Conrad William S, Oriol Lucie, Kollman Grace J, Faget Lauren, Hnasko Thomas S
University of California, San Diego, Department of Neurosciences, La Jolla CA, USA.
Veterans Affairs San Diego Healthcare System, San Diego CA, USA.
bioRxiv. 2024 Oct 30:2024.02.28.582356. doi: 10.1101/2024.02.28.582356.
Most studies on the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) have focused on dopamine neurons and their role in processes such as motivation, learning, movement, and associated disorders such as addiction and Parkinson's disease. However there has been increasing attention on other VTA and SNc cell types that release GABA, glutamate, or a combination of neurotransmitters. Yet the relative distributions and proportions of neurotransmitter-defined cell types across VTA and SNc has remained unclear. Here, we used fluorescent in situ hybridization in male and female mice to label VTA and SNc neurons that expressed mRNA encoding the canonical vesicular transporters for dopamine, GABA, or glutamate: vesicular monoamine transporter (VMAT2), vesicular GABA transporter (VGAT), and vesicular glutamate transporter (VGLUT2). Within VTA, we found that no one type was particularly more abundant, instead we observed similar numbers of VMAT2+ (44%), VGAT+ (37%) and VGLUT2+ (41%) neurons. In SNc we found that a slight majority of neurons expressed VMAT2 (54%), fewer were VGAT+ (42%), and VGLUT2+ neurons were least abundant (16%). Moreover, 20% of VTA neurons and 10% of SNc neurons expressed more than one vesicular transporter, including 45% of VGLUT2+ neurons. We also assessed within VTA and SNc subregions and found remarkable heterogeneity in cell-type composition. And by quantifying density across both anterior-posterior and medial-lateral axes we generated heatmaps to visualize the distribution of each cell type. Our data complement recent single-cell RNAseq studies and support a more diverse landscape of neurotransmitter-defined cell types in VTA and SNc than is typically appreciated.
大多数关于腹侧被盖区(VTA)和黑质致密部(SNc)的研究都集中在多巴胺能神经元及其在动机、学习、运动等过程中的作用,以及成瘾和帕金森病等相关疾病上。然而,人们越来越关注VTA和SNc中释放γ-氨基丁酸(GABA)、谷氨酸或神经递质组合的其他细胞类型。然而,VTA和SNc中神经递质定义的细胞类型的相对分布和比例仍不清楚。在这里,我们在雄性和雌性小鼠中使用荧光原位杂交技术标记表达多巴胺、GABA或谷氨酸经典囊泡转运体mRNA的VTA和SNc神经元:囊泡单胺转运体(VMAT2)、囊泡GABA转运体(VGAT)和囊泡谷氨酸转运体(VGLUT2)。在VTA内,我们发现没有一种类型特别丰富,相反,我们观察到VMAT2+(44%)、VGAT+(37%)和VGLUT2+(41%)神经元数量相似。在SNc中,我们发现大多数神经元表达VMAT2(54%),较少的是VGAT+(42%),而VGLUT2+神经元最少(16%)。此外,20%的VTA神经元和10%的SNc神经元表达不止一种囊泡转运体,其中包括45%的VGLUT2+神经元。我们还评估了VTA和SNc亚区域内的情况,发现细胞类型组成存在显著异质性。通过量化前后轴和内外轴上的密度,我们生成了热图以可视化每种细胞类型的分布。我们的数据补充了最近的单细胞RNA测序研究,并支持VTA和SNc中神经递质定义的细胞类型比通常认为的更加多样化。