Benzodiazepine and beta-carboline modulation of GABA-stimulated 36Cl-influx in cultured spinal cord neurons.

GABAA agonists stimulate 36Cl-influx in spinal cord cultured neurons in a concentration-dependent manner. This effect of GABAA receptor stimulation is enhanced by benzodiazepines like clonazepam, diazepam and flurazepam and attenuated by (+)bicuculline and picrotoxinin. The beta-carbolines, methyl-6, 7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM) and propyl-beta-carboline-3-carboxylate (beta-CCPr) exhibited opposite effects, with DMCM attenuating, while beta-CCPr potentiating GABA's effect. These results are consistent with the behavioral and electrophysiological effect of benzodiazepines and beta-carbolines with GABA receptor complex.