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首页> 外文期刊>Journal of Neurophysiology >Zinc and copper influence excitability of rat olfactory bulb neurons by multiple mechanisms.
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Zinc and copper influence excitability of rat olfactory bulb neurons by multiple mechanisms.

机译：锌和铜通过多种机制影响大鼠嗅球神经元的兴奋性。

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Zinc and copper are highly concentrated in several mammalian brain regions, including the olfactory bulb and hippocampus. Whole cell electrophysiological recordings were made from rat olfactory bulb neurons in primary culture to compare the effects of zinc and copper on synaptic transmission and voltage-gated ion channels. Application of either zinc or copper eliminated GABA-mediated spontaneous inhibitory postsynaptic potentials. However, in contrast to the similarity of their effects on inhibitory transmission, spontaneous glutamate-mediated excitatory synaptic activity was completely blocked by copper but only inhibited by zinc. Among voltage-gated ion channels, zinc or copper inhibited TTX-sensitive sodium channels and delayed rectifier-type potassium channels but did not prevent the firing of evoked single action potentials or dramatically alter their kinetics. Zinc and copper had distinct effects on transient A-type potassium currents. Whereas copper only inhibited the A-type current, zinc modulation of A-type currents resulted in either potentiation or inhibition of the current depending on the membrane potential. The effects of zinc and copper on potassium channels likely underlie their effects on repetitive firing in response to long-duration step depolarizations. Copper reduced repetitive firing independent of the initial membrane voltage. In contrast, whereas zinc reduced repetitive firing at membrane potentials associated with zinc-mediated enhancement of the A-type current (-50 mV), in a significant proportion of neurons, zinc increased repetitive firing at membrane potentials associated with zinc-mediated inhibition of the A-type current (-90 mV). Application of zinc or copper also inhibited voltage-gated Ca(2+) channels, suggesting a possible role for presynaptic modulation of neurotransmitter release. Despite similarities between the effects of zinc and copper on some ligand- and voltage-gated ion channels, these data suggest that their net effects likely contribute to differential modulation of neuronal excitability.
机译：锌和铜高度集中在嗅觉球茎和海马体等几个哺乳动物的大脑区域。从大鼠嗅球神经元在原代培养物中进行全细胞电生理记录，以比较锌和铜对突触传递和电压门控离子通道的影响。锌或铜的应用消除了GABA介导的自发抑制性突触后电位。然而，与它们对抑制性传递的作用相似的相反，自发谷氨酸介导的兴奋性突触活性被铜完全阻断，而仅被锌抑制。在电压门控离子通道中，锌或铜抑制了TTX敏感的钠通道，而延迟了整流器型钾通道，但并未阻止激发诱发的单动电位或显着改变其动力学。锌和铜对瞬时A型钾电流有明显的影响。铜仅抑制A型电流，而锌对A型电流的调制则根据膜电位导致电流增强或抑制。锌和铜对钾通道的影响很可能是其对长时间持续去极化作用下重复烧成的影响的基础。铜减少了重复点火，与初始膜电压无关。相反，尽管锌减少了与锌介导的A型电流（-50 mV）增强相关的膜电位的重复放电，但在相当大比例的神经元中，锌却增加了与锌介导的抑制A型电流相关的膜电位的重复放电。 A型电流（-90 mV）。锌或铜的应用还抑制了电压门控的Ca（2+）通道，暗示神经递质释放的突触前调制的可能作用。尽管锌和铜对某些配体和电压门控离子通道的作用相似，但这些数据表明它们的净作用可能有助于神经元兴奋性的差异调节。

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