Antidepressants promote formation of heterocomplexes of dopamine D2 and somatostatin subtype 5 receptors in the mouse striatum.

The interaction between the dopaminergic and somatostatinergic systems is considered to play a potential role in mood regulation. Chronic administration of antidepressants influences release of both neurotransmitters. The molecular basis of the functional cooperation may stem from the physical interaction of somatostatin receptor subtypes and dopamine D2 receptors since they colocalize in striatal interneurons and were shown to undergo ligand-dependent heterodimerization in heterologous expression systems. In present study we adapted in situ proximity ligation assay to investigate the occurrence of D2-Sst5 receptor heterocomplexes, and their possible alterations in the striatum of mice treated acutely and repeatedly (21days) with antidepressant drugs of different pharmacological profiles (escitalopram and desipramine). Additionally we analysed number of heterocomplexes in primary striatal neuronal cultures incubated with both antidepressant drugs for 1h and 6days. The studies revealed that antidepressants increase formation of D2-Sst5 receptors heterodimers. These findings provide interesting evidence that dopamine D2 and somatostatin Sst5 heterodimers may be considered as potential mediators of antidepressant effects, since the heterodimerization of these receptors occurs in native brain tissue as well as in primary striatal neuronal cultures where receptors are expressed at physiological levels.