Toxicity Evaluation of Acrylamide on the Early Life Stages of the Zebrafish Embryos (<i>Danio rerio</i>)

Abstract

Acrylamide is a chemical used mainly in industrial applications and the treatment of drinking and wastewater, making it easy to enter aquatic ecosystems. There are few studies known about the toxicity of acrylamide to aquatic organisms which have shown evidence of a number of histopathological effects. To assess the effects of acrylamide to freshwater fish, Zebrafish (Danio rerio) embryos were exposed to serial concentrations of acrylamide (0, 100, 300, and 500 mg/L) to investigate the acute toxicity effects on teleost embryogenesis. Embryos less than 24 hrs old were exposed under static non-renewal conditions for ten days or until hatching. The toxic endpoints evaluated include: egg/embryo viability, hatchability, and morphological/developmental anomalies during organogenesis. The acute toxicity test resulted in a 48 h-LC50 of 585 mg/L for egg viability. Exposure of embryos significantly reduced hatchability and larval survival, in a concentration dependent manner. Dimethyl sulfoxide (DMSO) was used as a solvent carrier to permeate the uptake of acrylamide through the chorion membrane. No significant damages or complications were observed in embryos exposed to DMSO. At 500 mg/L, the highest test concentration, the survival of embryos was greatly reduced within 24 hrs of exposure. The lower test, 100 mg/L, produced a significant number of developmental anomalies to the Zebrafish that included dorsal tail flexure, severe pericardial edema, facial and cranial defects and decreased heartrate (40 bpm). Premature hatching of embryos and developmental arrest was observed in all concentrations. The severity of these anomalies was concentration-dependent and resulted in low survival rate and high frequency of malformations. These results indicate that acrylamide is teratogenic and provide support for sub-lethal toxicity testing using Zebrafish embryos.

Developmental and Neurotoxicity of Acrylamide to Zebrafish

“…The early adverse physiological effects were observed in the yolk extension in the developing embryo, followed by pericardial yolk sac edema, swim bladder deficiency, and curvature of the body. Similar developmental abnormalities were reported in zebrafish embryos and larvae following psoralen exposure [17], indicating that organogenesis may be the developmental stage that is most sensitive to toxicants [36]. We found that the severity of these abnormalities increased with the acrylamide concentration and was accompanied by mortality [37].…”

“…Acrylamide also inhibited hatching with increasing concentration and duration of exposure. The reasons behind this could be due to the induction of developmental defects [36]. However, our results in 100 mg/L show that even malformation occurred, the hatching rate was not changed significantly.…”

“…Acrylamide treatment caused a concentration-dependent increase in developmental malformations in the zebrafish embryos, which occurred within 24 h of acrylamide exposure, indicating possible teratogenic effects [36]. The early adverse physiological effects were observed in the yolk extension in the developing embryo, followed by pericardial yolk sac edema, swim bladder deficiency, and curvature of the body.…”

“…Therefore, embryo mortality can be directly linked to the severity of developmental malformations. In addition, the reduced heart rate indicated cardiac dysfunction from pericardial edema [24,36] and included notable reductions in heartbeat. Pericardial edema formation collapses the yolk sphere, which prevents the heart from undergoing normal chamber formation [38].…”

“…71.08) was purchased from Sigma-Aldrich (A9099; St. Louis, MO, USA). Exposure concentrations of 10, 30, 100, and 300 mg/L (0.14, 0.42, 1.4 and 4.2 mM, respectively) were selected from previous studies [18,36]. For zebrafish, test solutions were prepared on the day of the experiment in E3 medium (0.292 g NaCl, 0.013 g KCl, 0.044 g CaCl, and 0.081 g MgSO 4 in 1 L) containing a 0.1% dimethyl sulfoxide (DMSO) solution.…”