Neurobehavioral and Oxidative Stress Effects of SiO2 Nanoparticles in Zebrafish and the Protective Role of N-Acetylcysteine

Abstract

Background/Objectives: Silicon dioxide nanoparticles (SiO₂NPs) do not exist in isolation in the environment but can interact with other substances, thus influencing their toxic effects on aquatic organisms. We assessed the combined impact of SiO₂NPs and N-acetylcysteine (NAC), an antioxidant with the potential to counteract nanoparticle-induced oxidative stress (OS). Methods: Behavioral assessments, including the social interaction test and color preference test, were performed to evaluate neurobehavioral changes. OS biomarkers, including malondialdehyde (MDA) levels for lipid peroxidation and the activity of key antioxidant enzymes such as glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD), were assessed to evaluate the extent of cellular damage. Results: The results indicate that prolonged exposure to SiO₂NPs induces significant behavioral disruptions, including reduced exploratory behavior and increased anxiety-like responses. Furthermore, biochemical analysis revealed increased OS, suggesting nanoparticle-induced cellular toxicity. NAC co-treatment partially reversed these effects, particularly improving locomotor outcomes and antioxidant response, but was less effective on social behavior. Conclusions: These findings highlight the ecological and health risks posed by SiO₂NPs and point toward the need for further toxicological studies on their long-term biological effects.

Keywords: N-acetylcysteine; color preference test; oxidative stress; silicon dioxide nanoparticles; social test; zebrafish.

Figure 1

Experimental design illustrating zebrafish exposure to SiO₂NPs and NAC, followed by behavioral, immunological, and oxidative stress assessments.

Figure 2

Effects of SiO₂NPs and NAC on the social preference of zebrafish in the T-maze test. (A) Total distance moved (cm). (B) Velocity (cm/s). The experimental groups include control, 500 µg/mL SiO₂NPs, 10 mg/L NAC, and the combined administration of 500 µg/mL SiO₂NPs and 10 mg/L NAC. Data are presented as mean ± standard deviation (SD) (n = 5/group). Statistical significance was assessed by ANOVA followed by Tukey’s correction for multiple comparisons. Asterisks indicate significance levels: * p < 0.05, ** p < 0.01.

Figure 3

Effects of SiO₂NPs and NAC on the social preference of zebrafish in the T-maze test. (A) Time spent in left arm (s). (B) Time spent in right arm (s). The experimental groups include control, 500 µg/mL SiO₂NPs, 10 mg/L NAC, and the combined administration of 500 µg/mL SiO₂NPs and 10 mg/L NAC. Data are presented as mean ± standard deviation (SD) (n = 5/group). Statistical significance was assessed by ANOVA followed by Tukey’s correction for multiple comparisons. Asterisks indicate significance levels: * p < 0.05, ** p < 0.01.

Figure 4

Effects of SiO₂NP and NAC administration on total distance moved (A), velocity (B), time spent in left arm (s) (C), and time spent in right arm (s) (D) in zebrafish during the color preference test. The experimental groups include control, 500 µg/mL SiO₂NPs, 10 mg/L NAC, and the combined administration of 500 µg/mL SiO₂NPs and 10 mg/L NAC. Data are presented as mean ± standard deviation (SD) (n = 5/group). Statistical significance was assessed by ANOVA followed by Tukey’s correction for multiple comparisons. Asterisks indicate significance levels: * p < 0.05, ** p < 0.01.

Figure 5

Effects of SiO₂NP and NAC administration on mobility cumulative duration (s) (A), and immobility cumulative duration (s) (B) The experimental groups include control, 500 µg/mL SiO₂NPs, 10 mg/L NAC, and the combined administration of 500 µg/mL SiO₂NPs and 10 mg/L NAC. Data are presented as mean ± standard deviation (SD) (n = 5/group). Statistical significance was assessed by ANOVA followed by Tukey’s correction for multiple comparisons. Asterisks indicate significance levels: ** p < 0.01.

Figure 6

Levels of oxidative stress markers in zebrafish tissue after exposure to 500 µg/mL SiO₂ nanoparticles, 10 mg/L N-acetylcysteine, and their combination (SiO₂NPs 500 µg/mL + NAC 10 mg/L). (A) Superoxide dismutase (SOD), (B) catalase (CAT), (C) glutathione peroxidase (GPx), and (D) malondialdehyde (MDA). Data are expressed as mean ± standard deviation (SD) (n = 3/group). Statistical significance was assessed by one-way ANOVA followed by Tukey’s post hoc test. Asterisks indicate significance levels: * p < 0.05, ** p < 0.01.