Biogenic amines mimic the effects of cAMP.A, Responses to 10 msec flashes recorded in photoreceptors from WT flies in the absence and presence of dopamine (DA; 10 μm) and octopamine (OA; 100 μm). B,C, Time-to-peak (B) and time-to-half-decay (C) of macroscopic light responses in WT photoreceptors under control conditions and in the presence of octopamine (OA; 100 μm;n = 16), tyramine (TA; 1 mm; n = 8), serotonin (5-HT; 1 mm; n = 9), histamine (HA; 1 mm; n = 5), dopamine (DA; n = 13), and dopamine plus butaclamol (BTL; 10 μm plus 10 μm dopamine; n = 4). *p < 0.05.