TDHL (Tergurid) is a dopamine receptor agonist with a K_d of 0.39 nM for D2 receptor and an orally available 5-HT-2 receptor antagonist. IC50 & Target: Kd: 0.39 nM (Dopamine D2-receptor)^[2], 5-HT2^[1] In Vitro: Proliferation and migration of cultured primary human pulmonary artery smooth muscle cells (PASMC) were dose-dependently blocked by TDHL^[1].Terguride is found to bind selectively to the pituitary dopamine D2-receptors with a high affinity (K_d=0.39 nM)^[2]. In Vivo: TDHL abolished 5-HT-induced pulmonary vasoconstriction. Chronic terguride treatment prevented dose-dependently the development and progression of MCT-induced PAH in rats^[1]. In reserpinized rats, terguride at 0.03 mg/kg, p.o. significantly reduces the serum prolactin (PRL) level. In rats bearing estrogen-induced pituitary prolactinoma, chronic terguride induces shrinkage of the prolactinoma as well as reduction of the high serum PRL level. In lactating rats, terguride (1.0 mg/kg, s.c.) reduces milk production in the mammary gland^[2].