2-Aminoethyl Diphenylborinate Blocks GABAA-Receptor-Mediated Currents in Rat Medial Preoptic Neurons

The effect of 2-aminoethyl diphenylborinate (2-APB), a commonly used drug to modulate inositol-1,4,5-triphosphate (IP3) receptors and transient receptor potential (TRP) channels, on GABAA receptor-mediated currents was studied in neurons from the medial preoptic nucleus (MPN) of rat. 2-APB gradually and reversibly reduced the currents evoked by GABA but had no effect on the currents evoked by glycine. The blocking effect was not mediated by alterations in intracellular calcium concentration and showed a concentration dependence with half maximal effect at ~50 µM 2-APB, for currents evoked by 100 µM, as well as by 1.0 mM GABA, suggesting that 2-APB is not competing with GABA for its binding site at the GABAA receptor. Thus, the present study describes a novel pharmacological property of 2-APB as a non-competitive blocker of GABAA receptors and calls for caution in the interpretation of the results where 2-APB is used to affect IP3 receptors or TRP channels.