NR2B subunit selective NMDA antagonists inhibit neurotoxic effect of alcohol-withdrawal in primary cultures of rat cortical neurones

Abstract

N-Methyl- d-aspartate (NMDA) receptor-mediated glutamatergic neurotransmission is thought to play a central role in the development of alcohol dependence and this alteration is supposed to be due to a differential up-regulation of the NR2B type of subunits. In this work, we examined the effect of some known (CP-101,606; CI-1041 and Co-101,244) and novel indole-2-carboxamide derivative NR2B subunit selective NMDA receptor antagonists (SSNAs) (RG-13579 and RG-1103) on the neurotoxic effect of withdrawal in ethanol pre-treated cultures of rat cortical neurones. The extent of neurotoxicity was estimated by measuring the activity of lactate dehydrogenase (LDH) that was released into the culture medium during the 24 h withdrawal period. Here, we demonstrate that NR2B SSNAs given in the course of the withdrawal potently reduced the LDH release in ethanol pre-treated cultures. One of our novel compound, RG-1103, proved to be more potent than the reference NR2B SSNAs tested in this work having similar potency as the most potent but non-subunit selective NMDA receptor antagonist dizocilpine (MK-801). Acamprosate, a currently used therapeutic drug for the treatment of alcoholism was also effective although only in high micromolar concentrations. According to these observations, NR2B SSNAs are potent inhibitors of ethanol-withdrawal-induced neurotoxicity and considering that these agents have acceptable side effect profiles, they could be promising therapeutic candidates in the pharmacotherapy for physical signs of acute alcohol-withdrawal and associated neuronal damage.