摘要钡是动植物营养所必须的一种微量元素，人体代谢过程也必不可少，具有重要的生理功能。钡元素广泛存在于自然界中,人体可以通过食物、饮水及空气等从自然环境中摄取钡。正常情况下,钡是人体一种非必需的无毒的稀有微量元素,但过量摄入钡盐对人体会产生急、慢性毒性作用,如肌肉毒性,免疫毒性,生殖毒性,致畸、致癌、致突变等危害。随着钡应用范围的不断扩大,人们应该认识到暴露于钡危害的风险并引起高度重视。71128

在内皮细胞、巨噬细胞、神经吞噬细胞及神经细胞当中，存在一种同工酶，叫一氧化氮合酶（NOS）。在神经元中的NOS酶，在大脑的不同区域会呈现出选择性分布。一氧化氮合酶可以分为两种类型，一种是原生型（cNOS），另一种是诱生型（iNOS）。原生型又分为神经元型和内皮型，是Ca2+/钙调蛋白依赖的，当Ca2+浓度增高时才会有活性，其NO合成持续的时间少，水平也低。在人类的皮肤表面，cNOS通路起到生物调理功能和本身的稳定功能。由于NOS酶及其活跃，所以研究生成NO的酶好像比较容易一些，尤其是发现了NOS酶拮抗剂，很大程度的促进了一些NO功能的研究。

鲫鱼的脑部属于中枢神经系统，但是缺乏大脑皮层，它的机能活动主要表现在调节小脑，中脑，间脑，和脑干每个部分的关联方面。 鲫鱼的脑部分为端脑：由嗅球，嗅束和大脑半球组成，以不完全的纵隔把大脑分为左右两个侧脑室（也称公共脑室），借室间孔和间脑的第三脑室相互连接，负责嗅觉功能，处于脑的最前端； 间脑：在大脑的后方，脑垂体处于间脑前腹面，负责暗花功能；中脑：在间脑后背方，负责视觉功能；小脑：前面连接中脑，后面连接延脑，负责运动功能； 延脑：在脑的最末端，前面连接小脑，后面连接脊髓，负责味觉功能。在鱼脑中，分布着有10对脑神经，分别为嗅神经、滑车神经、视神经、动眼神经、听神经、舌咽神经、三叉神经、外展神经、颜面神经、迷走神经。

实验分别加入1.2g、12g、24g的BaCl2，分别构成0.1mmol/L BaCl2、1.0mmol/L BaCl2、2.0mmol/L 的BaCl2 溶液，作为本次实验的实验组，以不含有 BaCl2的自来水作为实验的对照组，构成钡对鲫鱼脑部NOS酶的影响模型，观察并记录鲫鱼在饲养的96 h中行为的变化。饲养结束后，测定在不同浓度的BaCl2水溶液中的鲫鱼体重的变化和NOS酶活性的变化。实验的测定结果表明，加入金属钡，使鲫鱼的行为变缓慢，体重下降。在金属钡的作用下，鲫鱼脑部的NOS酶活性降低，发生明显的抑制作用。

该论文有图5幅，表1个，参考文献12篇。

毕业论文关键词：钡  鲫鱼  脑  总一氧化氮合酶  诱导型一氧化氮合酶  内皮型一氧化氮合酶

Effect of Barium on the Activity of NOS in Carassius auratus Gill

Abstract Barium is a trace element in animal and plant nutrition, and it is also essential for the metabolism of human body. Barium is widely found in nature, and it can be used in the natural environment, such as food, drinking water and air. Under normal circumstances, barium is human a non essential non-toxic rare trace elements, but excessive intake of barium salt of the human body to produce acute and chronic toxic effects, such as muscle toxicity, immunotoxicity, reproductive toxicity, teratogenic, carcinogenic, caused by mutation and other hazards. With the continuous expansion of the application of barium, people should realize the risk of exposure to barium .

Nitric oxide synthase (NOS) is a kind of isozyme, which is found in endothelial cells, macrophages, nerve cells and nerve cells. When nitric oxide synthase exists in neurons, it can be selectively distributed in different brain regions. NOS is pided into primary type (cNOS) and induced type (iNOS) two species. The former can be pided into neuronal (nNOS and nNOS, bNOS and NOS1) and endothelial (eNOS, ecNOS, NOS3) is a Ca2 + / calmodulin dependent and only in intracellular Ca2 + levels increased only when the activity and the synthesis of no duration short (a few seconds to a few minutes) and at a low level. In human skin, the cNOS pathway provides biological regulation and self stabilization. Because the nitric oxide is not stable, it seems that it is more likely to study the production of nitric oxide, especially the discovery of nitric oxide synthase antagonist, which has greatly promoted the study of the function of nitric oxide .