Department of Bioscience Technology, Chung Yuan Christian University, Chung-Li 32023, Taiwan.
Department of Chemistry, Chung Yuan Christian University, Chung-Li 32023, Taiwan.
Int J Environ Res Public Health. 2020 Jun 27;17(13):4632. doi: 10.3390/ijerph17134632.
The available arable land is unable to fulfill the food production need of rapidly the exponentially growing human population in the world. Pesticides are one of those different measures taken to meet this demand. As a plant growth regulator to block gibberellin, paclobutrazol (PBZ) is used excessively throughout the world to promote early fruit setting, and to increase seed setting which might be harmful because PBZ is a very stable compound; therefore, it can bioaccumulate into the food chain of an ecosystem. In the present study, we discovered unexpected effects of PBZ on zebrafish larvae and adult behaviors by challenging them with low dose exposure. Zebrafish larvae aged 4 days post-fertilization (dpf) were exposed for 24 h at 10 µg/L (0.01 ppm) and 100 µg/L (0.1 ppm) of PBZ, respectively, and adults were incubated at 100 µg/L (0.1 ppm) and 1000 µg/L (1 ppm) concentrations of PBZ, respectively, for fourteen days. After incubation, the locomotor activity, burst, and rotation movement for the larvae; and multiple behavioral tests such as novel tank exploration, mirror biting, shoaling, predator avoidance, and social interaction for adult zebrafish were evaluated. Brain tissues of the adult fish were dissected and subjected to biochemical analyses of the antioxidant response, oxidative stress, superoxide dismutase (SOD), and neurotransmitter levels. Zebrafish larvae exposed to PBZ exhibited locomotion hyperactivity with a high burst movement and swimming pattern. In adult zebrafish, PBZ resulted in anxiolytic exploratory behavior, while no significant results were found in social interaction, shoal making, and predator avoidance behaviors. Interestingly, high dose PBZ exposure significantly compromised the innate aggressive behavior of the adult fish. Biochemical assays for oxidative stress, antioxidant response, and superoxide dismutase (SOD) showed significant reductions in their relative contents. In conclusion, for the first time, our behavior assays revealed that chronic PBZ exposure induced behavioral alterations in both larvae and the adult zebrafish. Because PBZ is a widely-used plant growth regulator, we suggest that it is necessary to conduct more thorough tests for its biosafety and bioaccumulation.
可耕地无法满足世界上人口快速增长的粮食生产需求。杀虫剂是满足这一需求的措施之一。多效唑（PBZ）作为一种抑制赤霉素的植物生长调节剂，被全世界广泛用于促进早期果实结实和增加结实率，但由于 PBZ 是一种非常稳定的化合物，因此可能是有害的；因此，它可以在生态系统的食物链中生物累积。在本研究中，我们通过低剂量暴露挑战，发现 PBZ 对斑马鱼幼虫和成年鱼行为的意外影响。受精后 4 天（dpf）的斑马鱼幼虫分别暴露于 10µg/L（0.01ppm）和 100µg/L（0.1ppm）的 PBZ 中 24 小时，成年鱼分别在 100µg/L（0.1ppm）和 1000µg/L（1ppm）的 PBZ 浓度下孵育 14 天。孵育后，评估幼虫的运动活性、爆发和旋转运动；以及成年斑马鱼的多种行为测试，如新奇鱼缸探索、镜像咬、群集、捕食者回避和社交互动。成年鱼的脑组织被解剖，并进行抗氧化反应、氧化应激、超氧化物歧化酶（SOD）和神经递质水平的生化分析。暴露于 PBZ 的斑马鱼幼虫表现出运动过度活跃，爆发运动和游泳模式较高。在成年斑马鱼中，PBZ 导致焦虑探索行为，而在社交互动、群集形成和捕食者回避行为中没有发现显著结果。有趣的是，高剂量 PBZ 暴露显著损害了成年鱼的先天攻击行为。氧化应激、抗氧化反应和超氧化物歧化酶（SOD）的生化测定显示其相对含量显著降低。总之，这是首次发现慢性 PBZ 暴露在幼虫和成年斑马鱼中均诱导行为改变。由于 PBZ 是一种广泛使用的植物生长调节剂，我们建议有必要对其进行更彻底的生物安全性和生物累积测试。
