Evaluation of Brain Neurotransmitters by Morpho-Functional Method

This review discribes some of the morphological tools which have allowed not only to discribe the chemical nature of neuronal pathways in the central nervous system but also to approach their physiology and their functions: Enzyme histochemistry; this technique shows the entity of an enzyme in nervous tissue. Immunocyto-histochemistry; based on antigen antibody reaction constitute the basic neuroanatomical and neurocytological studies concerning their neuropeptides and neurotransmitters. In situ hybridization with cloned or synthetic probes and radioactive or enzymatic labelings, permit to localize the specific sequence of nucleic acids (RNA of DNA) corresponding to a persumed neurotransmitter or neuropeptide. Using radioactive ligands permit to demonstrate receptors by autoradiography technique. Finally several combinations of these different methods can be used to detect the neurotransmitters and their receptors or of the corresponding mRNA. Considering the possibilities and limitations of these modern methods, we conclude their implication for the understanding of cytophysiology of neurons in normal or pathological aspects.