MORPHOFUNCTIONAL STUDIES OF NEUROPEPTIDES IN CENTRAL-NERVOUS-SYSTEM

This review describes some of the morphological tools which have allowed not only to describe the peptidergic neuronal pathways in the central nervous system but also to approach their physiology and their functions: immunohistochemistry with its different labels, and its possible association with hodological techniques; immunocytochemistry with the pre- and post-embedding methods; in situ hybridization with cloned or synthetic probes and radioactive or enzymatic labelings; demonstration of peptide receptors by radioactive ligands, antibodies or antiidiotypes. Finally several combinations of these different methods are described like multiple immunocytochemical labelings for several neuropeptides or for neuropeptides and other mediators: combination of immunohistochemistry and of radioautography after labeled transmitter uptake; simultaneous detection of neuropeptides and of their receptors or of the corresponding mRNAs. Possibilities and limitations of these single or combined methods for the understanding for the cytophysiology of peptidergic neurons are finally described.