The Changing View of Acrylamide Neurotoxicity

Application of Polysaccharide Biopolymer in Petroleum Recovery

Polysaccharide biopolymers are biomacromolecules derived from renewable resources with versatile functions including thickening, crosslinking, adsorption, etc. Possessing high efficiency and low cost, they have brought wide applications in all phases of petroleum recovery, from well drilling to wastewater treatment. The biopolymers are generally utilized as additives of fluids or plugging agents, to correct the fluid properties that affect the performance and cost of petroleum recovery. This review focuses on both the characteristics of biopolymers and their utilization in the petroleum recovery process. Research on the synthesis and characterization of polymers, as well as controlling their structures through modification, aims to develop novel recipes of biopolymer treatment with new application realms. The influences of biopolymer in many petroleum recovery cases were also evaluated to permit establishing the correlations between their physicochemical properties and performances. As their performance is heavily affected by the local environment, screening and testing polymers under controlled conditions is the necessary step to guarantee the efficiency and safety of biopolymer treatments.

Effect of Acrylamide Supplementation on the CART-, VAChT-, and nNOS-Immunoreactive Nervous Structures in the Porcine Stomach

Acrylamide is found in food products manufactured with high-temperature processing, and exposure to acrylamide contained in food products may cause a potential risk to human health. The aim of this investigation was to demonstrate the changes in the population of CART-, nNOS-, and VAChT-immunoreactive enteric neurons in the porcine stomach in response to supplementation of low and high acrylamide doses. The study was carried out with 15 Danish landrace gilts divided into three experimental groups: the control group-animals were administered empty gelatine capsules; the low-dose group-animals were administrated a tolerable daily intake (TDI) dose (0.5 µg/kg of body weight (b.w.)/day) of acrylamide capsules, and the high-dose group-animals were administrated high-dose (ten times higher than TDI: 5 µg/kg b.w./day) acrylamide capsules for 28 days. Using the double immunofluorescence staining method, it was established that supplementation with low and high doses of acrylamide resulted in alterations of the porcine stomach neuron phenotype, which was reflected in an increased number of CART-, VAChT-, and nNOS-immunoreactive neurons. These changes were accompanied by an increased density of CART-, VAChT-, and nNOS-positive fibres. The results suggest that the enteric nervous system plays an important role in protecting the gastrointestinal tract during acrylamide intoxication.

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.

Apoptosis and astrogliosis perturbations and expression of regulatory inflammatory factors and neurotransmitters in acrylamide-induced neurotoxicity under ω3 fatty acids protection in rats

This study was aimed to investigate the potential ameliorative effects of omega-3 (ω3) fatty acids against acrylamide (ACR)-induced neurotoxicity. Thirty-two adult male Sprague Dawley rats were randomly assigned into four groups (n = 8) as follows: control, ω3 fatty acids (1000 mg/kg bwt/day orally), ACR-treated (50 mg/kg bwt/day IP) and ACR plus ω3 fatty acids group. Treatments were performed every other day for 21 consecutive days. ACR induced abnormal gait and elevated serum levels of proinflammatory cytokines (IL-6 and TNF-α), brain and spinal cord MDA levels and decreased brain and spinal cord GSH levels. Moreover, it reduced neurotransmitters (acetylcholine, GABA, serotonin and noradrenaline levels) and increased AChE activity in brain tissues. Histopathologically, ACR caused various degenerative changes, necrosis and glial cell activation in the cerebrum, cerebellum, hippocampus, spinal cord and sciatic nerve. Likewise, the histomorphometric analysis was constant with ACR-induced neurotoxicity. The ACR induced axonal atrophy and myelin disruption and decreased g-ratio of the sciatic nerve. Immunohistochemically, strong positive expressions of apoptotic marker caspase-3 and astroglial GFAP in the examined tissues were detected. Contrariwise, concurrent administration of ω3 fatty acids partially attenuated ACR impacts, as it improved the gait performance, reduced oxidative stress and pro-inflammatory cytokines, and modulate the levels of the neurotransmitters. It also ameliorated the intensity of ACR-induced histopathological and histomorphometric alterations within the examined nervous tissues. It could be concluded that ω3 fatty acids have antioxidant, anti-inflammatory and anti-apoptotic potentials against ACR neurotoxicity via suppression of oxidative stress, lipid peroxidation and pro-inflammatory cytokines, and inhibition of AChE activity and downregulation of caspase-3 and GFAP expressions in the nervous tissues.

Xanthan gum and Locust bean gum gel supports in vitro development of porcine oocytes derived from early antral follicles

Early antral follicle (EAF)-derived porcine oocytes develop more readily on polyacrylamide-gel (PAG) than on plastic plates. Xanthan gum (XG) and locust bean gum (LBG) are edible polysaccharides. We investigated XG-LBG gel supports in the development of EAF-derived porcine oocytes. XG and LBG were mixed in a 1:1 ratio to form a substrate. We cultured oocyte granulosa cell complexes (OGCs) from the EAFs on XG-LBG gels of various concentrations. The oocyte diameters were comparable among the 0.3, 0.5, and 1.0% gels; granulosa cell proliferation was greater on the 1.0% gel. The proliferation and survival rates of the granulosa cells, and the histone H4 at lysine 12 acetylation levels were higher in OGCs cultured on 1.0% XG-LBG than those grown on 0.3% PAG. Development to the blastocyst stage was 13.8% for the XG-LBG gels and 9.4% for PAG. In conclusion, XG-LBG are safe and efficient substrates for in vitro culture of oocytes.

Redox status and fatty acid composition of Mactra corallina digestive gland following exposure to acrylamide

Acrylamide (ACR), a ubiquitous agent, has various chemical and industrial applications, and it is found in backed or fried carbohydrate-rich food. It has been related to multiple toxicological effects, and it causes high cytotoxicity through oxidative stress. The present study aimed to investigate the potential effect of ACR toxicity administered at different concentrations (5, 10, and 20 mg/L), during 5 days, in order to evaluate the fatty acid (FA) composition and redox state in the digestive gland of Mactra corallina. The results showed, in ACR-treated clams, a significant increase in malondialdehyde, hydrogen peroxide, protein carbonyl, and metallothionein levels, as well as an alteration of the enzymatic (superoxide dismutase, glutathione peroxidase, and catalase) and non-enzymatic (reduced glutathione and ascorbic acid) antioxidant status. However, acetylcholinesterase activity was inhibited in a concentration-dependent manner. In our experiment, the n-3 (Omega-3) and n-6 (Omega-6) polyunsaturated fatty acid levels were significantly changed in all ACR-treated groups. A decrease in eicosapentaenoic acid (C20:5n-3, EPA) and docosahexaenoic acid (C22:6n-3, DHA) was observed in 10-mg/L and 20-mg/L ACR-treated groups. Nevertheless, arachidonic acid (C20:4n-6, ARA) and its precursor linoleic acid (C18:2n-6, LA) were increased. Besides oxidative stress parameters, FA composition may be an additional tool for assessing ACR contamination.

Straightforward and rapid determination of acrylamide in coffee beans by means of HS-SPME/GC-MS

A straightforward and rapid preparation procedure for the extraction of the acrylamide from coffee beans, by means of the volatile silylated derivatives of acrylamide (AA) and headspace solid phase microextraction (HS-SPME) is described. Commercially available SPME fibre coated with polydimethylsiloxane (PDMS) was used. The silylation reactions of the AA were executed with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). The deuterium labelled d₃-acrylamide was used as an internal standard. The acrylamide level was quantified using gas chromatography coupled with the mass spectrometry (GC-MS) in the selected ion monitoring (SIM) mode. The limit of quantification (LOQ) for measuring acrylamide was 3 µg/kg. The described method demonstrates satisfactory repeatability (RSD = 2.6%), with an intermediate precision (RSD = 9.4%) and recovery (99-105%).

The impact of low and high doses of acrylamide on the intramural neurons of the porcine ileum

The present study was designed to assess the influence of acrylamide supplementation, in tolerable daily intake (TDI) dose and a dose ten times higher than TDI, on the neurochemical phenotype of the ENS neurons and synthesis of proinflammatory cytokines in the wall of the porcine ileum. The study was performed on 15 juvenile female Danish Landrace pigs, divided into three groups: C group- animals receiving empty gelatine capsules, LD group- animals receiving capsules with the TDI dose (0.5 μg/kg b.w./day) of acrylamide and HD group- animals receiving acrylamide in a dose ten times higher than the TDI (5 μg/kg b.w./day) in a morning meal for 28 days. It was established that supplementation of acrylamide led to an increase in substance P (SP)-, calcitonin gene-related peptide (CGRP)-, galanin (GAL)- and vesicular acetylcholine transporter (VAChT)-like immunoreactive (LI) neurons as well as a decrease in neuronal nitric oxide synthase (nNOS) -like immunoreactivity in all types of ileum intramural plexuses. Moreover, using ELISA method, an increase in the level of proinflammatory cytokines (IL-1β, IL-6 and TNF- α) was noted in the ileum wall. The results suggest that SP, CGRP, GAL, nNOS and VACHT participate in the regulation of inflammatory conditions induced by acrylamide supplementation.

Role of microglial activation and neuroinflammation in neurotoxicity of acrylamide in vivo and in vitro

Acrylamide, a soft electrophile, is widely used in the industry and laboratories, and also contaminates certain foods. Neurotoxicity and neurodegenerative effects of acrylamide have been reported in humans and experimental animals, although the underlying mechanism remains obscure. Activation of microglia and neuroinflammation has been demonstrated in various neurodegenerative diseases as well as other pathologies of the brain. The present study aimed to investigate the role of microglial activation and neuroinflammation in acrylamide neurotoxicity. Male 10-week-old Wistar rats were exposed to acrylamide by gavage at 0, 0.2, 2, or 20 mg/kg BW, once per day for 5 weeks. The results showed that 5-week exposure to acrylamide induced inflammatory responses in the cerebral cortex, evident by upregulated mRNA and protein expression of pro-inflammatory cytokines IL-1β, IL-6, and IL-18. Acrylamide also induced activation of microglia, indicated by increased expression of microglial markers, CD11b and CD40, and increased CD11b/c-positive microglial area and microglial process length. In vitro studies using BV-2 microglial cells confirmed microglial inflammatory response, as evident by time- (0-36 h; 50 μM) and dose- (0-500 μM; 24 h) dependent increase in mRNA expression of IL-1β and IL-18, as well as the inflammatory marker iNOS. Furthermore, acrylamide-induced upregulation of pro-inflammatory cytokines was mediated through the NLRP3 inflammasome pathway, as evident by increased expression of NLRP3, caspase 1, and ASC in the rat cerebral cortex, and by the inhibitory effects of NLRP3 inflammasome inhibitor on the acrylamide-induced upregulation of NLRP3, caspase 1, IL-1β, and IL-18 in BV-2 microglia.

Schwann cells protect against CaMKII- and PKA-dependent Acrylamide-induced Synapsin I phosphorylation

OBJECTIVES

To explore the effects of Acrylamide (ACR), as well as the influence of Schwann cells (SCs), on the signal transduction pathway and phosphorylation of Synapsin I in a Human neuroblastoma cell line (NB-1).

METHODS

NB-1s, NB-1s co-cultured with SCs, and a negative control group (NB-1 cells without ACR) were exposed to gradient concentrations of ACR for 48 h. Cell proliferation and viability were determined by MTT. Protein and mRNA expression levels of typical kinases (i.e., cAMP-dependent protein kinase [PKA], calcium/calmodulin-dependent protein kinase II [CaMKII], and mitogen-activated protein kinase-extracellular signal-regulated kinases [MAPK-Erk]), their phosphorylation status, as well as Synapsin I and its phosphorylation status, were tested by western blotting and polymerase chain reaction, respectively. Further, the effect of SCs on ACR-induced NB-1 cell toxicity was evaluated.

RESULTS

(1) The MTT assay showed a sustained, dose- and time-dependent inhibition of NB-1s exposed to ACR. (2) ACR exposure increased the phosphorylation of CaMKII and PKA, which subsequently increased the phosphorylation of Synapsin I (at Serine603 [a substrate site of CaMKII] and Serine9 [a substrate site of PKA]). Pretreatment with CaMKII and PKA inhibitors blocked the ACR-mediated increase in phosphorylation. The above-described results were all significantly different when compared to the control group (p < 0.05). (3) When co-cultured with SCs, ACR-induced NB-1 inhibition was obviously decreased, and the trend of change of phosphorylated CaMKII, PKA, and Synapsin I were changed (first slightly increased and then decreased), which was inconsistent with what we observed in NB-1s cultured alone.

CONCLUSIONS

The toxic effects of ACR on neurons may be mediated by CaMKII and PKA-dependent signaling pathways in which Synapsin I may act as a downstream effector. Furthermore, glial cells (SCs) may be able to prevent a certain degree of ACR-induced neuronal damage.

Tau hyperphosphorylation and P-CREB reduction are involved in acrylamide-induced spatial memory impairment: Suppression by curcumin

Acrylamide (ACR) is an axonal toxicant that produces peripheral neuropathy in laboratory animals and humans. Epidemiological study found that diet ACR exposure was associated with a mild cognitive decline in men. However, limited information is available as regards its potential and underlying mechanism to cause memory alterations. Curcumin is a polyphenol with neuroprotective and cognitive-enhancing properties. In this study, we aimed to investigate the mechanism of ACR-induced spatial memory impairment and the beneficial effect of curcumin. ACR exposure at 10 mg/kg/d for 7 weeks caused slight gait abnormality and spatial memory deficits, which was associated with an activation of glial cells, a reduction of phosphorylated cAMP response elements binding protein (P-CREB) and an aggregation of hyperphosphorylated tau including p-tau (Ser262), AT8 (p-tau Ser202/Thr205) and PHF1 (p-tau Ser396/404) in the hippocampus and cortex. ACR markedly regulate the expression of glycogen synthase kinase-3β (GSK-3β) and cyclin-dependent kinase-5 (cdk5) to accelerate tau hyperphosphorylation. ACR inhibited the protein phosphatase 2A (PP2A) and lysosomal protease cathepsin D to decrease the p-tau dephosphorylation and degradation. The P-CREB and brain derived neurotrophic factor (BDNF) were significantly decreased by ACR. The upstream signalings of P-CREB, extracellular signal-related kinase (ERK) and Akt were markedly inhibited. The protein kinase RNA-like endoplasmic reticulum kinase (PERK) -eukaryotic initiation factor-2α (eIF2α) - activating transcription factor 4 (ATF4) signaling which negatively regulate memory processes by suppressing CREB was activated by ACR. Curcumin alleviated ACR-induced spatial memory impairment through reversing tau abnormalities and P-CREB reduction in the hippocampus. These results offered deeper insight into the mechanisms of and presented a potential new treatment for ACR-induced neurotoxicity.

The effects of acrylamide and vitamin E on kidneys in pregnancy: an experimental study

Objectives: The objective of this study is to investigate possible damages to kidney tissues of pregnant rats and their fetuses exposed to acrylamide during pregnancy and possible protective effects of vitamin E against these damages. Material and methods: Rats were randomly assigned to five groups of control, corn oil, vitamin E, acrylamide, vitamin E + acrylamide, six pregnant rats in each. Mother and fetal kidney tissues were examined for malondialdehyde (MDA), reductase glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), total antioxidant status (TAS), total oxidant status (TOS), urea, creatine, trace elements such as Zn and Cu in the serum and histopathological analyses were conducted. Results: It was determined that acrylamide, administered during pregnancy, statistically significantly increased MDA and TOS levels, maternal serum urea, creatinine, and Zn levels, while it decreased GSH, TAS, SOD, and CAT levels (p ≤ .05) when compared with all other groups in the kidney tissues of pregnant rats and their fetuses and caused tubular degeneration, hemorrhage, narrowing, and closure in Bowman's space, and, in the E vitamin group, it statistically significantly increased GSH, TAS, SOD, CAT, urea, creatinine, and Zn levels when compared with other groups and lowered TOS and MDA levels to those of the control group (p < .05) and there were no differences between the groups histologically. Conclusion: It was observed that acrylamide administered during pregnancy caused oxidative stress in kidney tissues of mother rats and their fetuses, resulting in tissue damage, and vitamin E application, which is considered to be a powerful antioxidant, inhibited oxidative stress.

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.

Dietary Acrylamide and the Risks of Developing Cancer: Facts to Ponder

Acrylamide (AA) is a water soluble white crystalline solid commonly used in industries. It was listed as an industrial chemical with potential carcinogenic properties. However to date, AA was used to produce polyacrylamide polymer, which was widely used as a coagulant in water treatment; additives during papermaking; grouting material for dams, tunnels, and other underground building constructions. AA in food could be formed during high-temperature cooking via several mechanisms, i.e., formation via acrylic acid which may be derived from the degradation of lipid, carbohydrates, or free amino acids; formation via the dehydration/decarboxylation of organic acids (malic acid, lactic acid, and citric acid); and direct formation from amino acids. The big debate is whether this compound is toxic to human beings or not. In the present review, we discuss the formation of AA in food products, its consumption, and possible link to the development of any cancers. We discuss the body enzymatic influence on AA and mechanism of action of AA on hormone, calcium signaling pathways, and cytoskeletal filaments. We also highlight the deleterious effects of AA on nervous system, reproductive system, immune system, and the liver. The present and future mitigation strategies are also discussed. The present review on AA may be beneficial for researchers, food industry, and also medical personnel.

Effects of subchronic acrylamide treatment on the endocrine pancreas of juvenile male Wistar rats

Acrylamide (AA) is a well-known industrial monomer with carcinogenic, mutagenic, neurotoxic and endocrine disruptive effects on living organisms. AA has been the subject of renewed interest owing to its presence in various food products. We investigated the potential adverse effects of oral AA treatment on the endocrine pancreas of juvenile rats using histochemical, immunohistochemical, stereological and biochemical methods. Thirty juvenile male Wistar rats were divided into one control and two AA treatment groups: one treated with 25 mg/kg AA and the other treated with 50 mg/kg AA for 21 days. We found a significant decrease in β-cell mass. The significant decrease in β-cell optical density and unchanged blood glucose levels indicate that normoglycemia in AA treated rats may result from intensive exocytosis of insulin-containing secretory granules. By contrast with β-cells, we observed increased α-cell mass. The slight increase in α-cell cytoplasmic volume suggests retention of glucagon in α-cells, which is consistent with the significant increase in α-cell optical density for AA treated animals. The number of islets of Langerhans did not change significantly in AA treated groups. Our findings suggest that AA treatment causes decreased β-cell mass and moderate α-cell mass increase in the islets of Langerhans of juvenile male Wistar rats.

Application of mutagen sensitivity assay in a glioma case-control study

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MSA is an appropriate molecular epidemiology tool in case control studies.

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Case-control status/exposure categories are not associated with the number of breaks.

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Cell lines of glioma patients did not show reduced DNA repair capacity in response to acrylamide in the MSA assay.

Few risk factors for glioma have been identified other than ionizing radiation. The alkylating agent acrylamide is a compound found in both occupational and the general environment and identified as one of the forty known or suspected neurocarcinogens in animal models. The mutagen sensitivity assay (MSA) has been used to indirectly show reduced DNA repair capacity upon exposure to ionizing radiation in those with glioma compared to controls. In this study, MSA was used to assess its applicability to a glioma case-control study and to test the hypothesis that subjects with glioma may have lower DNA repair capacity after exposure to selected potential human neurocarcinogens (i.e. acrylamide), compared to controls. Approximately 50 case and 50 control subjects were identified from a clinic-based study that investigated environmental risk factors for glioma, who completed an exposure survey, and had frozen immortalized lymphocytes available. A total of 50 metaphase spreads were read and reported for each participant. The association of case-control status with MSA for acrylamide, i.e. breaks per spread, was examined by multivariable logistic regression models. The mean number of breaks per slide was similar between hospital-based controls and cases. In addition, case-control status or exposure categories were not associated with the number of breaks per spread. Although the MSA has been shown as a useful molecular epidemiology tool for identifying individuals at higher risk for cancer, our data do not support the hypothesis that glioma patients have reduced DNA repair capacity in response to exposure to acrylamide. Further research is needed before the MSA is utilized in large-scale epidemiological investigations of alkylating agents.

Microencapsulated fluorescent pH probe as implantable sensor for monitoring the physiological state of fish embryos

In vivo physiological measurement is a major challenge in modern science and technology, as is environment conservation at the global scale. Proper toxicological testing of widely produced mixtures of chemicals is a necessary step in the development of new products, allowing us to minimize the human impact on aquatic ecosystems. However, currently available bioassay-based techniques utilizing small aquatic organisms such as fish embryos for toxicity testing do not allow assessing in time the changes in physiological parameters in the same individual. In this study, we introduce microencapsulated fluorescent probes as a promising tool for in vivo monitoring of internal pH variation in zebrafish embryos. The pH alteration identified under stress conditions demonstrates the applicability of the microencapsulated fluorescent probes for the repeated analysis of the embryo’s physiological state. The proposed approach has strong potential to simultaneously measure a range of physiological characteristics using a set of specific fluorescent probes and to finally bring toxicological bioassays and related research fields to a new level of effectiveness and sensitivity.

Late effect of developmental exposure to glycidol on hippocampal neurogenesis in mice: Loss of parvalbumin-expressing interneurons

Developmental exposure to glycidol of rats causes axonal injury targeting axon terminals in dams and transient disruption of late-stage differentiation of hippocampal neurogenesis, accompanying sustained increase in the number of reelin-producing or calretinin-expressing interneurons in offspring. The molecular mechanism of disruptive neurogenesis probably targets the newly generating nerve terminals. We previously found differences between mice and rats in the effects on hippocampal neurogenesis after developmental exposure to the same neurotoxic substances. In the present study, we examined the effects and underlying mechanisms of developmental exposure to glycidol on hippocampal neurogenesis in mice. Glycidol (800 or 1600ppm) was administered in drinking water to mated female mice from gestational day 6 to postnatal day 21. Compared to mice drinking water without glycidol (control), the exposed dams showed axon terminal injury at both concentrations of glycidol. The offspring of the dams that had received 1600ppm glycidol had fewer parvalbumin (PVALB)⁺ γ-aminobutyric acid (GABA)-ergic interneurons and neuron-specific nuclear protein⁺ postmitotic neurons in the hilus of the hippocampal dentate gyrus. Thus, exposure of glycidol to adult mice induced axonal degeneration equivalent to that seen in the rat; however, the target mechanism for the disruption of hippocampal neurogenesis by developmental exposure was different from that in rats, with the hilar neuronal population not affected until adulthood. Considering the role of PVALB⁺ GABAergic interneurons in the brain, developmental glycidol exposure in mice may cause a decline in cognitive function in later life, and involve a different mechanism from that targeting axon terminals in rats.

Effect of epigallocatechin-3-gallate on acrylamide-induced oxidative stress and apoptosis in PC12 cells

Acrylamide (ACR) is a chemical intermediate utilized in industry. ACR is also formed during heating of foods containing carbohydrates and amino acids. Therefore, humans are widely exposed to ACR, and ACR neurotoxicity in humans is a significant public health issue attracting wide attention. In this study, we investigated the potential neuroprotective effects of epigallocatechin-3-gallate (EGCG), the most abundant polyphenolic compound in green tea, in PC12 cells treated with ACR. ACR-treated PC12 cells pretreated with various concentrations of EGCG (2.5, 5 and 10 μM) for 24 h had increased viability and acetylcholinesterase activity and reduced apoptosis and necrosis compared to cells exposed to ACR alone. EGCG reduced the expression of bax mRNA, decreased cytochrome c release, reduced intracellular calcium levels, inactivated caspase 3 and increased mitochondrial membrane potential, suggesting that EGCG prevents ACR-induced apoptosis through a mitochondrial-mediated pathway. In addition, EGCG inhibited the formation of reactive oxygen species and lipid peroxidation while enhancing superoxide dismutase activity and glutathione levels, thereby reducing oxidative stress. Our results indicate that pretreatment of PC12 cells with EGCG attenuates ACR-induced apoptosis by reducing oxidative stress. Therefore, drinking green tea may reduce nerve injury induced by ACR.

Extract of Ginkgo biloba promotes neuronal regeneration in the hippocampus after exposure to acrylamide

Previous studies have demonstrated a neuroprotective effect of extract of Ginkgo biloba against neuronal damage, but have mainly focused on antioxidation of extract of Ginkgo biloba. To date, limited studies have determined whether extrasct of Ginkgo biloba has a protective effect on neuronal damage. In the present study, acrylamide and 30, 60, and 120 mg/kg extract of Ginkgo biloba were administered for 4 weeks by gavage to establish mouse models. Our results showed that 30, 60, and 120 mg/kg extract of Ginkgo biloba effectively alleviated the abnormal gait of poisoned mice, and up-regulated protein expression levels of doublecortin (DCX), brain-derived neurotrophic factor, and growth associated protein-43 (GAP-43) in the hippocampus. Simultaneously, DCX- and GAP-43-immunoreactive cells increased. These findings suggest that extract of Ginkgo biloba can mitigate neurotoxicity induced by acrylamide, and thereby promote neuronal regeneration in the hippocampus of acrylamide-treated mice.

Acrylamide: a common food toxin related to physiological functions and health

Acrylamide (AA) is a highly reactive organic compound capable of polymerization to form polyacrylamide, which is commonly used throughout a variety of industries. Given its toxic effect on humans and animals, the last 20 years have seen an increased interest in research devoted to the AA. One of the main sources of AA is food. AA appears in heated food following the reaction between amino acids and reduced sugars. Large concentrations of AA can be found in popular staples such as coffee, bread or potato products. An average daily consumption of AA is between 0.3-2.0 microg/kg b.w. Inhalation of acrylamide is related with occupational exposure. AA delivered with food is metabolized in the liver by cytochrome P450. AA biotransformation and elimination result in formation of toxic glycidamide (GA). Both, AA and GA can be involved in the coupling reaction with the reduced glutathione (GSH) forming glutathione conjugates which are excreted with urine. Biotransformation of AA leads to the disturbance in the redox balance. Numerous research proved that AA and GA have significant influence on physiological functions including signal propagation in peripheral nerves, enzymatic and hormonal regulation, functions of muscles, reproduction etc. In addition AA and GA show neurotoxic, genotoxic and cancerogenic properties. In 1994, International Agency for Research on Cancer (IARC) classified acrylamide as a potentially carcinogenic substance to human.

Aluminium and Acrylamide Disrupt Cerebellum Redox States, Cholinergic Function and Membrane-Bound ATPase in Adult Rats and Their Offspring

Accumulation of aluminium and acrylamide in food is a major source of human exposure. Their adverse effects are well documented, but there is no information about the health problems arising from their combined exposure. The aim of the present study was to examine the possible neurotoxic effects after co-exposure of pregnant and lactating rats to aluminium and acrylamide in order to evaluate redox state, cholinergic function and membrane-bound ATPases in the cerebellum of adult rats and their progeny. Pregnant female rats have received aluminium (50 mg/kg body weight) via drinking water and acrylamide (20 mg/kg body weight) by gavage, either individually or in combination from the 14th day of pregnancy until day 14 after delivery. Exposure to these toxicants provoked an increase in malondialdehyde (MDA) and advanced oxidation protein product (AOPP) levels and a decrease in SOD, CAT, GPx, Na⁺K⁺-ATPase, Mg²⁺-ATPase and AChE activities in the cerebellum of mothers and their suckling pups. A reduction in GSH, NPSH and vitamin C levels was also observed. These changes were confirmed by histological results. Interestingly, co-exposure to these toxicants exhibited synergism based on physical and biochemical variables in the cerebellum of mothers and their progeny.

Functional metabolic interactions of human neuron-astrocyte 3D in vitro networks

The generation of human neural tissue-like 3D structures holds great promise for disease modeling, drug discovery and regenerative medicine strategies. Promoting the establishment of complex cell-cell interactions, 3D culture systems enable the development of human cell-based models with increased physiological relevance, over monolayer cultures. Here, we demonstrate the establishment of neuronal and astrocytic metabolic signatures and shuttles in a human 3D neural cell model, namely the glutamine-glutamate-GABA shuttle. This was indicated by labeling of neuronal GABA following incubation with the glia-specific substrate [2-(13)C]acetate, which decreased by methionine sulfoximine-induced inhibition of the glial enzyme glutamine synthetase. Cell metabolic specialization was further demonstrated by higher pyruvate carboxylase-derived labeling in glutamine than in glutamate, indicating its activity in astrocytes and not in neurons. Exposure to the neurotoxin acrylamide resulted in intracellular accumulation of glutamate and decreased GABA synthesis. These results suggest an acrylamide-induced impairment of neuronal synaptic vesicle trafficking and imbalanced glutamine-glutamate-GABA cycle, due to loss of cell-cell contacts at synaptic sites. This work demonstrates, for the first time to our knowledge, that neural differentiation of human cells in a 3D setting recapitulates neuronal-astrocytic metabolic interactions, highlighting the relevance of these models for toxicology and better understanding the crosstalk between human neural cells.

Neurotransmissional, structural, and conduction velocity changes in cerebral ganglions of Lumbricus terrestris on exposure to acrylamide

Acrylamide (ACR), an environmental toxin though being investigated for decades, remains an enigma with respect to its mechanism/site of actions. We aim to explicate the changes in cerebral ganglions and giant fibers along with the behavior of worms on ACR intoxication (3.5-17.5 mg/mL of medium/7 days). Neurotransmitter analysis revealed increased levels of excitatory glutamate and inhibitory gamma amino butyrate with reduced levels of dopamine, serotonin, melatonin, and epinephrine (p < 0.001). Scanning electron microscopy showed architectural changes in cerebral ganglions at 3.5 mg/mL/ACR. The learning behavior as evidenced by Pavlovian and maze tests was also altered well at 3.5 mg/mL of ACR. Electrophysiological assessment showed a reduction in conduction velocity of the medial and lateral giant nerve fibers. We speculate that the observed dose/time-dependent changes in neurotransmission, neurosecretion, and conduction velocity on ACR intoxication at 17.5 mg/ml, possibly, could be due to its effect on nerve fibers governing motor functions. The bioaccumulation factor in the range of 0.38-0.99 mg/g of ACR causes a detrimental impact on giant fibers affecting behavior of worm. The observations made using the simple invertebrate model implicate that the cerebral ganglionic variations in the worms may be useful to appreciate the pathology of the neurological diseases which involve motor neuron dysfunction, esp where the availability of brain samples from the victims are scarce.

Acrylamide affects proliferation and differentiation of the neural progenitor cell line C17.2 and the neuroblastoma cell line SH-SY5Y

Acrylamide is a well-known neurotoxic compound and people get exposed to the compound by food consumption and environmental pollutants. Since acrylamide crosses the placenta barrier, the fetus is also being exposed resulting in a risk for developmental neurotoxicity. In this study, the neural progenitor cell line C17.2 and the neuroblastoma cell line SH-SY5Y were used to study proliferation and differentiation as alerting indicators for developmental neurotoxicity. For both cell lines, acrylamide reduced the number of viable cells by reducing proliferation and inducing cell death in undifferentiated cells. Acrylamide concentrations starting at 10fM attenuated the differentiation process in SH-SY5Y cells by sustaining cell proliferation and neurite outgrowth was reduced at concentrations from 10pM. Acrylamide significantly reduced the number of neurons starting at 1μM and altered the ratio between the different phenotypes in differentiating C17.2 cell cultures. Ten micromolar of acrylamide also reduced the expression of the neuronal and astrocyte biomarkers. Although the neurotoxic concentrations in the femtomolar range seem to be specific for the SH-SY5Y cell line, the fact that micromolar concentrations of acrylamide seem to attenuate the differentiation process in both cell lines raises the interest to further investigations on the possible developmental neurotoxicity of acrylamide.

Biochemical investigation of the toxic effects of acrylamide administration during pregnancy on the liver of mother and fetus and the protective role of vitamin E

OBJECTIVES

To investigate the toxic effects occurring in the liver tissues of the pregnant rats and the fetuses, which are administered acrylamide and vitamin E as a protector during pregnancy.

MATERIALS AND METHODS

This research was conducted with the permission of Laboratory Animals Ethical Board of Inonu University Faculty of Medicine. Forty rats, of which their pregnancy is validated via vaginal smear, were distributed into five different groups. On the 20th day of pregnancy, pregnant rats and fetuses are decapitated. Malondialdehyde (MDA), reduced glutathione (GSH), total antioxidant status (TAS), total oxidant status (TOS) and xanthine oxidase (XO) levels were measured in the liver samples taken from mother and fetuses.

RESULTS

It was detected that acrylamide administered during pregnancy increased MDA, TOS, XO levels statistically significantly and decreased the GSH level (p ≤ 0.05) in the pregnant rat liver tissue when compared to all other groups. In the vitamin E administered group; GSH, TAS levels significantly increased statistically and TOS and XO levels dropped to levels of the control group (p ≤ 0.05), in comparison to all other groups. Among all groups, no biochemical changes were observed in the fetus liver tissue (p > 0.05).

CONCLUSION

The liver of pregnant rats functions as a protective pre-filter by detoxifying acrylamide effectively and the acrylamide that reaches fetus liver is detoxified by the cytochrome P-450 system of the fetus liver. To be able to figure out the biochemical mechanism, more advanced studies are needed.

Evaluation of cII gene mutation in the brains of Big Blue mice exposed to acrylamide and glycidamide in drinking water

Potential health risks for humans from dietary exposure to acrylamide (AA) and its reactive epoxide metabolite, glycidamide (GA), exist because substantial amounts of AA are found in a variety of fried and baked starchy foods. AA is tumorigenic in rodents, and a large number of studies indicate that AA is genotoxic in multiple organs of mice and rats. Although AA is neurotoxic, there are no reports on AA-induced gene mutations in the mouse brain. Therefore, to investigate if gene mutation can be induced by AA or its metabolite GA, we screened brains for cII mutant frequency (MF) and scored for mutation types in previously treated male and female Big Blue mice with 0, 1.4 mM, and 7.0 mM AA or GA in drinking water for up to 4 weeks. High doses of AA and GA induced similar cII MFs in males and females but only the induced cII MF in males was significantly higher than the corresponding male control MF (p < 0.05). Molecular analysis of the cII mutants from males showed that AA and GA each induced at least a 2.5-fold increase in the incidence of G:C → T:A, A:T → T:A, and A:T → C:G transversions compared to the vehicle controls, with similar mutational spectra observed when comparing AA with GA treatment. These results suggest that the MFs and types of mutations induced by AA and GA in the brain are consistent with AA exerting its genotoxicity via metabolism to GA.

Cerebral ganglionic variations and movement behaviors of Lumbricus terrestris on exposure to neurotoxin

BACKGROUND

Invertebrate worms serve as models for understanding the features of neurological functions. Acrylamide (ACR), the well-known neurotoxin, is a water-soluble chemical widely used in various industrial and laboratory processes. ACR is also found in food items which are cooked under high temperature.

PURPOSE

The study attempts to assess the neuropathological changes in cerebral ganglions along with the locomotion and neuronal behavior of Lumbricus terrestris on ACR intoxication.

METHODS

The dosage of acrylamide induced neurotoxicity ranged from 0-17.5 mg/kg body weight for 7 days. The time/dose dependent changes in the oxidant and antioxidant status, activities of Na(+)/K(+)ATPase, Ca(2+)/Mg(2+) ATPase and 5' Nucleotidase were assessed along with the locomotor behavioral analysis.

RESULT

The activities of super oxidase dismutase and catalases were not altered appreciably. However, the glutathione family, lipid peroxide, protein carbonyl content and vitamin C did show significant variations (p<0.001) in a dose-dependent manner, depicting more of oxidative stress, when compared to control worms. The activities of Na(+)/K(+) ATPase was significantly affected (p<0.001) at 3.5 mg/kg bw itself while those of both Ca(2+) and 5' Nucleotidase were found to be affected at 7.0 mg/kg bw of ACR. Mg(2+) ATPase showed significant reduction (p<0.001) in its activity only at 10.5 mg/kg bw of ACR. These dose dependent biochemical variations observed were found to be linked with the behavior of the worms as evident from the latency of movement in a dose-dependent manner which is less pronounced at 7.0 mg and more pronounced at 17.5 mg/kg bw of ACR.

CONCLUSION

The study suggests that ACR disrupts GSSS/GSH balance and perturbs ionic homeostasis in worms and thus affect the motor function highlighting their (GSH-ions) interrelationship in influencing neuromuscular activity. These simple analyses implicate that the cerebral ganglionic variations in the worms may be useful to appreciate the pathology of the neurological diseases (provided sophisticated analyses are employed) especially which involve movement dysfunction, where the brain tissue samples from the affected human patients are scarce.

Neuroprotective Effect of Calpeptin on Acrylamide-Induced Neuropathy in Rats

Acrylamide (ACR) is a vinyl monomer with established human neurotoxic effects, which is characterized by the accumulation of neurofilaments (NFs) in the distal swellings of large axons in peripheral and central nervous systems. However, the mechanisms of neurotoxicity remain unclear. The objective is to investigate the neuroprotective effect of calpeptin (CP) on ACR-induced neuropathy and its mechanism. Female adult Wistar rats were randomly divided into four groups (control, CP, ACR, and ACR + CP group). Control group received 0.9 % saline, ACR and ACR + CP groups received 30 mg/kg ACR by intraperitoneal injection. In addition, CP and ACR + CP groups also received 200 µg/kg CP. Gait analysis and hind limb splay were measured weekly to analyze neurobehavioral changes. The calpain activity and the changes of NFs protein levels in spinal cord are determined. Compared with control group, body weight of rats in ACR group decreased by 11.3 % (P < 0.01), while in ACR + CP group body weight increased significantly by 8.3 % (P < 0.01) compared with ACR group by the end of the 4th week; gait score of rats in both ACR and ACR + CP groups increased significantly by 167 % and 100 % (P < 0.01) compared with control group, while it decreased significantly by 25.1 % (P < 0.01) in ACR + CP group compared with ACR group; the distance of hind limb splay in both ACR and ACR + CP groups increased by 76.7 % and 49.5 % (P < 0.01) compared with control group, while it decreased by 15.4 % (P < 0.01) in ACR + CP group compared with ACR group; calpain activity of spinal cord at ACR and ACR + CP groups increased significantly by 14.9 % and 10.0 % (P < 0.01) compared with control group, while it decreased 4.2 % (P < 0.01) in ACR + CP group compared with ACR group; compared with control group, the levels of light NF (NF-L), medium NF (NF-M) and heavy NF (NF-H) subunits increased by 81.2 %, 263.6 % and 22.6 % (P < 0.01) in the supernatant of ACR group in spinal cord tissue and increased by 28.4 %, 96.6 % and 10.6 % (P < 0.01) in ACR + CP group, while the levels of NF-L, NF-M and NF-H subunits decreased by 29.1 %, 45.9 % and 9.8 % (P < 0.01) in ACR + CP group compared with ACR group. The present results suggested that CP can relieve ACR neuropathy by decrease calpain activity and NFs degradation. The changes of calpain activity and NFs may be one of the mechanisms of ACR-induced neuropathy.

Freshwater Planarians as an Alternative Animal Model for Neurotoxicology

Traditional toxicology testing has relied on low-throughput, expensive mammalian studies; however, timely testing of the large number of environmental toxicants requires new in vitro and in vivo platforms for inexpensive medium- to high-throughput screening. Herein, we describe the suitability of the asexual freshwater planarian Dugesia japonica as a new animal model for the study of developmental neurotoxicology. As these asexual animals reproduce by binary fission, followed by regeneration of missing body structures within approximately 1 week, development and regeneration occur through similar processes allowing us to induce neurodevelopment "at will" through amputation. This short time scale and the comparable sizes of full and regenerating animals enable parallel experiments in adults and developing worms to determine development-specific aspects of toxicity. Because the planarian brain, despite its simplicity, is structurally and molecularly similar to the mammalian brain, we are able to ascertain neurodevelopmental toxicity that is relevant to humans. As a proof of concept, we developed a 5-step semiautomatic screening platform to characterize the toxicity of 9 known neurotoxicants (consisting of common solvents, pesticides, and detergents) and a neutral agent, glucose, and quantified effects on viability, stimulated and unstimulated behavior, regeneration, and brain structure. Comparisons of our findings with other alternative toxicology animal models, such as zebrafish larvae and nematodes, demonstrated that planarians are comparably sensitive to the tested chemicals. In addition, we found that certain compounds induced adverse effects specifically in developing animals. We thus conclude that planarians offer new complementary opportunities for developmental neurotoxicology animal models.

Determination of Heterocyclic Amines and Acrylamide in Agricultural Products with Liquid Chromatography-Tandem Mass Spectrometry

Heterocyclic amines (HCAs) and acrylamide are unintended hazardous substances generated by heating or processing of foods and are known as carcinogenic and mutagenic agents by the animal experiments. A simple method was established for a rapid and accurate determination of 12 types of HCAs (IQ, MeIQ, Glu-P-1, Glu-P-2, MeIQx, Trp-P-1, Trp-P-2, PhIP, AαC, MeAαC, Harman and Norharman) and acrylamide in three food matrices (non-fat liquid, non-fat solid and fat solid) by isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). In every sample, a mixture of internal standards including IQ-d3, MeIQx-d3, PhIP-d3, Trp-P-2-(13)C2-(15)N and MeAαC-d3 was spiked for quantification of HCAs and (13)C3-acrylamide was also spiked for the analysis of acrylamide. HCAs and acrylamide in sample were extracted with acetonitrile and water, respectively, and then two solid-phase extraction cartridges, ChemElut: HLB for HCAs and Accucat: HLB for acrylamide, were used for efficiently removing interferences such as pigment, lipid, polar, nonpolar and ionic compounds. Established method was validated in terms of recovery, accuracy, precision, limit of detection, limit of quantitation, and linearity. This method showed good precision (RSD < 20%), accuracy (71.8~119.1%) and recovery (66.0~118.9%). The detection limits were < 3.1 ng/g for all analytes. The correlation coefficients for all the HCAs and acrylamide were > 0.995, showing excellent linearity. These methods for the detection of HCAs and acrylamide by LC-MS/MS were applied to real samples and were successfully used for quantitative monitoring in the total diet study and this can be applied to risk assessment in various food matrices.

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 Potential for Plant Derivatives against Acrylamide Neurotoxicity

Certain industrial chemicals and food contaminants have been demonstrated to possess neurotoxic activity and have been suspected to cause brain-related disorders in humans. Acrylamide (ACR), a confirmed neurotoxicant, can be found in trace amount in commonly consumed human aliments as a result of food processing or cooking. This discovery aroused a great concern in the public, and increasing efforts are continuously geared towards the resolution of this serious threat. The broad chemical diversity of plants may offer the resources for novel antidotes against neurotoxicants. With the goal of attenuating neurotoxicity of ACR, several plants extracts or derivatives have been employed. This review presents the plants and their derivatives that have been shown most active against ACR-induced neurotoxicity, with a focus on their origin, pharmacological activity, and antidote effects.