Specific binding of [3H]citalopram to SERT in dorsal and median raphe nuclei as a function of age and SERT genotype. Brain sections from P21, P28, and P90 mice were incubated with increasing concentrations of [3H]citalopram. Nonspecific binding was defined by sertraline (20µM). (A) Representative coronal sections showing [3H]citalopram binding at the level of plate 64 (Paxinos and Franklin, 1997) in P21, P28, and P90, SERT+/+, SERT+/−, and SERT−/− mice. Saturation binding isotherms in dorsal raphe (B) and median raphe (C) of P21, P28, and P90, SERT+/+, SERT+/−, and SERT−/− mice. The Bmax values for each curve are summarized in Fig. 4. There were no significant differences in Kd values among ages or between SERT+/+ and SERT+/− mice. There was no significant difference between males and females for any age or SERT genotype; therefore, data for both genders were pooled. SERT+/+, n = 8–11 (males n = 5 and females n = 3–6 pooled); SERT+/−, n = 5–10 (males n = 3–5 and females 2–5 pooled); and SERT−/−, n = 2–4 (males n = 1 to 2 and females n = 1 to 2 pooled) mice per group. Note that because binding in SERT−/− mice was not different from background the sample size was not further increased.