Post-embedding Immunohistochemistry in the Localisation of Receptors and Ion Channels

Abstract

Post-embedding techniques are powerful approaches for the analysis of the chemical architecture of the brain and have proved useful to investigate disease processes at the molecular level. These techniques involve immunohistochemical reactions on tissue that is previously fixed, dehydrated, embedded in resin and sectioned. As a result, immunoreactions only occur on the surface of the sections, and this make post-embedding techniques to have lower sensitivity than other immunoelectron microscopy approaches. However, among other advantages, post-embedding techniques are the only reliable methods to localise any receptor/ion channel at excitatory synapses and also enable the simultaneous localisation of different molecules in the cell or subcellular compartments using secondary antibodies conjugated with gold particles of different size. In this chapter, we introduce the post-embedding immunoperoxidase for light microscopy and post-embedding immunogold for electron microscopy and also discuss the limitations inherent to these approaches. We describe the main scope and protocols which have been successfully utilised at our research centres for the examination and analysis of neuronal surface and intracellular and receptor/ion channel in the brain.