氯化镉暴露对斑马鱼幼鱼神经行为毒性作用

为探索低剂量镉持续暴露对斑马鱼胚胎和幼鱼神经发育的影响,将受精后36h(36hpf)的斑马鱼胚胎暴露于不同浓度氯化镉受试液中持续至受精后6d(6dpf)。在一般毒性观察的基础上,采用高通量视频跟踪技术检测了48孔板中幼鱼的自发运动能力和对外界刺激产生的惊恐反应及恢复能力。结果显示:在不引起外观形态明显改变的暴露剂量下幼鱼自发运动表现异常。其中,0.1～0.5μmol·L-1暴露组幼鱼自发运动增多、轨迹紊乱、刻板式转向运动增加、触壁活动减少;1.0μmol·L-1暴露组幼鱼出现运动抑制、静止和原地震颤等状态,幼鱼的自发运动距离与氯化镉浓度关系呈现剂量依赖性倒"U"型,这种行为毒性效应与乙醇急性暴露引起的运动效应相似。光照惊恐反射实验中,暴露组幼鱼对突发的光暗变化表现敏感或迟钝。在撤除光源后暗适应减慢或加快。以上结果说明,斑马鱼胚胎和幼鱼对氯化镉的神经发育毒性作用敏感,并且高通量的幼鱼神经行为学方法在外源性化学物的毒性评价中能够提高检测效率,具有良好的应用前景。

Toxic Effects of Cadmium Chloride Exposure on Neurobehavior of Zebrafish Larvae

To realize the developmental neurotoxicity of cadmium on zebrafish embryos and larvae,the neurobehavioral response of individual zebrafish larva ( 6 days post-fertilization) in 48-well microtiter plates was investigated after cadmium chloride ( 0. 5-2. 0 μmol·L-1 ) administered to the embryos ( 36 hours post-fertilization) by immersion. Movement of larvae were recorded and analyzed by using a video-tracking system. Results showed that low-concentration cadmium chloride evokes the spontaneous movement tracks of larvae disorder. The tereotypic circling swimming of larvae increased,but the touching wall response reduced in range of 0. 1-0. 5 μmol·L-1 exposure dose. Larvae represented motorial inhibition,tremor and freezing at 1. 0 μmol·L-1 cadmium chloride. Moreover,the distance moved of larvae showed the "Inverted U" dose-response to the concentration of cadmium chloride,which the locomotor activity pattern was similar to that caused by acute ethanol exposure. Light-evoked startle escape response results showed that cadmium chloride can promote or reduce the sensibility of larvae to light or dark transition. Accordingly,the habituation of activity presented postpone or accelerate in dark after light stimulation. These results demonstrated that the development of nerve of zebrafish embryos and larvae were sensitive to toxicity of cadmium chloride. In addition,zebrafish larvae were a type of powerful model in developmental neurotoxicity of exogenous assessment by using high-throughput neurobehavioral detections.