On the properties of identified dopaminergic neurons in the mouse substantia nigra and ventral tegmental area
On the properties of identified dopaminergic neurons in the mouse substantia nigra and ventral tegmental area
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DOI：
10.1111/ejn.13364
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发表时间：
2017-01-01
影响因子：
3.4
通讯作者：
Mercuri, Nicola Biagio
中科院分区：
文献类型：
--
作者：
Krashia, Paraskevi;Martini, Alessandro;Mercuri, Nicola Biagio
我们研究了在酪氨酸羟化酶启动子（TH-GFP）控制下表达增强型绿色荧光蛋白（eGFP）的小鼠黑质背侧部（SNpc）和腹侧被盖区（VTA）多巴胺能神经元的特性。通过使用水平中脑切片中不同SNpc和VTA亚区的细胞定位的实用图，我们看到自发放电、膜特性、TH-GFP阳性神经元（TH-GFP（+））中的细胞体大小和超极化激活电流（I-h）的幅度在亚区之间显著变化，遵循中外侧梯度。用Zd 7288阻断I-h抑制了大多数外侧亚区的放电，但对中间/内侧VTA几乎没有影响。此外，TH-GFP（+）细胞被Met（5）-脑啡肽激发。来自大量神经元的细胞外记录显示，所有TH-GFP（+）细胞被多巴胺抑制，这表明这是体外鉴定多巴胺能神经元的可靠方法。多巴胺敏感和多巴胺不敏感神经元的同时记录表明，多巴胺不敏感细胞（假定的非多巴胺能神经元）不受Zd 7288的影响，但受到Met（5）-脑啡肽的抑制。在膜片钳下，多巴胺在大多数TH-GFP（+）神经元中产生数量相似的外向电流，尽管内侧VTA细胞显示多巴胺敏感性降低。帕吉林延长多巴胺电流，而可卡因增强多巴胺介导的SNPC和腹侧被盖区的反应。我们的工作提供了新的见解，小鼠中脑多巴胺能神经元沿着内侧-外侧轴的变异性，并指出不同的电生理和药理学方法的组合的必要性，可靠地识别这些细胞，以区分它们从非多巴胺能神经元在中脑。
We studied the properties of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA) in mice expressing the enhanced green fluorescent protein (eGFP) under the control of the tyrosine hydroxylase promoter (TH-GFP). By using a practical map of cell positioning in distinct SNpc and VTA subregions in horizontal midbrain slices we saw that the spontaneous firing, membrane properties, cell body size and magnitude of the hyperpolarization-activated current (I-h) in TH-GFP-positive neurons (TH-GFP(+)) vary significantly among subregions, following a mediolateral gradient. Block of I-h with Zd7288 inhibited firing in the most lateral subregions, but had little effect in the intermediate/medial VTA. In addition, TH-GFP(+) cells were excited by Met(5)-Enkephalin. Extracellular recordings from a large neuron number showed that all TH-GFP(+) cells were inhibited by dopamine, suggesting that this is a reliable approach for identifying dopaminergic neurons invitro. Simultaneous recordings from dopamine-sensitive and dopamine-insensitive neurons showed that dopamine-insensitive cells (putative non-dopaminergic neurons) are unaffected by Zd7288 but inhibited by Met(5)-Enkephalin. Under patch-clamp, dopamine generated a quantitatively similar outward current in most TH-GFP(+) neurons, although medial VTA cells showed reduced dopamine sensitivity. Pargyline prolonged the dopamine current, whereas cocaine enhanced dopamine-mediated responses in both the SNpc and the VTA. Our work provides new insights into the variability in mouse midbrain dopaminergic neurons along the medial-lateral axis and points to the necessity of a combination of different electrophysiological and pharmacological approaches for reliably identifying these cells to distinguish them from non-dopaminergic neurons in the midbrain.