Acrylamide treatment alters the level of Ca2+ and Ca2+-related protein kinase in spinal cords of rats.

This study aimed to analyze the neurological changes induced by acrylamide (ACR) poisoning and their underlying mechanisms within the spinal cords of male adult Wistar rats. The rats were randomly divided into three groups (n = 9 rats per group). ACR was intraperitoneally injected to produce axonopathy according to the daily dosing schedules of 20 or 40 mg/kg/day of ACR for eight continuous weeks (three times per week). During the exposure period, body weights and gait scores were assessed, and the concentration of Ca2+ was calculated in 27 mice. Protein kinase A (PKA), protein kinase C (PKC), cyclin-dependent protein kinase 5 (CDK5), and P35 were assessed by electrophoretic resolution and Western blotting. The contents of 3'-cyclic adenosine monophosphate (cAMP) and calmodulin (CaM) were determined using ELISA kits, and the activities of calcium/calmodulin-dependent protein kinase II (CaMKII), PKA, and PKC were determined using the commercial Signa TECTPKAassay kits. Compared with control rats, treatment with 20 and 40 mg/kg of ACR decreased body weight and increased gait scores at 8 weeks. Intracellular Ca2+ levels increased significantly in treated rats; CaM, PKC, CDK5, and P35 levels were significantly decreased; and PKA and cAMP levels remained unchanged. CaMKII, PKA, and PKC activities increased significantly. The results indicated that ACR can damage neurofilaments by affecting the contents and activities of CaM, CaMKII, PKA, cAMP, PKC, CDK5, and P35, which could result in ACR toxic neuropathy.

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.

Dietary acrylamide and cancer risk: an updated meta-analysis.

The debate on the potential carcinogenic effect of dietary acrylamide is open. In consideration of the recent findings from large prospective investigations, we conducted an updated meta-analysis on acrylamide intake and the risk of cancer at several sites. Up to July 2014, we identified 32 publications. We performed meta-analyses to calculate the summary relative risk (RR) of each cancer site for the highest versus lowest level of intake and for an increment of 10 µg/day of dietary acrylamide, through fixed-effects or random-effects models, depending on the heterogeneity test. Fourteen cancer sites could be examined. No meaningful associations were found for most cancers considered. The summary RRs for high versus low acrylamide intake were 0.87 for oral and pharyngeal, 1.14 for esophageal, 1.03 for stomach, 0.94 for colorectal, 0.93 for pancreatic, 1.10 for laryngeal, 0.88 for lung, 0.96 for breast, 1.06 for endometrial, 1.12 for ovarian, 1.00 for prostate, 0.93 for bladder and 1.13 for lymphoid malignancies. The RR was of borderline significance only for kidney cancer (RR = 1.20; 95% confidence interval, CI, 1.00-1.45). All the corresponding continuous estimates ranged between 0.95 and 1.03, and none of them was significant. Among never-smokers, borderline associations with dietary acrylamide emerged for endometrial (RR = 1.23; 95% CI, 1.00-1.51) and ovarian (RR = 1.39; 95% CI, 0.97-2.00) cancers. This systematic review and meta-analysis of epidemiological studies indicates that dietary acrylamide is not related to the risk of most common cancers. A modest association for kidney cancer, and for endometrial and ovarian cancers in never smokers only, cannot be excluded.

The modifying effect of CYP2E1, GST, and mEH genotypes on the formation of hemoglobin adducts of acrylamide and glycidamide in workers exposed to acrylamide.

This study assesses the association of acrylamide (AA) and glycidamide (GA) hemoglobin adducts (AAVal and GAVal) and their ratios with genetic polymorphisms of the metabolic enzymes cytochrome P450 2E1 (CYP2E1), exon 3 and 4 of microsomal epoxide hydrolase (mEH3 and mEH4), glutathione transferase theta (GSTT1), and mu (GSTM1) or/and the combinations of these polymorphisms, involved in the activation and detoxification of AA in humans. Fifty-one AA-exposed workers and 34 controls were recruited and provided a post-shift blood sample. AAVal and GAVal were determined simultaneously using isotope-dilution liquid chromatography-electronspray ionization/tandem mass spectrometry (LC-ESI-MS/MS). Genetic polymorphisms of CYP2E1, mEH3 and 4, GSTT1, and GSTM1 were also analyzed. Our results reveal that the GAVal/AAVal ratio, potentially reflecting the proportion of AA metabolized to GA, ranged from 0.13 to 0.45 with a mean at 0.27. Multivariate regression analysis demonstrates that the joint effect of CYP2E1, GSTM1, and mEH4 genotypes was significantly associated with AAVal and GAVal levels after adjustment for AA exposures. These results suggest that mEH4 and the combined genotypes of CYP2E1, GSTM1 and mEH4 may be associated with the formation of AAVal and GAVal. Further studies may be needed to shed light on the roles that phase I and II enzymes play in AA metabolism.

Should veterinarians consider acrylamide that potentially occurs in starch-rich foodstuffs as a neurotoxin in dogs?

Three clinically healthy Labrador puppies developed ataxia, hypermetria and convulsions shortly after eating the burnt crust of maize porridge. Two of the puppies died. Acrylamide toxicity was considered based on the history of all 3 puppies developing nervous signs after being exposed to a starch-based foodstuff that was subjected to high temperature during preparation. Acrylamide-induced neurotoxicity is thought to partially result from a distal axonopathy.

Association of CYP2E1, GST and mEH genetic polymorphisms with urinary acrylamide metabolites in workers exposed to acrylamide.

This study elucidates the association of acrylamide metabolites, N-acetyl-S-(2-carbamoylethyl)-cysteine (AAMA), N-acetyl-S-(1-carbamoyl-2-hydroxyethyl)-cysteine (GAMA2), and N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-cysteine (GAMA3) in urine with genetic polymorphisms of the metabolic enzymes cytochrome P450 2E1 (CYP2E1), microsomal epoxide hydrolase (mEH) in exon 3 and exon 4, glutathione transferase theta (GSTT1) and mu (GSTM1), involved in the activation and detoxification of acrylamide (AA) in humans. Eighty-five workers were recruited, including 51 AA-exposed workers and 34 administrative staffs serve as controls. Personal air sampling was performed for the exposed workers. Each subject provided pre- and post-shift urine samples and blood samples. Urinary AAMA, GAMA2 and GAMA3 levels were simultaneously quantified using liquid chromatography-electronspray ionization/tandem mass spectrometry (LC-ESI-MS/MS). CYP2E1, mEH (in exon 3 and exon 4), GSTT1, and GSTM1 were analyzed using polymerase chain reaction (PCR). Our results reveal that AA personal exposures ranged from 4.37 × 10⁻³ to 113.61 µg/m³ with a mean at 15.36 µg/m³. The AAMA, GAMA2, and GAMA3 levels in the exposed group significantly exceeded those in controls. The GAMAs (the sum of GAMA2 and GAMA3)/AAMA ratios, potentially reflecting the proportion of AA metabolized to glycidamide (GA), varied from 0.003 to 0.456, and indicate high inter-individual variability in the metabolism of AA to GA in this study population. Multivariate regression analysis demonstrates that GSTM1 genotypes significantly modify the excretion of urinary AAMA and the GAMAs/AAMA ratio, exon 4 of mEH was significantly associated with the urinary GAMAs levels after adjustment for AA exposures. These results suggest that mEH and/or GSTM1 may be associated with the formation of urinary AAMA and GAMAs. Further study may be needed to shed light on the role of both enzymes in AA metabolism.

Exposure to acrylamide and human cancer--a review and meta-analysis of epidemiologic studies.

BACKGROUND: Acrylamide has been associated to cancer risk in rodents, but data on humans are inconclusive. We thus carried out a critical review and meta-analysis of studies of exposure to acrylamide and cancer. METHODS: We identified 586 publications, 25 presented relevant results. We conducted meta-analyses of studies of dietary intake based on random-effects models by calculating pooled relative risks (RR) and the corresponding 95% confidence intervals (CI). We combined results of occupational studies according to a fixed-effect model. RESULTS: The summary RRs for an increase of 10 µg/day of acrylamide intake were close to unity for all the cancers considered, ranging from 0.98 for esophageal cancer to 1.01 for colon, endometrial, ovarian and kidney cancer. None of the estimates was significant. Exclusion of one case-control study from Sweden resulted in a summary RR of kidney cancer of 1.04 (95% CI 1.00-1.08). The combined standardized mortality ratios for high occupational exposure were 1.67 (95% CI 0.83-2.99) for pancreatic cancer and 2.22 (95% CI 0.81-4.84) for kidney cancer. CONCLUSIONS: Available studies consistently suggest a lack of an increased risk of most types of cancer from exposure to acrylamide. The main association that requires further monitoring involves kidney cancer.

A prospective study on dietary acrylamide intake and the risk for breast, endometrial, and ovarian cancers.

BACKGROUND: Acrylamide is a probable human carcinogen formed during cooking of many common foods. Epidemiologic studies on acrylamide and breast cancer risk have been null; however, positive associations with ovarian and endometrial cancers have been reported. We studied acrylamide intake and risk for breast, endometrial, and ovarian cancers in a prospective cohort study. METHODS: We assessed acrylamide intake among 88,672 women in the Nurses' Health Study using food frequency questionnaires administered every 4 years. Between 1980 and 2006, we identified 6,301 cases of invasive breast cancer, 484 cases of invasive endometrial adenocarcinoma, and 416 cases of epithelial ovarian cancer. We used Cox proportional hazards models to study the association between acrylamide and cancer risk. RESULTS: We found no association between acrylamide intake and breast cancer overall or according to estrogen and progesterone receptor status. We found an increased risk for endometrial cancer among high acrylamide consumers (adjusted relative risk for highest versus lowest quintile = 1.41; 95% CI, 1.01-1.97; P for trend = 0.03). We observed a nonsignificant suggestion of increased risk for ovarian cancer overall (relative risk, 1.25; 95% CI, 0.88-1.77; P trend = 0.12), with a significantly increased risk for serous tumors (relative risk, 1.58; 95% CI, 0.99-2.52; P trend = 0.04). Associations did not differ by smoking status. CONCLUSIONS: We observed no association between acrylamide and breast cancer. Risk for endometrial cancer and possibly ovarian cancer was greater among high acrylamide consumers. IMPACT: This is the second prospective study to report positive associations with endometrial and ovarian cancers. These associations should be further evaluated to inform public health policy.

[Effects of tacrolimus (FK506) on heat-shock proteins 70, Bcl-2 and Bax expression in nervous tissue of acrylamide-induced rat].

OBJECTIVE: To investigate the effects of tacrolimus (FK506) on behavioral function and heat-shock proteins (HSP70) expression in nervous tissues of acrylamide (ACR)-induced rats. METHODS: Totally 40 health Wistar rats were randomly divided into control group, model group, low and high doses of FK506 groups. All four groups were treated five times per week for four weeks. Gait score was measured every week. And rats were sacrificed on day 28, the cerebrum, spinal cord and sciatic nerve were dissected, and homogenized in ice bath, then the levels of HSP70 and Bcl-2, Bax were analyzed by western bloting. RESULTS: Compared with the ACR model group, the gait score in low and high doses of FK506 groups decreased by 30.1% and 47.7% respectively in the 4th week. In the cerebrum and sciatic nerve pellet, the level of HSP70 in the FK506 groups increased by 11.6%, 33.3% and 56.3%, 58.5% (P < 0.01), but no significant changes existed in spinal cord. The level of Bcl-2 in the sciatic nerve pellet increased by 39.1% (P < 0.01) but no significant changes existed in the cerebrum and spinal cord from low dose of FK506 group. And the level of Bax in the spinal cord pellet markedly increased by 46.8% but not in cerebrum and sciatic nerve pellet; Whereas in the tissues mentioned above, the levels of Bcl-2 were enhanced remarkably by 16.3%, 14.8% and 56.0% (P < 0.01) in the high dose of FK506 group. And the level of Bax in the cerebrum and spinal cord pellet markedly increased by 16.4% and 40.2% but not in sciatic nerve. The values of Bcl-2/Bax in low and high doses of FK506 groups clearly increased by 15.9%, 33.3%, 36.9% and 30.1%, 49.1%, 60.1% (P < 0.01). CONCLUSION: The administration of FK506 has dramatically neuroprotective effects against the development of ACR neuropathy, which may be related to up-regulating the expression of HSP70 and Bcl-2 with down-regulating the expression of Bax.

A prospective study of dietary acrylamide intake and the risk of endometrial, ovarian, and breast cancer.

BACKGROUND: Acrylamide, a probable human carcinogen, was detected in various heat-treated carbohydrate-rich foods in 2002. The few epidemiologic studies done thus far have not shown a relationship with cancer. Our aim was to investigate the association between acrylamide intake and endometrial, ovarian, and breast cancer risk. METHODS: The Netherlands Cohort Study on diet and cancer includes 62,573 women, aged 55-69 years. At baseline (1986), a random subcohort of 2,589 women was selected using a case cohort analysis approach for analysis. The acrylamide intake of subcohort members and cases was assessed with a food frequency questionnaire and was based on chemical analysis of all relevant Dutch foods. Subgroup analyses were done for never-smokers to eliminate the influence of smoking; an important source of acrylamide. RESULTS: After 11.3 years of follow-up, 327, 300, and 1,835 cases of endometrial, ovarian, and breast cancer, respectively, were documented. Compared with the lowest quintile of acrylamide intake (mean intake, 8.9 mug/day), multivariable-adjusted hazard rate ratios (HR) for endometrial, ovarian, and breast cancer in the highest quintile (mean intake, 40.2 mug/day) were 1.29 [95% confidence interval (95% CI), 0.81-2.07; P(trend)=0.18], 1.78 (95% CI, 1.10-2.88; P(trend)=0.02), and 0.93 (95% CI, 0.73-1.19; P(trend)=0.79), respectively. For never-smokers, the corresponding HRs were 1.99 (95% CI, 1.12-3.52; P(trend)=0.03), 2.22 (95% CI, 1.20-4.08; P(trend)=0.01), and 1.10 (95% CI, 0.80-1.52; P(trend)=0.55). CONCLUSIONS: We observed increased risks of postmenopausal endometrial and ovarian cancer with increasing dietary acrylamide intake, particularly among never-smokers. Risk of breast cancer was not associated with acrylamide intake.

Dietary acrylamide and human cancer.

Low levels of acrylamide have been found in several foods cooked at high temperatures. While there is sufficient evidence for the carcinogenicity of acrylamide in experimental animals, the few epidemiologic studies conducted to date on occupational and dietary exposure to acrylamide have found no consistent evidence of association with human cancer risk. Using data from an integrated network of Italian and Swiss hospital-based case-control studies, we analyzed the relation between dietary acrylamide intake and cancers of the oral cavity and pharynx (749 cases, 1,772 controls), esophagus (395 cases, 1,066 controls), large bowel (1,394 cases of colon, 886 cases of rectal cancer, 4,765 controls), larynx (527 cases, 1,297 controls), breast (2,900 cases, 3,122 controls), ovary (1,031 cases, 2,411 controls) and prostate (1,294 cases, 1,451 controls). All the studies included incident, histologically confirmed cancer cases and controls admitted to the same network of hospitals for acute nonneoplastic conditions. We calculated odds ratios (ORs) using multivariate logistic regression models, adjusted for energy intake and other major covariates of interest. The ORs for the highest versus the lowest quintile of acrylamide intake were 1.12 (95% CI = 0.76-1.66) for cancer of the oral cavity/pharynx, 1.10 (95% CI = 0.65-1.86) for esophageal, 0.97 (95% CI = 0.80-1.18) for colorectal, 1.23 (95% CI = 0.80-1.90) for laryngeal, 1.06 (95% CI = 0.88-1.28) for breast, 0.97 (95% CI = 0.73-1.31) for ovarian and 0.92 (95% CI = 0.69-1.23) for prostate cancer. None of the trend in risk was significant. This uniquely large and comprehensive data set does not show any consistent association between intake of acrylamide and the risk of breast and several other common cancers.

Prospective study of dietary acrylamide and risk of colorectal cancer among women.

There has been considerable discourse about whether exposure to acrylamide in foods could increase the risk of human cancer. Acrylamide is classified as a probable human carcinogen, and animal studies have demonstrated an increased incidence of tumors in rats exposed to very high levels. Still, epidemiologic data of the effect of dietary acrylamide remain scant. We have undertaken the first prospective study of acrylamide in food and risk of colon and rectal cancers using prospective data from the Swedish Mammography Cohort. The cohort comprised 61,467 women at baseline between 1987 and 1990. Through 2003, the cohort contributed 823,072 person-years, and 504 cases of colon and 237 of rectal cancer occurred. Mean intake of acrylamide through diet was 24.6 mug/day (Q25-70 = 18.7-29.9). Coffee (44%), fried potato products (16%), crisp bread (15%) and other breads (12%) were the greatest contributors. After adjusting for potential confounders, there was no association between estimated acrylamide intake and colorectal cancer. Comparing extreme quintiles, the adjusted relative risks (95% CI; p for trend) were for colorectal cancer 0.9 (0.7-1.3; p = 0.80), colon cancer 0.9 (0.6-1.4; p = 0.83) and rectal cancer 1.0 (0.6-1.8; p = 0.77). Furthermore, intake of specific food items with elevated acrylamide (e.g., coffee, crisp bread and fried potato products) was not associated with cancer risk. In this large prospective study, we found no evidence that dietary intake of acrylamide is associated with cancers of the colon or rectum. Epidemiologic studies play an important role in assessing the possible health effects of acrylamide intake through food.

Determination of the major mercapturic acids of acrylamide and glycidamide in human urine by LC-ESI-MS/MS.

We developed a LC-MS/MS method for the quantitative determination of the mercapturic acid (MA) metabolites of acrylamide (AA) AAMA and of its oxidative metabolite glycidamide (GA) GAMA in urine samples from the general population. The method requires 4 mL of urine which is solid phase extracted prior to LC-MS/MS analysis. The metabolites are detected by ESI-tandem mass spectrometry in negative ionisation mode and quantified by isotope dilution. Detection limits ranged down to 1.5 microg/L urine for both AAMA and GAMA. The imprecision expressed as R.S.D. lay between 2% and 6% for both analytes (intra- and inter-assay). First results on a small group of 29 persons out of the general population ranged from 5 to 338 microg/L AAMA and

Neuropathology of skin denervation in acrylamide-induced neuropathy.

Previous studies have established the neurotoxicity and pathology of acrylamide to large-diameter nerves. It remains unclear (1) whether small-diameter sensory nerves are vulnerable to acrylamide and (2) if so, how the pathology evolves during intoxication. We investigated the influence of acrylamide on small-diameter sensory nerves by studying the pathology of sensory nerve terminals in the skin. The neurotoxic effects of acrylamide (400 ppm in drinking water) on mice were assessed by immunostaining the skin with protein gene product 9.5, a ubiquitin C-terminal hydrolase, particularly useful for demonstrating cutaneous nerve terminals. Within 5 days of acrylamide administration (the initial stage), epidermal nerves showed two major changes: (1) terminal swelling and (2) increased branching. There was a progressive reduction in epidermal nerve density (END) thereafter. Fifteen days after acrylamide intoxication (the late stage), reduction in END became evident (25.22 +/- 2.19 fibers/mm vs 41.74 +/- 2.60 fibers/mm in control mice, P < 0.003). At this stage, there was significant dermal nerve degeneration with ultrastructural demonstrations of vacuolar changes. These findings establish the pathological consequences of acrylamide neurotoxicity in cutaneous sensory nerves with far-reaching implications: (1) providing an animal system to study "dying-back" pathology of nociceptive nerves and (2) forming the ultrastructural foundation for interpreting the pathology of cutaneous nerve degeneration in skin biopsies.

[Effect of acrylamide on creatine kinase and adenosine triphosphate in brain of mice and its significance].

OBJECTIVE: To explore the changes of brain energy metabolism following acrylamide (ACR) poisoning. METHODS: Creatie kinase (CK), adenosine triphosphate (ATP), adenosine diphosphate(ADP), adenosine 5'-monophosphate(AMP) and glucose contents in brain were observed in O1a mice and 6J mice following ACR intoxication by enzyme analytical method. RESULTS: ATP, CK and glucose levels decreased transiently in O1a mice, while ATP level in 6J mice was significantly decreased (1.76 mumol/g, P < 0.01), as compared to the control (2.53 mumol/g) but ADP and AMP were increased, glucose was decreased. The activity of CK in poisoned group (1.13 mumol/g, P < 0.01) was lower than that of control (3.16 mumol/g and lasted for 5 weeks). CONCLUSION: The influence of ACR on O1a mice was slight and reversible but on 6J mice was severe and lasting. There was severe damage to the potential energy supply compensation, which might be the biochemical basis of neuron damage induced by acrylamide.