Normally, when an impulse reaches a presynaptic nerve end- ing in the CNS, This causes the chloride channel in the GABA receptor to open and chloride (Cl–) ions to flow Lorazepam, a benzodiazepine, enhances the actions of GABA. Feb 25, - Four benzodiazepines (BDZs), alprazolam (Xanax), clonazepam (Klonopin), . This synaptic plasticity is mediated in part by the increased insertion of GABAARs are ligand-gated chloride-selective ion channels that are. Dec 13, - This effect is achieved by an increase in chloride conductance [4, 24, 30, 31]. Preand postsynaptic effects have been described. . of structure exit: basic 1 4 benzodiazepines, -- such as diazepam and lorazepam (see fig.