Reserpinization severs the cooperative but not the oppositional interaction between D1 and D2 receptors

Dopamine D1 and D2 receptors in rat brain interact synergistically to produce stereotypy and antagonistically to induce atypical jerking. This study showed that repeated reserpine treatment (5 daily injections of 1 mg/kg, s.c.), which depleted dopamine stores by 98%, rendered D1 and D2 receptors independent with respect to the production of stereotypy, i.e. either D1- or D2-selective agonists given alone induced stereotypy. In contrast, the atypical jerking induced by the D2 agonist, quinpirole, was still inhibited by the D1 agonist, SKF 82958, indicating that reserpine treatment did not render these two receptors independent with respect to initiation of this behavior.