Baldicano Alyssa K, Martin Paul R, Grünert Ulrike
Faculty of Medicine and Health, Save Sight Institute, and Discipline of Ophthalmology, The University of Sydney, Sydney, New South Wales, Australia.
J Comp Neurol. 2025 Jul;533(7):e70078. doi: 10.1002/cne.70078.
Over 30 types of amacrine cells have been described in the primate retina, yet few are well characterized. Here, we investigated amacrine cells expressing the alpha subunit of calcium/calmodulin-dependent protein kinase II (CaMKII) in the retinas of human, macaque (Macaca fascicularis, Macaca nemestrina), and marmoset (Callithrix jacchus) monkeys using immunohistochemistry and intracellular injections, with a focus on displaced amacrine cells (dACs) in the ganglion cell layer. The spatial density of CaMKII-positive dACs decreases with the distance from the fovea, but in the peripheral temporal retina, the density of CaMKII-positive dACs nevertheless exceeds the density of retinal ganglion cells. In all species, CaMKII-positive dACs include cells expressing choline acetyltransferase (ChAT) cells, but in the human retina, only 60% of the ON ChAT population is CaMKII-positive. Conversely, in the marmoset and the macaque, about 80% of ON ChAT cells co-express CaMKII, but only 55% of ON ChAT cells in humans do so. Intracellular injections of CaMKII-positive dACs with the lipophilic dye DiI revealed ON starburst and semilunar Type 3 cells in all three species, but in the human retina, at least three additional types were detected. In the inner nuclear layer, CaMKII is expressed by multiple populations of amacrine cells, which are distinguished based on their soma size and staining intensity, but OFF ChAT cells do not co-express CaMKII. We conclude that ON- and OFF-ChAT cells show distinct patterns of CaMKII expression and that the diversity of CaMKII-expressing dACs in humans is greater than that in marmoset or macaque retina.
在灵长类动物视网膜中已描述了30多种无长突细胞，但对其中很少几种的特征了解得很清楚。在这里，我们使用免疫组织化学和细胞内注射技术，研究了人类、猕猴（食蟹猴、猪尾猕猴）和狨猴（普通狨猴）视网膜中表达钙/钙调蛋白依赖性蛋白激酶II（CaMKII）α亚基的无长突细胞，重点关注神经节细胞层中的移位无长突细胞（dACs）。CaMKII阳性dACs的空间密度随着与中央凹距离的增加而降低，但在周边颞侧视网膜中，CaMKII阳性dACs的密度仍然超过视网膜神经节细胞的密度。在所有物种中，CaMKII阳性dACs包括表达胆碱乙酰转移酶（ChAT）的细胞，但在人类视网膜中，只有60%的ON ChAT细胞群体是CaMKII阳性的。相反，在狨猴和猕猴中，约80%的ON ChAT细胞共表达CaMKII，但在人类中只有55%的ON ChAT细胞如此。用亲脂性染料DiI对CaMKII阳性dACs进行细胞内注射，在所有三个物种中都发现了ON爆发型和半月形3型细胞，但在人类视网膜中，至少还检测到另外三种类型。在内核层中，CaMKII由多个无长突细胞群体表达，这些群体根据其胞体大小和染色强度来区分，但OFF ChAT细胞不共表达CaMKII。我们得出结论，ON-和OFF-ChAT细胞显示出不同的CaMKII表达模式，并且人类中表达CaMKII的dACs的多样性大于狨猴或猕猴视网膜中的多样性。
