RU-27251, also known as 3,5-secoergoline or as 4-piperidin-3-yl-1H-indole, is a serotonin receptor modulator and dopamine receptor agonist of the partial ergoline family. Its affinity (K<sub>D</sub>) for the dopamine D<sub>2</sub><sup>high</sup> receptor was 72nM and for the dopamine D<sub>2</sub><sup>low</sup> receptor was 11,600nM. RU-27251 was first described in the scientific literature by 1983.