Benzodiazepines are synergic with 1-aminohutyric acid. Microiontophoretic evidence

Numerous literature data indicates that benzodiazepines inHuence neuronal activity in various sections of centrai nervous system, from spinal cord to the brain stem up to neocortex. I t was shown t ha t benzodiazepines increase t be presynaptic inhihition in the spinal cord [1-3] and various types of postsynaptic inhibition in the cerebellum [4] and nigrostriatal system [5]. Since these types of inhihition seem to be mediated by y-aminobutyric acid (GABA) [6], an assumption was made as to the inftuence of benzodiazepines on GABA-ergic synaptic transmission [5, ì]. However, from the works by Steiner and Felix [8] and Gihwiler [9] carried out on cerebellum and Deiters nucleus neurons, it seems that benzo~ diazepines not only fail to potentiate centrai inhibitory processes but even hamper them, being themselves GABA antagonista. In spite of recent polemics [10], so far the above mentioned contradiction has not been :;ettled [11]. We studied the interaction of chlordiazepoxide (CDP) with GABA during simultaneous microintophoretic application of both agents to the neurons of rabbit sensorimotor cortex. GABA seems one of the most likely inhihitor transmitters in the neocortex [6]. The influence of the systemically administered diazepam on GABA-ergic inhihitory processes in the cerehral cortex "\tas ~tudied in previous investigations [12, 13].