Acrylamide and its metabolite induce neurotoxicity via modulation of protein kinase C and AMP-activated protein kinase pathways

Acrylamide-Aggravated Liver Injury by Activating Endoplasmic Reticulum Stress in Female Mice with Diabetes

Acrylamide (ACR) is a common industrial contaminant with endocrine-disrupting toxicity. Numerous studies have indicated that females and diabetics are more sensitive to environmental contaminants. However, it remains unknown whether female diabetics are susceptible to ACR-induced toxicity and its potential mechanisms. Thus, the female ACR-exposure diabetic Balb/c mice model was established to address these issues. Results showed that ACR could induce liver injury in normal mice and cause more serious inflammatory cell infiltration, hepatocyte volume increase, and fusion in diabetic mice liver. Meanwhile, ACR could lead to exacerbation of diabetic symptoms in diabetic mice by disturbing the glucose and lipid metabolism in the liver, which mainly manifests as the accumulation of liver glycogen and liver lipids, the reduction of the activity/content of glycolytic and metabolizing enzyme as well as pentose phosphatase, upregulation of the gene expression in fatty acid transporter and gluconeogenesis, and downregulation of the gene expression in fatty acid synthesis and metabolism. Moreover, ACR exposure could induce oxidative stress, inflammation, and endoplasmic reticulum stress in the liver by a decrease in hepatic antioxidant enzyme activity and antioxidant content, an increase in inflammatory factor levels, and a change in the related protein expression of endoplasmic reticulum stress (ERS) and apoptosis-related pathways in diabetic mice. Statistical analysis results revealed that ACR-induced liver injury was highly correlated with inflammation and oxidative stress, and ERS and diabetic mice had a higher risk of liver injury than normal mice. Overall results suggested that female diabetic mice easily suffer from ACR-induced toxicity, and the reason was that ACR could induce further damage to the liver by worsening the condition of inflammation, oxidative stress, and ERS in the liver.

Disruption of intestinal epithelial permeability in the Co-culture system of Caco-2/HT29-MTX cells exposed individually or simultaneously to acrylamide and ochratoxin A

Mycotoxins and thermal processing hazards are common contaminants in various foods and cause severe problems in terms of food safety and health. Combined use of acrylamide (AA) and ochratoxin A (OTA) would result in more significant intestinal toxicity than either toxin alone, but the underlying mechanisms behind this poor outcome remain unclear. Herein, we established the co-culture system of Caco-2/HT29-MTX cells for simulating a real intestinal environment that is more sensitive to AA and OTA, and showed that the combination of AA and OTA could up-regulate permeability of the intestine via increasing LY permeabilization, and decreasing TEER, then induce oxidative stress imbalance (GSH, SOD, MDA, and ROS) and inflammatory system disorder (TNF-α, IL-1β, IL-10, and IL-6), thereby leading a rapid decline in cell viability. Western blot, PAS- and AB-staining revealed that AA and OTA showed a synergistic effect on the intestine mainly through the disruption of tight junctions (TJs) and a mucus layer. Furthermore, based on correlation analysis, oxidative stress was more relevant to the mucus layer and TJs. Therefore, our findings provide a better evaluation model and a potential mechanism for further determining or preventing the combined toxicity caused by AA and OTA.

From a toxin to an obesogen: a review of potential obesogenic roles of acrylamide with a mechanistic approach

Obesity and obesity-related disorders such as cancer, type 2 diabetes, and fatty liver have become a global health problem. It is well known that the primary cause of obesity is positive energy balance. In addition, obesity is the consequence of complex gene and environment interactions that result in excess calorie intake being stored as fat. However, it has been revealed that there are other factors contributing to the worsening of obesity. The presence of nontraditional risk factors, such as environmental endocrine-disrupting chemicals, has recently been associated with obesity and comorbidities caused by obesity. The aim of this review was to examine the evidence and potential mechanisms for acrylamide having endocrine-disrupting properties contributing to obesity and obesity-related comorbidities. Recent studies have suggested that exposure to environmental endocrine-disrupting obesogens may be a risk factor contributing to the current obesity epidemic, and that one of these obesogens is acrylamide, an environmental and industrial compound produced by food processing, particularly the processing of foods such as potato chips, and coffee. In addition to the known harmful effects of acrylamide in humans and experimental animals, such as neurotoxicity, genotoxicity, and carcinogenicity, acrylamide also has an obesogenic effect. It has been shown in the literature to a limited extent that acrylamide may disrupt energy metabolism, lipid metabolism, adipogenesis, adipocyte differentiation, and various signaling pathways, and may exacerbate the disturbances in metabolic and biochemical parameters observed as a result of obesity. Acrylamide exerts its main potential obesogenic effects through body weight increase, worsening of the levels of obesity-related blood biomarkers, and induction of adipocyte differentiation and adipogenesis. Additional mechanisms may be discovered. Further experimental studies and prospective cohorts are needed, both to supplement existing knowledge about acrylamide and its effects, and to clarify its established relationship with obesity and its comorbidities.

Acrylamide interferes with autophagy and induces apoptosis in Neuro-2a cells by interfering with TFEB-regulated lysosomal function

Acrylamide (ACR), a well-documented human neurotoxicant that is widely exists in starchy foods. More than 30% of human daily energy is provided by ACR-containing foods. Evidence indicated that ACR can induce apoptosis and inhibit autophagy, but the mechanisms are limited. Transcription Factor EB (TFEB) is a major transcriptional regulator of the autophagy-lysosomal biogenesis that regulates autophagy processes and cell degradation. Our study aimed to investigated the potential mechanisms of TFEB-regulated lysosomal function in ACR-caused autophagic flux inhibition and apoptosis in Neuro-2a cells. Our results found that ACR exposure inhibited the autophagic flux, as revealed by the elevated LC3-II/LC3-I and p62 levels and a notable increased autophagosomes. ACR exposure reduced the amounts of LAMP1 and mature cathepsin D and caused an accumulation of ubiquitinated proteins, which suggests lysosomal dysfunction. In addition, ACR increased cellular apoptosis via decreasing Bcl-2 expression, increasing Bax and cleaved caspase-3 expression, and raising the apoptotic rate. Interestingly, TFEB overexpression alleviated the ACR-induced lysosomal dysfunction, and then mitigated the autophagy flux inhibition and cellular apoptosis. On the other hand, TFEB knockdown exacerbated the ACR-induced lysosomal dysfunction, autophagy flux inhibition, and cellular apoptosis. These findings strongly suggested that TFEB- regulated lysosomal function is responsible for ACR-caused autophagic flux inhibition and apoptosis in Neuro-2a cells. The present study hopes to explore new sensitive indicators in the mechanism of ACR neurotoxicity and thus provide new targets for the prevention and treatment of ACR intoxication.

Research Progress of Programmed Cell Death Induced by Acrylamide

Acrylamide exposure through environment pollution and diet is very common in daily life. With the deepening of the study on the toxicity of acrylamide, it has attracted widespread attention for the effects of acrylamide on multiple organs through affecting a variety of programmed cell death. Multiple studies have shown that acrylamide could exert its toxic effect by inducing programmed cell death, but its specific molecular mechanism is still unclear. In this review, the research on the main forms of programmed cell death (apoptosis, autophagy, and programmed necrosis) induced by acrylamide and their possible mechanisms are reviewed. This review may provide basic data for further research of acrylamide and prevention of its toxicity.

Exposure to acrylamide inhibits testosterone production in mice testes and Leydig cells by activating ERK1/2 phosphorylation

Acrylamide (ACR) is formed during the cooking of starchy foods at high temperatures. Accumulating evidence has shown that ACR has toxic effects, but the mechanism of its potential reproductive toxicity remains unclear. In this study, we observed that ACR caused weight loss in mice. There was no significant difference in the weight of testis and epididymis between the low/medium-dose ACR group and the control group. And the number of epididymal sperms, testicular Leydig cells, serum testosterone level, testicular steroidogenic genes and enzymes, including cytochrome P450 family 11 subfamily A member 1 (CYP11A1) and cytochrome P450 family 17 subfamily A member 1 (CYP17A1), were decreased in the medium/high-dose ACR group. Additional cell experiments showed that the apoptosis rate and the level of reactive oxygen species (ROS) were increased, and testosterone levels and CYP17A1 protein expression were reduced in Leydig cells with treated ACR. Furthermore, the phosphorylation levels of extracellular signal-regulated kinases (ERK1/2) increased significantly; however, there was no significant difference in the levels of serine-threonine protein kinase (AKT) phosphorylation in the testis of mice and Leydig cells treated with ACR. These results suggest that ACR exposure leads to the damage of testicular structure and function and a decline in testosterone synthesis in Leydig cells and mouse testis, which may be related to the activated phosphorylation of ERK1/2.

Acrylamide-induced damage to postsynaptic plasticity is CYP2E1 dependent in an SH-SY5Y co-culture system

Acrylamide (ACR), a neurotoxic substance, is characterized by a range of industrial and population exposures. The effects of ACR on synapses have been examined, but the regulation and molecular mechanism of key proteins related to ACR and its metabolite glycidamide (GA) have not been elucidated. In this study, we constructed two co-culture systems to mimic neurons that do not express and overexpress CYP2E1. In these co-cultures, we observed the effects and relative influence of ACR and GA on cell survival as well as synaptic structural and functional plasticity. Next, we investigated the relationship between ACR-induced nerve damage and key proteins in the postsynaptic membrane. After ACR exposure, cell death and synaptic damage were significantly worse in CYP2E1-overexpressing co-culture systems, suggesting that ACR-induced neurotoxicity may be related to metabolic efficiency (including CYP2E1 activity). Moreover, with increasing doses of ACR, the key postsynaptic membrane proteins PSD-95 expression was reduced and CaMKII and NMDAR-2B phosphorylation was increased. ACR exposure also triggered a rapid dose- and time-dependent increase in intracellular Ca²⁺, whose changes can affect the expression of the above-mentioned key proteins. In summary, we clarified the relationship between ACR exposure, neuronal damage and postsynaptic plasticity and proposed an ACR-CYP2E1-GA: Ca²⁺-PSD-95-NMDAR-Ca²⁺-CaMKII effect chain. This information will further improve the development of an alternative pathway strategy for investigating the risk posed by ACR.

Silymarin abrogates acrylamide-induced oxidative stress-mediated testicular toxicity via modulation of antioxidant mechanism, DNA damage, endocrine deficit and sperm quality in rats

Acrylamide (ACR) is a toxic chemical formed in foods processed at high temperature; it is a food-borne toxicant with increasing public health attention due to its carcinogenic, neurotoxic and reproductive toxicities. However, till date, it is unknown whether silymarin (SIL) could attenuate ACR testicular toxicity. Therefore, the present study investigated the effect of SIL on ACR testiculotoxicity in rats. Rats were randomly divided and administered respective agents in Control group, ACR group, SIL group and ACR + SIL group for consecutive 14 days. Rat exposure to ACR resulted in significant reduction in the level of serum testosterone, whereas FSH and LH levels prominently increased compared to control. Acrylamide induced marked decreases in sperm count and sperm motility followed by a considerable increase in sperm abnormality percentage in the ACR-exposed rats in comparison to control. The testicular activities of glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) were significantly diminished, whereas malondialdehyde (MDA) level considerably increased. Additionally, ACR induced marked DNA fragmentation and histopathological lesions compared to control. Interestingly, the co-treatment of SIL with ACR attenuated the altered reproductive indices and restored antioxidant balance and DNA integrity. Overall, SIL prevents ACR-induced testicular reproductive deficits via modulation of antioxidant mechanism in rats.

The Mechanism of Acrylamide-Induced Neurotoxicity: Current Status and Future Perspectives

Acrylamide (ACR), a potential neurotoxin, is produced by the Maillard reaction between reducing sugars and free amino acids during food processing. Over the past decade, the neurotoxicity of ACR has caused increasing concern, prompting many related studies. This review summarized the relevant literature published in recent years and discussed the exposure to occupational, environmental, and daily ACR contamination in food. Moreover, ACR metabolism and the potential mechanism of ACR-induced neurotoxicity were discussed, with particular focus on the axonal degeneration of the nervous system, nerve cell apoptosis, oxidative stress, inflammatory response, and gut-brain axis homeostasis. Additionally, the limitations of existing knowledge, as well as new perspectives, were examined, specifically regarding the connection between the neurotoxicity caused by ACR and neurodegenerative diseases, NOD-like receptor protein 3 (NLRP3) inflammasome-related neuroinflammation, and microbiota-gut-brain axis signaling. This review might provide systematic information for developing an alternative pathway approach to assess ACR risk.

Perfluorohexane sulfonate induces memory impairment and downregulation of neuroproteins via NMDA receptor-mediated PKC-ERK/AMPK signaling pathway

Perfluorohexane sulfonate (PFHxS) is a widely used industrial chemical detected in human umbilical cord blood and breast milk, and has been suggested to exhibit developmental neurotoxicity. Previous studies on mice reported that neonatal exposure to PFHxS altered neuroprotein levels in the developing brain, and caused behavioral toxicity and cognitive dysfunction in the mature brain. However, the underlying mechanisms responsible for PFHxS-induced neuroprotein dysregulation are poorly understood. In this study, we examined the effect of neonatal exposure to PFHxS on memory function using an in vivo mice model. Furthermore, we examined the levels of growth associated protein-43 (GAP-43) and calcium/calmodulin dependent protein kinase II (CaMKII) (biomarkers of neuronal development) and the involved signaling pathways using differentiated neuronal PC12 cells. PFHxS decreased cell viability, GAP-43 and CaMKII levels, and neurite formation. These effects were mediated by the NMDA receptor, PKC-α, PKC-δ, AMPK and ERK pathways. MK801, an NMDA receptor antagonist, reduced the activation of PKC-α, PKC-δ, ERK and AMPK. The activation of ERK was suppressed by pharmacological and knockdown inhibition of PKC-α and -δ. Interestingly, the AMPK pathway was selectively inhibited by inhibiting PKC-δ but not PKC-ɑ. Consistent with PFHxS-induced neuronal death, and GAP-43 and CaMKII downregulation, neonatal exposure to PFHxS caused significant memory impairment in adult mice. Collectively, these results demonstrate that PFHxS induces persistent developmental neurotoxicity, as well as GAP-43 and CaMKII downregulation via the NMDA receptor-mediated PKCs (α and δ)-ERK/AMPK pathways.