Effect of subchronic acrylamide exposure on the expression of neuronal and inducible nitric oxide synthase in rat brain

Blood RNA-sequencing analysis in acrylamide-induced neurotoxicity and depressive symptoms in rats

Acrylamide (ACR) is a by-product of the Maillard reaction, which occurs when food reacts at high temperatures. Occupational exposure is a risk factor for chronic ACR toxicity. ACR may cause neurotoxicity and depressive symptoms with high concentration in the blood; however, the underlying mechanism remains unknown. We showed the rats developed neurotoxic symptoms after being fed with ACR for 28 days, such as reduced activity and hind limb muscle weakness. We investigated whether ACR exposure causes gene expression differences by blood RNA sequencing and analyzed the differential expression of depressive symptoms-associated genes. The result indicated that IFN-γ the key regulator of neurotoxicity and depressive symptoms was induced by ACR. ACR induced the ubiquitin-mediated proteolysis pathway and JAK/STAT pathways gene expression. ACR upregulated the expression of IFN-γ, inducing neuroinflammation and neurotoxicity. ACR also upregulated the expression of JAK2, STAT1, PI3K, AKT, IκBα, UBE2D4, NF-κB, TNF-α, and iNOS in rat brain tissues and Neuro-2a cells. Thus, IFN-γ induction by ACR may induce depressive symptoms, and the ubiquitin-mediated proteolysis pathway and JAK/STAT pathways may involve in ACR neurotoxicity and depressive symptoms.

The role of Bax/Bcl-2 and Nrf2-Keap-1 signaling pathways in mediating the protective effect of boric acid on acrylamide-induced acute liver injury in rats

INTRODUCTION

This study aims to investigate whether boric acid (BA) can protect rats from acrylamide (AA)-induced acute liver injury.

MATERIALS AND METHODS

AA was used to induce acute liver injury. Thirty rats were divided into five group including Group 1 (saline), Group 2 (AA), Group 3 (20 mg/kg BA), Group 4 (10 mg/kg BA+AA) and Group 5 (20 mg/kg BA+AA). Their blood and liver were harvested to be kept for analysis. Liver function enzyme activities were performed by spectrophotometric method. Catalase (CAT), superoxide dismutase (SOD) activity, and malondialdehyde levels were determined by colorimetric method. The in-silico studies were performed using the "blind docking" method.

RESULTS

Administration AA to rats, biochemical parameters, liver histology, and expression levels of apoptotic markers were negatively affected. However, after the administration of BA, the altered biochemical parameters, liver histology, and expression levels of apoptotic markers were reversed. Moreover, the mechanisms of AA-induced deterioration in the levels of SOD, CAT, and Nrf2-Keap-1 and the mechanisms of the protective effect of BA against these deteriorations were explained by in silico studies.

CONCLUSION

Thus, the present study could explain the interactions between AA and thiol-containing amino acid residues of Keap-1, the effect of BA on these interactions, and the biochemical toxicity caused by the AA. In this sense, this work is the first of its kind in the literature. Based on the biochemical, histopathological, and in silico results, it can be suggested that BA has the potential to be used as a protective agent against AA-induced liver injury.

Negative Association between Acrylamide Exposure and Metabolic Syndrome Markers in Adult Population

Metabolic syndrome encompasses multiple conditions that increase the risk of cardiovascular disease, and exposure to environmental chemicals can cause metabolic syndrome. This cross-sectional study analyzed data from the US National Health and Nutrition Examination Survey (2003-2006) on 4318 adult participants to assess the association between acrylamide (AA) exposure and metabolic syndrome. Concentrations of hemoglobin-adducted AA (HbAA) and hemoglobin-adducted glycidamide (HbGA) were evaluated. Metabolic syndrome markers related to HbAA and HbGA and the effect of exposure to AA and GA on the prevalence of metabolic syndrome were studied by ANOVA and multivariate logistic regression analyses, respectively. HbAA concentration inversely correlated with the number of metabolic syndrome markers (p < 0.05). An increased HbAA concentration was noted with reduced high triglyceride and low high-density lipoprotein cholesterol levels in the adjusted model (p < 0.05). High fasting plasma glucose level significantly correlated with HbGA concentration in the adjusted model. In conclusion, AA exposure alters metabolic syndrome markers in adults. Additional clinical and animal studies will clarify the role of AA exposure at different stages in the progression of metabolic syndrome-related diseases.

Vitamin E and 5-amino salicylic acid ameliorates acrylamide-induced peripheral neuropathy by inhibiting caspase-3 and inducible nitric oxide synthase immunoexpression

Acrylamide is a fundamental cause of accidental toxicity in humans. This study aimed to investigate the neuroprotective effect of vitamin E (Vit. E), 5-amino salicylic acid (5-ASA), and their combination against acrylamide-induced sciatic nerve toxicity. For this purpose, 25 male Wister rats were divided into 5 groups: control, acrylamide, acrylamide + Vit. E, acrylamide + 5-ASA, and acrylamide + Vit. E + 5-ASA. Food intake and body weight were assessed after 7 days. Furthermore, the gait score was also evaluated for each rat. The sciatic nerve was dissected, fixed, and processed for routine light and electron microscopic examination. Haematoxylin and eosin, osmium tetroxide for myelin sheath, and toluidine blue for semithin section were used. In addition, immunohistochemistry for caspase-3 and inducible nitric oxide synthase (iNOS) were performed. The results showed reduced food intake and body weight in acrylamide rats. Abnormal gait score was also recorded in acrylamide rats with significant improvement in Vit. E, and Vit. E + 5-ASA groups. Histologically, Vit. E and 5-ASA provided potential protection against decreased sciatic nerve axon density, disrupted myelination, and the alteration in the immunohistochemistry induced by acrylamide. Vit. E and its combination with 5-ASA provided more evident protection compared to 5-ASA alone. 5-ASA significantly decreased apoptotic cell death (caspase-3 immunoexpression) while Vit. E failed. Both Vit. E and 5-ASA significantly decreased iNOS immunoexpression in the sciatic nerve, where 5-ASA was superior to Vit. E. These findings concluded that both Vit. E and 5-ASA protect against acrylamide-induced peripheral neuropathy through downregulation of both caspase-3 and iNOS immunoexpression.

The influence of single nucleotide polymorphisms on the association between dietary acrylamide intake and endometrial cancer risk

It is unclear whether the association between dietary acrylamide intake and endometrial cancer risk as observed in some epidemiological studies reflects a causal relationship. We aimed at clarifying the causality by analyzing acrylamide-gene interactions for endometrial cancer risk. The prospective Netherlands Cohort Study on diet and cancer includes 62,573 women, aged 55–69 years. At baseline, a random subcohort of 2589 women was selected for a case cohort analysis approach. Acrylamide intake of subcohort members and endometrial cancer cases (n = 315) was assessed with a food frequency questionnaire. Single nucleotide polymorphisms (SNPs) in genes in acrylamide metabolism, sex steroid systems, oxidative stress and DNA repair were assessed through a MassARRAY iPLEX Platform. Interaction between acrylamide and SNPs was assessed with Cox proportional hazards analysis, based on 11.3 years of follow-up. Among the results for 57 SNPs and 2 gene deletions, there were no statistically significant interactions after adjustment for multiple testing. However, there were nominally statistically significant interactions for SNPs in acrylamide-metabolizing enzymes: CYP2E1 (rs915906 and rs2480258) and the deletions of GSTM1 and GSTT1. Although in need of confirmation, the interactions between acrylamide intake and CYP2E1 SNPs contribute to the evidence for a causal relationship between acrylamide and endometrial cancer risk.

Possible effects of nitric oxide synthases on odor-induced behavioral changes in mice

Although exposure to olfactory stimulants can induce neurobehavioral changes, there is a lack of data regarding specific effects on neurotransduction, especially nitric oxide (NO)-mediated neurotransduction. We investigated the relationship between altered behavioral performance and changes in the expression of nitric oxide synthase (NOS), nNOS, iNOS, and eNOS, in 2-methylbutyric (2MB) acid-exposed mice. Mice were exposed to 2MB acid by inhalation and olfactory preference/avoidance and motor coordination were measured. Additionally, we examined NOS expression in the olfactory bulb of the mouse brain. Mice exposed to 2MB acid showed significant changes in olfactory preference and rotarod activity as compared with controls. Although there was no change in nNOS and iNOS expressions in the olfactory bulb of 2MB acid-exposed mice, eNOS expression increased significantly in the olfactory bulb of 9.0M 2MB acid-exposed mice. These data indicate that altered eNOS expression in the olfactory bulb may contribute to 2MB acid-induced behavioral changes.

Quercetin protects mouse brain against lead-induced neurotoxicity

Quercetin (QE), the major bioflavonoid in the human diet, has been reported to have many benefits and medicinal properties. However, its protective effects against lead (Pb)-induced neurotoxicity have not been clarified. The aim of the present study was to investigate the effects of QE on neurotoxicity in mice exposed to Pb. Mice were exposed to lead acetate (20 mg/kg body weight/day) intragastrically with or without QE (15 and 30 mg/kg body weight/day) coadministration for 3 months. The data showed that QE significantly prevented Pb-induced neurotoxicity in a dose-dependent manner. Exploration of the underlying mechanisms of QE action revealed that QE administration decreased Pb contents in blood (13.2, 19.1%) and brain (17.1, 20.0%). QE markedly increased NO production (39.1, 61.1%) and PKA activity (51.0, 57.8%) in brains of Pb-treated mice. Additionally, QE remarkably suppressed Pb-induced oxidative stress in mouse brain. Western blot analysis showed that QE increased the phosphorylations of Akt, CaMKII nNOS, eNOS, and CREB in brains of Pb-treated mice. The results suggest that QE can inhibit Pb-induced neurotoxicity and partly restore PKA, Akt, NOS, CaMKII, and CREB activities.

Structural and ultrastructural evidence of neurotoxic effects of fried potato chips on rat postnatal development

OBJECTIVE

Acrylamide (ACR), a proved rodent carcinogen and neurotoxic agent, is present in significant quantities in commonly consumed foods such as fried potato chips (FPC) and French fries, raising a health concern worldwide. We investigated and compared the neurotoxic effects of ACR and FPC on postnatal development.

METHODS

Female rats were treated with ACR (30 mg/kg of body weight), fed a diet containing approximately 30% of FPC during pregnancy, or fed a standard diet (control) and their offspring were examined.

RESULTS

Female rats treated with ACR or fed a diet containing FPC during pregnancy gave birth to litters with delayed growth and decreased body and brain weights. Light microscopic studies of the cerebellar cortex of treated animals revealed drastic decreases in Purkinje cells and internal granular layers. Different patterns of cell death were detected in Purkinje cells and neurons in the brains of pups born to treated mothers. Ultrastructural analysis of Purkinje cells revealed changes in the endoplasmic reticulum, loss of the normal arrangement of polyribosomes, swollen mitochondria with abnormally differentiated cristae, and an abnormal Golgi apparatus. The gastrocnemius muscle in the ACR and FPC groups showed extensive degeneration of myofibrils as evidenced by poorly differentiated A, H, and Z bands.

CONCLUSION

The present study reveals for the first time that rat fetal exposure to ACR, as a pure compound or from a maternal diet of FPC, causes cerebellar cortical defects and myodegeneration of the gastrocnemius muscle during the postnatal development of pups. These results warrant a systematic study of the health effects of the consumption of FPC and French fries in the general population.

Effects of lead exposure on nitric oxide-associated gene expression in the olfactory bulb of mice

Lead (Pb) is known to have toxic effects on the brain; however, data regarding its specific toxic effects on the olfactory bulb are lacking. Therefore, we investigated the relationship between acute Pb exposure and alterations in gene expression associated with the nitric oxide signaling pathway in the olfactory bulb of mice. After administration of Pb (intraperitoneal injections of 1 or 10 mg/kg Pb(CH(3)CO(2))(2) · 3H(2)O once per day for 4 days), body weight, motor activity, and gene expression in the olfactory bulb of mice were examined. High doses of Pb resulted in significant decreases in body weight, but motor coordination was not significantly altered until 11 days after the end of Pb treatment. The expression patterns of dimethylarginine dimethylaminohydrolase 1 (Ddah1), superoxide dismutase 1 (Sod1), and superoxide dismutase (Ccs) were increased, whereas expression of the Stratifin (Sfn) gene was significantly decreased following treatment with 10 mg/kg Pb. The expression patterns of nitric oxide synthases at the mRNA and protein levels, however, were not significantly altered by treatment with 10 mg/kg Pb. These findings indicate that Pb-induced neurotoxicity may be modulated in part by the expression of Ddah1, Sod1, Ccs, and Sfn in the olfactory bulb.

Review of methods for the reduction of dietary content and toxicity of acrylamide

Potentially toxic acrylamide is largely derived from heat-induced reactions between the amino group of the free amino acid asparagine and carbonyl groups of glucose and fructose in cereals, potatoes, and other plant-derived foods. This overview surveys and consolidates the following dietary aspects of acrylamide: distribution in food originating from different sources; consumption by diverse populations; reduction of the acrylamide content in the diet; and suppression of adverse effects in vivo. Methods to reduce adverse effects of dietary acrylamide include (a) selecting potato, cereal, and other plant varieties for dietary use that contain low levels of the acrylamide precursors, namely, asparagine and glucose; (b) removing precursors before processing; (c) using the enzyme asparaginase to hydrolyze asparagine to aspartic acid; (d) selecting processing conditions (pH, temperature, time, processing and storage atmosphere) that minimize acrylamide formation; (e) adding food ingredients (acidulants, amino acids, antioxidants, nonreducing carbohydrates, chitosan, garlic compounds, protein hydrolysates, proteins, metal salts) that have been reported to prevent acrylamide formation; (f) removing/trapping acrylamide after it is formed with the aid of chromatography, evaporation, polymerization, or reaction with other food ingredients; and (g) reducing in vivo toxicity. Research needs are suggested that may further facilitate reducing the acrylamide burden of the diet. Researchers are challenged to (a) apply the available methods and to minimize the acrylamide content of the diet without adversely affecting the nutritional quality, safety, and sensory attributes, including color and flavor, while maintaining consumer acceptance; and (b) educate commercial and home food processors and the public about available approaches to mitigating undesirable effects of dietary acrylamide.