted in contrasting behavioral phenotypes, allowing us to cleanly dissociate the opposing yet cooperative roles of D1 and D2 neurons.

A Novel Role for the Longevity-Associated Protein SLC39A11 as a Manganese Transporter

The identification of aging- and longevity-associated genes is important for promoting healthy aging. By analyzing a large cohort of Chinese centenarians, we previously found that single-nucleotide polymorphisms (SNPs) in the SLC39A11 gene (also known as ZIP11) are associated with longevity in males. However, the function of the SLC39A11 protein remains unclear. Here, we found that SLC39A11 expression is significantly reduced in patients with Hutchinson-Gilford progeria syndrome (HGPS). In addition, we found that zebrafish with a mutation in slc39a11 that significantly reduces its expression have an accelerated aging phenotype, including a shortened average lifespan, muscle atrophy and reduced swimming, impaired muscle regeneration, gut damage, and abnormal morphology in the reproductive system. Interestingly, these signs of premature aging were more pronounced in male zebrafish than in females. RNA-sequencing analysis revealed that cellular senescence may serve as a potential mechanism for driving this slc39a11 deficiency-induced phenotype in mutant zebrafish. Moreover, immunofluorescence showed significantly increased DNA damage and reactive oxygen species signaling in slc39a11 mutant zebrafish. Using inductively coupled plasma mass spectrometry (ICP-MS), we found that manganese significantly accumulates in slc39a11 mutant zebrafish, as well as in the serum of both global Slc39a11 knockout and hepatocyte-specific Slc39a11 knockout mice, suggesting that this metal transporter regulates systemic manganese levels. Finally, using cultured human fibroblasts, we found that both knocking down SLC39A11 and exposure to high extracellular manganese increased cellular senescence. These findings provide compelling evidence that SLC39A11 serves to protect against the aging process, at least in part by regulating cellular manganese homeostasis.

Role of diet in the risks of esophageal adenocarcinoma and squamous cell carcinoma: an updated umbrella review

PURPOSE

This updated umbrella review aimed to evaluate the evidence regarding the associations between dietary factors and the risks of esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC).

METHODS

The PubMed, Embase, Cochrane Library, and Web of Science databases were searched to identify relevant studies. The quality of the included meta-analyses was evaluated using A MeaSurement Tool to Assess systematic Reviews 2 (AMSTAR 2). For each association, the number of cases, random effects pooled effect size, 95% confidence intervals (CIs), heterogeneity, 95% prediction interval (PrI), small-study effect, and excess significance bias were recalculated to determine the evidence level.

RESULTS

We identified 33 meta-analyses describing 58 dietary factors associated with ESCC and 29 meta-analyses describing 38 dietary factors associated with EAC. There was convincing evidence regarding the association of 2 dietary factors (areca nut and high alcohol) with the risk of ESCC. There was highly suggestive evidence regarding the association of only 1 dietary factor (healthy pattern) with the risk of ESCC. There was suggestive evidence regarding the association of 11 dietary factors with the risk of ESCC, including fruit, citrus fruit, vegetables, pickled vegetables, maté tea, moderate alcohol, hot beverages and foods, hot tea, salt, folate, and vitamin B6. There was convincing evidence regarding the association of one dietary factor (vitamin B6) with the risk of EAC. There was suggestive evidence regarding the association of 4 dietary factors with the risk of EAC, including processed meat, dietary fibre, carbohydrate, and vitamin B12. The convincing evidence regarding the associations between dietary factors and the risks of ESCC and EAC remained robust in sensitivity analyses.

CONCLUSIONS

This umbrella review highlighted convincing evidence regarding the associations of areca nut and high alcohol with a higher risk of ESCC. Additionally, an association between vitamin B6 and a decreased risk of EAC was observed. Further research is needed to examine the dietary factors with weak evidence regarding their associations with ESCC and EAC.

Genetic control of MRI contrast using the manganese transporter Zip14

PURPOSE

Gene-expression reporter systems, such as green fluorescent protein, have been instrumental to understanding biological processes in living organisms at organ system, tissue, cell, and molecular scales. More than 30 years of work on developing MRI-visible gene-expression reporter systems has resulted in a variety of clever application-specific methods. However, these techniques have not yet been widely adopted, so a general-purpose expression reporter is still required. Here, we demonstrate that the manganese ion transporter Zip14 is an in vivo MRI-visible, flexible, and robust gene-expression reporter to meet this need.

METHODS

Plasmid constructs consisting of a cell type-specific promoter, gene coding for human Zip14, and a histology-visible tag were packaged into adeno-associated viruses. These viruses were intracranially injected into the mouse brain. Serial in vivo MRI was performed using a vendor-supplied 3D-MPRAGE sequence. No additional contrast agents were administered. Animals were sacrificed after the last imaging timepoint for immunohistological validation.

RESULTS

Neuron-specific overexpression of Zip14 produced substantial and long-lasting changes in MRI contrast. Using appropriate viruses enabled both anterograde and retrograde neural tracing. Expression of Zip14 in astrocytes also enabled MRI of glia populations in the living mammalian brain.

CONCLUSIONS

The flexibility of this system as an MRI-visible gene-expression reporter will enable many applications of serial, high-resolution imaging of gene expression for basic science and therapy development.

Substituting red meat with insects in burgers: Estimating the public health impact using risk-benefit assessment

In Western societies, reducing red meat consumption gained prominence due to health, environmental, and animal welfare considerations. We estimated the public health impact of substituting beef with house cricket (Acheta domesticus) in European diets (Denmark, France, and Greece) using the risk-benefit assessment (RBA) methodology, building upon the EFSA-funded NovRBA project. The overall health impact of substituting beef patties with insect powder-containing patties was found to be impacted by the amount of cricket powder incorporated in the patties. While using high amounts of cricket powder in meat substitutes may be safe, it does not inherently offer a healthier dietary option compared to beef. Adjustment of cricket powder levels is needed to yield a positive overall health impact. The main driver of the outcome is sodium, naturally present in substantial amounts in crickets. Moreover, the way that cricket powder is hydrated before being used for the production of patties (ratio of powder to water), influences the results. Our study highlighted that any consideration for dietary substitution should be multidimensional, considering nutritional, microbiological and toxicological aspects, and that the design of new food products in the framework of dietary shifts should consider both health risks and benefits associated with the food.

Elevated thyroid manganese reduces thyroid iodine to induce hypothyroidism in mice, but not rats, lacking SLC30A10 transporter

Elevated manganese (Mn) accumulates in the brain and induces neurotoxicity. SLC30A10 is an Mn efflux transporter that controls body Mn levels. We previously reported that full-body Slc30a10 knockout mice (1) recapitulate the body Mn retention phenotype of humans with loss-of-function SLC30A10 mutations and (2) unexpectedly develop hypothyroidism induced by Mn accumulation in the thyroid, which reduces intra-thyroid thyroxine. Subsequent analyses of National Health and Nutrition Examination Survey data identified an association between serum Mn and subclinical thyroid changes. The emergence of thyroid deficits as a feature of Mn toxicity suggests that changes in thyroid function may be an underappreciated, but critical, modulator of Mn-induced disease. To better understand the relationship between thyroid function and Mn toxicity, here we further defined the mechanism of Mn-induced hypothyroidism using mouse and rat models. Slc30a10 knockout mice exhibited a profound deficit in thyroid iodine levels that occurred contemporaneously with increases in thyroid Mn levels and preceded the onset of overt hypothyroidism. Wild-type Mn-exposed mice also exhibited increased thyroid Mn levels, an inverse correlation between thyroid Mn and iodine levels, and subclinical hypothyroidism. In contrast, thyroid iodine levels were unaltered in newly generated Slc30a10 knockout rats despite an increase in thyroid Mn levels, and the knockout rats were euthyroid. Thus, Mn-induced thyroid dysfunction in genetic or Mn exposure-induced mouse models occurs due to a reduction in thyroid iodine subsequent to an increase in thyroid Mn levels. Moreover, rat and mouse thyroids have differential sensitivities to Mn, which may impact the manifestations of Mn-induced disease in these routinely used animal models.

Intramuscular Pulsed Radiofrequency Upregulates BNDF-TrKB Expression in the Spinal Cord in Rats as an Alternative Treatment for Complicated Pain

Two cases of complicated pain exist: posterior screw fixation and myofascial pain. Intramuscular pulsed radiofrequency (PRF) may be an alternative treatment for such patients. This is a two-stage animal study. In the first stage, two muscle groups and two nerve groups were subdivided into a high-temperature group with PRF at 58 °C and a regular temperature with PRF at 42 °C in rats. In the second stage, two nerve injury groups were subdivided into nerve injury with PRF 42 °C on the sciatic nerve and muscle. Blood and spinal cord samples were collected. In the first stage, the immunohistochemical analysis showed that PRF upregulated brain-derived neurotrophic factor (BDNF) in the spinal cord in both groups of rats. In the second stage, the immunohistochemical analysis showed significant BDNF and tropomyosin receptor kinase B (TrkB) expression within the spinal cord after PRF in muscles and nerves after nerve injury. The blood biomarkers showed a significant increase in BDNF levels. PRF in the muscle in rats could upregulate BDNF-TrkB in the spinal cord, similar to PRF on the sciatica nerve for pain relief in rats. PRF could be considered clinically for patients with complicated pain and this study also demonstrated the role of BDNF in pain modulation. The optimal temperature for PRF was 42 °C.

Unlocking the brain's zinc code: implications for cognitive function and disease

Zn2+ transport across neuronal membranes relies on two classes of transition metal transporters: the ZnT (SLC30) and ZIP (SLC39) families. These proteins function to decrease and increase cytosolic Zn2+ levels, respectively. Dysfunction of ZnT and ZIP transporters can alter intracellular Zn2+ levels resulting in deleterious effects. In neurons, imbalances in Zn2+ levels have been implicated as risk factors in conditions such as Alzheimer's disease and neurodegeneration, highlighting the pivotal role of Zn2+ homeostasis in neuropathologies. In addition, Zn2+ modulates the function of plasma membrane proteins, including ion channels and receptors. Changes in Zn2+ levels, on both sides of the plasma membrane, profoundly impact signaling pathways governing cell development, differentiation, and survival. This review is focused on recent developments of neuronal Zn2+ homeostasis, including the impact of Zn2+ dyshomeostasis in neurological disorders, therapeutic approaches, and the increasingly recognized role of Zn2+ as a neurotransmitter in the brain.

Ultrastructural, molecular and haemato-immunological changes: Multifaceted toxicological effects of microcystin-LR in rohu, Labeo rohita

No water body is resilient to afflicts of algal bloom, if goes unmanaged. With the increasing trend of intensification, eutrophication and climate change, Labeo rohita (rohu) is highly anticipated to suffer from the deleterious effects of bloom and eventually its toxins. A comprehensive study was conducted to understand the toxicopathological effects of microcystin-LR (MC-LR) in rohu following intraperitoneal injection of 96 h-LD50 dose i.e., 713 μg kg-1. Substantial changes in micro- and ultrastructural level were evident in histopathology and transmission electron microscope (TEM) study. The haematological, biochemical, cellular and humoral innate immune biomarkers were significantly altered (p < 0.05) in MC-LR treated fish. The mRNA transcript levels of IL-1β, IL-10, IgM and IgZ in liver and kidney tissues were significantly up-regulated in 12 hpi and declined in 96 hpi MC-LR exposed fish. The relative mRNA expression of caspase 9 in the liver and kidney indicates mitochondrial-mediated apoptosis which was strongly supported by TEM study. In a nutshell, our study illustrates for the first time MC-LR induced toxicological implications in rohu displaying immunosuppression, enhanced oxidative stress, pathophysiology, modulation in mRNA transcription, genotoxicity, structural and ultrastructural alterations signifying it as a vulnerable species for MC-LR intoxication.

Synergistic suppression of BDNF via epigenetic mechanism deteriorating learning and memory impairment caused by Mn and Pb co-exposure

Microglia, the resident immune cells of the central nervous system (CNS), play a dual role in neurotoxicity by releasing the NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome and brain-derived neurotrophic factor (BDNF) in response to environmental stress. Suppression of BDNF is implicated in learning and memory impairment induced by exposure to manganese (Mn) or lead (Pb) individually. Methyl CpG Binding Protein 2 (MeCp2) and its phosphorylation status are related to BDNF suppression. Protein phosphatase2A (PP2A), a member of the serine/threonine phosphatases family, dephosphorylates substrates based on the methylation state of its catalytic C subunit (PP2Ac). However, the specific impairment patterns and molecular mechanisms resulting from co-exposure to Mn and Pb remain unclear. Therefore, the purpose of this study was to explore the effects of Mn and Pb exposure, alone and in combination, on inducing neurotoxicity in the hippocampus of mice and BV2 cells, and to determine whether simultaneous exposure to both metals exacerbate their toxicity. Our findings reveal that co-exposure to Mn and Pb leads to severe learning and memory impairment in mice, which correlates with the accumulation of metals in the hippocampus and synergistic suppression of BDNF. This suppression is accompanied by up-regulation of the epigenetic repressor MeCp2 and its phosphorylation status, as well as demethylation of PP2Ac. Furthermore, inhibition of PP2Ac demethylation using ABL127, an inhibitor for its protein phosphatase methylesterase1 (PME1), or knockdown of MeCp2 via siRNA transfection in vitro effectively increases BDNF expression and mitigates BV2 cell damage induced by Mn and Pb co-exposure. We also observe abnormal activation of microglia characterized by enhanced release of the NLRP3 inflammasome, Casepase-1 and pro-inflammatory cytokines IL-1β, in the hippocampus of mice and BV2 cells. In summary, our experiments demonstrate that simultaneous exposure to Mn and Pb results in more severe hippocampus-dependent learning and memory impairment, which is attributed to epigenetic suppression of BDNF mediated by PP2A regulation.

Neuroprotective Strategies and Cell-Based Biomarkers for Manganese-Induced Toxicity in Human Neuroblastoma (SH-SY5Y) Cells

Manganese (Mn) is an essential heavy metal in the human body, while excess Mn leads to neurotoxicity, as observed in this study, where 100 µM of Mn was administered to the human neuroblastoma (SH-SY5Y) cell model of dopaminergic neurons in neurodegenerative diseases. We quantitated pathway and gene changes in homeostatic cell-based adaptations to Mn exposure. Utilizing the Gene Expression Omnibus, we accessed the GSE70845 dataset as a microarray of SH-SY5Y cells published by Gandhi et al. (2018) and applied statistical significance cutoffs at p < 0.05. We report 74 pathway and 10 gene changes with statistical significance. ReactomeGSA analyses demonstrated upregulation of histones (5 out of 10 induced genes) and histone deacetylases as a neuroprotective response to remodel/mitigate Mn-induced DNA/chromatin damage. Neurodegenerative-associated pathway changes occurred. NF-κB signaled protective responses via Sirtuin-1 to reduce neuroinflammation. Critically, Mn activated three pathways implicating deficits in purine metabolism. Therefore, we validated that urate, a purine and antioxidant, mitigated Mn-losses of viability in SH-SY5Y cells. We discuss Mn as a hypoxia mimetic and trans-activator of HIF-1α, the central trans-activator of vascular hypoxic mitochondrial dysfunction. Mn induced a 3-fold increase in mRNA levels for antioxidant metallothionein-III, which was induced 100-fold by hypoxia mimetics deferoxamine and zinc.

Alleviation of microcystin-leucine arginine -induced hepatotoxicity: An updated overview

OBJECTIVES

Contamination of surface waters is a major health threat for all living creatures. Some types of blue-green algae that naturally occur in fresh water, are able to produce various toxins, like Microcystins (MCs). Microcystin-leucine arginine (MC-LR) produced by Microcystis aeruginosa is the most toxic and abundant isoforms of MCs, and it causes hepatotoxicity. The present article reviews preclinical experiments examined different treatments, including herbal derivatives, dietary supplements and drugs against MC-LR hepatotoxicity.

METHODS

We searched scientific databases Web of Science, Embase, Medline (PubMed), Scopus, and Google Scholar using relevant keywords to find suitable studies until November 2023.

RESULTS

MC-LR through Organic anion transporting polypeptide superfamily transporters (OATPs) penetrates and accumulates in hepatocytes, and it inhibits protein phosphatases (PP1 and PP2A). Consequently, MC-LR disturbs many signaling pathways and induces oxidative stress thus damages cellular macromolecules. Some protective agents, especially plants rich in flavonoids, and natural supplements, as well as chemoprotectants were shown to diminish MC-LR hepatotoxicity.

CONCLUSION

The reviewed agents through blocking the OATP transporters (nontoxic nostocyclopeptide-M1, captopril, and naringin), then inhibition of MC-LR uptake (naringin, rifampin, cyclosporin-A, silymarin and captopril), and finally at restoration of PPAse activity (silybin, quercetin, morin, naringin, rifampin, captopril, azo dyes) exert hepatoprotective effect against MC-LR.

Microcystin-leucine arginine induces the proliferation of cholangiocytes and cholangiocarcinoma cells through the activation of the Wnt/β-catenin signaling pathway

Background

Microcystin-leucine arginine (MC-LR) is a cyanobacterial hepatotoxic toxin found in water sources worldwide, including in northeastern Thailand, where opisthorchiasis-associated cholangiocarcinoma (CCA) is most prevalent. MC-LR is a potential carcinogen; however, its involvement in liver fluke-associated CCA remains ambiguous. Here, we aimed to evaluate the effect of MC-LR on the progression of CCA via the Wnt/β-catenin pathway in vitro.

Methods

Cell division, migration, cell cycle transition, and MC-LR transporter expression were evaluated in vitro through MTT assay, wound healing assay, flow cytometry, and immunofluorescence staining, respectively. Following a 24-h treatment of cultured cells with 1, 10, 100, and 1,000 nM of MC-LR, the proliferative effect of MC-LR on the Wnt/β-catenin signaling pathway was investigated using immunoblotting and qRT-PCR analysis. Immunohistochemistry was used to determine β-catenin expression in CCA tissue compared to adjacent tissue.

Results

Human immortalized cholangiocyte cells (MMNK-1) and a human cell line established from opisthorchiasis-associated CCA (KKU-213B) expressed the MC-LR transporter and internalized MC-LR. Exposure to 10 nM and 100 nM of MC-LR notably enhanced cells division and migration in both cell lines (P < 0.05) and markedly elevated the percentage of S phase cells (P < 0.05). MC-LR elevated PP2A expression by activating the Wnt/β-catenin signaling pathway and suppressing phosphatase activity. Inhibition of the β-catenin destruction complex genes (Axin1 and APC) led to the upregulation of β-catenin and its downstream target genes (Cyclin D1 and c-Jun). Inhibition of Wnt/β-catenin signaling by MSAB confirmed these results. Additionally, β-catenin was significantly expressed in cancerous tissue compared to adjacent areas (P < 0.001).

Conclusions

Our findings suggest that MC-LR promotes cell proliferation and progression of CCA through Wnt/β-catenin pathway. Further evaluation using invivo experiments is needed to confirm this observation. This finding could promote health awareness regarding MC-LR intake and risk of CCA.

Manganese in autism spectrum disorder and attention deficit hyperactivity disorder: The state of the art

The objective of the present narrative review was to synthesize existing clinical and epidemiological findings linking manganese (Mn) exposure biomarkers to autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD), and to discuss key pathophysiological mechanisms of neurodevelopmental disorders that may be affected by this metal. Existing epidemiological data demonstrated both direct and inverse association between Mn body burden and ASD, or lack of any relationship. In contrast, the majority of studies revealed significantly higher Mn levels in subjects with ADHD, as well as direct relationship between Mn body burden with hyperactivity and inattention scores in children, although several studies reported contradictory results. Existing laboratory studies demonstrated that impaired attention and hyperactivity in animals following Mn exposure was associated with dopaminergic dysfunction and neuroinflammation. Despite lack of direct evidence on Mn-induced neurobiological alterations in patients with ASD and ADHD, a plethora of studies demonstrated that neurotoxic effects of Mn overexposure may interfere with key mechanisms of pathogenesis inherent to these neurodevelopmental disorders. Specifically, Mn overload was shown to impair not only dopaminergic neurotransmission, but also affect metabolism of glutamine/glutamate, GABA, serotonin, noradrenaline, thus affecting neuronal signaling. In turn, neurotoxic effects of Mn may be associated with its ability to induce oxidative stress, apoptosis, and neuroinflammation, and/or impair neurogenesis. Nonetheless, additional detailed studies are required to evaluate the association between environmental Mn exposure and/or Mn body burden and neurodevelopmental disorders at a wide range of concentrations to estimate the potential dose-dependent effects, as well as environmental and genetic factors affecting this association.

Hepatic HIF2 is a key determinant of manganese excess and polycythemia in SLC30A10 deficiency

Manganese is an essential yet potentially toxic metal. Initially reported in 2012, mutations in SLC30A10 are the first known inherited cause of manganese excess. SLC30A10 is an apical membrane protein that exports manganese from hepatocytes into bile and from enterocytes into the lumen of the gastrointestinal tract. SLC30A10 deficiency results in impaired gastrointestinal manganese excretion, leading to manganese excess, neurologic deficits, liver cirrhosis, polycythemia, and erythropoietin excess. Neurologic and liver disease are attributed to manganese toxicity. Polycythemia is attributed to erythropoietin excess. The goal of this study was to determine the basis of erythropoietin excess in SLC30A10 deficiency. Here, we demonstrate that transcription factors hypoxia-inducible factor 1a (Hif1a) and 2a (Hif2a), key mediators of the cellular response to hypoxia, are both upregulated in livers of Slc30a10-deficient mice. Hepatic Hif2a deficiency corrected erythropoietin expression and polycythemia and attenuated aberrant hepatic gene expression in Slc30a10-deficient mice, while hepatic Hif1a deficiency had no discernible impact. Hepatic Hif2a deficiency also attenuated manganese excess, though the underlying cause of this is not clear at this time. Overall, our results indicate that hepatic HIF2 is a key determinant of pathophysiology in SLC30A10 deficiency and expand our understanding of the contribution of HIFs to human disease.

Methylphenidate alleviates cognitive dysfunction caused by early manganese exposure: Role of catecholaminergic receptors

Environmental manganese (Mn) exposure is associated with impaired attention and psychomotor functioning, as well as impulsivity/hyperactivity in children and adolescents. We have shown previously that developmental Mn exposure can cause these same dysfunctions in a rat model. Methylphenidate (MPH) lessens impairments in attention, impulse control, and psychomotor function in children, but it is unknown whether MPH ameliorates these dysfunctions when induced by developmental Mn exposure. Here, we sought to (1) determine whether oral MPH treatment ameliorates the lasting attention and sensorimotor impairments caused by developmental Mn exposure, and (2) elucidate the mechanism(s) of Mn neurotoxicity and MPH effectiveness. Rats were given 50 mg Mn/kg/d orally over PND 1-21 and assessed as adults in a series of attention, impulse control and sensorimotor tasks during oral MPH treatment (0, 0.5, 1.5, or 3.0 mg/kg/d). Subsequently, selective catecholaminergic receptor antagonists were administered to gain insight into the mechanism(s) of action of Mn and MPH. Developmental Mn exposure caused persistent attention and sensorimotor impairments. MPH treatment at 0.5 mg/kg/d completely ameliorated the Mn attentional dysfunction, whereas the sensorimotor deficits were ameliorated by the 3.0 mg/kg/d MPH dose. Notably, the MPH benefit on attention was only apparent after prolonged treatment, while MPH efficacy for the sensorimotor deficits emerged early in treatment. Selectively antagonizing D1, D2, or α2A receptors had no effect on the Mn-induced attentional dysfunction or MPH efficacy in this domain. However, antagonism of D2R attenuated the Mn sensorimotor deficits, whereas the efficacy of MPH to ameliorate those deficits was diminished by D1R antagonism. These findings demonstrate that MPH is effective in alleviating the lasting attentional and sensorimotor dysfunction caused by developmental Mn exposure, and they clarify the mechanisms underlying developmental Mn neurotoxicity and MPH efficacy. Given that the cause of attention and psychomotor deficits in children is often unknown, these findings have implications for the treatment of environmentally induced attentional and psychomotor dysfunction in children more broadly.

Ultrasmall Mn-doped iron oxide nanoparticles with dual hepatobiliary and renal clearances for T1 MR liver imaging

Although magnetic nanoparticles demonstrate significant potential as magnetic resonance imaging (MRI) contrast agents, their negative contrasts, liver accumulation, and limited excretion hinder their application. Herein, we developed ultrasmall Mn-doped iron oxide nanoparticles (UMIOs) with distinct advantages as T1 MRI contrast agents. Exceptionally small particle sizes (ca. 2 nm) and magnetization values (5 emu gMn+Fe-1) of UMIOs provided optimal T1 contrast effects with an ideally low r2/r1 value of ∼1. Furthermore, the use of Mn as a dopant facilitated hepatocyte uptake of the particles, allowing liver imaging. In animal studies, UMIOs exhibited significantly enhanced contrasts for sequential T1 imaging of blood vessels and the liver, distinguishing them from conventional magnetic nanoparticles. UMIOs were systematically cleared via dual hepatobiliary and renal excretion pathways, highlighting their safety profile. These characteristics imply substantial potential of UMIOs as T1 contrast agents for the accurate diagnosis of liver diseases.

Cross-sectional and prospective associations of early childhood circulating metals with early and mid-childhood cognition in the Project Viva cohort

BACKGROUND

Relatively little is known about the immediate and prospective neurodevelopmental impacts of joint exposure to multiple metals (i.e., metal mixtures) in early childhood.

OBJECTIVES

To estimate associations of early childhood (∼3 years of age) blood metal concentrations with cognitive test scores at early and mid-childhood (∼8 years of age).

METHODS

We studied children from the Project Viva cohort. We measured erythrocyte concentrations of seven essential (Co, Cu, Mg, Mn, Mo, Se, and Zn) and eight non-essential metals (As, Ba, Cd, Cs, Hg, Pb, Sn, and Sr) in early childhood blood samples. Trained research assistants administered cognitive tests assessing vocabulary, visual-motor ability, memory, and general intelligence (standard deviations: ∼10 points), in early and mid-childhood. We employed multivariable linear regression to examine associations of individual metals with test scores adjusting for confounders, other concurrently measured metals, and first-trimester maternal blood metals. We also estimated joint associations and explored interaction between metals in mixture analyses.

RESULTS

We analyzed 349 children (median whole blood Pb ∼1 μg/dL). In cross-sectional analyses, each doubling of Pb was associated with lower visual-motor function (mean difference: -2.43 points, 95% confidence interval (CI): -4.01, -0.86) and receptive vocabulary, i.e., words understood (-1.45 points, 95% CI: -3.26, 0.36). Associations of Pb with mid-childhood cognition were weaker and less precise by comparison. Mg was positively associated with cognition in cross-sectional but not prospective analyses, and cross-sectional associations were attenuated in a sensitivity analysis removing adjustment for concurrent metals. We did not observe joint associations nor interactions.

DISCUSSION

In this cohort with low blood Pb levels, increased blood Pb was robustly associated with lower cognitive ability in cross-sectional analyses, even after adjustment for prenatal Pb exposure, and regardless of adjustment for metal co-exposures. However, associations with mid-childhood cognition were attenuated and imprecise, suggesting some buffering of Pb neurotoxicity in early life.

WHAT THIS STUDY ADDS

Relatively few studies have comprehensively separated the effects of neurotoxic metals such as lead (Pb) from pre- and postnatal co-occurring metals, nor examined persistence of associations across childhood. In a cohort of middle-class children, we found higher early childhood (∼3 y) blood Pb was associated with lower scores on cognitive tests, independent of other metals and prenatal blood Pb. However, early childhood Pb was only weakly associated with cognition in mid-childhood (∼8 y). Our results suggest the effects of low-level Pb exposure may attenuate over time in some populations, implying the presence of factors that may buffer Pb neurotoxicity in early life.

Lipophilic Group-Modified Manganese(II)-Based Contrast Agents for Vascular and Hepatobiliary Magnetic Resonance Imaging

Effective vascular and hepatic enhancement and better safety are the key drivers for exploring gadolinium-free hepatobiliary contrast agents. Herein, a facile strategy proposes that the high lipophilicity may be favorable to enhancing sequentially vascular and hepatobiliary signal intensity based on the structure-activity relationship that both hepatic uptake and interaction with serum albumins partly depend on lipophilicity. Therefore, 11 newly synthesized derivatives of manganese o-phenylenediamine-N,N,N',N'-tetraacetic acid (MnLs) were evaluated as vascular and hepatobiliary agents. The maximum signal intensities of the heart, liver, and kidneys were strongly correlated with log P, a key indicator of lipophilicity. The most lipophilic agent, MnL6, showed favorable relaxivity when binding with serum albumin, good vascular enhancement, rapid excretion, and reliable hepatobiliary phases comparable to a classic hepatobiliary agent, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for in vivo liver tumor imaging. Inhibition experiments confirmed the hepatic targeting of MnL6 is mediated by organic anion-transporting polypeptides.

Effects of the catastrophic 2020 Yangtze River seasonal floods on microcystins and environmental conditions in Three Gorges Reservoir Area, China

Introduction

During July and August 2020, Three Gorges Reservoir Area (TGRA) suffered from catastrophic seasonal floods. Floods changed environmental conditions and caused increase in concentration of microcystins (MCs) which is a common and potent cyanotoxin. However, the effects and seasonal variations of MCs, cyanobacteria, and environmental conditions in TGRA after the 2020 Yangtze River extreme seasonal floods remain largely unclear, and relevant studies are lacking in the literature.

Methods

A total of 12 representative sampling sites were selected to perform concentration measurement of relevant water quality objectives and MCs in the representative area of the TGRA. The sampling period was from July 2020 to October 2021, which included the flood period. Organic membrane filters were used to perform the DNA extraction and analyses of the 16S rRNA microbiome sequencing data.

Results

Results showed the seasonal floods result in significant increases in the mean values of microcystin-RR (MCRR), microcystin-YR (MCYR), and microcystin-LR (MCLR) concentration and some water quality objectives (i.e., turbidity) in the hinterland of TGRA compared with that in non-flood periods (p < 0.05). The mean values of some water quality objectives (i.e., total nitrogen (TN), total phosphorus (TP), total dissolved phosphorus (TDP), and turbidity), MC concentration (i.e., MCRR, MCYR, and MCLR), and cyanobacteria abundance (i.e., Cyanobium_PCC-6307 and Planktothrix_NIVA-CYA_15) displayed clear tendency of increasing in summer and autumn and decreasing in winter and spring in the hinterland of TGRA.

Discussions

The results suggest that seasonal floods lead to changes in MC concentration and environmental conditions in the hinterland of TGRA. Moreover, the increase in temperature leads to changes in water quality objectives, which may cause water eutrophication. In turn, water eutrophication results in the increase in cyanobacteria abundance and MC concentration. In particular, the increased MC concentration may further contribute to adverse effects on human health.

The cytotoxicity of microcystin-LR: ultrastructural and functional damage of cells

Microcystin-LR (MC-LR) is a toxin produced by cyanobacteria, which is widely distributed in eutrophic water bodies and has multi-organ toxicity. Previous cytotoxicity studies have mostly elucidated the effects of MC-LR on intracellular-related factors, proteins, and DNA at the molecular level. However, there have been few studies on the adverse effects of MC-LR on cell ultrastructure and function. Therefore, research on the cytotoxicity of MC-LR in recent years was collected and summarized. It was found that MC-LR can induce a series of cytotoxic effects, including decreased cell viability, induced autophagy, apoptosis and necrosis, altered cell cycle, altered cell morphology, abnormal cell migration and invasion as well as leading to genetic damage. The above cytotoxic effects were related to the damage of various ultrastructure and functions such as cell membranes and mitochondria. Furthermore, MC-LR can disrupt cell ultrastructure and function by inducing oxidative stress and inhibiting protein phosphatase activity. In addition, the combined toxic effects of MC-LR and other environmental pollutants were investigated. This review explored the toxic targets of MC-LR at the subcellular level, which will provide new ideas for the prevention and treatment of multi-organ toxicity caused by MC-LR.

Sensorimotor dysfunction due to developmental manganese exposure is less severe in adult female than male rats and partially improved by acute methylphenidate treatment

Epidemiological studies have reported associations between elevated manganese (Mn) exposure and poorer psychomotor performance in children. Our studies in adult male rats have established that this relationship is causal and that prolonged methylphenidate (MPH) treatment is efficacious in treating this area of dysfunction. However, it is unclear if sensitivity to these Mn deficits differs between females and males, and whether existing pharmacological therapies are efficacious in improving sensorimotor dysfunction in females. To address these questions, we used our rat model of childhood environmental Mn exposure and the Montoya staircase test to determine whether 1) there are sex differences in the lasting sensorimotor dysfunction caused by developmental Mn exposure, and 2) MPH treatment is efficacious in ameliorating the sensorimotor deficits in females. Female and male neonates were treated orally with Mn (50 mg Mn/kg/d) from postnatal day 1 to 21 and evaluated for skilled forelimb sensorimotor performance as adults. Subsequently, the efficacy of acute oral MPH treatment (doses of 0, 0.5, and 3.0 mg MPH/kg/d) was assessed in females using a within-subject MPH treatment design. Developmental postnatal Mn exposure produced lasting sensorimotor reaching and grasping deficits that were milder in females than in males. Acute MPH treatment of Mn-exposed females with the 0.5 mg/kg/d dose attenuated the reaching dysfunction without alleviating grasping dysfunction. These findings show sex-based variations in sensitivity to the sensorimotor impairment caused by developmental Mn exposure, and they are consistent with prior studies showing less vulnerability of females to Mn-induced dysfunction in other functional domains, possibly due to the protective effects of estrogen. Given our previous work showing the efficacy of MPH treatment to alleviate Mn-induced inattention, impulsiveness, and sensorimotor dysfunctions in adult male rats, they also highlight the need for further research into sex-based differences in cognitive and behavioral areas of brain function, and the efficacy of therapeutics in treating behavioral dysfunction in females. Supported by NIEHS R01ES028369.

AAV-mediated hepatic expression of SLC30A10 and the Thr95Ile variant attenuates manganese excess and other phenotypes in Slc30a10-deficient mice

The manganese (Mn) export protein SLC30A10 is essential for Mn excretion via the liver and intestines. Patients with SLC30A10 deficiency develop Mn excess, dystonia, liver disease, and polycythemia. Recent genome-wide association studies revealed a link between the SLC30A10 variant T95I and markers of liver disease. The in vivo relevance of this variant has yet to be investigated. Using in vitro and in vivo models, we explore the impact of the T95I variant on SLC30A10 function. While SLC30A10 I95 expressed at lower levels than T95 in transfected cell lines, both T95 and I95 variants protected cells similarly from Mn-induced toxicity. Adeno-associated virus 8-mediated expression of T95 or I95 SLC30A10 using the liver-specific thyroxine binding globulin promoter normalized liver Mn levels in mice with hepatocyte Slc30a10 deficiency. Furthermore, Adeno-associated virus-mediated expression of T95 or I95 SLC30A10 normalized red blood cell parameters and body weights and attenuated Mn levels and differential gene expression in livers and brains of mice with whole body Slc30a10 deficiency. While our in vivo data do not indicate that the T95I variant significantly compromises SLC30A10 function, it does reinforce the notion that the liver is a key site of SLC30A10 function. It also supports the idea that restoration of hepatic SLC30A10 expression is sufficient to attenuate phenotypes in SLC30A10 deficiency.

Novel Pathogenic Variants Leading to Sporadic Amyotrophic Lateral Sclerosis in Greek Patients

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive disease that affects motor neurons, leading to paralysis and death usually 3-5 years after the onset of symptoms. The investigation of both sporadic and familial ALS highlighted four main genes that contribute to the pathogenesis of the disease: SOD1, FUS, TARDBP and C9orf72. This study aims to provide a comprehensive investigation of genetic variants found in SOD1, FUS and TARDBP genes in Greek sporadic ALS (sALS) cases. Our sequencing analysis of the coding regions of the abovementioned genes that include the majority of the variants that lead to ALS in 32 sALS patients and 3 healthy relatives revealed 6 variants in SOD1, 19 variants in FUS and 37 variants in TARDBP, of which the SOD1 p.D90A and the FUS c.*356G>A (rs886051940) variants have been previously associated with ALS, while two novel nonsense pathogenic variants were also identified, namely FUS p.R241* and TDP-43 p.Y214*. Our study contributes to the worldwide effort toward clarifying the genetic basis of sALS to better understand the disease's molecular pathology.

Molecular Organization and Regulation of the Mammalian Synapse by the Post-Translational Modification SUMOylation

Neurotransmission occurs within highly specialized compartments forming the active synapse where the complex organization and dynamics of the interactions are tightly orchestrated both in time and space. Post-translational modifications (PTMs) are central to these spatiotemporal regulations to ensure an efficient synaptic transmission. SUMOylation is a dynamic PTM that modulates the interactions between proteins and consequently regulates the conformation, the distribution and the trafficking of the SUMO-target proteins. SUMOylation plays a crucial role in synapse formation and stabilization, as well as in the regulation of synaptic transmission and plasticity. In this review, we summarize the molecular consequences of this protein modification in the structural organization and function of the mammalian synapse. We also outline novel activity-dependent regulation and consequences of the SUMO process and explore how this protein modification can functionally participate in the compartmentalization of both pre- and post-synaptic sites.

Loss of SLC30A10 manganese transporter alters expression of neurotransmission genes and activates hypoxia-inducible factor signaling in mice

The essential metal manganese (Mn) induces neuromotor disease at elevated levels. The manganese efflux transporter SLC30A10 regulates brain Mn levels. Homozygous loss-of-function mutations in SLC30A10 induce hereditary Mn neurotoxicity in humans. Our prior characterization of Slc30a10 knockout mice recapitulated the high brain Mn levels and neuromotor deficits reported in humans. But, mechanisms of Mn-induced motor deficits due to SLC30A10 mutations or elevated Mn exposure are unclear. To gain insights into this issue, we characterized changes in gene expression in the basal ganglia, the main brain region targeted by Mn, of Slc30a10 knockout mice using unbiased transcriptomics. Compared with littermates, >1000 genes were upregulated or downregulated in the basal ganglia sub-regions (i.e. caudate putamen, globus pallidus, and substantia nigra) of the knockouts. Pathway analyses revealed notable changes in genes regulating synaptic transmission and neurotransmitter function in the knockouts that may contribute to the motor phenotype. Expression changes in the knockouts were essentially normalized by a reduced Mn chow, establishing that changes were Mn dependent. Upstream regulator analyses identified hypoxia-inducible factor (HIF) signaling, which we recently characterized to be a primary cellular response to elevated Mn, as a critical mediator of the transcriptomic changes in the basal ganglia of the knockout mice. HIF activation was also evident in the liver of the knockout mice. These results: (i) enhance understanding of the pathobiology of Mn-induced motor disease; (ii) identify specific target genes/pathways for future mechanistic analyses; and (iii) independently corroborate the importance of the HIF pathway in Mn homeostasis and toxicity.

SUMOylation effects on neural stem cells self-renewal, differentiation, and survival

SUMO (small ubiquitin-like modifier) conjugation or SUMOylation, a post-translational modification, is a crucial regulator of protein function and cellular processes. In the context of neural stem cells (NSCs), SUMOylation has emerged as a key player, affecting their proliferation, differentiation, and survival. By modifying transcription factors, such as SOX1, SOX2, SOX3, SOX6, Bmi1, and Nanog, SUMOylation can either enhance or impair their transcriptional activity, thus impacting on NSCs self-renewal. Moreover, SUMOylation regulates neurogenesis and neuronal differentiation by modulating key proteins, such as Foxp1, Mecp2, MEF2A, and SOX10. SUMOylation is also crucial for the survival and proliferation of NSCs in both developing and adult brains. By regulating the activity of transcription factors, coactivators, and corepressors, SUMOylation acts as a molecular switch, inducing cofactor recruitment and function during development. Importantly, dysregulation of NSCs SUMOylation has been implicated in various disorders, including embryonic defects, ischemic cerebrovascular disease, glioma, and the harmful effects of benzophenone-3 exposure. Here we review the main findings on SUMOylation-mediated regulation of NSCs self-renewal, differentiation and survival. Better understanding NSCs SUMOylation mechanisms and its functional consequences might provide new strategies to promote neuronal differentiation that could contribute for the development of novel therapies targeting neurodegenerative diseases.

Lead exposure induced transgenerational developmental neurotoxicity by altering genome methylation in Drosophila melanogaster

Heavy metal toxicity is a significant global health concern, with particular attention given to lead (Pb) exposure due to its adverse effects on cognitive development, especially in children exposed to low concentrations. While Pb neurotoxicity has been extensively studied, the analysis and molecular mechanisms underlying the transgenerational effects of Pb exposure-induced neurotoxicity remain poorly understood. In this study, we utilized Drosophila, a powerful developmental animal model, to investigate this phenomenon. Our findings demonstrated that Pb exposure during the developmental stage had a profound effect on the neurodevelopment of F0 fruit flies. Specifically, we observed a loss of correlation between the terminal motor area and muscle fiber area, along with an increased frequency of the β-lobe midline crossing phenotype in mushroom bodies. Western blot analysis indicated altered expression levels of synaptic vesicle proteins, with a decrease in Synapsin (SYN) and an increase in Bruchpilot (BRP) expression, suggesting changes in synaptic vesicle release sites. These findings were corroborated by electrophysiological data, showing an increase in the amplitude of evoked excitatory junctional potential (EJP) and an increase in the frequency of spontaneous excitatory junctional potential (mEJP) following Pb exposure. Importantly, our results further confirmed that the developmental neurotoxicity resulting from grandparental Pb exposure exhibited a transgenerational effect. The F3 offspring displayed neurodevelopmental defects, synaptic function abnormalities, and repetitive behavior despite lacking direct Pb exposure. Our MeDIP-seq analysis further revealed significant alterations in DNA methylation levels in several neurodevelopmental associated genes (eagle, happyhour, neuroglian, bazooka, and spinophilin) in the F3 offspring exposed to Pb. These findings suggest that DNA methylation modifications may underlie the inheritance of acquired phenotypic traits resulting from environmental Pb exposure.

Hippocampal synaptic plasticity injury mediated by SIRT1 downregulation is involved in chronic pain-related cognitive dysfunction

AIMS

Cognitive dysfunction associated with chronic pain may be caused by impaired synaptic plasticity. Considering the impact of silent information regulator 1 (SIRT1) on synaptic plasticity, we explored the exact role of SIRT1 in cognitive impairment caused by chronic pain.

METHODS

We evaluated the memory ability of mice with the fear conditioning test (FCT) after spared nerve injury (SNI) model. Western blotting and immunofluorescence were used to analyze the expression levels of SIRT1. Hippocampal synaptic plasticity was detected with Golgi staining, transmission electron microscopy, and long-term potentiation (LTP). In the intervention study, AAV9-CaMKIIα-Cre-EGFP was injected to SIRT1flox/flox mice to knockdown the expression levels of SIRT1. Besides, SNI mice were injected with AAV2/9-CaMKIIα-SIRT1-3*Flag-GFP or SRT1720 to increase the expression levels or enzymatic activity of SIRT1.

RESULTS

Our current results indicated that cognitive function in SNI mice was impaired, SIRT1 expression in glutaminergic neurons in the hippocampal CA1 area was downregulated, and synaptic plasticity was altered. Selective knockdown of SIRT1 in hippocampus damaged synaptic plasticity and cognitive function of healthy mice. In addition, the impaired synaptic plasticity and cognitive dysfunction of SNI mice could be improved by the upregulation of SIRT1 expression or enzyme activity.

CONCLUSIONS

Reduced SIRT1 expression in hippocampus of SNI mice may induce cognitive impairment associated with chronic pain by mediating the impaired synaptic plasticity.

An Industry-Relevant Metal Mixture, Iron Status, and Reported Attention-Related Behaviors in Italian Adolescents

BACKGROUND

Exposure to environmental metals has been consistently associated with attention and behavioral deficits in children, and these associations may be modified by coexposure to other metals or iron (Fe) status. However, few studies have investigated Fe status as a modifier of a metal mixture, particularly with respect to attention-related behaviors.

METHODS

We used cross-sectional data from the Public Health Impact of Metals Exposure study, which included 707 adolescents (10-14 years of age) from Brescia, Italy. Manganese, chromium, and copper were quantified in hair samples, and lead was quantified in whole blood, using inductively coupled plasma mass spectrometry. Concentrations of Fe status markers (ferritin, hemoglobin, transferrin) were measured using immunoassays or luminescence assays. Attention-related behaviors were assessed using the Conners Rating Scales Self-Report Scale-Long Form, Parent Rating Scales Revised-Short Form, and Teacher Rating Scales Revised-Short Form. We employed Bayesian kernel machine regression to examine associations of the metal mixture with these outcomes and evaluate Fe status as a modifier.

RESULTS

Higher concentrations of the metals and ferritin were jointly associated with worse self-reported attention-related behaviors: metals and ferritin set to their 90th percentiles were associated with 3.0% [β = 0.03 ; 95% credible interval (CrI): - 0.01 , 0.06], 4.1% (β = 0.04 ; 95% CrI: 0.00, 0.08), and 4.1% (β = 0.04 ; 95% CrI: 0.00, 0.08) higher T -scores for self-reported attention deficit/hyperactivity disorder (ADHD) index, inattention, and hyperactivity, respectively, compared with when metals and ferritin were set to their 50th percentiles. These associations were driven by hair manganese, which exhibited nonlinear associations with all self-reported scales. There was no evidence that Fe status modified the neurotoxicity of the metal mixture. The metal mixture was not materially associated with any parent-reported or teacher-reported scale.

CONCLUSIONS

The overall metal mixture, driven by manganese, was adversely associated with self-reported attention-related behavior. These findings suggest that exposure to multiple environmental metals impacts adolescent neurodevelopment, which has significant public health implications. https://doi.org/10.1289/EHP12988.

Melatonin modulates the differentiation of neural stem cells exposed to manganese via SIRT1/β-catenin signaling

Excessive exposure of children to manganese (Mn) in the environment has a bearing on developmental neurotoxicity. Although melatonin (Mel) can play a neuroprotective role by modulating the differentiation of neural stem cells (NSCs) in the developing brain, its specific mechanism under Mn overexposure remains to be explored. Here, we cultured primary NSCs as an available model to investigate the relevant molecular mechanism of Mel mitigation on Mn-induced disorder of NSCs differentiation through sirtuin 1 (SIRT1)/β-catenin pathway. It was found that Mel could facilitate the differentiation of Mn-treated NSCs into neurons. Further, our results uncovered that the pro-differentiation mechanism of Mel depended upon ascending the activity of SIRT1, thereby weakening β-catenin acetylation and increasing phosphorylation of β-catenin ser675 in the cytoplasm, which facilitates the nuclear translocation of β-catenin. Furthermore, the role of SIRT1 in Mel-mediated signal transduction was investigated through the pretreatment of NSCs using a highly specific SIRT1 inhibitor, EX527. After EX527 pretreatment, Mel could not maintain its protective effect. Overall, our results revealed that Mel could alleviate Mn-induced disorder of NSCs differentiation through the activation of the SIRT1/β-catenin pathway.

Manganese - a scoping review for Nordic Nutrition Recommendations 2023

Manganese is an essential trace element that is required for multiple enzymes in the human body. The general population is mainly exposed to manganese via food intake, in particular plant foods. In areas with elevated concentrations of manganese in groundwater, drinking water can also be an important source of exposure. The gastrointestinal absorption of manganese is below 10%, and it appears to be influenced by the amount of manganese in the diet and by the nutritional status of the individual, especially the iron status. In blood, most of the manganese is found in the cellular fractions. Manganese is primarily eliminated via the bile followed by excretion via faeces. To date, no specific biomarkers of manganese intake have been identified. The dietary intake of manganese in the Nordic countries has been reported to be within the range that has been reported for other European countries (2-6 mg/day). Since manganese is found in nutritionally adequate amounts in food, deficiency is not of public health concern. On the other hand, there is emerging epidemiological evidence that various suggested manganese biomarkers may be negatively associated with children's neurodevelopment. However, the limited number of prospective studies, the lack of appropriate exposure biomarkers, and validated neurodevelopmental outcomes render data uncertain and inconclusive. In 2013, the European Food Safety Authority considered the evidence to be insufficient to derive an average requirement or a population reference intake, and instead an adequate intake for adults was set at 3.0 mg/day.

Modulation of Tau Pathology in Alzheimer's Disease by Dietary Bioactive Compounds

Tau is a microtubule-associated protein essential for microtubule assembly and stability in neurons. The abnormal intracellular accumulation of tau aggregates is a major characteristic of brains from patients with Alzheimer's disease (AD) and other tauopathies. In AD, the presence of neurofibrillary tangles (NFTs), which is composed of hyperphosphorylated tau protein, is positively correlated with the severity of the cognitive decline. Evidence suggests that the accumulation and aggregation of tau cause synaptic dysfunction and neuronal degeneration. Thus, the prevention of abnormal tau phosphorylation and elimination of tau aggregates have been proposed as therapeutic strategies for AD. However, currently tau-targeting therapies for AD and other tauopathies are limited. A number of dietary bioactive compounds have been found to modulate the posttranslational modifications of tau, including phosphorylation, small ubiquitin-like modifier (SUMO) mediated modification (SUMOylation) and acetylation, as well as inhibit tau aggregation and/or promote tau degradation. The advantages of using these dietary components over synthetic substances in AD prevention and intervention are their safety and accessibility. This review summarizes the mechanisms leading to tau pathology in AD and highlights the effects of bioactive compounds on the hyperphosphorylation, aggregation and clearance of tau protein. The potential of using these bioactive compounds for AD prevention and intervention is also discussed.

Heavy Metal Exposure: Molecular Pathways, Clinical Implications, and Protective Strategies

Heavy metals are often found in soil and can contaminate drinking water, posing a serious threat to human health. Molecular pathways and curation therapies for mitigating heavy metal toxicity have been studied for a long time. Recent studies on oxidative stress and aging have shown that the molecular foundation of cellular damage caused by heavy metals, namely, apoptosis, endoplasmic reticulum stress, and mitochondrial stress, share the same pathways as those involved in cellular senescence and aging. In recent aging studies, many types of heavy metal exposures have been used in both cellular and animal aging models. Chelation therapy is a traditional treatment for heavy metal toxicity. However, recently, various antioxidants have been found to be effective in treating heavy metal-induced damage, shifting the research focus to investigating the interplay between antioxidants and heavy metals. In this review, we introduce the molecular basis of heavy metal-induced cellular damage and its relationship with aging, summarize its clinical implications, and discuss antioxidants and other agents with protective effects against heavy metal damage.

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

Treatment with 1, 10 Phenanthroline-5-Amine Reduced Amyloid Burden in a Mouse Model of Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is the most prevalent age-related dementia, and, despite numerous attempts to halt or reverse its devastating progression, no effective therapeutics have yet been confirmed clinically. However, one class of agents that has shown promise is certain metal chelators.

OBJECTIVE

For the novel assessment of the effect of oral administration of 1,10-phenanthroline-5-amine (PAA) on the severity of amyloid plaque load, we used a transgenic (Tg) mouse model with inserted human autosomally dominant (familial) AD genes: amyloid-β protein precursor (AβPP) and tau.

METHODS

AβPP/Tau transgenic mice that model AD were allotted into one of two groups. The control group received no treatment while the experimental group received PAA in their drinking water starting at 4 months of age. All animals were sacrificed at 1 year of age and their brains were stained with two different markers of amyloid plaques, Amylo-Glo+ and HQ-O.

RESULTS

The control animals exhibited numerous dense core plaques throughout the neo- and allo- cortical brain regions. The experimental group treated with PAA, however, showed 62% of the amyloid plaque burden seen in the control group.

CONCLUSIONS

Oral daily dosing with PAA will significantly reduce the amyloid plaque burden in transgenic mice that model AD. The underlying mechanism for this protection is not fully known; however, one proposed mechanism involves inhibiting the "metal-seeding" of Aβ.

MeCP2 ubiquitination and sumoylation, in search of a function†

MeCP2 (Methyl CpG binding protein 2) is an intrinsically disordered protein that binds to methylated genome regions. The protein is a critical transcriptional regulator of the brain, and its mutations account for 95% of Rett syndrome (RTT) cases. Early studies of this neurodevelopmental disorder revealed a close connection with dysregulations of the ubiquitin system (UbS), notably as related to UBE3A, a ubiquitin ligase involved in the proteasome-mediated degradation of proteins. MeCP2 undergoes numerous post-translational modifications (PTMs), including ubiquitination and sumoylation, which, in addition to the potential functional outcomes of their monomeric forms in gene regulation and synaptic plasticity, in their polymeric organization, these modifications play a critical role in proteasomal degradation. UbS-mediated proteasomal degradation is crucial in maintaining MeCP2 homeostasis for proper function and is involved in decreasing MeCP2 in some RTT-causing mutations. However, regardless of all these connections to UbS, the molecular details involved in the signaling of MeCP2 for its targeting by the ubiquitin-proteasome system (UPS) and the functional roles of monomeric MeCP2 ubiquitination and sumoylation remain largely unexplored and are the focus of this review.

EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Turck D, Bohn T, Castenmiller J, de Henauw S, Hirsch‐Ernst K, Knutsen HK, Maciuk A, Mangelsdorf I, McArdle HJ, Pentieva K, Siani A, Thies F, Tsabouri S, Vinceti M, Bornhorst J, Cubadda F, Dopter A, FitzGerald R, de Sesmaisons Lecarré A, das Neves Ferreira P, Fabiani L, Horvath Z, Matijević L, Naska A. Scientific opinion on the tolerable upper intake level for manganese

Following a request from the European Commission (EC), the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the tolerable upper intake level (UL) for manganese. Systematic reviews of the literature of human and animal data were conducted to assess evidence regarding excess manganese intake (including authorised manganese salts) and the priority adverse health effect, i.e. manganese-induced neurotoxicity. Available human and animal studies support neurotoxicity as a critical effect, however, data are not sufficient and suitable to characterise a dose-response relationship and identify a reference point for manganese-induced neurotoxicity. In the absence of adequate data to establish an UL, estimated background dietary intakes (i.e. manganese intakes from natural dietary sources only) observed among high consumers (95th percentile) were used to provide an indication of the highest level of intake where there is reasonable confidence on the absence of adverse effects. A safe level of intake of 8 mg/day was established for adults ≥ 18 years (including pregnant and lactating women) and ranged between 2 and 7 mg/day for other population groups. The application of the safe level of intake is more limited than an UL because the intake level at which the risk of adverse effects starts to increase is not defined.

Semaglutide ameliorates cognition and glucose metabolism dysfunction in the 3xTg mouse model of Alzheimer's disease via the GLP-1R/SIRT1/GLUT4 pathway

Disorders of brain glucose metabolism is known to affect brain activity in neurodegenerative diseases including Alzheimer's disease (AD). Furthermore, recent evidence has shown an association between AD and type 2 diabetes. Numerous reports have found that glucagon-like peptide-1 (GLP-1) receptor agonists improve the cognitive behavior and pathological features in AD patients and animals, which may be related to the improvement of glucose metabolism in the brain. However, the mechanism by which GLP-1 agonists improve the brain glucose metabolism in AD patients remains unclear. In this study, we found that SIRT1 is closely related to expression of GLP-1R in hippocampus of 3xTg mice. Therefore, we used semaglutide, a novel GLP-1R agonist currently undergoing two phase 3 clinical trials in AD patients, to observe the effect of SIRT1 after semaglutide treatment in 3XTg mice and HT22 cells, and to explore the mechanism of SIRT1 in the glucose metabolism disorders of AD. The mice were injected with semaglutide on alternate days for 30 days, followed by behavioral experiments including open field test, new object recognition test, and Y-maze. The content of glucose in the brain was also measured by using 18FDG-PET-CT scans. We measured the expression of Aβ and tau in the hippocampus, observed the expression of GLUT4 which is downstream of SIRT1, and tested the Glucose oxidase assay (GOD-POD) and Hexokinase (HK) in HT22 cells. Here, we found in the 3xTg mouse model of AD and in cultured HT22 mouse neurons that SIRT1 signaling is involved in the impairment of glucose metabolism in AD. Semaglutide can increased the expression levels of SIRT1 and GLUT4 in the hippocampus of 3xTg mice, accompanied by an improvement in learning and memory, decreased in Aβ plaques and neurofibrillary tangles. In addition, we further demonstrated that semaglutide improved glucose metabolism in the brain of 3xTg mice in vitro, semaglutide promoted glycolysis and improved glycolytic disorders, and increased the membrane translocation of GLUT4 in cultured HT22 cells. These effects were blocked by the SIRT1 inhibitor (EX527). These findings indicate that semaglutide can regulate the expression of GLUT4 to mediate glucose transport through SIRT1, thereby improving glucose metabolism dysfunction in AD mice and cells. The present study suggests that SIRT1/GLUT4 signaling pathway may be an important mechanism for GLP-1R to promote glucose metabolism in the brain, providing a reliable strategy for effective therapy of AD.

Lead and cadmium co-exposure modified PC12 viability and ER stress: study from a 3 × 3 factorial design

Background

Although exposure to individual metal does exhibit its toxicity, combined exposures provide a more effective representation of the toxic effects of different heavy metal exposures on public health as well as ecosystems. Furthermore, there are few studies on composite exposure to low concentrations of heavy metals, which is more consistent with real-life exposure. The purpose of this study was to explore the neurotoxicity induced by combined exposure to low concentrations of Lead (Pb) and cadmium (Cd) and the potential interaction of their mixture in vitro.

Methods

PC12 cells were incubation with the corresponding concentration of cadmium chloride and/or lead acetate. Viability of PC12 cells was measured by CCK8 assay after 12, 24 and 48h incubation. Next, We measured the ROS, mitochondrial membrane potential (MMP) and apoptosis produced by different treated cells using ROS assay kit, JC-1 MMP assay kit and annexin V-FITC/propidium iodide (PI) apoptosis assay kit, respectively. Expression of proteins related to PI3K/AKT and endoplasmic reticulum (ER) stress in PC12 cells were tested by western blotting. Our study was the first to analyze the interaction between Pb and Cd using a 3 × 3 factorial design approach to observe neurotoxicity.

Results

The results showed that the combined exposure of them was more cytotoxic than the single metal. The activation of PI3K/AKT signaling pathway and several parameters related to oxidative stress and ER stress were significantly altered in combined exposure to low concentrations of Pb and Cd compared with the Pb or Cd. Regarding apoptosis and ER stress, a synergistic interaction between Pb and Cd was evident. Moreover, evoked ER stress as a mechanism involved in the apoptosis of PC12 cells by the combined exposure to Pb and Cd.

Conclusion

The present study provides a theoretical basis used for the toxicological assessment of metal mixtures induced neurotoxicity of concern in terms of public health, and more effective control measures should be taken for the environmental pollution caused by various mixed heavy metals discharged from industry and agriculture.