[New trends on biochemical mechanism of action of benzodiazepines (author's transl)].

The benzodiazepines (BZD) are widely used in clinical practice as anxiolytics, muscle relaxants, sedatives and anticonvulsants. Electrophysiological studies have shown a specific interaction of BZD with - aminobutyric acid (GABA), an inhibitory neurotransmitter, of which they enhance the physiological effects. The discovery of saturable and stereospecific binding sites with high affinity for BZD, and their brain distribution indicates a predominantly cortical action of BZD. Furthermore, BZD receptors seem to be linked to GABA receptors--modulating their inhibitory effects--and closely connected to the chloride conductance mechanism associated to the GABA receptor. The discovery of BZD receptors suggests the existence of endogenous ligands. Inosine, hypoxanthine or nicotinamide are reported to have BZD-like activities, in spite of a relative low affinity for their binding sites. Their putative role as endogenous anxiolytics needs to be supported by behavioral studies.