(+)-Dihydrexidine hydrochloride is an agonist of dopamine D1 receptor(EC50 of 72± 21 nM).

D1 receptor:(EC50)72±21 nM

(+)-Dihydrexidine hydrochloride (DHX) is a high-potency, bioavailable agonist of D1 dopamine receptors. It is inactive (IC50 > 10 μM) against 40 other binding sites except D2 dopamine receptors (IC50 = 130 nM) and alpha-2 adrenoreceptors (IC50 = 230 nM). DHX competes stereoselectively and potently for D1 binding sites in rat striatal membranes labeled with [3H]SCH23390 with an IC50 of approximately 10 nM, compared to around 30 nM for the prototypical D1 agonist SKF38393.

To assess the functional status of striatal neurons in response to D1 receptor activation, AC5+/+ and AC5-/- mice were injected with the D1 agonist (+)-Dihydrexidine (30 mg/kg, i.p.). After 45 minutes, the dorsal-lateral striatum and NAc were separately collected for RT-PCR analysis. The results indicate that (+)-Dihydrexidine significantly enhances the induction of immediate early genes c-fos, egr-1, and junB in the NAc of AC5-/- mice compared to AC5+/+ mice, while the induction in the dorsal-lateral striatum is suppressed in AC5-/- mice [3].