Ethanol-induced state-dependent learning is mediated by 5-hydroxytryptamine3 receptors but not byN-methyl-d-aspartate receptor complex

Involvement ofN-methyl-d-aspartate (NMDA) receptor complex and 5-hydroxytryptamine₃ (5-HT₃) receptors in state-dependent learning (SDL) induced by ethanol (EtOH) was investigated in the step-through passive avoidance task in rats. Pre-training injections of EtOH or MK-801 reduced step-through latency in the test session conducted 24 h after the training session. Pre-test as well as pre-training injections of EtOH failed to reduce the latency, while pre-training and pre-test injections of MK-801 reduced the latency. These results show that EtOH but not MK-801 produces SDL. SDL induced by EtOH was blocked by ICS205-930 injected before either the training or test session. However, ICS205-930 failed to block SDL induced by diazepam and muscimol. These results suggest that NMDA receptor complex may not be involved in SDL, and that 5-HT₃ receptors may contribute to SDL induced by EtOH but not by diazepam and muscimol.