Amisulpride is believed to work by blocking, or antagonizing, the dopamine D2 receptor, reducing its signalling. The effectiveness of amisulpride in treating dysthymia and the negative symptoms of schizophrenia is believed to stem from its blockade of the presynaptic dopamine D2 receptors. These presynaptic receptors regulate the release of dopamine into the synapse, so by blocking them amisulpride increases dopamine concentrations in the synapse. This increased dopamine concentration is theorized to act on dopamine D1 receptors to relieve depressive symptoms (in dysthymia) and the negative symptoms of schizophrenia.