The gold-standard fixative for immunohistochemistry is 4% formaldehyde; however, it limits antibody access to target molecules that are buried within specialized neuronal components, such as ionotropic receptors at the postsynapse and voltage-gated ion channels at the axon initial segment, often requiring additional antigen-exposing techniques to detect their authentic signals. To solve this problem, we used glyoxal, a two-carbon atom di-aldehyde. We found that glyoxal fixation greatly improved antibody penetration and immunoreactivity, uncovering signals for buried molecules by conventional immunohistochemical procedures at light and electron microscopic levels. It also enhanced immunosignals of most other molecules, which are known to be detectable in formaldehyde-fixed sections. Furthermore, we unearthed several specific primary antibodies that were once judged to be unusable in formaldehyde-fixed tissues, allowing us to successfully localize so far controversial synaptic adhesion molecule Neuroligin 1. Thus, glyoxal is a highly effective fixative for immunostaining, and a side-by-side comparison of glyoxal and formaldehyde fixation is recommended for routine immunostaining in neuroscience research.

中文翻译：

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乙二醛固定：解决神经科学研究中免疫组织化学问题的方法

免疫组化的金标准固定液是4%甲醛；然而，它限制了抗体接触埋藏在特殊神经元成分中的目标分子，例如突触后的离子型受体和轴突起始段的电压门控离子通道，通常需要额外的抗原暴露技术来检测其真实信号。为了解决这个问题，我们使用了乙二醛，一种双碳原子二醛。我们发现乙二醛固定极大地改善了抗体的渗透和免疫反应性，通过传统的免疫组织化学程序在光和电子显微镜水平上揭示了埋藏分子的信号。它还增强了大多数其他分子的免疫信号，已知这些分子可以在甲醛固定切片中检测到。此外，我们发现了几种曾经被认为在甲醛固定组织中无法使用的特异性一抗，使我们能够成功定位迄今为止有争议的突触粘附分子 Neuroligin 1。因此，乙二醛是一种高效的免疫染色固定剂，并且是一种副作用。建议对神经科学研究中的常规免疫染色进行乙二醛和甲醛固定的旁路比较。