Immunocytochemistry and In Situ Hybridization: Their Combinations for Cytofunctional Approaches of Central and Peripheral Neurons

Abstract

The birth of new concepts in chemical neurotransmission, like cotransmission, volume transmission, or neuronal versatility, frequently occurred thanks to the advances in neurocytochemichal technologies. First, the identification and in situ localization of neurotransmitters, related enzymes, and receptors greatly benefited from the development of more and more specific and sensitive cytochemical techniques. For instance, after histochemistry of acetylcholinesterase, the chemical neuroanatomy of monoamine neurons originated from histofluorescence methods. It is the development, however, of immunocytochemistry (ICC)at optic and electron microscope levels which has given an universal and versatile tool for such cartographies, first of neuropeptides, then of enzymes of neurotransmitter metabolism, and finally of the neurotransmitters themselves after the pioneering work of Steinbusch and colleagues (36) for serotonin. However these mappings,completed by that of receptors through ligand binding or ICC, does not allow, for example, the assumption that identified protein molecules are truly synthetized within sites where they are detected.