Immunohistochemistry of Brain Tissues

Immunohistochemistry (IHC) is the basis of histological or pathological analysis and is widely used to enable the detection and characterization of proteins in various organ tissues, including brain tissues. IHC is commonly performed on formalin-fixed paraffin-embedded (FFPE) tissues because of their easy storage and versatility. IHC is a key method for providing more accurate analysis of localization and function of neurons, neuroendocrine cells, and neural stem cells in the brain and other nervous systems. The related cells such as glial cells and neurovascular units have also been analyzed by IHC. Visualization of antibody–antigen interactions can be performed primarily in one of the following ways: chromogenically stained IHC and fluorescently stained IHC. In chromogenically stained IHC, an antibody is chemically conjugated to an enzyme, such as peroxidase, that can be reacted with a suitable substrate to give a colored product. In fluorescently stained IHC, the antibodies are finally tagged with fluorescent chemicals such as fluorescein isothiocyanate (FITC) or rhodamine. Here, we describe the standard methods of IHC applied to brain slice sections. Furthermore, an automated immunostainer is presented as another option for standardized immunohistochemistry.