Bakke Marit Jørgensen, Horsberg Tor Einar
Department of Pharmacology and Toxicology, Norwegian School of Veterinary Science, PO Box 8146 Dep., N-0033 Oslo, Norway.
Aquat Toxicol. 2007 Nov 30;85(2):96-103. doi: 10.1016/j.aquatox.2007.08.003. Epub 2007 Aug 14.
Neurotoxins from algal blooms have been reported to cause mortality in a variety of species, including sea birds, sea mammals and fish. Farmed fish cannot escape harmful algal blooms and their potential toxins, thus they are more vulnerable for exposure than wild stocks. Sublethal doses of the toxins are likely to affect fish behaviour and may impair cognitive abilities. In the present study, changes in the metabolic activity in different parts of the Atlantic salmon (Salmo salar) brain involved in central integration and cognition were investigated after exposure to sublethal doses of three algal-produced neurotoxins; saxitoxin (STX), brevetoxin (BTX) and domoic acid (DA). Fish were randomly selected to four groups for i.p. injection of saline (control) or one of the neurotoxins STX (10 microg STX/kg bw), BTX (68 microg BTX/kg bw) or DA (6 mg DA/kg bw). In addition, 14C-2-deoxyglucose was i.m. injected to measure brain metabolic activity by autoradiography. The three regions investigated were telencephalon (Tel), optic tectum (OT) and cerebellum (Ce). There were no differences in the metabolic activity after STX and BTX exposure compared to the control in these regions. However, a clear increase was observed after DA exposure. When the subregions with the highest metabolic rate were pseudocoloured in the three brain regions, the three toxins caused distinct differences in the respective patterns of metabolic activation. Fish exposed to STX displayed similar patterns as the control fish, whereas fish exposed to BTX and DA showed highest metabolic activity in subregions different from the control group. All three neurotoxins affected subregions that are believed to be involved in cognitive abilities in fish.
据报道，藻华产生的神经毒素会导致包括海鸟、海洋哺乳动物和鱼类在内的多种物种死亡。养殖鱼类无法躲避有害藻华及其潜在毒素，因此它们比野生种群更容易受到毒素暴露的影响。亚致死剂量的毒素可能会影响鱼类行为，并可能损害其认知能力。在本研究中，研究了大西洋鲑（Salmo salar）大脑中参与中枢整合和认知的不同部位在暴露于亚致死剂量的三种藻类产生的神经毒素（石房蛤毒素（STX）、短裸甲藻毒素（BTX）和软骨藻酸（DA））后的代谢活性变化。将鱼随机分为四组，腹腔注射生理盐水（对照组）或三种神经毒素之一：STX（10微克STX/千克体重）、BTX（68微克BTX/千克体重）或DA（6毫克DA/千克体重）。此外，肌肉注射14C-2-脱氧葡萄糖，通过放射自显影测量大脑代谢活性。研究的三个区域是端脑（Tel）、视顶盖（OT）和小脑（Ce）。与对照组相比，STX和BTX暴露后这些区域的代谢活性没有差异。然而，DA暴露后观察到明显增加。当在三个脑区中对代谢率最高的亚区域进行伪彩色处理时，三种毒素在各自的代谢激活模式上造成了明显差异。暴露于STX的鱼表现出与对照鱼相似的模式，而暴露于BTX和DA的鱼在与对照组不同的亚区域表现出最高的代谢活性。所有三种神经毒素都影响了被认为与鱼类认知能力有关的亚区域。
