Summary of responses to active compounds by DCAR-1-expressing oocytes. 3,4-Dihydroxybenzaldehyde (DHB; 10 μm, n = 9; 30 μm, n = 7; 100 μm, n = 9; 300 μm, n = 7), 3,4-dihydroxybenzoic acid (DHBA; 10 μm, n = 6; 30 μm, n = 10; 100 μm, n = 9; 300 μm, n = 11), 3,4-dihydroxyphenylacetic acid (DOPAC; 10 μm, n = 7; 30 μm, n = 10; 100 μm, n = 11; 300 μm, n = 9), 3,4-dihydroxymandelic acid (DHMA; 10 μm, n = 6; 30 μm, n = 5; 100 μm, n = 7; 300 μm, n = 9), and dihydrocaffeic acid (DHCA; 10 μm, n = 5; 30 μm, n = 12; 100 μm, n = 7; 300 μm, n = 10) were all able to induce current responses in DCAR-1-expressing oocytes. DHB was identified as a candidate active substance in the solution of DOPS that induced a current response in oocytes injected with dcar-1 cRNA (data not shown).