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

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