The effect of in vivo ethanol consumption on cyclic AMP and δ-opioid receptors in mouse striatum

In this study the effect of in vivo ethanol consumption on cyclic AMP (cAMP) and [ d-Ala 2, d-Leu 5]enkephalin (DADLE) inhibition of forskolin-stimulated cAMP production was examined in mouse striatum. Effects of ethanol on striatal δ-opioid receptor (DOR) density and mRNA were also examined. Mice had unlimited access to 7% (v/v) ethanol alone or water for 1 or 7 days and were then sacrificed and striatum removed for analysis. There was no difference in basal cAMP formation between water and ethanol-treated mouse striatum following 7 day treatment, and a small, but statistically significant increase in basal cAMP in the ethanol group following 1 day treatment. Both 1 day and 7 day ethanol treatment did not significantly alter the percentage increase in cAMP following treatment with 10 μM forskolin. There was a significant effect of ethanol treatment on the maximum inhibitory effect of DADLE on forskolin-stimulated cAMP formation following both 1 and 7 day ethanol treatment. The DADLE IC 50 was unaffected by ethanol treatment. Saturation binding studies ([ 3H]Deltorphin II) indicated no effect of ethanol on B max or K d in striatum. Similarly, no difference between water and ethanol-treated was observed for DOR mRNA in striatum. These data indicate that ethanol consumption can alter opioid regulation of cAMP formation. However, this effect is not related to changes in any δ-opioid receptor parameters that were examined.