Effects of voluntary alcohol drinking on striatal density of the D2R‐D2R homoreceptor, A2AR‐D2R, and sigma1R‐ D2R heteroreceptor complexes. Rats were exposed to intermittent access to 20% ethanol (alcohol, 4.7 ± 0.4 g/kg/24 h) or 2 bottles of water (age‐matched alcohol‐naïve control), respectively, for at least 12 weeks. Effects of alcohol drinking on the density of D2R complexes in the nucleus accumbens (NAc) core and shell and the dorsal striatum (STR) were quantified using in situ proximity ligation assay (PLA). Data were analyzed using 2‐way ANOVA followed by Bonferroni post hoc with brain region and drinking condition as factors (n = 3 to 4, per group). There was a significant effect of alcohol drinking on D2R‐D2R homoreceptor complexes, but no drinking condition*brain region interaction (A). Alcohol drinking significantly increased the density of A2AR‐D2R heteroreceptor complexes in the NAc shell and the dorsal striatum, but not in the NAc core (B). Alcohol drinking significantly decreased the density of sigma1R‐D2R heteroreceptor complexes in the dorsal STR, but not in the NAc core or shell (C). Values represent group mean±SEM number of positive PLA dots per nuclei/sample field, for each rat given as mean values of 3 pictures (40 × 40 μm). **p < 0.01 compared to corresponding alcohol‐naïve controls.