Interactions between amino acid neurotransmitters and flurazepam in the neocortex of unanesthetized rats.

The effects induced by the benzodiazepine flurazepam (FLU) upon neuronal responses to glutamic acid (GLUT), gamma-aminobutyric acid (GABA), and glycine (GLY) were studied in the cortex of unanesthetized rats using single-unit extracellular recordings in conjunction with iontophoretic techniques. The application of FLU (5-20 nA) did not affect excitatory responses to GLUT, but the spontaneous firing rate was depressed by equivalent doses of this benzodiazepine. A selective increase of GABA, but not of GLY-induced responses was seen when either low currents (5-10 nA) of FLU or GLUT driving currents were used to study the neuronal responses of the inhibitory amino acids upon steady neuronal firing. Our data demonstrate that in unanesthetized animals FLU does not affect GLUT-induced effects while it selectively increases GABA-mediated inhibition.