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【medical-news】锌在脑回路中扮演着重要角色
Zinc plays important role in brain circuitry
To the multitude of substances that regulate neuronal signaling in the brain and spinal cord add a new key player: zinc. By engineering a mouse with a mutation affecting a neuronal zinc target, researchers have demonstrated a central role for zinc in modulating signaling among the neurons. Significantly, they found the mutant mouse shows the same exaggerated response to noise as children with the genetic disorder called "startle disease," or hyperekplexia.
The findings shed light on a nagging mystery in neurobiology: why the connections among certain types of neurons contain considerable pools of free zinc ions. And even though many studies had shown that zinc can act toxically on transmission of neural impulses, half a century of experiment researchers had not been able to show conclusively that the metal plays a role in normal nerve cell transmission.
However, in an article in the November 22, 2006, issue of the journal Neuron, published by Cell Press, Heinrich Betz and colleagues conclusively demonstrate just such a role for zinc.
In their experiments, the researchers produced mice harboring a mutant form of a gene for a receptor for zinc in neurons--thereby compromising the neurons' ability to respond to zinc. The mutation in the receptor, called the glycine receptor, targets the same receptor known to be mutated in humans with hyperekplexia. The receptor functions as a modulator of neurons in both motor and sensory signaling pathways in the brain and spinal cord.
The genetic approach used by the researchers was a more targeted technique than previous experiments in which researchers reduced overall neuronal zinc levels using chemicals called chelators that soak up zinc ions.
The resulting mutant mice showed tremors, delayed ability to right themselves when turned over, abnormal gait, altered transmission of visual signals, and an enhanced startle response to sudden noise.
Electrophysiological studies of the mutant animals' brain and spinal neurons showed significant zinc-related abnormalities in transmission of signals at the connections, called synapses, among neurons.
Betz and his colleagues wrote that "The data presented in our paper disclose a pivotal role of ambient synaptic [zinc ion] for glycinergic neurotransmission in the context of normal animal behavior." They also concluded that their results implied that manipulating synaptic zinc levels could affect the neuronal action of zinc, but that such manipulation "highlights the complexity of potential therapeutic interventions," which could cause an imbalance between the excitatory and inhibitory circuitry in the central nervous system.
In a preview of the paper in the same issue of Neuron, Alan R. Kay, Jacques Neyton, and Pierre Paoletti wrote "Undoubtedly this work is important, since it directly demonstrates that zinc acts as an endogenous modulator of synaptic transmission." They wrote that the findings "will certainly revive the flagging hopes of zincologists. This work provides a clear demonstration that interfering with zinc modulation of a synaptic pathway leads to a significant alteration in the phenotype of the animal." The three scientists added that the finding "puts a nice dent in the zinc armor, which held firm for more than 50 years." 本人认领了，48小时之后交稿，否则请其他战友认领。 呵呵，本人花了一个半小时搞定了，没有仔细检查，请多多指教。
Zinc plays important role in brain circuitry（锌在脑回路中起着重要作用 ）
To the multitude of substances that regulate neuronal signaling in the brain and spinal cord add a new key player: zinc.（在大量调控大脑和脊髓信号传递的物质中又增加了一个非常重要的角色：锌） By engineering a mouse with a mutation affecting a neuronal zinc target, researchers have demonstrated a central role for zinc in modulating signaling among the neurons. （研究者通过生物工程使鼠突变成神经元带有锌靶点的个体）Significantly, they found the mutant mouse shows the same exaggerated response to noise as children with the genetic disorder called "startle disease," or hyperekplexia.（他们发现突变鼠出现明显的对噪音的过度反应，类似儿童的遗传性骇病和过度惊吓症）
The findings shed light on a nagging mystery in neurobiology: why the connections among certain types of neurons contain considerable pools of free zinc ions.（这个发现揭开了这个困扰神经生物界的一个谜：为和有的神经元之间的联系含有大量的自由锌离子） And even though many studies had shown that zinc can act toxically on transmission of neural impulses, half a century of experiment researchers had not been able to show conclusively that the metal plays a role in normal nerve cell transmission.（尽管很多的研究显示锌对神经冲动的传递具有毒性作用，但是半个世纪来仍没有实验能过确认这种金属在正常神经细胞的传递中起作用。）
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作者:admin@医学,生命科学 2011-05-02 17:11
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