Nonylphenol induces mortality and reduces hatching rate through increase of oxidative stress and dysfunction of antioxidant defense system in marine medaka embryo

Abstract

Nonylphenol (NP) is a hydrophobic xenobiotic compound classified as an endocrine disrupting chemical (EDC) and accumulates in environmental compartments owing to its extensive use. In this study, the detrimental effects of 4-nonylphenol (4-NP) were investigated in marine medaka (Oryzias javanicus) embryos and novel insights into their toxicities are provided. Following exposure to different concentrations of 4-NP (200-1000 μg/L), the mortality, hatching rate, and survival rate of larvae were measured. Biochemical endpoints, including intracellular oxidative stress, apoptosis, antioxidant defense, and vitellogenin level, were analyzed to assess the toxicity and endocrine disrupting potential of 4-NP. 4-NP treatment during post fertilization reduced hatching rate in a dose-dependent manner. Exposure to waterborne 4-NP induced oxidative stress and dysfunction of antioxidant defense systems, which led to apoptotic cellular death. In hatched larvae, the survival rate decreased as vitellegenin level with increasing exposure concentrations owing to persistent 4-NP. Our study provides evidence of cellular stress induction/toxicity caused by 4-NP and endocrine disrupting potential in marine medaka embryos.