Figure 4. Antagonist effects on SmGPR-3 activity.

(A) Yeast YEX108 auxotrophic his strain expressing SmGPR-3 was incubated with agonist (DA, 100 µM) and test antagonist or vehicle. Antagonists were tested at 100 µM except for flupenthixol, which was used at 10 µM. The data were normalized relative to the control sample that contained 100 µM DA but no antagonist. To test for drug induced toxicity, assays were repeated in the presence of 100 µM test antagonist in histidine-supplemented (his+) medium, which enables the cell to grow irrespective of receptor activation (His +ve control; see text for details). Abbreviations are as follows: SPIP, spiperone; PROP, propanolol; CLZP, clozapine; BUSP, buspirone; MINS, mianserin; CPRH, cyproheptadine; FLPX, flupenthixol; PRMZ, promethazine; HLRD, haloperidol. B–F. Dose-dependent inhibiton by haloperidol (IC₅₀ = 1.4 µM), flupenthixol (IC₅₀ = 3.9 µM), promethazine (IC₅₀ = 28.0 µM), mianserin (IC₅₀ = 45.0 µM) clozapine (IC₅₀>100 µM). The error bars are the means ± SEM for 3–4 experiments and at least 2 clones (in triplicates).