Sensitization of ethanol-induced place preference as a result of up-regulation of type 1 inositol 1,4,5-trisphosphate receptors in mouse nucleus accumbens.

This study involved mice that received 4 days of ethanol (EtOH) vapor inhalation and then were assessed for type 1 inositol 1,4,5-trisphosphate receptor (IP3 Rs-1) expression and the development of EtOH-induced place preference at various time points in withdrawal. IP3 R-1 protein was found to be significantly increased in the nucleus accumbens (NAcc) of mice immediately after 4-day EtOH vapor inhalation, while it significantly reduced to the control level during the next 3 days of withdrawal from EtOH inhalation. EtOH (2 g/kg, i.p.)-induced place preference after 3 days of withdrawal from EtOH vapor inhalation increased dose dependently for 4 days, which was significantly inhibited by 2-aminophenoxyethane-borate, an antagonist for IP3 Rs. EtOH conditioning significantly increased, compared to alcohol-naïve control mice, both IP3 R-1 protein and the release of dopamine in the NAcc of mice after 3 days of withdrawal from EtOH vapor inhaled for 4 days, and this increase of IP3 R-1 protein was completely abolished by intracerebroventricular injection of FK506, an inhibitor for calcineurin. These results indicate that the sensitization of EtOH-induced place preference is due to up-regulated IP3 R-1 via calcineurin-mediated pathway after enhanced release of dopamine in the NAcc on EtOH administration during EtOH conditioning. We revealed signal transduction pathways that may promote sensitization of ethanol (EtOH)-induced place preference. EtOH facilitated the release of dopamine (DA) in the Nucleus accumbens (NAcc), enhancing calcineurin function via dopamine D1-like and D2-like receptor activation, which in turn resulted in increased NFATc4 expression. Increase in NFATc4 may further facilitate transcription factor binding to IP3 R-1 promoter domain to stimulate IP3 R-1 synthesis. Such increased IP3 R-1 elevates intracellular Ca(2+) concentration via facilitated mobilization of Ca(2+) from the intracellular Ca(2+) stores to the cytosol.