神经肽Y(NPY)是在哺乳动物视网膜中大量表达的肽类神经递质。自从它被发现,已经在几种物种的视网膜中研究了NPY,但是形态的详细表征,细胞类型,连接从未在包括人类和猪在内的大型哺乳动物中进行过。由于猪的大小和细胞组成是非常适合视网膜研究的动物,我们选择将人视网膜的内源性NPY系统与猪的内源性NPY系统进行比较,以支持该领域的未来研究。在本研究中,使用免疫组织化学,共聚焦显微镜和3D重建,我们发现NPY在这两个物种的GABA能和钙视网膜色素免疫反应性(-ir)无长突细胞以及人类的小白蛋白-ir无长突细胞中表达。此外,我们鉴定了至少两种不同类型的中宽视野NPY-ir无长突细胞。最后,我们检测到NPY-ir无长突细胞与黑素素-和非黑素素-ir神经节细胞之间可能的突触并置,GABA能和多巴胺能无长突细胞,杆状双极细胞,和水平单元格,表明NPY-ir细胞在调节图像和非图像形成的视网膜信号中起着不同的作用。这些发现扩展了对人和猪视网膜中NPY和NPY表达细胞的现有知识,显示出高度的可比性。本研究中描述的NPY-ir细胞的广泛分布和连通性进一步突出了NPY信号传导在视网膜功能中的潜在重要性。
Neuropeptide Y (NPY) is a peptide neurotransmitter abundantly expressed in the mammalian retina. Since its discovery, NPY has been studied in retinas of several species, but detailed characterization of morphology, cell-type, and connectivity has never been conducted in larger mammals including humans and pigs. As the pig due to size and cellular composition is a well-suited animal for retinal research, we chose to compare the endogenous NPY system of the human retina to that of pigs to support future research in this field. In the present
study, using immunohistochemistry, confocal microscopy and 3D reconstructions, we found NPY to be expressed in GABAergic and calretinin-immunoreactive (-ir) amacrine cells of both species as well as parvalbumin-ir amacrine cells of humans. Furthermore, we identified at least two different types of medium- to wide-field NPY-ir amacrine cells. Finally, we detected likely synaptic appositions between the NPY-ir amacrine cells and melanopsin- and nonmelanopsin-ir ganglion cells, GABAergic and dopaminergic amacrine cells, rod bipolar cells, and horizontal cells, suggesting that NPY-ir cells play diverse roles in modulation of both image and non-image forming retinal signaling. These findings extend existing knowledge on NPY and NPY-expressing cells in the human and porcine retina showing a high degree of comparability. The extensive distribution and connectivity of NPY-ir cells described in the present
study further highlights the potential importance of NPY signaling in retinal function.