食物相铬在豹纹鳃棘鲈鱼不同脑区的生物累积

为研究食物来源的铬(Cr)在鱼脑部生物累积的情况, 用含有不同浓度(0、10、50和250 mg/kg)不同形态及价态Cr有机Cr为吡啶甲酸铬CrPic, 无机Cr为CrCl₃和K₂Cr₂O₇(Cr(Ⅲ); Cr(Ⅵ)]的饲料投喂豹纹鳃棘鲈(Plectropomus. leopardus)幼鱼66d, 并以原子吸收光谱法(AAS)在第7、第12、第18、第40和第66天取样测定幼鱼的下丘脑、前脑、中脑和后脑区域中Cr生物累积量。结果表明, 食物中铬在幼鱼4种脑组织中的累积量普遍在暴露前期(7—40d)显著增加, 而在最后一个时期(66d)显著减少。但是, 总铬的生物蓄积量在4种脑区并未以剂量和时间依赖性方式存在。此外, 在相同浓度和时间条件下, 不同铬源CrPic、Cr(Ⅲ)和Cr(Ⅵ)的处理, 总铬在不同脑区的含量基本呈现CrPic > Cr(Ⅲ) > Cr(Ⅲ)的规律, 具有明显的组织差异性。研究发现食物来源的Cr在鱼类等水生动物大脑不同脑区的累积与Cr不同形态、价态和浓度紧密相关, 为进一步评估食物中的Cr对中枢神经系统毒性作用及其毒理机制奠定基础。

BIOACCUMULATION OF CHROMIUM IN DIFFERENT BRAIN REGIONS OF PLECTROPOMUS LEOPARDUS DURING DIETARY EXPOSURE

Excessive intake of chromium (Cr) cause neurotoxicity to fish, though, the information on the bioaccumulation of Cr in fish brain under dietary exposure is still lacking. To evaluate the effects of dietary Cr exposure on the brain of coral trout (Plectropomus leopardus), fish were fed with a gradient levels of organic Cr (as chromium picolinate (CrPic)) and inorganic Cr CrCl₃ (Cr(Ⅲ), K₂Cr₂O₇ (Cr(Ⅵ))] at 0, 10, 50, and 250 mg/kg for 66 days. Samples were collected to measure Cr accumulation in hypothalamus, forebrain, midbrain, hindbrain regions of brain at 7, 12, 18, 40 and 66 days using atomic absorption spectrometry (AAS). The results showed that Cr bioaccumulation in the four brain tissues increased significantly from day 7 to day 40, but decreased significantly after day 66 under both organic and inorganic Cr treatment. However, the total bioaccumulated Cr in four regions of brain did not increase with the increasing dietary Cr level and exposure time, indicating a dose- and time-independent pattern. The accumulated amount of Cr in the brain after dietary exposure followed the order CrPic > Cr(Ⅵ) > Cr(Ⅲ). These findings demonstrated that the dietary organic Cr had significantly higher bioaccumulation than inorganic Cr, providing a theoretical knowledge for further evaluation of the toxic effect of form-specific Cr in food on central nervous system and evaluation of its toxicological mechanism.