Dopamine D1 Receptor Gs-Mediated cAMP Accumulation Assay

The agonist and antagonist properties of TP-22 against the human D1 receptor were evaluated in functional assays performed at Eurofins³ using CHO cells expressing D1 and according to previously reported protocols (Zhou et al., 1990). To assess the agonist properties, TP-22 was tested using eight different concentrations in two experiments with samples in duplicate. Cellular agonist effect was calculated as % of control response to the reference agonist DA (EC₅₀ = 24 nM). To assess the antagonist properties, cells were stimulated with DA (125 nM) and the effect of TP-22 on cAMP production was assessed using eight different concentrations in two experiments with samples in duplicate. The antagonist effect was calculated as % inhibition of reference agonist response. The standard D1R antagonist SCH 23390 was tested as reference compound (IC₅₀ = 2.9 nM, K_b = 0.45 nM).