Acrylamide axonopathy revisited

Dietary acrylamide disrupts the functioning of the biological clock

Acrylamide (ACR) is a known carcinogen and neurotoxin. It is chronically consumed in carbohydrate-rich snacks processed at high temperatures. This calls for systematic research into the effects of ACR intake, best performed in an experimental model capable of detecting symptoms of its neurotoxicity at both high and low doses. Here, we study the influence of 10 µg/g (corresponding to the concentrations found in food products) and, for comparison, 60, 80 and 110 µg/g dietary ACR, on the fruit fly Drosophila melanogaster. We show that chronic administration of ACR affects lifespan, activity level and, most importantly, the daily and circadian pattern of locomotor activity of Drosophila. ACR-treated flies show well-defined and concentration-dependent symptoms of ACR neurotoxicity; a reduced anticipation of upcoming changes in light conditions and increased arrhythmicity in constant darkness. The results suggest that the rhythm-generating neural circuits of their circadian oscillator (biological clock) are sensitive to ACR even at low concentrations if the exposure time is sufficiently long. This makes the behavioural readout of the clock, the rhythm of locomotor activity, a useful tool for studying the adverse effects of ACR and probably other compounds.

ROS-dependent degeneration of human neurons induced by environmentally relevant levels of micro- and nanoplastics of diverse shapes and forms

Our study explores the pressing issue of micro- and nanoplastics (MNPs) inhalation and their subsequent penetration into the brain, highlighting a significant environmental health concern. We demonstrate that MNPs can indeed penetrate murine brain, warranting further investigation into their neurotoxic effects in humans. We then proceed to test the impact of MNPs at environmentally relevant concentrations, with focusing on variations in size and shape. Our findings reveal that these MNPs induce oxidative stress, cytotoxicity, and neurodegeneration in human neurons, with cortical neurons being more susceptible than nociceptors. Furthermore, we examine the role of biofilms on MNPs, demonstrating that MNPs can serve as a vehicle for pathogenic biofilms that significantly exacerbate these neurotoxic effects. This sequence of investigations reveals that minimal MNPs accumulation can cause oxidative stress and neurodegeneration in human neurons, significantly risking brain health and highlights the need to understand the neurological consequences of inhaling MNPs. Overall, our developed in vitro testing battery has significance in elucidating the effects of environmental factors and their associated pathological mechanisms in human neurons.

Toxic encephalopathy, vision loss, and memory disorder caused by acute acrylamide exposure

Acrylamide (ACR) is an irritant that can cause damage to the eyes, skin, and nervous and reproductive systems. This study aims to illustrate a case of central nervous system and optic nerve damage from exposure to ACR. In this case, a 49-year-old male material handler was accidentally splashed with ACR solution on both of his upper limbs. Consequently, he was admitted to the hospital with toxic encephalopathy, characterized by cerebellar ataxia and slurred speech. Magnetic resonance imaging scan, a brain computed tomography scan blood sample analyses, optic coherence tomography, electroneuromyogram, and visual evoked potentials examination were performed. After 20 days of receiving symptomatic support treatment, the patient continued to experience disturbances in consciousness. Then, he developed vision loss, memory disorders, and symptoms of peripheral neuropathy such as skin peeling, extremity weakness, and absent tendon reflexes. This case report underscores the severe consequences of acute dermal exposure to high concentrations of ACR, resulting in toxic encephalopathy, visual impairment, and memory disorders, which will contribute to a broader understanding of ACR toxicity.

Transcriptome analysis of the cerebral cortex of acrylamide-exposed wild-type and IL-1β-knockout mice

Acrylamide is an environmental electrophile that has been produced in large amounts for many years. There is concern about the adverse health effects of acrylamide exposure due to its widespread industrial use and also presence in commonly consumed foods and others. IL-1β is a key cytokine that protects the brain from inflammatory insults, but its role in acrylamide-induced neurotoxicity remains unknown. We reported recently that deletion of IL-1β gene exacerbates ACR-induced neurotoxicity in mice. The aim of this study was to identify genes or signaling pathway(s) involved in enhancement of ACR-induced neurotoxicity by IL-1β gene deletion or ACR-induced neurotoxicity to generate a hypothesis mechanism explaining ACR-induced neurotoxicity. C57BL/6 J wild-type and IL-1β KO mice were exposed to ACR at 0, 12.5, 25 mg/kg by oral gavage for 7 days/week for 4 weeks, followed by extraction of mRNA from mice cerebral cortex for RNA sequence analysis. IL-1β deletion altered the expression of genes involved in extracellular region, including upregulation of PFN1 gene related to amyotrophic lateral sclerosis and increased the expression of the opposite strand of IL-1β. Acrylamide exposure enhanced mitochondria oxidative phosphorylation, synapse and ribosome pathways, and activated various pathways of different neurodegenerative diseases, such as Alzheimer disease, Parkinson disease, Huntington disease, and prion disease. Protein network analysis suggested the involvement of different proteins in related to learning and cognitive function, such as Egr1, Egr2, Fos, Nr4a1, and Btg2. Our results identified possible pathways involved in IL-1β deletion-potentiated and ACR-induced neurotoxicity in mice.

Increased IP3R-3 degradation induced by acrylamide promoted Ca2+-dependent calpain activation and axon damage in rats

Occupational and environmental exposure to acrylamide (ACR) can cause selective peripheral and central nerve fiber degeneration. IP3R-3 is an important transmembrane Ca²⁺ channel on the endoplasmic reticulum (ER), previous studies have found that ACR could induce Ca²⁺-dependent calpain activation and axon injury, but the exact role of IP3R-3 in ACR neuropathy is still unclear. Here we show that ACR exposure (40mg/kg) markedly increased the ubiquitination of IP3R-3 in rat spinal cords, and promoted the degradation of IP3R-3 through the ubiquitin-proteasome pathway. Furthermore, the normal structure of ER, especially the mitochondrial associated membranes (MAMs) component, was significantly impaired in ACR neuropathy, and the ER stress pathway was activated, which indicated that the aberrant increase of cytoplasmic Ca²⁺ could be attributed the destruction of IP3R-3. Further investigation demonstrated that the proteasome inhibitor MG-132 effectively rescued the IP3R-3 loss, attenuated the intracellular Ca²⁺ increase, and reduced the axon loss of Neuron 2a (N2a) cells following ACR exposure. Moreover, the calpain inhibitor ALLN also reduced the loss of IP3R-3 and axon injury in N2a cells, but did not alleviate the Ca²⁺ increase in cytosol, supporting that the abnormal ubiquitination of IP3R-3 was the upstream of the cellular Ca²⁺ rise and axon damage in ACR neuropathy. Taken together, our results suggested that the aberrant IP3R-3 degradation played an important role in the disturbance of Ca²⁺ homeostasis and the downstream axon loss in ACR neuropathy, thus providing a potential therapeutic target for ACR neurotoxicity.

High fried food consumption impacts anxiety and depression due to lipid metabolism disturbance and neuroinflammation

Western dietary patterns have been unfavorably linked with mental health. However, the long-term effects of habitual fried food consumption on anxiety and depression and underlying mechanisms remain unclear. Our population-based study with 140,728 people revealed that frequent fried food consumption, especially fried potato consumption, is strongly associated with 12% and 7% higher risk of anxiety and depression, respectively. The associations were more pronounced among male and younger consumers. Consistently, long-term exposure to acrylamide, a representative food processing contaminant in fried products, exacerbates scototaxis and thigmotaxis, and further impairs exploration ability and sociality of adult zebrafish, showing anxiety- and depressive-like behaviors. Moreover, treatment with acrylamide significantly down-regulates the gene expression of tjp2a related to the permeability of blood-brain barrier. Multiomics analysis showed that chronic exposure to acrylamide induces cerebral lipid metabolism disturbance and neuroinflammation. PPAR signaling pathway mediates acrylamide-induced lipid metabolism disorder in the brain of zebrafish. Especially, chronic exposure to acrylamide dysregulates sphingolipid and phospholipid metabolism, which plays important roles in the development of anxiety and depression symptoms. In addition, acrylamide promotes lipid peroxidation and oxidation stress, which participate in cerebral neuroinflammation. Acrylamide dramatically increases the markers of lipid peroxidation, including (±)5-HETE, 11(S)-HETE, 5-oxoETE, and up-regulates the expression of proinflammatory lipid mediators such as (±)12-HETE and 14(S)-HDHA, indicating elevated cerebral inflammatory status after chronic exposure to acrylamide. Together, these results both epidemiologically and mechanistically provide strong evidence to unravel the mechanism of acrylamide-triggered anxiety and depression, and highlight the significance of reducing fried food consumption for mental health.

Quercetin ameliorates acute acrylamide induced spleen injury

Acrylamide is used for industrial and laboratory purposes; it also is produced during cooking of carbohydrate-rich food at high temperature. We investigated the therapeutic potential of quercetin for treatment of acute acrylamide induced injury to the spleen. We used female albino rats treated with acrylamide for 10 days followed by oral administration of quercetin in three doses for 5 days. We observed significantly reduced total body weight, spleen weight, red blood cells, total proteins, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glucose-6-phophate dehydrogenase, reduced glutathione, concentration of serum IgG and IgM after acrylamide induced toxicity compared to controls. We also found that white blood cells, triglycerides, cholesterol and lipid oxidation were increased significantly after acrylamide induced toxicity in rats compared to controls. Histoarchitecture of spleen was affected adversely by acrylamide toxicity. Administration of quercetin ameliorated adverse effects of acrylamide in a dose-dependent manner. Quercetin appears to ameliorate acrylamide induced injury to the spleen by increasing endogenous antioxidants and improving histoarchitecture and immune function.

Palliative effect of Moringa olifera-mediated zinc oxide nanoparticles against acrylamide-induced neurotoxicity in rats

Repeated acrylamide (ACR) exposure in experimental animals and humans causes variable degrees of neuronal damage. Because of its unique features, several green synthesized nanomaterials are explored for neuromodulatory activity. Hence, this study investigated the effect of green synthesized zinc oxide nanoparticles using Moriga olifera leaves extract (MO-ZnONP) against acrylamide (ACR)-induced neurobehavioral and neurotoxic impacts in rat. Forty male Sprague Dawley rats were distributed into four groups orally given distilled water, MO-ZnONP (10 mg/kg b.wt), ACR (20 mg/kg b.wt), or MO-ZnONP + ACR for 60 days. Gait quality and muscular, motor, and sensory function were assessed. Acetylcholinesterase (AChE), dopamine, catalase, malondialdehyde (MDA), and Zn brain contents were determined. Brain histopathology and immunohistochemical localization of the amyloid-β protein and abnormal Tau were performed. The results revealed that MO-ZnONP significantly reduced ACR-induced sensory dysfunctions, hind limb abnormality, and motor deficits. Additionally, the ACR-induced increase in dopamine and AChE were significantly supressed by MO-ZnONP. Besides, MO-ZnONP significantly restored catalase and Zn content but reduced increased MDA brain content resulting from ACR. Furthermore, the ACR-induced neurodegenerative changes and increased amyloid-β and phosphorylated Tau immunoexpression was significantly abolished by MO-ZnONP. Conclusively, MO-ZnONP could be used as a biologically effective compound for mitigating ACR's neurotoxic and neurobehavioral effects.

Mitochondrial dysfunction promotes the necroptosis of Purkinje cells in the cerebellum of acrylamide-exposed rats

Acrylamide (ACR) is a common neurotoxicant that can induce central-peripheral neuropathy in human beings. ACR from occupational setting and foods poses a potential threat to people's health. Purkinje cells are the only efferent source of cerebellum, and their output is responsible for coordinating motor activity. Recent studies have reported that Purkinje cell injury is one of the earliest neurotoxicity at any dose rate of ACR. However, the mechanism underlying ACR-mediated damage to Purkinje cells remains unclear. This research aimed to investigate whether necroptosis is involved in ACR-induced Purkinje cell death and its regulatory mechanism. In this study, rats were treated with ACR (40 mg/kg/every other day) for 6 weeks to establish an animal model of ACR neuropathy. Furthermore, an intervention experiment was achieved by rapamycin (RAPA), which is commonly used to activate mitophagy and maintain mitochondrial homeostasis. The results demonstrated ACR exposure caused necroptosis of Purkinje cells, mitochondrial dysfunction, and inflammatory response. By contrast, RAPA alleviated mitochondrial dysfunction and inhibited activation of necroptosis signaling pathway following ACR. In conclusion, our findings suggest that mitochondrial dysfunction and activation of necroptotic signaling are associated with the loss of Purkinje cells in ACR poisoning, which can be a potential therapeutic target for ACR neurotoxicity.

The role of additives on acrylamide formation in food products: a systematic review

Acrylamide (AA) is a toxic substance formed in many carbohydrate-rich food products, whose formation can be reduced by adding some additives. Furthermore, the type of food consumed determines the AA intake. According to the compiled information, the first route causing AA formation is the Maillard reaction. Some interventions, such as reducing AA precursors in raw materials, (i.e., asparagine), reducing sugars, or decreasing temperature and processing time can be applied to limit AA formation in food products. The L-asparaginase is more widely used in potato products. Also, coatings loaded with proteins, enzymes, and phenolic compounds are new techniques for reducing AA content. Enzymes have a reducing effect on AA formation by acting on asparagine; proteins by competing with amino acids to participate in Maillard, and phenolic compounds through their radical scavenging activity. On the other hand, some synthetic and natural additives increase the formation of AA. Due to the high exposure to AA and its toxic effects, it is essential to recognize suitable food additives to reduce the health risks for consumers. In this sense, this study focuses on different additives that are proven to be effective in the reduction or formation of AA in food products.

Neuronal differentiation pathways and compound-induced developmental neurotoxicity in the human neural progenitor cell test (hNPT) revealed by RNA-seq

There is an increased awareness that the use of animals for compound-induced developmental neurotoxicity (DNT) testing has limitations. Animal-free innovations, especially the ones based on human stem cell-based models are pivotal in studying DNT since they can mimic processes relevant to human brain development. Here we present the human neural progenitor test (hNPT), a 10-day protocol in which neural progenitor cells differentiate into a neuron-astrocyte co-culture. The study aimed to characterise differentiation over time and to find neurodevelopmental processes sensitive to compound exposure using transcriptomics. 3992 genes regulated in unexposed control cultures (p ≤ 0.001, log2FC ≥ 1) showed Gene Ontology (GO-) term enrichment for neuronal and glial differentiation, neurite extension, synaptogenesis, and synaptic transmission. Exposure to known or suspected DNT compounds (acrylamide, chlorpyrifos, fluoxetine, methyl mercury, or valproic acid) at concentrations resulting in 95% cell viability each regulated unique combinations of GO-terms relating to neural progenitor proliferation, neuronal and glial differentiation, axon development, synaptogenesis, synaptic transmission, and apoptosis. Investigation of the GO-terms 'neuron apoptotic process' and 'axon development' revealed common genes that were responsive across compounds, and might be used as biomarkers for DNT. The GO-term 'synaptic signalling', on the contrary, whilst also responsive to all compounds tested, showed little overlap in gene expression regulation patterns between the conditions. This GO-term may articulate compound-specific effects that may be relevant for revealing differences in mechanism of toxicity. Given its focus on neural progenitor cell to mature multilineage neuronal cell maturation and its detailed molecular readout based on gene expression analysis, hNPT might have added value as a tool for neurodevelopmental toxicity testing in vitro. Further assessment of DNT-specific biomarkers that represent these processes needs further studies.

Neuroprotection by melatonin against acrylamide-induced brain damage in pinealectomized rats

The current study aimed to evaluate the neuroprotective effect of exogenous melatonin against acrylamide (ACR)-induced oxidative stress and inflammatory and apoptotic responses in the brain tissues in pinealectomized rats (PINX). ACR is a toxic chemical carcinogen that occurs owing to the preparation of carbohydrate-rich foods at high temperatures or other thermal processes. The rats who underwent pinealectomy and sham pinealectomy were exposed to ACR (25 mg/kg b.w., orally) alone or with exogenous melatonin (10 mg/kg b.w., i.p.) for 21 consecutive days. Alterations of brain oxidant/antioxidant status, dopamine (DA), Brain-Derived Neurotropic Factor (BDNF) inflammatory mediator and apoptosis during exposure to ACR in pinealectomized rats were more than without pinealectomized rats. Histopathological changes were more in brain tissue of pinealectomized rats after ACR administration. Exogenous melatonin treatment in ACR -exposed rats following pinealectomy increased the activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) and improved brain total antioxidant status (TAS) compared to PINX+ACR. Moreover, melatonin suppressed lipid peroxidation, inflammatory pathways and apoptosis in ACR-intoxicated brain tissues. In addition, after exposure to ACR on pinealectomized rats, melatonin treatment ameliorated BDNF and DA levels in brain tissues. Furthermore, exogenous melatonin intervention in ACR-intoxicated rats significantly rescued the architecture of neuronal tissues. In summary, the present study, for the first time, suggested that exogenous melatonin treatment could reduce oxidative damage by increasing the activities of antioxidant enzymes, inhibiting lipid peroxidation and inflammation, and improving histopathological alterations in the brain tissue of pinealectomized rats after ACR administration.

The involvement of oxidative stress, neuronal lesions, neurotransmission impairment, and neuroinflammation in acrylamide-induced neurotoxicity in C57/BL6 mice

Acrylamide (ACR) is a typical environmental contaminant, presenting potential health hazards that have been attracting increasing attention. Its neurotoxicity is known to cause significant damage to health. However, the mechanisms of ACR-induced neurotoxicity require further clarification. This study uses a mouse model to explore how ACR-induced oxidative stress, neuronal lesions, neurotransmission impairment, and neuroinflammation mutually contribute to neurotoxicity. A distinct increase in the cellular reactive oxygen species (ROS) levels, malondialdehyde (MDA), and 8-hydroxy-2-deoxyguanosine (8-OHdG) content and a significant decrease in the glutathione (GSH) content after ACR exposure were indicative of oxidative stress. Moreover, ACR caused neurological defects associated with gait abnormality and neuronal loss while suppressing the acetylcholine (ACh) and dopamine (DA) levels and increasing the protein expression of α-synuclein (α-syn), further inhibiting cholinergic and dopaminergic neuronal function. Additionally, ACR treatment caused an inflammatory response via nuclear factor-kappa B (NF-κB) activation and increased the protein expression of NOD-like receptor protein-3 (NLRP3), consequently activating the NLRP3 inflammasome constituents, including cysteinyl aspartate specific proteinase 1 (Caspase-1), apoptosis-associated speck-like protein containing CARD (ASC), N domain gasdermin D (N-GSDMD), interleukin-1β (IL-1β), and IL-18. The results revealed the underlying molecular mechanism of ACR-induced neurotoxicity via oxidative stress, neurotransmission impairment, and neuroinflammation-related signal cascade. This information will further improve the development of an alternative pathway strategy for investigating the risk posed by ACR. The hypothetical mechanism of ACR-induced neurotoxicity in vivo.

Characterization of primary glutathione conjugates with acrylamide and glycidamide: Toxicokinetic studies in Sprague Dawley rats treated with acrylamide

Acrylamide (AA) is classified as a probable human carcinogen and is ubiquitous in foods processed at high temperatures. The carcinogenicity of AA has been attributed to its active metabolite, glycidamide (GA). Both AA and GA can spontaneously or enzymatically conjugate with glutathione (GSH) to form their corresponding GSH conjugates. Profiling AA-glutathione conjugate (AA-GSH) and GA-glutathione conjugates (2 isomers: GA2-GSH and GA3-GSH) in serum would better illustrate AA detoxification compared with urinary metabolite analysis. However, the lack of AA-, GA2, and GA3-GSH study remains a critical data gap. Our study aimed to investigate the toxicokinetics of AA-, GA2-and GA3-GSH in Sprague Dawley rats treated with 0.1 mg/kg, 1.0 mg/kg, or 5.0 mg/kg AA. Blood samples were collected for LC-MS/MS analysis of the GSH conjugate products. Within 24 h of treatment, we observed rapid formation, elimination, and linear kinetics of AA-, GA2-and GA3-GSH. The ∑GA-GSH AUC/AA-GSH AUC ratios were 0.14-0.29, similar to ∑GA/AA AUC in serum but different from ∑GA/AA-derived urinary mercapturic acids in rodents. Our analysis of AA- and GA-GSHs values represents direct detoxification of AA and GA in vivo. This study advances our understanding of sex and inter-species differences in AA detoxification and may refine the existing kinetic models for a more relevant risk extrapolation.

Investigation of nanoplastic cytotoxicity using SH-SY5Y human neuroblastoma cells and polystyrene nanoparticles

Nanoplastics have spread widely throughout not only the oceans but also the atmosphere, and recently created great concern about human health relevant to ingestion and accumulation of the nanoparticles by aquatic organisms in the human food-chain. However, how the nanoplastics have an affect on actual human body remains largely unknown, and in particular, little knowledge about nanoplastic exposure to the nervous system in human has been obtained in vitro and still less vivo. Here, we evaluated how much concentration of nanoplastics had a direct impact on cells in the nervous system as the fundamental information. Specifically, the cytotoxicity was investigated by exposure of polystyrene nanoparticles (PS) to cultured neural cells, human neuroblastoma cells, SH-SY5Y. Our results demonstrated that the PS exposure induced the cytotoxicity in the cells promoted differentiation into neuronal phenotype, and the adverse effect was comparable to or exceed that of acrylamide, a well-recognized potent neurotoxin. Also, the cells under PS exposure exhibited shrinkage of neurite outgrowth, morphology alteration and swelling of the nuclei, and spilling of intracellular components. Moreover, our findings indicate that the concentration of nanoplastics caused the cytotoxicity on neuronal cells is likely to be much higher than those predicted from the marine environment.

Special Issue on Toxicologic Neuropathology of the Peripheral Nervous System: A Special Compendium of Past, Present, and Future Developments in a Neglected Field

Neuropathology of the peripheral nervous system (PNS) is an underappreciated area in toxicologic pathology. Toxicity to nerves and ganglia can result from toxic insults following exposure to environmental, occupational, and industrial chemicals; drugs and biologics; cosmetics and food additives; and even physical agents such as noise. The following introduction provides an overview of this special issue of Toxicologic Pathology on toxicologic neuropathology of the PNS and highlights the range of key topics in this field that are reviewed in this compilation.

Developmental and Neurotoxicity of Acrylamide to Zebrafish

Acrylamide is a commonly used industrial chemical that is known to be neurotoxic to mammals. However, its developmental toxicity is rarely assessed in mammalian models because of the cost and complexity involved. We used zebrafish to assess the neurotoxicity, developmental and behavioral toxicity of acrylamide. At 6 h post fertilization, zebrafish embryos were exposed to four concentrations of acrylamide (10, 30, 100, or 300 mg/L) in a medium for 114 h. Acrylamide caused developmental toxicity characterized by yolk retention, scoliosis, swim bladder deficiency, and curvature of the body. Acrylamide also impaired locomotor activity, which was measured as swimming speed and distance traveled. In addition, treatment with 100 mg/L acrylamide shortened the width of the brain and spinal cord, indicating neuronal toxicity. In summary, acrylamide induces developmental toxicity and neurotoxicity in zebrafish. This can be used to study acrylamide neurotoxicity in a rapid and cost-efficient manner.

Acrylamide-induced peripheral neuropathy: manifestations, mechanisms, and potential treatment modalities

Acrylamide is a chemical monomer; its polymer compounds are used in the manufacture of plastic, papers, adhesive tapes, dyes, and food packaging. Lately, scientists found that cooking (mainly roasting, baking, and frying) yields acrylamide. In addition to fried/baked potatoes, coffee and bakery products still contain substantial amounts of acrylamide. Acrylamide has toxic effects on different body systems include genitourinary, reproductive, nervous system, along with being a carcinogenic substance. The neurotoxicity of acrylamide includes central and peripheral neuropathy. In humans, the clinical manifestations include sensory or motor peripheral neuropathy, drowsiness, or cerebellar ataxia. Likewise, it presents with skeletal muscle weakness, hindlimb dysfunction, ataxia, and weight loss in animals. The suggested mechanisms for acrylamide neurotoxicity include direct inhibition of neurotransmission, cellular changes, inhibition of key cellular enzymes, and bonding of kinesin-based fast axonal transport. Moreover, it is suggested that acrylamide's molecular effect on SNARE core kinetics is carried out through the adduction of NSF and/or SNARE proteins. Lately, scientists showed disruption of focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2) cell signaling pathways in human differentiating neuroblastoma SH-SY5Y cells, exposed to acrylamide. Different treatment modalities have been revealed to shield against or hasten recovery from acrylamide-induced neuropathy in preclinical studies, including phytochemical, biological, and vitamin-based compounds. Still, additional studies are needed to elucidate the pathogenesis and to identify the best treatment modality.

Acrylamide inhibits autophagy, induces apoptosis and alters cellular metabolic profiles

Acrylamide (ACR) is generated during thermal processing of carbohydrate-rich foods at high temperature and can directly enter the body through ingestion, inhalation and skin contact. The toxicity of ACR has been widely studied. The main results of these studies show that exposure to ACR can cause neurotoxicity in both animals and humans, and show reproductive toxicity and carcinogenicity in rodent animal models. However, the mechanism of toxicity of ACR has not been studied by metabolomics approaches, and the effect of ACR on autophagy remains unknown. Here, U₂OS cell were treated with ACR 6 and 24 h and collected for further study. We have demonstrated that ACR inhibited autophagic flux, and increased ROS content. Accumulation of ROS resulted in increase of apoptosis rates and secretion of inflammatory factors. In addition, significant differences in metabolic profiles were observed between ACR treated and control cells according to multiple analysis models. A total of 73 key differential metabolites were identified. They were involved in multiple metabolic pathways. Among them, exposure to ACR caused glycolysis/gluconeogenesis attenuation by decreasing levels of glycolytic intermediates, reduced the rate of the TCA cycle, while elevating levels of several amino acid metabolites and lipid metabolites. In summary, our study provides useful evidence of cytotoxicity caused by ACR via metabolomics and multiple bioanalytic methods.

Subchronic exposure to acrylamide caused behaviour disorders and related pathological and molecular changes in rat cerebellum

Acrylamide (ACR) is a neurotoxin with moderate acute toxicity. Significant level of ACR exists in diet and drinking water. Occupational exposure causes motor function impairment, but the underlying mechanisms remain poorly defined. This study aims to explore whether microtubule-associated protein tau phosphorylation, excessive activation of protein kinase RNA-like endoplasmic reticulum kinase (PERK) signaling pathway and BDNF decline are involved in cerebellar neuron lesions and motor dysfunction after subchronic ACR exposure. The present results displayed that ACR caused gait abnormality and hind foot splay in rats. The HE and Nissl staining results revealed that ACR exposure aggravated cerebellar neuron lesions especially in purkinje cell layer. ACR markedly increased tau phosphorylation at Ser262 and Ser396/404 and inhibited the level of phosphorylation of glycogen synthase kinase 3β (P-GSK3β) at Ser9. The PERK-eukaryotic initiation factor-2α (eIF2α)-activating transcription factor 4 (ATF4) pathway was activated to promote CHOP expression and then to accelerate neuron lesions. Furthermore, ACR significantly decreased P-CREB at Ser133 and BDNF expression, which might be related to the inhibition of upstream signals from extracellular signal-related kinase (ERK) and protein kinase B (Akt). This work helps to elucidate the underlying mechanisms of ACR-induced neurotoxicity and present a potential target for prevention against the neurotoxicity.

Brain-derived neurotrophic factor protects against acrylamide-induced neuronal and synaptic injury via the TrkB-MAPK-Erk1/2 pathway

Acrylamide has been shown to be neurotoxic. Brain-derived neurotrophic factor (BDNF) can alleviate acrylamide-induced synaptic injury; however, the underlying mechanism remains unclear. In this study, dibutyryl-cyclic adenosine monophosphate-induced mature human neuroblastoma (NB-1) cells were exposed with 0–100 μg/mL acrylamide for 24–72 hours. Acrylamide decreased cell viability and destroyed synapses. Exposure of co-cultured NB-1 cells and Schwann cells to 0–100 μg/mL acrylamide for 48 hours resulted in upregulated expression of synapsin I and BDNF, suggesting that Schwann cells can activate self-protection of neurons. Under co-culture conditions, activation of the downstream TrkB-MAPK-Erk1/2 pathway strengthened the protective effect. Exogenous BDNF can increase expression of TrkB, Erk1/2, and synapsin I, while exogenous BDNF or the TrkB inhibitor K252a could inhibit these changes. Taken together, Schwann cells may act through the BDNF-TrkB-MAPK-Erk1/2 signaling pathway, indicating that BDNF plays an important role in this process. Therefore, exogenous BDNF may be an effective treatment strategy for acrylamide-induced nerve injury. This study was approved by the Laboratory Animal Welfare and Ethics Committee of the National Institute of Occupational Health and Poison Control, a division of the Chinese Center for Disease Control and Prevention (approval No. EAWE-2017-008) on May 29, 2017.

Acute in vitro effects on embryonic rat dorsal root ganglion (DRG) cultures by in silico predicted neurotoxic chemicals: Evaluations on cytotoxicity, neurite length, and neurophysiology

The Hard-Soft Acid and Base hypothesis can be used to predict the potential bio-reactivity (electrophilicity) of a chemical with intracellular proteins, resulting in neurotoxicity. Twelve chemicals predicted to be neurotoxic were evaluated in vitro in rat dorsal root ganglia (DRG) for effects on cytotoxicity (%LDH), neuronal structure (total neurite length/neuron, NLPN), and neurophysiology (mean firing rate, MFR). DRGs were treated acutely on days in vitro (DIV) 7 (1-100 μM) with test chemical; %LDH and NLPN were measured after 48 h. 4-cyclohexylhexanone (4-C) increased %LDH release at 50 (29%) and 100 μM (56%), citronellal (Cit) and 1-bromopropane increased %LDH at 100 μM (22% and 26%). 4-C, Cit, 2,5 Hexanedione (2,5Hex), phenylacetylaldehyde (PAA) and 2-ethylhexanal decreased mean NLPN at 48 h; 50 and 100 μM for 4-C (28% and 60%), 100 μM Cit (52%), 100 μM 2,5- Hex (37%) 100 μM PAA (41%) and 100 μM for 2-ethylhexanal (23%). Separate DRG cultures were treated on DIV 14 and changes in MFR measured. Four compounds decreased MFR at 50 or 100 μM: Acrylamide (-83%), 3,4-dichloro-1-butene (-93%), 4-C (-89%) and hexane (-79%, 50 μM). Changes in MFR and NLPN occurred in absence of cytotoxicity. While the current study showed little cytotoxicity, it gave insight to initial changes in MFR. Results provide insight for future chronic exposure experiments to evaluate neurotoxicity.

Application of the hard and soft, acids and bases (HSAB) theory as a method to predict cumulative neurotoxicity

Xenobiotic electrophiles can form covalent adducts that may impair protein function, damage DNA, and may lead a range of adverse effects. Cumulative neurotoxicity is one adverse effect that has been linked to covalent protein binding as a Molecular Initiating Event (MIE). This paper describes a mechanistic in silico chemical screening approach for neurotoxicity based on Hard and Soft Acids and Bases (HSAB) theory. We evaluated the applicability of HSAB-based electrophilicity screening protocol for neurotoxicity on 19 positive and 19 negative reference chemicals. These reference chemicals were identified from the literature, using available information on mechanisms of neurotoxicity whenever possible. In silico screening was based on structural alerts for protein binding motifs and electrophilicity index in the range of known neurotoxicants. The approach demonstrated both a high positive prediction rate (82-90 %) and specificity (90 %). The overall sensitivity was relatively lower (47 %). However, when predicting the toxicity of chemicals known or suspected of acting via non-specific adduct formation mechanism, the HSAB approach identified 7/8 (sensitivity 88 %) of positive control chemicals correctly. Consequently, the HSAB-based screening is a promising approach of identifying possible neurotoxins with adduct formation molecular initiating events. While the approach must be expanded over time to capture a wider range of MIEs involved in neurotoxicity, the mechanistic nature of the screen allows users to flag chemicals for possible adduct formation MIEs. Thus, the HSAB based toxicity screening is a promising strategy for toxicity assessment and chemical prioritization in neurotoxicology and other health endpoints that involve adduct formation.

Acrylamide Induced Toxicity and the Propensity of Phytochemicals in Amelioration: A Review

Acrylamide is widely found in baked and fried foods, produced in large amount in industries and is a prime component in toxicity. This review highlights various toxicities that are induced due to acrylamide, its proposed mode of action including oxidative stress cascades and ameliorative mechanisms using phytochemicals. Acrylamide formation, the mechanism of toxicity and the studies on the role of oxidative stress and mitochondrial dysfunctions are elaborated in this paper. The various types of toxicities caused by Acrylamide and the modulation studies using phytochemicals that are carried out on various type of toxicity like neurotoxicity, hepatotoxicity, cardiotoxicity, immune system, and skeletal system, as well as embryos have been explored. Lacunae of studies include the need to explore methods for reducing the formation of acrylamide in food while cooking and also better modulators for alleviating the toxicity and associated dysfunctions along with identifying its molecular mechanisms.

A study of digital image analysis on the acrylamide derivative monomers induced apoptosis in rat cerebrum

Nowadays, apoptosis is mostly evaluated visually in histological studies. By using the quantitative digital image analysis, this study aimed to investigate the effect of acrylamide-based monomers (acrylamide [AAm], methacrylamide [MAAm], N-isopropylacrylamide [NIPAm]) on the cerebrum tissues in rats, which are the most common water-soluble monomers in the production of polymeric hydrogels used as biomaterials. The Wistar albino rats weighing ~220-240 g were divided into control and three test groups. The control group received 1 mL of saline, and the test groups received 1 mL of aqueous 50 mg/kg/day intramuscular injection of AAm, MAAm, and NIPAm, respectively. At the end of the experiments, brain tissues of all rats euthanized by intramuscular injection of sodium pentobarbital were removed. Terminal deoxynucleotide transferase dUTP nick and labeling (TUNEL) method was applied to brain tissue sections. The monomers have been shown to cause apoptosis due to oxidative stress in cerebrum tissue. Based on apoptosis by tunneling method, quantitative digital image analysis of cell fragments was performed with Olympus cellSens Dimension 1.15 software, and the number, total count area, selected area, average area, and ROI% values of the fragments were found. In addition, the total area and ROI% values of the fragments increased linearly with increasing the molar mass of monomers from the digital image analysis data. Quantitative digital image analysis can facilitate the monitoring of apoptosis caused by the oxidative stress of monomers used in the production of the biomaterials.

Role of Oxidative Stress, MAPKinase and Apoptosis Pathways in the Protective Effects of Thymoquinone Against Acrylamide-Induced Central Nervous System Toxicity in Rat

The present study evaluated biochemical endpoints characterizing acrylamide (ACR) neurotoxicity in the cortex of rats, following the possible neuroprotective activity of thymoquinone (TQ), an active constituent of Nigella sativa. ACR (50 mg/kg, intraperitoneal [i.p.]) concurrently with TQ (2.5, 5 and 10 mg/kg, i.p.) for 11 days were administered to rats. As positive control, vitamin E was used. After 11 days of injections, narrow beam test (NBT) was performed. The levels of reduced glutathione (GSH) and malondialdehyde (MDA) were measured and Western blotting was done for mitogen-activated protein kinases (MAPKinases) and apoptosis pathways proteins in the rats' cortex. Additionally, Evans blue assay was done to evaluate the integrity of blood brain barrier (BBB). Administration of ACR significantly induced gait abnormalities. A significant decrease and increase in the levels of GSH and MDA was observed in the cortex of ACR-treated rats, respectively. The elevation in the levels of caspases 3 and 9, glial fibrillary acidic protein (GFAP) content, and Bax/Bcl-2, P-P38/P38 and P-JNK/JNK ratios accompanied by reduction in myelin basic protein (MBP) content and P-ERK/ERK ratio were noticed in the ACR group. TQ (5 mg/kg) improved gait abnormalities, and restored these changes. ACR affected the integrity of BBB while TQ was able to maintain the integrity of this barrier. TQ reversed the alterations in the protein contents of MAP kinase and apoptosis signaling pathways as well as MBP and GFAP contents, induced by ACR. It protected against ACR-mediated neurotoxicity, partly through its antioxidant and antiapoptotic properties.

Sensitivity of glutathione S-transferases to high doses of acrylamide in albino wistar rats: Affinity purification, biochemical characterization and expression analysis

The main objectives of this study were to purify the glutathione S-transfereses (GSTs) and assess the effect of high doses of acrylamide (ACR) on male albino Wistar rat liver, kidney, testis and bran GST activities, and expression analysis of GST. ACR (50 mg/300 ml) was ingested for 40 days (20 doses) in drinking water on alternative days, on 40 day post ingestion the control and treated tissues were collected for GST purification by affinity column and biochemical characterization of GSTs by substrate specificities, and GST expression by immuno dot blots. In the analysis of the purified GSTs, we observed that liver GSTs were resolved in to three bands known as Yc, Yb and Ya; kidney GSTs were resolved in to two bands known as Yc and Ya; testis and brain GSTs were resolved as four bands known as Yc, Yb, Yβ and Yδ on 12.5% sodium dodecyl sulfate polyacrylamide gel (SDS PAGE). In the analysis of biochemical characterization, we observed a significant decrease (p < 0.05) in the specific activities of liver GST isoforms with the substrates 1-chloro 2,4-dinitrobenzene (CDNB), bromosulfophthalein (BSP), p-nitrophenyl acetate (pNPA), p-nitrobenzyl chloride (pNBC) and cumene hydroperoxide (CHP), but showed no activity with ethacrynic acid (ECA) and significant decrease (p < 0.05) in the specific activities of kidney GST isoforms with the substrates CDNB, pNPA, pNBC and CHP, but showed no activity with BSP and ECA, and a significant decrease (p < 0.05) in the specific activities of testis and brain GST isoforms with the substrates CDNB, BSP, pNPA, pNBC, ECA and CHP. In the analysis of immuno dot blots, we observed a decreased expression of liver, kidney, testis and brain GSTs. Through the affinity purification and biochemical characterization, we observed a tissue specific distribution of GSTs that is liver GSTs possess Yc, Yb and Ya sub units known as alpha (α) and mu (μ) class GSTs; kidney GSTs possess Yc and Ya sub units known as (α) alpha class GST; testis and brain GSTs possess Yc, Yb, Yβ and Yδ sub units known as alpha (α), mu (μ) and pi (π) class GSTs. Purification studies, biochemical characterization and immuno dot blot analysis were revealed the GSTs were sensitive to high doses of ACR and the high level exposure to ACR cause the damage of detoxification function of GST due to decreased expression and hence lead to cellular dysfunction of vital organs.

Mechanisms of soft and hard electrophile toxicities

Electron-deficient chemicals (electrophiles) react with compounds that have one or more unshared valence electron pairs (nucleophiles). The resulting covalent reactions between electrophiles and nucleophiles (e.g., Michael addition, SN2 reactions) are important, not only to Organic Chemistry, but also to the fields of Molecular Biology and Toxicology. Specifically, covalent bond formation is the operational basis of many critically important cellular processes; e.g., enzyme function, neurotransmitter release, and membrane-vesicle fusion. Given this context it is understandable that these reactions are also relevant to Toxicology, since a significant number of xenobiotic chemicals are toxic electrophiles that can react with endogenous nucleophilic residues. Therefore, the purpose of this Review is to discuss electrophile-nucleophile chemistry as it pertains to cell injury and resulting organ toxicity. Our discussion will involve an introduction to the Hard and Soft, Acids and Bases (HSAB) theory of Pearson. The HSAB concept provides a framework for calculation of quantum chemical parameters that classify the electrophile and nucleophile covalent components according to their respective electronic nature (softness/hardness) and reactivity (electrophilicity/nucleophilicity). The calculated quantum indices in conjunction with corroborative in vivo, in chemico (cell free) and in vitro research can offer an illuminating approach to mechanistic discovery. Accordingly, we will provide examples that demonstrate how this approach has been used to discern mechanisms and sites of electrophile action.

Gestational exposure to acrylamide inhibits mouse placental development in vivo

Acrylamide, a carcinogen and neurotoxic substance, recently has been discovered in various heat-treated carbohydrate-rich foods. The aim of this study was to investigate the effects of acrylamide exposure on placental development. Pregnant mice received acrylamide by gavage at dosages of 0, 10, and 50 mg/kg/day from gestational days (GD) 3 until GD 8 or GD 13. The results showed that acrylamide feeding significantly decreased the numbers of viable embryos and increased the numbers of resorbed embryos on GD 13. Acrylamide exposure reduced the absolute and relative weight of placentas and embryos, and inhibited the development of ectoplacental cone (EPC) and placenta, as shown by the atrophy of EPC and reduced placental area. Acrylamide markedly reduced the numbers of labyrinth vessels. Expression levels of most placental key genes such as Esx1, Hand1, and Hand2 mRNA dramatically decreased in acrylamide-treated placentas. Furthermore, acrylamide treatment inhibited proliferation and induced apoptosis of placentas, as shown by decreased Ki67-positive cells and Bcl-2 protein, and increased the expression of Bax, cleaved-caspase-3, and cleaved-caspase-8 proteins. In conclusion, our results indicated that gestational exposure to acrylamide inhibits placental development through dysregulation of placental key gene expression and labyrinth vessels, suppression of proliferation, and apoptosis induction in mice.

Glutathione S-transferase is a good biomarker in acrylamide induced neurotoxicity and genotoxicity

Glutathione S-transferases (GSTs) are major defence enzymes of the antioxidant enzymatic system. Cytosolic GSTs are more involved in the detoxification than mitochondrial and microsomal GSTs. GSTs are localized in the cerebellum and hippocampus of the rat brain. Acrylamide (AC) is a well assessed neurotoxin of both animals and humans and it produces skeletal muscle weakness and ataxia. AC is extensively used in several industries such as cosmetic, paper, textile, in ore processing, as soil conditioners, flocculants for waste water treatment and it is present in daily consumed food products, like potato chips, French fries, bread, breakfast cereals and beverages like coffee; it is detected on tobacco smoking. GST acts as a biomarker in response to acrylamide. AC can interact with DNA and therefore generate mutations. In rats, low level expression of glutathione S-trasferase (GST) decreases both memory and life span. The major aim of this review is to provide better information on the antioxidant role of GST against AC induced neurotoxicity and genotoxicity.

Acrylamide Production in Autoclaved Rodent Feed

Sterilization of rodent feed by steam autoclaving is a common practice in many research institutions. Often we only considerthe beneficial effects of this process-the reduction of microbial contamination-and forget that the high temperatures andpressures can have negative effects on diet quality. The purpose of our study was to assess both the physical and chemicalchanges to a standard rodent feed autoclaved at multiple sterilization temperatures and the effects of the treated diets on mice. Pelleted NIH31 rodent feed was autoclaved at 4 sterilization temperatures (230, 250, 260, and 270 °F). Feed pellet hardness and the acrylamide concentrations of the diets were tested and compared with irradiated NIH31 feed. Study diets were fed to mice for 28 d, after which tissue samples were collected for analysis of acrylamide, glycidamide (the active metabolite of acrylamide), and genotoxicity. Both feed pellet hardness and acrylamide concentration increased with increasing sterilization temperatures; however, neither affected feed intake or body weight gain. Plasma acrylamide and glycidamide weresignificantly elevated only in mice fed NIH31 diet autoclaved at 270 °F compared with the irradiated feed, whereas urineacrylamide and glycidamide metabolites were significantly elevated in most autoclaved diets. Liver DNA adducts, whichcorrelate with genotoxicity, were significantly elevated in all autoclaved diets compared with the irradiated diet. Institutionsthat autoclave their animal diets should carefully consider the temperatures necessary to achieve feed sterilization and thetype of studies in which these autoclaved diets are used.

Acrylamide Defects the Expression Pattern of the Circadian Clock and Mitochondrial Dynamics in C57BL/6J Mice Liver and HepG2 Cells

Circadian rhythm helps organisms adapt to their environment and control a variety of physiological and metabolic processes. Acrylamide is a toxic compound that can be produced during food processing. The aim of this research is to investigate whether the circadian clock is involved in the toxicity mechanisms of acrylamide in mice liver. Our results revealed that acrylamide markedly induced circadian gene oscillation disorder and blocked circadian-related protein in mice liver and HepG2 cells. Simultaneously, the balance of the daily oscillation of the antioxidant enzymes was impeded under acrylamide treatment. Furthermore, acrylamide treatment elevated the mitochondrial dynamic gene expressions and influenced the mitochondrial morphology at the night phase. Acrylamide blocked circadian protein expression via repressing the phosphorylation of AKT or inducing oxidative stress. Taken together, our work reveals acrylamide as a clock-repressing compound generated through the Maillard browning reaction in certain foods that may possess a toxic effect via circadian clock mechanisms.

Therapeutic activity of sour orange albedo extract and abundant flavanones loaded silica nanoparticles against acrylamide-induced hepatotoxicity

The current research aims to demonstrate the therapeutic effect of sour orange albedo extract (SOAE) and two flavanones loaded-tetraethylorthosilicate (TEOS) using sol-gel technique, in adose100 mg/kg body weight taken orally or45 days against acrylamide (ACR)toxicity in rats. This was achieved through measuring the activities of specific biochemical parameters related to liver functions in tissue of ACR intoxicated rats as compared to normal one. Liver functions included alanine and aspartate aminotransferases, antioxidants and oxidative stress biomarkers; superoxide dismutase, catalase, glutathione and lipid peroxide (malondialdehyde, MDA). Moreover, histological examination of liver was performed to confirm the biochemical findings. The present results clearly indicated disturbances in all biochemical parameters, such as increase in the liver function enzyme activities and MDA level. Results of ATPase enzyme activities revealed significant decrease in ACR intoxicated rats and liver biomarker enzymes declared significant decrease. On the other hand, treatment of intoxicated rats with the previous different nano-particles natural product demonstrated improvement in all biochemical parameters under investigation.

Acrylamide acute neurotoxicity in adult zebrafish

Acute exposure to acrylamide (ACR), a type-2 alkene, may lead to a ataxia, skeletal muscles weakness and numbness of the extremities in human and laboratory animals. In the present manuscript, ACR acute neurotoxicity has been characterized in adult zebrafish, a vertebrate model increasingly used in human neuropharmacology and toxicology research. At behavioral level, ACR-treated animals exhibited “depression-like” phenotype comorbid with anxiety behavior. At transcriptional level, ACR induced down-regulation of regeneration-associated genes and up-regulation of oligodendrocytes and reactive astrocytes markers, altering also the expression of genes involved in the presynaptic vesicle cycling. ACR induced also significant changes in zebrafish brain proteome and formed adducts with selected cysteine residues of specific proteins, some of them essential for the presynaptic function. Finally, the metabolomics analysis shows a depletion in the monoamine neurotransmitters, consistent with the comorbid depression and anxiety disorder, in the brain of the exposed fish.

Metabonomic analysis of toxic action of long-term low-level exposure to acrylamide in rat serum

This study assessed the effects of long-term, low-dose acrylamide (AA) administration in rats using ultra-performance liquid chromatography–mass spectrometry. Forty male Wistar rats were randomly divided into the following four groups: control, low-dose AA (0.2 mg/kg BW), middle-dose AA (1 mg/kg BW), and high-dose AA (5 mg/kg BW). AA was administered to rats via drinking water ad libitum. After 16-week treatment, rat serum was collected for metabonomic analysis. Biochemical tests were further conducted to verify metabolic alterations. Eleven metabolites were identified with significant changes in intensities (increased or reduced) as a result of treatment. These metabolites included citric acid, pantothenic acid, isobutyryl-l-carnitine, eicosapentaenoic acid, docosahexaenoic acid, sphingosine 1-phosphate, LysoPC(20:4), LysoPC(22:6), LysoPE(20:3), undecanedioic acid, and dodecanedioic acid. Results indicate that chronic exposure to AA at no observed adverse effect level does not exert a toxic effect on rats at the body metabolism level. AA disturbed the metabolism of lipids and energy, affected the nervous system of rats, and induced oxidative stress and liver dysfunction.

Histological and Ultrastructure Study of the Testes of Acrylamide Exposed Adult Male Albino Rat and Evaluation of the Possible Protective Effect of Vitamin E Intake

Acrylamide (AA) is a hazardous unavoidable gonadal toxin. Hence, the aim of this study is to clarify its harmful effects on the testis of adult albino rat by light and electron microscope and to evaluate the possible role of Vitamin E (Vit E) in the prevention of such effects. Thirty-five adult male albino rats were enrolled in this study. They were divided into three groups: Group I (control); Group II (AA exposed), and Group III (AA and concomitant Vit E treated group). Animals of Groups II and III were further subdivided into two equal subgroups (each subgroup included five rats): (a) rats were sacrificed after 4 weeks and (b) rats were sacrificed after 6 weeks. The testes of each rat were dissected out, processed, and examined by Hematoxylin and Eosin, Periodic acid-Schiff and Mallory's trichrome stains as well as electron microscopic study. The study revealed that AA induces testicular damage at the histological and ultrastructural level in the form of degeneration and arrested spermatogenesis. Moreover, decreased seminiferous tubules diameters and epithelial height were detected. These changes are maximally improved in Vit E treated group. Hence, we could conclude that AA causes degenerative changes of the testes of albino rats and arrest of spermatogenesis. The AA-induced histological and ultrastructural changes of the testes could be explained by oxidative stress. These effects changes are proportional to the duration of exposure. Moreover, it could be concluded that Vitamin E has a protective role against AA-induced testicular damage by its antioxidant and anti-apoptotic effects.

Modelling acrylamide acute neurotoxicity in zebrafish larvae

Acrylamide (ACR), a type-2 alkene, may lead to a synaptopathy characterized by ataxia, skeletal muscles weakness and numbness of the extremities in exposed human and laboratory animals. Currently, only the mildly affected patients undergo complete recovery, and identification of new molecules with therapeutic bioactivity against ACR acute neurotoxicity is urgently needed. Here, we have generated a zebrafish model for ACR neurotoxicity by exposing 5 days post-fertilization zebrafish larvae to 1 mM ACR for 3 days. Our results show that zebrafish mimics most of the pathophysiological processes described in humans and mammalian models. Motor function was altered, and specific effects were found on the presynaptic nerve terminals at the neuromuscular junction level, but not on the axonal tracts or myelin sheath integrity. Transcriptional markers of proteins involved in synaptic vesicle cycle were selectively altered, and the proteomic analysis showed that ACR-adducts were formed on cysteine residues of some synaptic proteins. Finally, analysis of neurotransmitters profile showed a significant effect on cholinergic and dopaminergic systems. These data support the suitability of the developed zebrafish model for screening of molecules with therapeutic value against this toxic neuropathy.

Protective effect of 5, 7-dihydroxyflavone on brain of rats exposed to acrylamide or γ-radiation

5, 7-Dihydroxyflavone (DHF), a natural plant flavonoid, have shown a variety of beneficial effects. Neurotoxic effects of acrylamide (ACR) or gamma irradiation (IR) have been established in humans and animals. The current study was designed to evaluate whether DHF could restrain ACR or IR induced neurotoxicity in rats and to explore the underlying mechanisms. The study was carried out by investigating some biochemical and biophysical parameters as well as histopathological examination. The daily oral administration of ACR (25mg/kg b.wt.) for 21days or exposure to single dose of IR (5Gy) induced brain damage throughout the significant decrease in catecholamine contents and brain derived neurotrophic factor (BDNF) in brain tissue with a concomitant significant decrease in serum activity of creatinine kinase-BB. Moreover, the brain levels of MDA and β-amyloid and activities of acetylcholinesterase and caspase-3 were remarkably augmented in ACR-induced rats. Additionally, the electrical properties of erythrocytes membrane were significantly disturbed. The administration of DHF (50mg/kg b.wt. daily for 21day) to rats exposed to either ACR or IR significantly reversed the alteration in all studied parameters. Histopathological investigation of brain tissues supported the neuroprotective effect of DHF on brain. From the obtained data, it can be concluded that the DHF has neuroprotective effect against ACR or IR induced-neurotoxicity.

Inhibitory effects of Japanese horseradish (Wasabia japonica) on the formation and genotoxicity of a potent carcinogen, acrylamide

BACKGROUND

The formation of acrylamide (AA) in cooked foods has raised human health concerns. AA is metabolized by cytochrome P450 2E1 (CYP2E1) to glycidamide (GA), which forms DNA adducts. This study examined the inhibitory effects of wasabi (Japanese horseradish, Wasabia japonica) roots and leaves as well as their active component, allyl isothiocyanate (AIT), on the formation and genotoxicity of AA.

RESULTS

AA formation (51.8 ± 4.2 µg kg^-1 ) was inhibited with ≥2 mg mL^-1 of AIT. Wasabi roots also inhibited AA formation (∼90% reduction), but wasabi leaves were not effective at 2 mg mL^-1 . Wasabi roots and leaves decreased the number of cells with micronuclei by approximately 33 and 24% respectively compared with the AA treatment group. Moreover, wasabi roots and leaves (100 mg kg^-1 body weight (BW) day^-1 for each) decreased AA (100 mg kg^-1 BW day^-1 )-induced DNA damage. The AA-induced CYP2E1 activity was decreased by 39 and 26% with wasabi roots and leaves respectively. Further, the activity of glutathione S-transferase, which catalyzes the detoxification of AA via glutathione conjugation, increased by 54 and 33% with wasabi roots and leaves respectively.

CONCLUSION

These results indicate that wasabi roots and leaves are effective ingredients for inhibiting the formation and genotoxicity of AA. © 2016 Society of Chemical Industry.

Acrylamide Retards the Slow Axonal Transport of Neurofilaments in Rat Cultured Dorsal Root Ganglia Neurons and the Corresponding Mechanisms

Chronic acrylamide (ACR) exposure induces peripheral-central axonopathy in occupational workers and laboratory animals, but the underlying mechanisms remain unclear. In this study, we first investigated the effects of ACR on slow axonal transport of neurofilaments in cultured rat dorsal root ganglia (DRG) neurons through live-cell imaging approach. Then for the underlying mechanisms exploration, the protein level of neurofilament subunits, motor proteins kinesin and dynein, and dynamitin subunit of dynactin in DRG neurons were assessed by western blotting and the concentrations of ATP was detected using ATP Assay Kit. The results showed that ACR treatment results in a dose-dependent decrease of slow axonal transport of neurofilaments. Furthermore, ACR intoxication significantly increases the protein levels of the three neurofilament subunits (NF-L, NF-M, NF-H), kinesin, dynein, and dynamitin subunit of dynactin in DRG neurons. In addition, ATP level decreased significantly in ACR-treated DRG neurons. Our findings indicate that ACR exposure retards slow axonal transport of NF-M, and suggest that the increase of neurofilament cargoes, motor proteins, dynamitin of dynactin, and the inadequate ATP supply contribute to the ACR-induced retardation of slow axonal transport.

Acrylamide alters glycogen content and enzyme activities in the liver of juvenile rat

Acrylamide (AA) is spontaneously formed in carbohydrate-rich food during high-temperature processing. It is neurotoxic and potentially cancer causing chemical. Its harmful effects on the liver, especially in a young organism, are still to be elucidated. The study aimed to examine main liver histology, its glycogen content and enzyme activities in juvenile rats treated with 25 or 50mg/kg bw of AA for 3 weeks. Liver samples were fixed in formalin, routinely processed for paraffin embedding, sectioning and histochemical staining. Examination of haematoxylin and eosin (H&E)-stained sections showed an increase in the volume of hepatocytes, their nuclei and cytoplasm in both AA-treated groups compared to the control. In Periodic acid-Schiff (PAS)-stained sections in low-dose group was noticed glycogen reduction, while in high-dose group was present its accumulation compared to the control, respectively. Serum analysis showed increased activity of aspartate aminotransferase (AST), and decreased activity of alanine aminotransferase (ALT) in both AA-treated groups, while the activity of alkaline phosphatase (ALP) was increased in low-dose, but decreased in high-dose group compared to the control, respectively. Present results suggest a prominent hepatotoxic potential of AA which might alter the microstructural features and functional status in hepatocytes of immature liver.

The effect of lipoic acid on acrylamide-induced neuropathy in rats with reference to biochemical, hematological, and behavioral alterations

CONTEXT

Acrylamide (ACR) is a well-known neurotoxicant and carcinogenic agent which poses a greater risk for human and animal health.

OBJECTIVE

The present study evaluates the beneficial effects of α-lipoic acid (LA) on ACR-induced neuropathy.

MATERIALS AND METHODS

A total of 40 male rats were divided into four groups: a placebo group; LA-treated group, administered orally 1% (w/w) LA mixed with diet; ACR-treated group, given 0.05% (w/v) ACR dissolved in drinking water; and LA + ACR-treated group, given LA 1% 7 d before and along with ACR 0.05% for 21 d. After 28 d, blood samples were collected, the rats were decapitated, and the tissues were excised for the measurement of brain biomarkers, antioxidant status, and hematological analysis. Also, the gait score of rats was evaluated.

RESULTS

ACR-exposed rats exhibited abnormal gait deficits with significant (p < 0.05) decline in acetylcholine esterase (AChE) and creatine kinase in serum and brain tissues, respectively. However, the lactate dehydrogenase activity was increased in serum by 123%, although it decreased in brain tissues by -74%. ACR significantly (p < 0.05) increased the malondialdehyde level by 273% with subsequent depletion of glutathione S-transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GR) activities and reduced the glutathione (GSH) level in brain tissue. Interestingly, LA significantly (p < 0.05) improved brain enzymatic biomarkers, attenuated lipid peroxidation (LPO), and increased antioxidant activities compared with the ACR-treated group.

DISCUSSION AND CONCLUSION

These results suggested that LA may have a role in the management of ACR-induced oxidative stress in brain tissues through its antioxidant activity, attenuation of LPO, and improvement of brain biomarkers.

The impact of vitamin E against acrylamide induced toxicity on skeletal muscles of adult male albino rat tongue: Light and electron microscopic study

Acrylamide, one of the major environmental public health problems, results from its increased accumulation in the process of cooking food materials. This study aimed to demonstrate the light and electron microscopic structural effects of acrylamide on the skeletal muscle fibers of adult male albino rat tongue and to investigate the possible protective effect of vitamin E co-administration. Thirty adult male albino Sprague-Dawley rats were divided into 3 groups, each group included 10 rats. Group I (control), group II which was subdivided into two equal subgroups: subgroup IIa: included 5 rats that received acrylamide orally once daily for 20 days. Subgroup IIb: included 5 rats that received acrylamide orally once daily for 40 days. Group III was also subdivided into two equal subgroups: subgroup IIIa: included 5 rats that received acrylamide and vitamin E orally once daily for 20 days. Subgroup IIIb: included 5 rats that received acrylamide and vitamin E orally once daily for 40 days. At the end of the experiment the tongue was dissected out for histological and electron microscopic studies, another muscle sample was homogenized and processed for biochemical estimation of malondialdehyde (MDA) and total antioxidant capacity (TAC). Light microscopic study of tongue skeletal muscles in acrylamide exposed animals revealed abnormal wavy course and splitting of the muscle fibers with fatty infiltration in between. Moreover, pyknosis and remnants of nuclei were detected. EM revealed marked aggregation of mitochondria of different size and shape with giant cells formation, and partial loss of myofilaments. There were statistically significant increase in MDA and decrease in TAC indicating oxidative stress in acrylamide administrated groups (group II) than the control group which increased by prolonged duration (subgroup IIb versus subgroup IIa, p < 0.0001). This oxidative stress could explain the histological changes in tongue muscles of acrylamide exposed rats. Co-administration of vitamin E with acrylamide ameliorated most of the above mentioned histological changes in the animals used and signs of improvement that became better with prolonged administration of it (subgroup IIIb versus subgroup IIIa, p < 0.0001) were detected. It could be concluded that, chronic exposure to acrylamide might lead to skeletal muscle damage in rat tongue which becomes worth with prolonged duration of exposure. Acrylamide induced oxidative stress is the implicated mechanism of such histological changes. This toxic effect of acrylamide could be minimized when vitamin E is given concomitantly with it by its antioxidant effect.

Hazardous effects of fried potato chips on the development of retina in albino rats

OBJECTIVE

To evaluate the hazardous effects of fried potato chips upon the retina of two developmental stages of the albino rats aged 7 and 14 days from parturition.

METHODS

PREGNANT RATS WERE ARRANGED INTO TWO GROUPS: control pregnant rats and consequently their delivered newborns until reaching 7 and 14 days old from parturition and fried potato chips group in which pregnant rats at the 6th day of gestation maintained on diet formed of fried potato chips supplied from the market mixed with standard diet at a concentration of 50% per each till 7 and 14 post-partum. Three fold integrated approaches were adopted, namely, histological, ultrastructural and proteomic analysis.

RESULTS

Histological examination of the retina of the experimental offsprings revealed many histopathological changes, including massive degeneration, vacuolization and cell loss in the ganglion cell layer, as well as general reduction in retinal size. At the ultrastructural level, the retina of experimental offsprings exhibited number of deformities, including ill differentiated and degenerated nuclear layer, malformed and vacuolated pigment epithelium with vesiculated and fragmented rough endoplasmic reticulum, degenerated outer segment of photoreceptors, as well as swollen choriocapillaris and loss of neuronal cells. Proteomic analysis of retina of the two experimental developmental stages showed variations in the expressed proteins as a result of intoxication which illustrated the adverse toxic effects of fried potato chips upon the retina.

CONCLUSIONS

It can be concluded that the effect of fried potato chips on the development of retina in rats may be due to the presence of acrylamide or its metabolite.