Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico.
Section on Molecular Neuroscience, National Institute of Mental Heath-Intramural Research Program, NIH, Bethesda, MD, USA.
J Neuroendocrinol. 2020 Apr;32(4):e12831. doi: 10.1111/jne.12831. Epub 2020 Feb 13.
The origin and functional significance of vasopressin (AVP)-containing fibres in limbic regions has been an ongoing subject of investigation for several years. We have previously identified AVP-magnocellular neurones of rat hypothalamus that provide glutamatergic projections to the hippocampus, amygdala, lateral habenula and locus coeruleus. However, we also reported AVP-immunopositive fibres in those regions that are thin and make Gray type II synapses, which are unlikely to be of magnocellular origin. Therefore, in the present study, we characterised AVP mRNA co-expression with expression of mRNAs marking glutamatergic (vesicular glutamate transporter [VGLUT]) and GABAergic (vesicular GABA transporter [VGAT]) neuronal traits in rat and mouse brain, using high-resolution in situ hybridisation methods, including a radio-ribonucleotide and RNAscope 2.5 HD duplex assay, with Slc17a7, Slc17a6, Slc32a1 and Avp probes corresponding to mRNAs of VGLUT1, VGLUT2, VGAT and AVP, respectively. We located 18 cell groups expressing Avp and identified their molecular signatures for VGLUT and VGAT mRNA expression. Avp cell groups of hypothalamus and midbrain are mainly VGLUT mRNA-expressing, whereas those in regions derived from cerebral nuclei are mainly VGAT mRNA-expressing, suggesting a functional segregation of glutamate/GABA co-transmission with AVP. A newly identified Slc17a7 and Slc17a6 (but not Slc32a1) expressing vasopressinergic cell group was found in layer II-III neurones of the central entorhinal cortex, which projects to the hippocampus. These data support the notion of a complex role for AVP with respect to modulating multiple central circuits controlling behaviour in specific ways depending on co-transmission with glutamate or GABA, potentially giving rise to a functional classification of AVPergic neurones in the central nervous system.
血管加压素（AVP）在边缘区域中的纤维的起源和功能意义一直是多年来研究的主题。我们之前已经确定了大鼠下丘脑的含有 AVP 的大细胞神经元，这些神经元提供谷氨酸能投射到海马体、杏仁核、外侧缰核和蓝斑。然而，我们还报告了在这些区域中发现的 AVP 免疫阳性纤维，这些纤维很细，形成 Gray Ⅱ型突触，不太可能来自大细胞。因此，在本研究中，我们使用高分辨率原位杂交方法，包括放射性核苷酸和 RNAscope 2.5 HD 双探针检测，研究了 AVP mRNA 与标记谷氨酸能（囊泡谷氨酸转运体 [VGLUT]）和 GABA 能（囊泡 GABA 转运体 [VGAT]）神经元特征的 mRNA 在大鼠和小鼠脑内的共表达，包括 Slc17a7、Slc17a6、Slc32a1 和 Avp 探针，分别对应于 VGLUT1、VGLUT2、VGAT 和 AVP 的 mRNA。我们定位了 18 个表达 Avp 的细胞群，并确定了它们的 VGLUT 和 VGAT mRNA 表达的分子特征。下丘脑和中脑的 Avp 细胞群主要表达 VGLUT mRNA，而源自脑核的那些细胞群主要表达 VGAT mRNA，这表明谷氨酸/GABA 共传递与 AVP 之间存在功能分离。在中央内嗅皮质的 II-III 层神经元中发现了一个新的表达 Slc17a7 和 Slc17a6（但不表达 Slc32a1）的血管加压素能细胞群，该细胞群投射到海马体。这些数据支持 AVP 具有调节多个中枢回路的复杂作用的观点，以特定方式控制行为，具体取决于与谷氨酸或 GABA 的共传递，这可能导致中枢神经系统中 AVP 能神经元的功能分类。
