Characteristics of tetrahydroprotoberberines on dopamine D1 and D2 receptors in calf striatum
Abstract
AIM: To study the characteristics of tetrahydroprotoberberines (THPB) on dopamine
D1 and D2 receptors and elucidate their structure-activity relationship.
METHODS: Radioligand assay in vitro with a two-site model program analysis.
RESULTS: Four THPB with two hydorxyl groups on C2 and C9 or C2 and C10 exhibited
RH and RL two binding sites to D1 receptors and guanosine triphosphate regulated
the RH binding site of SPD and THPB-132A in competition assay, while eleven THPB
including nonhydroxy-THPB, monohydroxy-THPB, and THPB with two hydroxyl groups
attaching to C3 and C10 showed one binding site to D1 receptors under the same
conditions. However, the tested eleven THPB all manifested one binding site to D2
receptors in competition assay, and the 2-hydroxy-THPB had the most potent
affinity for D2 receptors.
CONCLUSION: Dihydroxy-THPB with two hydroxyl groups attaching to C2 and C9 or C2
and C10 possess the intrinsic activity of agonist to D1 receptors, while the
other THPB do not. The tested eleven THPB all are the antagonists of D2
receptors.
Keywords:
D1 and D2 receptors and elucidate their structure-activity relationship.
METHODS: Radioligand assay in vitro with a two-site model program analysis.
RESULTS: Four THPB with two hydorxyl groups on C2 and C9 or C2 and C10 exhibited
RH and RL two binding sites to D1 receptors and guanosine triphosphate regulated
the RH binding site of SPD and THPB-132A in competition assay, while eleven THPB
including nonhydroxy-THPB, monohydroxy-THPB, and THPB with two hydroxyl groups
attaching to C3 and C10 showed one binding site to D1 receptors under the same
conditions. However, the tested eleven THPB all manifested one binding site to D2
receptors in competition assay, and the 2-hydroxy-THPB had the most potent
affinity for D2 receptors.
CONCLUSION: Dihydroxy-THPB with two hydroxyl groups attaching to C2 and C9 or C2
and C10 possess the intrinsic activity of agonist to D1 receptors, while the
other THPB do not. The tested eleven THPB all are the antagonists of D2
receptors.