芬普尼及酸性水的暴露對於斑馬魚胚胎發育及離子調節之影響

Abstract

人類活動引發的淡水酸化已成為全球性的問題，並且已對水生動物構成嚴重的威脅，而酸性水可能會增加水中污染物對水生動物的毒性。芬普尼 (fipronil)是一種苯基吡唑類殺蟲劑，目前廣泛使用於農業活動和寵物用藥。先前的研究表明，芬普尼的殘留物會對魚類造成多種毒性作用。然而，目前尚不清楚芬普尼是否會損害魚類的離子調節及酸化水是否會增強芬普尼的毒性。在這項研究中，斑馬魚胚胎被當成模式動物來回答這些問題。從受精後 4 小時開始，斑馬魚胚胎暴露在不同濃度 (0、0.1、0.5、1、5 和 10 ppm)的芬普尼中 96 小時。芬普尼以劑量依賴性的方式增加死亡率並延遲孵化。 芬普尼 (≧ 1 ppm) 的毒性亦使得身體及肌節的長度、眼睛、耳石囊和嗅窩的面積都與控制組相比呈現下降。此外，芬普尼還降低了側線毛細胞及皮膚離子細胞 (包括 HR 細胞和 NaR 細胞)的數量以及相關的離子調節功能。在酸性水 (pH5) 中，芬普尼導致離子細胞酸分泌的功能更嚴重地下降。這項研究首次表明芬普尼可以損傷皮膚離子細胞並威脅魚類在酸性環境中的生存。

Freshwater acidification caused by human activities has become a global issue, it poses a severe threat to aquatic animals. Acidified water may enhance the toxicity of aquatic pollutants to animals. Fipronil, a phenylpyrazole insecticide, has been widely used in agricultural activity and pet medication. Previous studies showed that fipronil residues can cause several toxic effects on fish. However, it is still unclear if fipronil can impair ion regulation in fish and if acidified water can enhance the toxicity of fipronil. In this study, zebrafish embryos were used as a model to answer these questions. Zebrafish embryos were exposed to different concentrations (0, 0.1, 0.5, 1, 5, and 10 ppm) of fipronil for 96 h from 4 h post-fertilization. Fipronil increased the mortality and delayed the hatching in a dose-dependent manner. Fipronil (≧ 1 ppm) also decreased several morphological endpoints including the length of the body and myotome, and the area of the eye, otic vesicle, and olfactory pit. Furthermore, fipronil also decreased the number of lateral-line hair cells and skin ionocytes (including HR cells and NaR cells) and associated ion regulatory functions. In acidified water (pH5), fipronil caused a more severe decline in acid secretion by ionocytes. This study shows for the first time that fipronil can damage skin ionocytes and threaten fish survival in acidified environments.