Melatonin Prevents the Transgenerational Toxicity of Microplastics in Zebrafish (Danio Rerio)

Abstract

As a novel pollutant, microplastic pollution has become a global environmental concern. Polystyrene is one of the most common and abundant forms of microplastics, which can lead to oxidative stress and damage the immune, digestive and reproductive systems of fish. Melatonin (MT) has a protective effect on the damage caused by pollutants. However, there is still a lack of research on the intergenerational toxicity of microplastics and the alleviation of microplastics toxicity by MT. In this study, the zebrafish was exposed to (0, 0.1 and 1 mg/L) polystyrene nanoplastics (PSNP) with or without (1 μM) MT for 14 days, and embryos were used for experiments. The 96 hours post-fertilization larvae were counted, including fertilization rate, survival rate, hatching rate, deformity rate and body length. The transcription level of growth hormone/insulin-like growth factor (GH-IGF) axis was detected, and the antioxidant capacity and apoptosis level were analyzed to reveal the intergenerational toxic effects of PSNP. Our study found that PSNP can inhibit the growth of offspring, reduce fertilization rate and survival rate, increase deformity rate and induce embryos to hatch in advance. The developmental toxicity of offspring was obviously improved after MT was added. High concentration of PSNP can significantly inhibit the expression levels of ghrh, ghra, ghrb and igf2a, which led to the shortening of larval body length. PSNP interferes with the GH-IGF axis of offspring, and MT supplementation can effectively alleviate the growth inhibition of PSNP. Long-term exposure of parents to high concentrations of PSNP will cause oxidative stress in offspring, damage immune system, reduce antioxidant capacity and induce apoptosis. MT can alleviate the growth inhibition and oxidative damage of offspring, but the negative effects brought by PSNP could not be completely eliminated. Our research will provide reference for the protective effect of MT on intergenerational toxicity induced by PSNP.

Keywords: PSNP, Melatonin, Intergenerational toxicity, zebrafish, GH-IGF axis