Figure 1.

(a, b) In vitro pharmacology of FPT at human 5-HT1A, 5-HT1B, 5-HT1D, and 5-HT1FRs. Note that FPT was a full agonist at 5-HT1B and 5-HT1DRs and a high-efficacy, partial agonist at 5-HT1ARs, as determined by efficacies to decrease cAMP levels relative to 5-CT. FPT’s rank order of potency, including its binding affinities as determined in competition binding assays with [3H]5-CT and its EC50 values in cAMP assays, was 5-HT1D > 5-HT1B > 5-HT1A. FPT showed nil affinity at 5-HT1FRs, so we did not test its functional activity at them. The table at the bottom of the figure summarizes the pharmacological observations. TSP, total specific binding/no compound present.