Figure 1.

Examples of graphical analysis applied to PET occupancy studies. Data in (A) and (B) are taken from a [¹¹C]WAY100635 study in the baboon brain at baseline and after i.v. administration of a 5HT_1A antagonist at doses of 1.5, 10, and 150 μg/kg. In both graphs, the cerebellum (dark symbols) is omitted from the regression analysis. (A) Baseline data are used along with the occupancy plot defined in Equation (2) to derive occupancy estimates for 1.5, 10, and 150 μg/kg, whereas in (B) the baseline data are omitted and Equation (6) is used to derive occupancy estimates for the 10 and 150 μg/kg doses. (C) Data are taken from a [¹¹C]WAY100635 study in the human brain at baseline and after p.o. administration of 30 mg of the 5HT_1A partial-agonist pindolol (Martinez et al, 2001). The plot illustrates that differential occupancy is achieved at the somatodendritic (dorsal raphe nuclei) and postsynaptic (other regions) 5HT_1A receptors after the administration of this partial agonist. All embedded equations express occupancy as a fraction of unity.