Acrylamide exposure induces growth retardation, neurotoxicity, stress, and immune/antioxidant disruption in Nile tilapia (Oreochromis niloticus): The alleviative effects of Chlorella vulgaris diets

This study looked at the toxic impacts of water-born acrylamide (ACR) on Nile tilapia (Oreochromis niloticus) in terms of behaviors, growth, immune/antioxidant parameters and their regulating genes, biochemical indices, tissue architecture, and resistance to Aeromonas hydrophila. As well as the probable ameliorative effect of Chlorella vulgaris (CV) microalgae as a feed additive against ACR exposure was studied. The 96-h lethal concentration 50 of ACR was investigated and found to be 34.67 mg/L for O. niloticus. For the chronic exposure study, a total of 180 healthy O. niloticus (24.33 ± 0.03 g) were allocated into four groups in tri-replicates (15 fish/replicate), C (control) and ACR groups were fed a basal diet and exposed to 0 and 1/10 of 96-h LC50 of ACR (3.46 mg/L), respectively. ACR+ CV5 and ACR+ CV10 groups were fed basal diets with 5 % and 10 % CV supplements, respectively and exposed to 1/10 of 96-h LC50 of ACR for 60 days. After the exposure trial (60 days) the experimental groups were challenged with A. hydrophila. The findings demonstrated that ACR exposure induced growth retardation (P˂0.01) (lower final body weight, body weight gain, specific growth rate, feed intake, protein efficiency ratio, final body length, and condition factor as well as higher feed conversion ratio). A substantial decrease in the immune/antioxidant parameters (P˂0.05) (lysozyme, serum bactericidal activity %, superoxide dismutase, and reduced glutathione) and neurotransmitter (acetylcholine esterase) (P˂0.01) was noticed with ACR exposure. A substantial increase (P˂0.01) in the serum levels of hepato-renal indicators, lipid peroxidation biomarker, and cortisol was noticed as a result of ACR exposure. ACR exposure resulted in up-regulation (P˂0.05) of the pro-inflammatory cytokines and down-regulation (P˂0.05) of the antioxidant-related gene expression. Furthermore, the hepatic, renal, brain, and splenic tissues were badly affected by ACR exposure. ACR-exposed fish were more sensitive to A. hydrophila infection and recorded the lowest survival rate (P˂0.01). Feeding the ACR-exposed fish with CV diets significantly improved the growth and immune/antioxidant status, as well as modulating the hepatorenal functions, stress, and neurotransmitter level compared to the exposed-non fed fish. In addition, modulation of the pro-inflammatory and antioxidant-related gene expression was noticed by CV supplementation. Dietary CV improved the tissue architecture and increased the resistance to A. hydrophila challenge in the ACR-exposed fish. Noteworthy, the inclusion of 10 % CV produced better results than 5 %. Overall, CV diets could be added as a feed supplement in the O. niloticus diet to boost the fish's health, productivity, and resistance to A. hydrophila challenge during ACR exposure.

Acrylamide toxicity in aquatic animals and its mitigation approaches: an updated overview

Acrylamide (ACR) is widely applied in various industrial activities, as well as in the water purification process. Furthermore, ACR is synthesized naturally in some starchy grains exposed to high temperatures for an extended time during the cooking process. Because of its widespread industrial usage, ACR might be released into water stream sources. Also, ACR poses a high risk of contaminated surface and ground-water resources due to its high solubility and mobility in water. Furthermore, animal studies have indicated that ACR exposure may cause cancer (in many organs such as lung, prostate, uterus, and pancreas), genetic damage (in both somatic and germ cells), and severe effects on reproduction and development. Recently, numerous studies have shown that ACR has a mild acute cytotoxic impact on aquatic species, particularly during early life stages. Besides, wide-spectrum usage of ACR in many industrial activities presented higher environmental risks as well as major hazards to consumer health. This literature was designed to include all potential and accessible reports on ACR toxicity related with aquatic species. The Preferred Reporting Items for Systematic Reviews were applied to evaluate the risk effects of ACR on aquatic organisms, the ACR sub-lethal concentration in the ecosystem, and the possible protective benefits of various feed additives against ACR toxicity in fish. The major findings are summarized in Tables 2 and 3. The primary aim of this literature was to specify the hazards of ACR toxicity related with fish welfare and possible suggested strategies to reduce its risks.

Neurotoxicity of acrylamide in adult zebrafish following short-term and long-term exposure: evaluation of behavior alterations, oxidative stress markers, expression of antioxidant genes, and histological examination of the brain and eyes

In the present work, 224 adult female zebrafish (56 fish in each group) were randomly divided into four groups (two control groups and two toxicity groups) as per duration of exposure (7 and 21 days). All fish of the two toxicity groups were exposed to 0.610 mM acrylamide (ACR) concentration for 7 and 21 days. The effects of ACR exposure on behavior, oxidative stress biomarkers, molecular expression of antioxidant genes (sod, cat, and nrf2), and histopathological examination of the brain and eye were examined. Our result shows that ACR exposure for 7 days produced an anxiety-like behavior in zebrafish. Short-term exposure of ACR resulted in alterations of oxidative stress markers (SOD and CAT activity, and the level of GSH and MDA) in the brain and eye of zebrafish. However, the antioxidant defense system of adult female zebrafish could be able to counteract the free radicals generated in long-term ACR exposure as indicated by non-significant difference in oxidative insult following short-term and long-term exposure. ACR exposure downregulated the mRNA expression of the sod, cat, and nrf2 (nuclear factor erythroid 2-related factor 2) genes in the brain and eye without significant difference between the two toxicity groups. Mild histological changes in the dorsal telencephalic area, tectum opticum, medulla, and hypothalamus area of the brain of zebrafish have been observed following short-term and long-term ACR exposure. In the eye, marked histological changes in the retinal pigmented epithelium layer (RPE), structural changes of the photoreceptor layer (PRL) with disorganized layer of rods and cones, and reduction of the relative thickness of the RPE, PRL, outer nuclear layer (ONL), and inner nuclear layer (INL) have been noted following ACR exposure for 21 days as compared to 7 days. ACR produced neurobehavioral aberrations and oxidative stress within 7 days of exposure, while various histological changes in the brain and eyes have been observed following long-term exposure (21 days) to ACR.

The potential adverse effects of acrylamide on the oxidative stress response, fatty acids profile, and histopathological aspect of the Mediterranean Holothuria forskali respiratory tree

Acrylamide (ACR), organic compound, has been widely used owing to its broad spectrum of chemical and industrial applications. This study aims at evaluating the response of the antioxidant defense system, fatty acid composition and histopathological aspect in the respiratory trees of Holothuria forskali against ACR exposure under laboratory conditions. Holothuries were exposed to 5, 10, and 20 mg L^-1 ACR concentrations for 5 days. A significant increase in n-6 polyunsaturated fatty acids levels especially the arachidonic acid (ARA, C20:4n-6) and its precursor linoleic acid (LA, C18:2n-6) in ACR-treated organisms. Regarding the n-3 levels, eicosapentaenoic acid (EPA, C20:5n-3) levels were increased in treated groups despite an acute decrease in docosahexaenoic acid (DHA, C22:6n-3) levels was observed. Our results showed a significant increase in hydrogen peroxide, malondialdehyde, protein carbonyl, and metallothionein levels along with an alteration of the antioxidants status in all treated sea cucumbers. The exposure to ACR prompted the inhibition of Acetylcholinesterase activity in a concentration-dependent manner. The histopathological aspect was marked especially with the infiltration of coelomic cells which confirms our biochemical findings. Our study provided novel insights to create a link between redox status and fatty acid composition disruptions to better understand ACR-triggered toxicity.

Acute and sublethal effects of acrylamide on the freshwater fish Anabas testudineus (Bloch, 1792)

Acrylamide, a synthetic compound, has a wide range of industrial applications that find multiple ways to reach aquatic ecosystem. The median lethal concentration of acrylamide determined using probit analysis in the fish Anabas testudineus was 132 µg L^-1 concentration together with altered behavioral patterns. Hematological and antioxidant status was evaluated at a sublethal concentration (one-tenth of LC₅₀-96 h), i.e., 13.2 µg L^-1 concentration for 24, 48, 72, and 96 h. A reduction in erythrocytes count, hemoglobin content, and packed cell volume with a significant (P < 0.05) increase in leukocyte counts and differential counts were observed. Erythrocyte indices like mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) increased, whereas the mean corpuscular hemoglobin concentration (MCHC) showed a significant (P < 0.05) decrease when compared with control groups. The activities of superoxide dismutase, catalase, and glutathione reductase in gill tissues showed significant (P < 0.05) reduction, whereas the levels of hydrogen peroxide and lipid peroxidation increased significantly (P < 0.05) indicating oxidative stress. The findings suggest that acrylamide at sublethal concentration caused alteration in hematological parameters and induced oxidative stress in gill tissue of the fish A. testudineus. Hence, restrictions on the use of acrylamide in food and industrial products are recommended since humans are the direct consumer of fish products.

Borax relieved the acrylamide-induced hematotoxic, hepatotoxic, immunotoxic and genotoxic damages in rainbow trout by regulating apoptosis and Nrf2 signaling pathway

Acrylamide(AA) is a compound with wide usage areas including paper, dyes, and plastics industries. Due to its broad spectrum and water solubility suggest that this vinyl compound may cause serious environmental problems. AA was shown to exhibit neurotoxic, immunotoxic, reproductive toxicant as well as carcinogenic potency on animals. Especially in recent years, the therapeutic effects of boron and boron containing compounds like borax(BX), ulexite(ULX) and colemanite(COL) had been reported. However, the ameliorative potential by boron compounds against AA-induced toxicities had not been investigated yet. Therefore, in this investigation rainbow trout were exposed acutely to AA in the presence and absence of BX. The hematological indices and genotoxic end-points were examined in the fish blood tissue. In addition to oxidative stress response, the levels of DNA damage, CASP3, TNF-α, Nrf-2 as well as IL-6 amounts were determined in both blood and liver tissues of fish. The obtained results executed that AA induced toxic conditions in both tissues. In fact, an increase in the amount of oxidative stress and ROS, and a decrease in GSH levels were observed. AA exposure led to an increase in CASP3levels and 8-OHdG formation. It was also found that Nrf-2 pathway contributed to the initiation of oxidative stress that associated with AA-induced toxicity. On the contrary, our findings indicated that co-exposure of BX with AA elicited oxidative stress and cell death. In a conclusion BX was suggested as a useful and effective natural agent for the prevention and early treatment of AA toxicity in fish.

The insulin gene as an energy homeostasis biomarker in Yangtze sturgeon (Acipenser dabryanus)

Insulin plays an important role in maintaining energy homeostasis and has the potential to be an indicator of energy homeostasis in the Yangtze sturgeon, Acipenser dabryanus. In this study, the Yangtze sturgeon insulin (Adinsulin) was cloned and characterized. To evaluate the possibility of insulin as an energy state assessment indicator, quantification real-time PCR (qRT-PCR) was used to evaluate expression changes in different tissues (the whole brain, esophagus, cardiac stomach, pyloric stomach, pyloric caeca, duodenum, valvula intestine, rectum, liver, pancreas, spleen, kidney, heart, muscle, gill and eye) from 6 fish (average weight 325.7 ± 22.3 g) and in three experiments including postprandial, fasting and re-feeding, and glucose tolerance treatment in which fish were divided into two groups including a group that administered a glucose solution (1 ul/g body weight) and another group that administered sterile water as control. In these three experiments, 6 fish were sampled, respectively, then been used to evaluate expression changes of insulin. All fish in feeding groups were fed in tanks (60.0 cm × 50.0 cm × 40.0 cm) with a commercial diet (crude protein ≥ 40%, crude fat ≥ 12%, coarse fiber ≤ 6%, crude ash ≤ 18%; TONGWEI CO., LTD, China) once a day at 16:00. The result showed that Adinsulin was highly expressed in the pancreas, which was the basis for the next experiment to use the pancreas as the test target. Adinsulin expression significantly increased 1 h after feeding and decreased rapidly after 3 h of feeding, but it was still significantly higher than that of the group without feeding (P < 0.01). Compared to the feeding group, the expression of Adinsulin was significantly reduced in the fasting group of 3 days (P < 0.01), 6 days (P < 0.01), 10 days (P < 0.05), 11 days (P < 0.05) and 13 days (P < 0.01) and was no significant difference in re-feeding for 1st day, 2nd day and 4th day, but there was difference between re-feeding group and fasting group. After glucose tolerance treatment, serum glucose levels increased significantly (P < 0.05), accompanied by a significant increase (P < 0.001) in insulin expression. This study result shows that insulin has the capacity to measure the energy homeostasis of Yangtze sturgeon. Further development of detection methods for sturgeon plasma or serum insulin will avoid slaughtering animals and is more practical in energy homeostasis assessment.

Comprehensive analysis of metabolic changes in rats exposed to acrylamide

Acrylamide (ACR) is a widely used environmentally hazardous compound that is known to be neurotoxic, genotoxic, carcinogenic, and reproductive toxicity. It is widely present in soil, water, agents used in chemical industries, and food. It can be distributed to all organs and tissues, and can cause damage to various human systems and those of other animals. Previous metabolomics studies have mainly focused on metabolites in serum and urine, but have lacked comprehensive analysis of major organs and tissues. In the current study, a gas chromatography-massspectrometry method was used to investigate mechanisms underlying organ toxicity, in an effort to identify potentially sensitive biomarkers in the main target tissues of rats after ACR exposure. Male Sprague-Dawley rats were assigned to two groups; a control group and a group treated with 20 mg kg^-1 ACR intragastrically for 6 weeks. Metabolite changes in the two groups were statistically analyzed. The respective numbers of altered metabolites in the hippocampus, cortex, kidney, serum, heart, liver, and kidney fat were 21, 21, 17, 5, 15, 14, and 6. There were 14 metabolic pathways related to amino acid, fatty acid, purine, and energy metabolism, revealing that the toxic mechanism of ACR may involve oxidative stress, inflammation, and amino acid metabolism and energy disorders.

The adverse effects of acrylamide exposure on the early development of marine medaka (Oryzias melastigma) and its mechanisms

Acrylamide (AA) can have deleterious effects on freshwater fish. However, its adverse effects on euryhaline fish are still unknown. In this study, embryos of Oryzias melastigma were exposed to different concentrations of AA to investigate its effect on early developmental disorders. After 21 days of exposure, AA significantly inhibited the hatching rate and delayed the hatching time of embryos, and led to developmental delay, teratogenesis, and locomotion impairments in larvae. RNA-sequencing data of larvae indicated that AA upregulated the expression of hemoglobin and myoglobin involved in oxygen transport and angiopoietin 1, integrin, and matrix metallopeptidases related to angiogenesis and downregulated the expression of early growth response genes and synaptotagmin-2 related to neural plasticity and neurotransmitter release. Overall, our study showed that AA caused deleterious effects on the early development of euryhaline fish through hypoxic stress and neurotoxicity, providing a scientific basis for the environmental risk assessment of marine AA.

Acrylamide-induced hematotoxicity, oxidative stress, and DNA damage in liver, kidney, and brain of catfish (Clarias gariepinus)

This study was carried out to explore the possible deleterious impacts of acrylamide (ACR) on catfish (Clarias gariepinus). The estimation of mortalities, the examination of the clinical picture, the evaluation of blood parameters, oxidative stress, DNA damage, and the histopathological picture were performed in the liver, kidney, and brain samples of the experimentally ACR-exposed catfish. The 96 hours LC₅₀ value was estimated to be 133 mg/L by the hydrostatic method. Fish were reared in water containing four different concentrations of ACR as follows: 20%, 40%, 60%, and 80% of the estimated LC₅₀ for 2 weeks. Abnormal behavioral, clinical, and postmortem responses were depicted. The anemic response including significant decreases in red blood cells, hemoglobin, and packed cell volume following the ascending concentrations of ACR were recorded. The malondialdehyde was significantly increased, whereas reduced glutathione level, superoxide dismutase, and total antioxidant capacity were significantly decreased. The DNA fragmentation assay illustrated a clear laddering pattern in all the tested organs. Notably, the brain was the most influenced organ. It is presumed that ACR contamination showed adverse impacts on the catfish.

Metabonomics analysis of liver in rats administered with chronic low-dose acrylamide

The current study aimed to investigate the hepatotoxicity of rats administered with chronic low-dose acrylamide (AA) by using metabonomics technology on the basis of ultraperformance liquid chromatography-mass spectrometry (UPLC-MS). A total of 40 male Wistar rats were randomly divided into the following four groups: control, low-dose AA (0.2 mg/kg bw, non-carcinogenic end-point based on the induction of morphological nerve changes in rats), middle-dose AA (1 mg/kg bw), and high-dose AA (5 mg/kg bw). The rats continuously received AA by administering it in drinking water daily for 16 weeks. After the treatment, rat livers were collected for metabonomics analysis and histopathology examination. Principal components analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) were used to investigate the metabonomics profile changes in rat liver tissues and screen the potential biomarkers.Fourteen metabolites were identified with significant changes in intensities (increased or decreased compared with the control group) as a result of treatment (p < 0.05 or p < 0.01). These metabolites included tauro-b-muricholic acid, docosapentaenoic acid, sphingosine 1-phosphate, taurodeoxycholic acid, lysoPE(20:5), cervonyl carnitine, linoleyl carnitine, docosahexaenoic acid, lysoPC(20:4), lysoPE(18:3), PA(20:4), stearidonyl carnitine, alpha-linolenic acid, and lysoPA(18:0).Results showed that chronic exposure to AA at NOAEL (0.2 mg/kg bw) exhibited no toxic effect in rat livers at the metabolic level. AA induced oxidative stress to the liver and disrupted lipid metabolism. The results of liver histopathology examination further supported the metabonomic results.

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.

Acrylamide induces locomotor defects and degeneration of dopamine neurons in Caenorhabditis elegans

Acrylamide can form in foods during the cooking process and cause multiple adverse effects. However, the neurotoxicity and mechanisms of acrylamide have not been fully elucidated. In Caenorhabditis elegans, we showed that 48 h exposure to 10-625 mg l(-1) acrylamide resulted in a significant decline in locomotor frequency of body bending, head thrashing and pharynx pumping. In addition, acrylamide exposure reduced crawling speeds and changed angles of body bending. It indicates that acrylamide induces locomotor defects, along with parkinsonian-like movement impairment, including bradykinesia and hypokinesia. Acrylamide also affected chemotaxis plasticity and reduced learning ability. Using transgenic nematodes, we found that acrylamide induced downexpression of P(dat-1) and led to the degeneration of dopaminergic neurons. Moreover, the enhanced expression of unc-54, encoding a subunit of α-synuclein was found. It illustrates that acrylamide is efficient in inducing crucial parkinsonian pathology, including dopaminergic damage and α-synuclein aggregation. These findings suggest the acrylamide-induced locomotor defects and neurotoxicity are associated with Parkinson's disease.