Vitamin C Attenuates Oxidative Stress and Behavioral Abnormalities Triggered by Fipronil and Pyriproxyfen Insecticide Chronic Exposure on Zebrafish Juvenile

Abstract

Chronic exposure to synthetic insecticides in the early life of a child can lead to a series of disorders. Several causes as parental age, maternal smoking, birth complications, and exposure to toxins such as insecticides on childhood can lead to Autism spectrum disorder (ASD) occurrence. The aim of this study was to evaluate the potential protective role of vitamin C (Vit. C) from children's supplements after 14 days chronic exposure to insecticide mixture fipronil (Fip) + pyriproxyfen (Pyr) on juvenile zebrafish for swimming performances, social behavior and oxidative stress associated with ASD model. Juvenile (14-17 mm) wild-type AB zebrafish (Danio rerio) (45 days) were exposed to relevant concentrations: vit. C (25 µg L^-1), Fip (600 µg L^-1/1.372 μM) + Pyr (600 µg L^-1/1.89 μM), and [Fip (600 µg L^-1/1.372 μM) + Pyr (600 µg L^-1 /1.89 μM)] + vit. C (25 µg L^-1). Our results showed that insecticides can disturb the social behavior of zebrafish during 14 days of the administration, decreased the swimming performances, and elevated the oxidative stress biomarkers of SOD (superoxide dismutase), GPx (glutathione peroxidase), and MDA (malondialdehyde). The vitamin C supplement significantly attenuated the neurotoxicity of insecticide mixture and oxidative stress. This study provides possible in vivo evidence to show that vitamin C supplements could attenuate oxidative stress and brain damage of fipronil and pyriproxyfen insecticide chronic exposure on zebrafish juvenile.

Keywords: autism spectrum disorder; insecticides; neurotoxicity; protective role; social behavior; vitamin C.

Figure 1

Schematic diagram of insecticide mixture and vitamin C administration. (d: days, Fip: fipronil, GPx: glutathione peroxidase, MDA: malondialdehyde, OS: oxidative stress, Pyr: pyriproxyfen, SOD: superoxide dismutase, Vit. C: vitamin C).

Figure 2

Zebrafish juvenile swimming performance test results during the experiment (n = 45 per group combined with triplicates experiments). (A) Total distance swam (cm). (B) Average velocity (cm/s). (C) Active status (s). (D) Inactive status (s). Green: control group, Blue: Vit. C group (14 d. 25 µg L⁻¹), Black: insecticide mixture group (600 µg L⁻¹ Fip + 600 µg L⁻¹ Pyr), Red: insecticide mixture and vit. C group (14 d. [600 µg L⁻¹ Fip + 600 µg L⁻¹ Pyr] + 25 µg L⁻¹ vit. C). The groups were compared to pretreatment days and the results were represented as average ± SD.

Figure 3

Time spent in maze arms during social interaction test by (A) control group and group exposed to (B) vit.C (14 d. 25 µg L⁻¹), (C) insecticide mixture (600 µg L⁻¹ Fip + 600 µg L⁻¹ Pyr), and (D) insecticide mixture and vit.C (14 d. [600 µg L⁻¹ Fip + 600 µg L⁻¹ Pyr] + 25 µg L⁻¹ vit. C) (n = 45 per group). Black: left arm, Red: center arm, and Blue: right arm. The groups were compared to pretreatment days and the results were represented as average ± SD.

Figure 4

The activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), and lipid peroxidation (MDA) levels in zebrafish chronically exposed to the chemicals. Data were expressed as average ± SD (*** p < 0.001 Tukey compared with control, * p < 0.05 Tukey compared with control, p < 0.05 ANOVA).

Figure 5

Schematic diagram of this experimental study. The juvenile zebrafish were exposed to a mixture of fipronil and pyriproxyfen. The insecticides triggered oxidative stress and behavioral abnormalities in zebrafish. However, these adverse effects were attenuated by vitamin C, which was showed by the reduction of oxidative stress marker expression in the brain and restoration of behavioral abnormalities in swimming performance and social interaction.